atrac3plus: Convert to the new bitstream reader

Signed-off-by: Anton Khirnov <anton@khirnov.net>

3 files changed, 275 insertions, 272 deletions

diff --git a/libavcodec/atrac3plus.c b/libavcodec/atrac3plus.c
index 076fb844a7..2731a80725 100644
--- a/libavcodec/atrac3plus.c
+++ b/libavcodec/atrac3plus.c
@@ -26,8 +26,9 @@
  */
 
 #include "libavutil/avassert.h"
+
 #include "avcodec.h"
-#include "get_bits.h"
+#include "bitstream.h"
 #include "atrac3plus.h"
 #include "atrac3plus_data.h"
 
@@ -212,20 +213,20 @@ av_cold void ff_atrac3p_init_vlcs(AVCodec *codec)
 /**
  * Decode number of coded quantization units.
  *
- * @param[in]     gb            the GetBit context
+ * @param[in]     bc            the Bitstream context
  * @param[in,out] chan          ptr to the channel parameters
  * @param[in,out] ctx           ptr to the channel unit context
  * @param[in]     avctx         ptr to the AVCodecContext
  * @return result code: 0 = OK, otherwise - error code
  */
-static int num_coded_units(GetBitContext *gb, Atrac3pChanParams *chan,
+static int num_coded_units(BitstreamContext *bc, Atrac3pChanParams *chan,
                            Atrac3pChanUnitCtx *ctx, AVCodecContext *avctx)
 {
-    chan->fill_mode = get_bits(gb, 2);
+    chan->fill_mode = bitstream_read(bc, 2);
     if (!chan->fill_mode) {
         chan->num_coded_vals = ctx->num_quant_units;
     } else {
-        chan->num_coded_vals = get_bits(gb, 5);
+        chan->num_coded_vals = bitstream_read(bc, 5);
         if (chan->num_coded_vals > ctx->num_quant_units) {
             av_log(avctx, AV_LOG_ERROR,
                    "Invalid number of transmitted units!\n");
@@ -233,7 +234,7 @@ static int num_coded_units(GetBitContext *gb, Atrac3pChanParams *chan,
         }
 
         if (chan->fill_mode == 3)
-            chan->split_point = get_bits(gb, 2) + (chan->ch_num << 1) + 1;
+            chan->split_point = bitstream_read(bc, 2) + (chan->ch_num << 1) + 1;
     }
 
     return 0;
@@ -318,21 +319,21 @@ static inline void unpack_vq_shape(int start_val, const int8_t *shape_vec,
     }
 }
 
-#define UNPACK_SF_VQ_SHAPE(gb, dst, num_vals)                            \
-    start_val = get_bits((gb), 6);                                       \
-    unpack_vq_shape(start_val, &atrac3p_sf_shapes[get_bits((gb), 6)][0], \
+#define UNPACK_SF_VQ_SHAPE(bc, dst, num_vals)                                  \
+    start_val = bitstream_read((bc), 6);                                       \
+    unpack_vq_shape(start_val, &atrac3p_sf_shapes[bitstream_read((bc), 6)][0], \
                     (dst), (num_vals))
 
 /**
  * Decode word length for each quantization unit of a channel.
  *
- * @param[in]     gb            the GetBit context
+ * @param[in]     bc            the Bitstream context
  * @param[in,out] ctx           ptr to the channel unit context
  * @param[in]     ch_num        channel to process
  * @param[in]     avctx         ptr to the AVCodecContext
  * @return result code: 0 = OK, otherwise - error code
  */
-static int decode_channel_wordlen(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
+static int decode_channel_wordlen(BitstreamContext *bc, Atrac3pChanUnitCtx *ctx,
                                   int ch_num, AVCodecContext *avctx)
 {
     int i, weight_idx = 0, delta, diff, pos, delta_bits, min_val, flag,
@@ -343,107 +344,107 @@ static int decode_channel_wordlen(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
 
     chan->fill_mode = 0;
 
-    switch (get_bits(gb, 2)) { /* switch according to coding mode */
+    switch (bitstream_read(bc, 2)) { /* switch according to coding mode */
     case 0: /* coded using constant number of bits */
         for (i = 0; i < ctx->num_quant_units; i++)
-            chan->qu_wordlen[i] = get_bits(gb, 3);
+            chan->qu_wordlen[i] = bitstream_read(bc, 3);
         break;
     case 1:
         if (ch_num) {
-            if ((ret = num_coded_units(gb, chan, ctx, avctx)) < 0)
+            if ((ret = num_coded_units(bc, chan, ctx, avctx)) < 0)
                 return ret;
 
             if (chan->num_coded_vals) {
-                vlc_tab = &wl_vlc_tabs[get_bits(gb, 2)];
+                vlc_tab = &wl_vlc_tabs[bitstream_read(bc, 2)];
 
                 for (i = 0; i < chan->num_coded_vals; i++) {
-                    delta = get_vlc2(gb, vlc_tab->table, vlc_tab->bits, 1);
+                    delta = bitstream_read_vlc(bc, vlc_tab->table, vlc_tab->bits, 1);
                     chan->qu_wordlen[i] = (ref_chan->qu_wordlen[i] + delta) & 7;
                 }
             }
         } else {
-            weight_idx = get_bits(gb, 2);
-            if ((ret = num_coded_units(gb, chan, ctx, avctx)) < 0)
+            weight_idx = bitstream_read(bc, 2);
+            if ((ret = num_coded_units(bc, chan, ctx, avctx)) < 0)
                 return ret;
 
             if (chan->num_coded_vals) {
-                pos = get_bits(gb, 5);
+                pos = bitstream_read(bc, 5);
                 if (pos > chan->num_coded_vals) {
                     av_log(avctx, AV_LOG_ERROR,
                            "WL mode 1: invalid position!\n");
                     return AVERROR_INVALIDDATA;
                 }
 
-                delta_bits = get_bits(gb, 2);
-                min_val    = get_bits(gb, 3);
+                delta_bits = bitstream_read(bc, 2);
+                min_val    = bitstream_read(bc, 3);
 
                 for (i = 0; i < pos; i++)
-                    chan->qu_wordlen[i] = get_bits(gb, 3);
+                    chan->qu_wordlen[i] = bitstream_read(bc, 3);
 
                 for (i = pos; i < chan->num_coded_vals; i++)
-                    chan->qu_wordlen[i] = (min_val + get_bitsz(gb, delta_bits)) & 7;
+                    chan->qu_wordlen[i] = (min_val + bitstream_read(bc, delta_bits)) & 7;
             }
         }
         break;
     case 2:
-        if ((ret = num_coded_units(gb, chan, ctx, avctx)) < 0)
+        if ((ret = num_coded_units(bc, chan, ctx, avctx)) < 0)
             return ret;
 
         if (ch_num && chan->num_coded_vals) {
-            vlc_tab = &wl_vlc_tabs[get_bits(gb, 2)];
-            delta = get_vlc2(gb, vlc_tab->table, vlc_tab->bits, 1);
+            vlc_tab = &wl_vlc_tabs[bitstream_read(bc, 2)];
+            delta = bitstream_read_vlc(bc, vlc_tab->table, vlc_tab->bits, 1);
             chan->qu_wordlen[0] = (ref_chan->qu_wordlen[0] + delta) & 7;
 
             for (i = 1; i < chan->num_coded_vals; i++) {
                 diff = ref_chan->qu_wordlen[i] - ref_chan->qu_wordlen[i - 1];
-                delta = get_vlc2(gb, vlc_tab->table, vlc_tab->bits, 1);
+                delta = bitstream_read_vlc(bc, vlc_tab->table, vlc_tab->bits, 1);
                 chan->qu_wordlen[i] = (chan->qu_wordlen[i - 1] + diff + delta) & 7;
             }
         } else if (chan->num_coded_vals) {
-            flag    = get_bits(gb, 1);
-            vlc_tab = &wl_vlc_tabs[get_bits(gb, 1)];
+            flag    = bitstream_read(bc, 1);
+            vlc_tab = &wl_vlc_tabs[bitstream_read(bc, 1)];
 
-            start_val = get_bits(gb, 3);
+            start_val = bitstream_read(bc, 3);
             unpack_vq_shape(start_val,
-                            &atrac3p_wl_shapes[start_val][get_bits(gb, 4)][0],
+                            &atrac3p_wl_shapes[start_val][bitstream_read(bc, 4)][0],
                             chan->qu_wordlen, chan->num_coded_vals);
 
             if (!flag) {
                 for (i = 0; i < chan->num_coded_vals; i++) {
-                    delta = get_vlc2(gb, vlc_tab->table, vlc_tab->bits, 1);
+                    delta = bitstream_read_vlc(bc, vlc_tab->table, vlc_tab->bits, 1);
                     chan->qu_wordlen[i] = (chan->qu_wordlen[i] + delta) & 7;
                 }
             } else {
                 for (i = 0; i < (chan->num_coded_vals & - 2); i += 2)
-                    if (!get_bits1(gb)) {
+                    if (!bitstream_read_bit(bc)) {
                         chan->qu_wordlen[i]     = (chan->qu_wordlen[i] +
-                                                   get_vlc2(gb, vlc_tab->table,
-                                                            vlc_tab->bits, 1)) & 7;
+                                                   bitstream_read_vlc(bc, vlc_tab->table,
+                                                                      vlc_tab->bits, 1)) & 7;
                         chan->qu_wordlen[i + 1] = (chan->qu_wordlen[i + 1] +
-                                                   get_vlc2(gb, vlc_tab->table,
-                                                            vlc_tab->bits, 1)) & 7;
+                                                   bitstream_read_vlc(bc, vlc_tab->table,
+                                                                      vlc_tab->bits, 1)) & 7;
                     }
 
                 if (chan->num_coded_vals & 1)
                     chan->qu_wordlen[i] = (chan->qu_wordlen[i] +
-                                           get_vlc2(gb, vlc_tab->table,
-                                                    vlc_tab->bits, 1)) & 7;
+                                           bitstream_read_vlc(bc, vlc_tab->table,
+                                                              vlc_tab->bits, 1)) & 7;
             }
         }
         break;
     case 3:
-        weight_idx = get_bits(gb, 2);
-        if ((ret = num_coded_units(gb, chan, ctx, avctx)) < 0)
+        weight_idx = bitstream_read(bc, 2);
+        if ((ret = num_coded_units(bc, chan, ctx, avctx)) < 0)
             return ret;
 
         if (chan->num_coded_vals) {
-            vlc_tab = &wl_vlc_tabs[get_bits(gb, 2)];
+            vlc_tab = &wl_vlc_tabs[bitstream_read(bc, 2)];
 
             /* first coefficient is coded directly */
-            chan->qu_wordlen[0] = get_bits(gb, 3);
+            chan->qu_wordlen[0] = bitstream_read(bc, 3);
 
             for (i = 1; i < chan->num_coded_vals; i++) {
-                delta = get_vlc2(gb, vlc_tab->table, vlc_tab->bits, 1);
+                delta = bitstream_read_vlc(bc, vlc_tab->table, vlc_tab->bits, 1);
                 chan->qu_wordlen[i] = (chan->qu_wordlen[i - 1] + delta) & 7;
             }
         }
@@ -452,7 +453,7 @@ static int decode_channel_wordlen(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
 
     if (chan->fill_mode == 2) {
         for (i = chan->num_coded_vals; i < ctx->num_quant_units; i++)
-            chan->qu_wordlen[i] = ch_num ? get_bits1(gb) : 1;
+            chan->qu_wordlen[i] = ch_num ? bitstream_read_bit(bc) : 1;
     } else if (chan->fill_mode == 3) {
         pos = ch_num ? chan->num_coded_vals + chan->split_point
                      : ctx->num_quant_units - chan->split_point;
@@ -469,13 +470,13 @@ static int decode_channel_wordlen(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
 /**
  * Decode scale factor indexes for each quant unit of a channel.
  *
- * @param[in]     gb            the GetBit context
+ * @param[in]     bc            the Bitstream context
  * @param[in,out] ctx           ptr to the channel unit context
  * @param[in]     ch_num        channel to process
  * @param[in]     avctx         ptr to the AVCodecContext
  * @return result code: 0 = OK, otherwise - error code
  */
-static int decode_channel_sf_idx(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
+static int decode_channel_sf_idx(BitstreamContext *bc, Atrac3pChanUnitCtx *ctx,
                                  int ch_num, AVCodecContext *avctx)
 {
     int i, weight_idx = 0, delta, diff, num_long_vals,
@@ -484,40 +485,40 @@ static int decode_channel_sf_idx(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
     Atrac3pChanParams *chan     = &ctx->channels[ch_num];
     Atrac3pChanParams *ref_chan = &ctx->channels[0];
 
-    switch (get_bits(gb, 2)) { /* switch according to coding mode */
+    switch (bitstream_read(bc, 2)) { /* switch according to coding mode */
     case 0: /* coded using constant number of bits */
         for (i = 0; i < ctx->used_quant_units; i++)
-            chan->qu_sf_idx[i] = get_bits(gb, 6);
+            chan->qu_sf_idx[i] = bitstream_read(bc, 6);
         break;
     case 1:
         if (ch_num) {
-            vlc_tab = &sf_vlc_tabs[get_bits(gb, 2)];
+            vlc_tab = &sf_vlc_tabs[bitstream_read(bc, 2)];
 
             for (i = 0; i < ctx->used_quant_units; i++) {
-                delta = get_vlc2(gb, vlc_tab->table, vlc_tab->bits, 1);
+                delta = bitstream_read_vlc(bc, vlc_tab->table, vlc_tab->bits, 1);
                 chan->qu_sf_idx[i] = (ref_chan->qu_sf_idx[i] + delta) & 0x3F;
             }
         } else {
-            weight_idx = get_bits(gb, 2);
+            weight_idx = bitstream_read(bc, 2);
             if (weight_idx == 3) {
-                UNPACK_SF_VQ_SHAPE(gb, chan->qu_sf_idx, ctx->used_quant_units);
+                UNPACK_SF_VQ_SHAPE(bc, chan->qu_sf_idx, ctx->used_quant_units);
 
-                num_long_vals = get_bits(gb, 5);
-                delta_bits    = get_bits(gb, 2);
-                min_val       = get_bits(gb, 4) - 7;
+                num_long_vals = bitstream_read(bc, 5);
+                delta_bits    = bitstream_read(bc, 2);
+                min_val       = bitstream_read(bc, 4) - 7;
 
                 for (i = 0; i < num_long_vals; i++)
                     chan->qu_sf_idx[i] = (chan->qu_sf_idx[i] +
-                                          get_bits(gb, 4) - 7) & 0x3F;
+                                          bitstream_read(bc, 4) - 7) & 0x3F;
 
                 /* all others are: min_val + delta */
                 for (i = num_long_vals; i < ctx->used_quant_units; i++)
                     chan->qu_sf_idx[i] = (chan->qu_sf_idx[i] + min_val +
-                                          get_bitsz(gb, delta_bits)) & 0x3F;
+                                          bitstream_read(bc, delta_bits)) & 0x3F;
             } else {
-                num_long_vals = get_bits(gb, 5);
-                delta_bits    = get_bits(gb, 3);
-                min_val       = get_bits(gb, 6);
+                num_long_vals = bitstream_read(bc, 5);
+                delta_bits    = bitstream_read(bc, 3);
+                min_val       = bitstream_read(bc, 6);
                 if (num_long_vals > ctx->used_quant_units || delta_bits == 7) {
                     av_log(avctx, AV_LOG_ERROR,
                            "SF mode 1: invalid parameters!\n");
@@ -526,34 +527,34 @@ static int decode_channel_sf_idx(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
 
                 /* read full-precision SF indexes */
                 for (i = 0; i < num_long_vals; i++)
-                    chan->qu_sf_idx[i] = get_bits(gb, 6);
+                    chan->qu_sf_idx[i] = bitstream_read(bc, 6);
 
                 /* all others are: min_val + delta */
                 for (i = num_long_vals; i < ctx->used_quant_units; i++)
                     chan->qu_sf_idx[i] = (min_val +
-                                          get_bitsz(gb, delta_bits)) & 0x3F;
+                                          bitstream_read(bc, delta_bits)) & 0x3F;
             }
         }
         break;
     case 2:
         if (ch_num) {
-            vlc_tab = &sf_vlc_tabs[get_bits(gb, 2)];
+            vlc_tab = &sf_vlc_tabs[bitstream_read(bc, 2)];
 
-            delta = get_vlc2(gb, vlc_tab->table, vlc_tab->bits, 1);
+            delta = bitstream_read_vlc(bc, vlc_tab->table, vlc_tab->bits, 1);
             chan->qu_sf_idx[0] = (ref_chan->qu_sf_idx[0] + delta) & 0x3F;
 
             for (i = 1; i < ctx->used_quant_units; i++) {
                 diff  = ref_chan->qu_sf_idx[i] - ref_chan->qu_sf_idx[i - 1];
-                delta = get_vlc2(gb, vlc_tab->table, vlc_tab->bits, 1);
+                delta = bitstream_read_vlc(bc, vlc_tab->table, vlc_tab->bits, 1);
                 chan->qu_sf_idx[i] = (chan->qu_sf_idx[i - 1] + diff + delta) & 0x3F;
             }
         } else {
-            vlc_tab = &sf_vlc_tabs[get_bits(gb, 2) + 4];
+            vlc_tab = &sf_vlc_tabs[bitstream_read(bc, 2) + 4];
 
-            UNPACK_SF_VQ_SHAPE(gb, chan->qu_sf_idx, ctx->used_quant_units);
+            UNPACK_SF_VQ_SHAPE(bc, chan->qu_sf_idx, ctx->used_quant_units);
 
             for (i = 0; i < ctx->used_quant_units; i++) {
-                delta = get_vlc2(gb, vlc_tab->table, vlc_tab->bits, 1);
+                delta = bitstream_read_vlc(bc, vlc_tab->table, vlc_tab->bits, 1);
                 chan->qu_sf_idx[i] = (chan->qu_sf_idx[i] +
                                       sign_extend(delta, 4)) & 0x3F;
             }
@@ -565,29 +566,29 @@ static int decode_channel_sf_idx(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
             for (i = 0; i < ctx->used_quant_units; i++)
                 chan->qu_sf_idx[i] = ref_chan->qu_sf_idx[i];
         } else {
-            weight_idx = get_bits(gb, 2);
-            vlc_sel    = get_bits(gb, 2);
+            weight_idx = bitstream_read(bc, 2);
+            vlc_sel    = bitstream_read(bc, 2);
             vlc_tab    = &sf_vlc_tabs[vlc_sel];
 
             if (weight_idx == 3) {
                 vlc_tab = &sf_vlc_tabs[vlc_sel + 4];
 
-                UNPACK_SF_VQ_SHAPE(gb, chan->qu_sf_idx, ctx->used_quant_units);
+                UNPACK_SF_VQ_SHAPE(bc, chan->qu_sf_idx, ctx->used_quant_units);
 
-                diff               = (get_bits(gb, 4)    + 56)   & 0x3F;
-                chan->qu_sf_idx[0] = (chan->qu_sf_idx[0] + diff) & 0x3F;
+                diff               = (bitstream_read(bc, 4) + 56)   & 0x3F;
+                chan->qu_sf_idx[0] = (chan->qu_sf_idx[0]    + diff) & 0x3F;
 
                 for (i = 1; i < ctx->used_quant_units; i++) {
-                    delta = get_vlc2(gb, vlc_tab->table, vlc_tab->bits, 1);
+                    delta = bitstream_read_vlc(bc, vlc_tab->table, vlc_tab->bits, 1);
                     diff               = (diff + sign_extend(delta, 4)) & 0x3F;
                     chan->qu_sf_idx[i] = (diff + chan->qu_sf_idx[i])    & 0x3F;
                 }
             } else {
                 /* 1st coefficient is coded directly */
-                chan->qu_sf_idx[0] = get_bits(gb, 6);
+                chan->qu_sf_idx[0] = bitstream_read(bc, 6);
 
                 for (i = 1; i < ctx->used_quant_units; i++) {
-                    delta = get_vlc2(gb, vlc_tab->table, vlc_tab->bits, 1);
+                    delta = bitstream_read_vlc(bc, vlc_tab->table, vlc_tab->bits, 1);
                     chan->qu_sf_idx[i] = (chan->qu_sf_idx[i - 1] + delta) & 0x3F;
                 }
             }
@@ -604,13 +605,13 @@ static int decode_channel_sf_idx(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
 /**
  * Decode word length information for each channel.
  *
- * @param[in]     gb            the GetBit context
+ * @param[in]     bc            the Bitstream context
  * @param[in,out] ctx           ptr to the channel unit context
  * @param[in]     num_channels  number of channels to process
  * @param[in]     avctx         ptr to the AVCodecContext
  * @return result code: 0 = OK, otherwise - error code
  */
-static int decode_quant_wordlen(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
+static int decode_quant_wordlen(BitstreamContext *bc, Atrac3pChanUnitCtx *ctx,
                                 int num_channels, AVCodecContext *avctx)
 {
     int ch_num, i, ret;
@@ -619,7 +620,7 @@ static int decode_quant_wordlen(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
         memset(ctx->channels[ch_num].qu_wordlen, 0,
                sizeof(ctx->channels[ch_num].qu_wordlen));
 
-        if ((ret = decode_channel_wordlen(gb, ctx, ch_num, avctx)) < 0)
+        if ((ret = decode_channel_wordlen(bc, ctx, ch_num, avctx)) < 0)
             return ret;
     }
 
@@ -637,13 +638,13 @@ static int decode_quant_wordlen(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
 /**
  * Decode scale factor indexes for each channel.
  *
- * @param[in]     gb            the GetBit context
+ * @param[in]     bc            the Bitstream context
  * @param[in,out] ctx           ptr to the channel unit context
  * @param[in]     num_channels  number of channels to process
  * @param[in]     avctx         ptr to the AVCodecContext
  * @return result code: 0 = OK, otherwise - error code
  */
-static int decode_scale_factors(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
+static int decode_scale_factors(BitstreamContext *bc, Atrac3pChanUnitCtx *ctx,
                                 int num_channels, AVCodecContext *avctx)
 {
     int ch_num, ret;
@@ -655,7 +656,7 @@ static int decode_scale_factors(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
         memset(ctx->channels[ch_num].qu_sf_idx, 0,
                sizeof(ctx->channels[ch_num].qu_sf_idx));
 
-        if ((ret = decode_channel_sf_idx(gb, ctx, ch_num, avctx)) < 0)
+        if ((ret = decode_channel_sf_idx(bc, ctx, ch_num, avctx)) < 0)
             return ret;
     }
 
@@ -665,18 +666,18 @@ static int decode_scale_factors(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
 /**
  * Decode number of code table values.
  *
- * @param[in]     gb            the GetBit context
+ * @param[in]     bc            the Bitstream context
  * @param[in,out] ctx           ptr to the channel unit context
  * @param[in]     avctx         ptr to the AVCodecContext
  * @return result code: 0 = OK, otherwise - error code
  */
-static int get_num_ct_values(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
+static int get_num_ct_values(BitstreamContext *bc, Atrac3pChanUnitCtx *ctx,
                              AVCodecContext *avctx)
 {
     int num_coded_vals;
 
-    if (get_bits1(gb)) {
-        num_coded_vals = get_bits(gb, 5);
+    if (bitstream_read_bit(bc)) {
+        num_coded_vals = bitstream_read(bc, 5);
         if (num_coded_vals > ctx->used_quant_units) {
             av_log(avctx, AV_LOG_ERROR,
                    "Invalid number of code table indexes: %d!\n", num_coded_vals);
@@ -688,7 +689,7 @@ static int get_num_ct_values(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
 }
 
 #define DEC_CT_IDX_COMMON(OP)                                           \
-    num_vals = get_num_ct_values(gb, ctx, avctx);                       \
+    num_vals = get_num_ct_values(bc, ctx, avctx);                       \
     if (num_vals < 0)                                                   \
         return num_vals;                                                \
                                                                         \
@@ -697,33 +698,33 @@ static int get_num_ct_values(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
             chan->qu_tab_idx[i] = OP;                                   \
         } else if (ch_num && ref_chan->qu_wordlen[i])                   \
             /* get clone master flag */                                 \
-            chan->qu_tab_idx[i] = get_bits1(gb);                        \
+            chan->qu_tab_idx[i] = bitstream_read_bit(bc);               \
     }
 
-#define CODING_DIRECT get_bits(gb, num_bits)
+#define CODING_DIRECT bitstream_read(bc, num_bits)
 
-#define CODING_VLC get_vlc2(gb, vlc_tab->table, vlc_tab->bits, 1)
+#define CODING_VLC bitstream_read_vlc(bc, vlc_tab->table, vlc_tab->bits, 1)
 
 #define CODING_VLC_DELTA                                                \
     (!i) ? CODING_VLC                                                   \
-         : (pred + get_vlc2(gb, delta_vlc->table,                       \
-                            delta_vlc->bits, 1)) & mask;                \
+         : (pred + bitstream_read_vlc(bc, delta_vlc->table,             \
+                                      delta_vlc->bits, 1)) & mask;      \
     pred = chan->qu_tab_idx[i]
 
 #define CODING_VLC_DIFF                                                 \
     (ref_chan->qu_tab_idx[i] +                                          \
-     get_vlc2(gb, vlc_tab->table, vlc_tab->bits, 1)) & mask
+     bitstream_read_vlc(bc, vlc_tab->table, vlc_tab->bits, 1)) & mask
 
 /**
  * Decode code table indexes for each quant unit of a channel.
  *
- * @param[in]     gb            the GetBit context
+ * @param[in]     bc            the Bitstream context
  * @param[in,out] ctx           ptr to the channel unit context
  * @param[in]     ch_num        channel to process
  * @param[in]     avctx         ptr to the AVCodecContext
  * @return result code: 0 = OK, otherwise - error code
  */
-static int decode_channel_code_tab(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
+static int decode_channel_code_tab(BitstreamContext *bc, Atrac3pChanUnitCtx *ctx,
                                    int ch_num, AVCodecContext *avctx)
 {
     int i, num_vals, num_bits, pred;
@@ -732,9 +733,9 @@ static int decode_channel_code_tab(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
     Atrac3pChanParams *chan     = &ctx->channels[ch_num];
     Atrac3pChanParams *ref_chan = &ctx->channels[0];
 
-    chan->table_type = get_bits1(gb);
+    chan->table_type = bitstream_read_bit(bc);
 
-    switch (get_bits(gb, 2)) { /* switch according to coding mode */
+    switch (bitstream_read(bc, 2)) { /* switch according to coding mode */
     case 0: /* directly coded */
         num_bits = ctx->use_full_table + 2;
         DEC_CT_IDX_COMMON(CODING_DIRECT);
@@ -770,13 +771,13 @@ static int decode_channel_code_tab(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
 /**
  * Decode code table indexes for each channel.
  *
- * @param[in]     gb            the GetBit context
+ * @param[in]     bc            the Bitstream context
  * @param[in,out] ctx           ptr to the channel unit context
  * @param[in]     num_channels  number of channels to process
  * @param[in]     avctx         ptr to the AVCodecContext
  * @return result code: 0 = OK, otherwise - error code
  */
-static int decode_code_table_indexes(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
+static int decode_code_table_indexes(BitstreamContext *bc, Atrac3pChanUnitCtx *ctx,
                                      int num_channels, AVCodecContext *avctx)
 {
     int ch_num, ret;
@@ -784,13 +785,13 @@ static int decode_code_table_indexes(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
     if (!ctx->used_quant_units)
         return 0;
 
-    ctx->use_full_table = get_bits1(gb);
+    ctx->use_full_table = bitstream_read_bit(bc);
 
     for (ch_num = 0; ch_num < num_channels; ch_num++) {
         memset(ctx->channels[ch_num].qu_tab_idx, 0,
                sizeof(ctx->channels[ch_num].qu_tab_idx));
 
-        if ((ret = decode_channel_code_tab(gb, ctx, ch_num, avctx)) < 0)
+        if ((ret = decode_channel_code_tab(bc, ctx, ch_num, avctx)) < 0)
             return ret;
     }
 
@@ -803,13 +804,13 @@ static int decode_code_table_indexes(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
  * This is a generalized version for all known coding modes.
  * Its speed can be improved by creating separate functions for each mode.
  *
- * @param[in]   gb          the GetBit context
+ * @param[in]   bc          the Bitstream context
  * @param[in]   tab         code table telling how to decode spectral lines
  * @param[in]   vlc_tab     ptr to the huffman table associated with the code table
  * @param[out]  out         pointer to buffer where decoded data should be stored
  * @param[in]   num_specs   number of spectral lines to decode
  */
-static void decode_qu_spectra(GetBitContext *gb, const Atrac3pSpecCodeTab *tab,
+static void decode_qu_spectra(BitstreamContext *bc, const Atrac3pSpecCodeTab *tab,
                               VLC *vlc_tab, int16_t *out, const int num_specs)
 {
     int i, j, pos, cf;
@@ -820,15 +821,15 @@ static void decode_qu_spectra(GetBitContext *gb, const Atrac3pSpecCodeTab *tab,
     unsigned val, mask = (1 << bits) - 1;
 
     for (pos = 0; pos < num_specs;) {
-        if (group_size == 1 || get_bits1(gb)) {
+        if (group_size == 1 || bitstream_read_bit(bc)) {
             for (j = 0; j < group_size; j++) {
-                val = get_vlc2(gb, vlc_tab->table, vlc_tab->bits, 1);
+                val = bitstream_read_vlc(bc, vlc_tab->table, vlc_tab->bits, 1);
 
                 for (i = 0; i < num_coeffs; i++) {
                     cf = val & mask;
                     if (is_signed)
                         cf = sign_extend(cf, bits);
-                    else if (cf && get_bits1(gb))
+                    else if (cf && bitstream_read_bit(bc))
                         cf = -cf;
 
                     out[pos++] = cf;
@@ -843,12 +844,12 @@ static void decode_qu_spectra(GetBitContext *gb, const Atrac3pSpecCodeTab *tab,
 /**
  * Decode huffman-coded IMDCT spectrum for all channels.
  *
- * @param[in]     gb            the GetBit context
+ * @param[in]     bc            the Bitstream context
  * @param[in,out] ctx           ptr to the channel unit context
  * @param[in]     num_channels  number of channels to process
  * @param[in]     avctx         ptr to the AVCodecContext
  */
-static void decode_spectrum(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
+static void decode_spectrum(BitstreamContext *bc, Atrac3pChanUnitCtx *ctx,
                             int num_channels, AVCodecContext *avctx)
 {
     int i, ch_num, qu, wordlen, codetab, tab_index, num_specs;
@@ -880,7 +881,7 @@ static void decode_spectrum(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
                 if (tab->redirect >= 0)
                     tab_index = tab->redirect;
 
-                decode_qu_spectra(gb, tab, &spec_vlc_tabs[tab_index],
+                decode_qu_spectra(bc, tab, &spec_vlc_tabs[tab_index],
                                   &chan->spectrum[ff_atrac3p_qu_to_spec_pos[qu]],
                                   num_specs);
             } else if (ch_num && ctx->channels[0].qu_wordlen[qu] && !codetab) {
@@ -900,7 +901,7 @@ static void decode_spectrum(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
         if (ctx->used_quant_units > 2) {
             num_specs = atrac3p_subband_to_num_powgrps[ctx->num_coded_subbands - 1];
             for (i = 0; i < num_specs; i++)
-                chan->power_levs[i] = get_bits(gb, 4);
+                chan->power_levs[i] = bitstream_read(bc, 4);
         }
     }
 }
@@ -913,22 +914,22 @@ static void decode_spectrum(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
  * Otherwise, all necessary bits will be directly stored
  * prefixed by two signal bits = 1,1.
  *
- * @param[in]   gb              ptr to the GetBitContext
+ * @param[in]   bc              ptr to the BitstreamContext
  * @param[out]  out             where to place decoded flags
  * @param[in]   num_flags       number of flags to process
  * @return: 0 = all flag bits are zero, 1 = there is at least one non-zero flag bit
  */
-static int get_subband_flags(GetBitContext *gb, uint8_t *out, int num_flags)
+static int get_subband_flags(BitstreamContext *bc, uint8_t *out, int num_flags)
 {
     int i, result;
 
     memset(out, 0, num_flags);
 
-    result = get_bits1(gb);
+    result = bitstream_read_bit(bc);
     if (result) {
-        if (get_bits1(gb))
+        if (bitstream_read_bit(bc))
             for (i = 0; i < num_flags; i++)
-                out[i] = get_bits1(gb);
+                out[i] = bitstream_read_bit(bc);
         else
             memset(out, 1, num_flags);
     }
@@ -939,63 +940,63 @@ static int get_subband_flags(GetBitContext *gb, uint8_t *out, int num_flags)
 /**
  * Decode mdct window shape flags for all channels.
  *
- * @param[in]     gb            the GetBit context
+ * @param[in]     bc            the Bitstream context
  * @param[in,out] ctx           ptr to the channel unit context
  * @param[in]     num_channels  number of channels to process
  */
-static void decode_window_shape(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
+static void decode_window_shape(BitstreamContext *bc, Atrac3pChanUnitCtx *ctx,
                                 int num_channels)
 {
     int ch_num;
 
     for (ch_num = 0; ch_num < num_channels; ch_num++)
-        get_subband_flags(gb, ctx->channels[ch_num].wnd_shape,
+        get_subband_flags(bc, ctx->channels[ch_num].wnd_shape,
                           ctx->num_subbands);
 }
 
 /**
  * Decode number of gain control points.
  *
- * @param[in]     gb              the GetBit context
+ * @param[in]     bc              the Bitstream context
  * @param[in,out] ctx             ptr to the channel unit context
  * @param[in]     ch_num          channel to process
  * @param[in]     coded_subbands  number of subbands to process
  * @return result code: 0 = OK, otherwise - error code
  */
-static int decode_gainc_npoints(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
+static int decode_gainc_npoints(BitstreamContext *bc, Atrac3pChanUnitCtx *ctx,
                                 int ch_num, int coded_subbands)
 {
     int i, delta, delta_bits, min_val;
     Atrac3pChanParams *chan     = &ctx->channels[ch_num];
     Atrac3pChanParams *ref_chan = &ctx->channels[0];
 
-    switch (get_bits(gb, 2)) { /* switch according to coding mode */
+    switch (bitstream_read(bc, 2)) { /* switch according to coding mode */
     case 0: /* fixed-length coding */
         for (i = 0; i < coded_subbands; i++)
-            chan->gain_data[i].num_points = get_bits(gb, 3);
+            chan->gain_data[i].num_points = bitstream_read(bc, 3);
         break;
     case 1: /* variable-length coding */
         for (i = 0; i < coded_subbands; i++)
             chan->gain_data[i].num_points =
-                get_vlc2(gb, gain_vlc_tabs[0].table,
-                         gain_vlc_tabs[0].bits, 1);
+                bitstream_read_vlc(bc, gain_vlc_tabs[0].table,
+                                   gain_vlc_tabs[0].bits, 1);
         break;
     case 2:
         if (ch_num) { /* VLC modulo delta to master channel */
             for (i = 0; i < coded_subbands; i++) {
-                delta = get_vlc2(gb, gain_vlc_tabs[1].table,
-                                 gain_vlc_tabs[1].bits, 1);
+                delta = bitstream_read_vlc(bc, gain_vlc_tabs[1].table,
+                                           gain_vlc_tabs[1].bits, 1);
                 chan->gain_data[i].num_points =
                     (ref_chan->gain_data[i].num_points + delta) & 7;
             }
         } else { /* VLC modulo delta to previous */
             chan->gain_data[0].num_points =
-                get_vlc2(gb, gain_vlc_tabs[0].table,
-                         gain_vlc_tabs[0].bits, 1);
+                bitstream_read_vlc(bc, gain_vlc_tabs[0].table,
+                                   gain_vlc_tabs[0].bits, 1);
 
             for (i = 1; i < coded_subbands; i++) {
-                delta = get_vlc2(gb, gain_vlc_tabs[1].table,
-                                 gain_vlc_tabs[1].bits, 1);
+                delta = bitstream_read_vlc(bc, gain_vlc_tabs[1].table,
+                                           gain_vlc_tabs[1].bits, 1);
                 chan->gain_data[i].num_points =
                     (chan->gain_data[i - 1].num_points + delta) & 7;
             }
@@ -1007,11 +1008,11 @@ static int decode_gainc_npoints(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
                 chan->gain_data[i].num_points =
                     ref_chan->gain_data[i].num_points;
         } else { /* shorter delta to min */
-            delta_bits = get_bits(gb, 2);
-            min_val    = get_bits(gb, 3);
+            delta_bits = bitstream_read(bc, 2);
+            min_val    = bitstream_read(bc, 3);
 
             for (i = 0; i < coded_subbands; i++) {
-                chan->gain_data[i].num_points = min_val + get_bitsz(gb, delta_bits);
+                chan->gain_data[i].num_points = min_val + bitstream_read(bc, delta_bits);
                 if (chan->gain_data[i].num_points > 7)
                     return AVERROR_INVALIDDATA;
             }
@@ -1038,23 +1039,23 @@ static inline void gainc_level_mode3s(AtracGainInfo *dst, AtracGainInfo *ref)
 /**
  * Implements coding mode 1 (master) for gain compensation levels.
  *
- * @param[in]     gb     the GetBit context
+ * @param[in]     bc     the Bitstream context
  * @param[in]     ctx    ptr to the channel unit context
  * @param[out]    dst    ptr to the output array
  */
-static inline void gainc_level_mode1m(GetBitContext *gb,
+static inline void gainc_level_mode1m(BitstreamContext *bc,
                                       Atrac3pChanUnitCtx *ctx,
                                       AtracGainInfo *dst)
 {
     int i, delta;
 
     if (dst->num_points > 0)
-        dst->lev_code[0] = get_vlc2(gb, gain_vlc_tabs[2].table,
-                                    gain_vlc_tabs[2].bits, 1);
+        dst->lev_code[0] = bitstream_read_vlc(bc, gain_vlc_tabs[2].table,
+                                              gain_vlc_tabs[2].bits, 1);
 
     for (i = 1; i < dst->num_points; i++) {
-        delta = get_vlc2(gb, gain_vlc_tabs[3].table,
-                         gain_vlc_tabs[3].bits, 1);
+        delta = bitstream_read_vlc(bc, gain_vlc_tabs[3].table,
+                                   gain_vlc_tabs[3].bits, 1);
         dst->lev_code[i] = (dst->lev_code[i - 1] + delta) & 0xF;
     }
 }
@@ -1062,58 +1063,58 @@ static inline void gainc_level_mode1m(GetBitContext *gb,
 /**
  * Decode level code for each gain control point.
  *
- * @param[in]     gb              the GetBit context
+ * @param[in]     bc              the Bitstream context
  * @param[in,out] ctx             ptr to the channel unit context
  * @param[in]     ch_num          channel to process
  * @param[in]     coded_subbands  number of subbands to process
  * @return result code: 0 = OK, otherwise - error code
  */
-static int decode_gainc_levels(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
+static int decode_gainc_levels(BitstreamContext *bc, Atrac3pChanUnitCtx *ctx,
                                int ch_num, int coded_subbands)
 {
     int sb, i, delta, delta_bits, min_val, pred;
     Atrac3pChanParams *chan     = &ctx->channels[ch_num];
     Atrac3pChanParams *ref_chan = &ctx->channels[0];
 
-    switch (get_bits(gb, 2)) { /* switch according to coding mode */
+    switch (bitstream_read(bc, 2)) { /* switch according to coding mode */
     case 0: /* fixed-length coding */
         for (sb = 0; sb < coded_subbands; sb++)
             for (i = 0; i < chan->gain_data[sb].num_points; i++)
-                chan->gain_data[sb].lev_code[i] = get_bits(gb, 4);
+                chan->gain_data[sb].lev_code[i] = bitstream_read(bc, 4);
         break;
     case 1:
         if (ch_num) { /* VLC modulo delta to master channel */
             for (sb = 0; sb < coded_subbands; sb++)
                 for (i = 0; i < chan->gain_data[sb].num_points; i++) {
-                    delta = get_vlc2(gb, gain_vlc_tabs[5].table,
-                                     gain_vlc_tabs[5].bits, 1);
+                    delta = bitstream_read_vlc(bc, gain_vlc_tabs[5].table,
+                                               gain_vlc_tabs[5].bits, 1);
                     pred = (i >= ref_chan->gain_data[sb].num_points)
                            ? 7 : ref_chan->gain_data[sb].lev_code[i];
                     chan->gain_data[sb].lev_code[i] = (pred + delta) & 0xF;
                 }
         } else { /* VLC modulo delta to previous */
             for (sb = 0; sb < coded_subbands; sb++)
-                gainc_level_mode1m(gb, ctx, &chan->gain_data[sb]);
+                gainc_level_mode1m(bc, ctx, &chan->gain_data[sb]);
         }
         break;
     case 2:
         if (ch_num) { /* VLC modulo delta to previous or clone master */
             for (sb = 0; sb < coded_subbands; sb++)
                 if (chan->gain_data[sb].num_points > 0) {
-                    if (get_bits1(gb))
-                        gainc_level_mode1m(gb, ctx, &chan->gain_data[sb]);
+                    if (bitstream_read_bit(bc))
+                        gainc_level_mode1m(bc, ctx, &chan->gain_data[sb]);
                     else
                         gainc_level_mode3s(&chan->gain_data[sb],
                                            &ref_chan->gain_data[sb]);
                 }
         } else { /* VLC modulo delta to lev_codes of previous subband */
             if (chan->gain_data[0].num_points > 0)
-                gainc_level_mode1m(gb, ctx, &chan->gain_data[0]);
+                gainc_level_mode1m(bc, ctx, &chan->gain_data[0]);
 
             for (sb = 1; sb < coded_subbands; sb++)
                 for (i = 0; i < chan->gain_data[sb].num_points; i++) {
-                    delta = get_vlc2(gb, gain_vlc_tabs[4].table,
-                                     gain_vlc_tabs[4].bits, 1);
+                    delta = bitstream_read_vlc(bc, gain_vlc_tabs[4].table,
+                                               gain_vlc_tabs[4].bits, 1);
                     pred = (i >= chan->gain_data[sb - 1].num_points)
                            ? 7 : chan->gain_data[sb - 1].lev_code[i];
                     chan->gain_data[sb].lev_code[i] = (pred + delta) & 0xF;
@@ -1126,12 +1127,12 @@ static int decode_gainc_levels(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
                 gainc_level_mode3s(&chan->gain_data[sb],
                                    &ref_chan->gain_data[sb]);
         } else { /* shorter delta to min */
-            delta_bits = get_bits(gb, 2);
-            min_val    = get_bits(gb, 4);
+            delta_bits = bitstream_read(bc, 2);
+            min_val    = bitstream_read(bc, 4);
 
             for (sb = 0; sb < coded_subbands; sb++)
                 for (i = 0; i < chan->gain_data[sb].num_points; i++) {
-                    chan->gain_data[sb].lev_code[i] = min_val + get_bitsz(gb, delta_bits);
+                    chan->gain_data[sb].lev_code[i] = min_val + bitstream_read(bc, delta_bits);
                     if (chan->gain_data[sb].lev_code[i] > 15)
                         return AVERROR_INVALIDDATA;
                 }
@@ -1145,35 +1146,35 @@ static int decode_gainc_levels(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
 /**
  * Implements coding mode 0 for gain compensation locations.
  *
- * @param[in]     gb     the GetBit context
+ * @param[in]     bc     the Bitstream context
  * @param[in]     ctx    ptr to the channel unit context
  * @param[out]    dst    ptr to the output array
  * @param[in]     pos    position of the value to be processed
  */
-static inline void gainc_loc_mode0(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
+static inline void gainc_loc_mode0(BitstreamContext *bc, Atrac3pChanUnitCtx *ctx,
                                    AtracGainInfo *dst, int pos)
 {
     int delta_bits;
 
     if (!pos || dst->loc_code[pos - 1] < 15)
-        dst->loc_code[pos] = get_bits(gb, 5);
+        dst->loc_code[pos] = bitstream_read(bc, 5);
     else if (dst->loc_code[pos - 1] >= 30)
         dst->loc_code[pos] = 31;
     else {
         delta_bits         = av_log2(30 - dst->loc_code[pos - 1]) + 1;
         dst->loc_code[pos] = dst->loc_code[pos - 1] +
-                             get_bits(gb, delta_bits) + 1;
+                             bitstream_read(bc, delta_bits) + 1;
     }
 }
 
 /**
  * Implements coding mode 1 for gain compensation locations.
  *
- * @param[in]     gb     the GetBit context
+ * @param[in]     bc     the Bitstream context
  * @param[in]     ctx    ptr to the channel unit context
  * @param[out]    dst    ptr to the output array
  */
-static inline void gainc_loc_mode1(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
+static inline void gainc_loc_mode1(BitstreamContext *bc, Atrac3pChanUnitCtx *ctx,
                                    AtracGainInfo *dst)
 {
     int i;
@@ -1181,7 +1182,7 @@ static inline void gainc_loc_mode1(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
 
     if (dst->num_points > 0) {
         /* 1st coefficient is stored directly */
-        dst->loc_code[0] = get_bits(gb, 5);
+        dst->loc_code[0] = bitstream_read(bc, 5);
 
         for (i = 1; i < dst->num_points; i++) {
             /* switch VLC according to the curve direction
@@ -1190,7 +1191,7 @@ static inline void gainc_loc_mode1(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
                                ? &gain_vlc_tabs[7]
                                : &gain_vlc_tabs[9];
             dst->loc_code[i] = dst->loc_code[i - 1] +
-                               get_vlc2(gb, tab->table, tab->bits, 1);
+                               bitstream_read_vlc(bc, tab->table, tab->bits, 1);
         }
     }
 }
@@ -1198,14 +1199,14 @@ static inline void gainc_loc_mode1(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
 /**
  * Decode location code for each gain control point.
  *
- * @param[in]     gb              the GetBit context
+ * @param[in]     bc              the Bitstream context
  * @param[in,out] ctx             ptr to the channel unit context
  * @param[in]     ch_num          channel to process
  * @param[in]     coded_subbands  number of subbands to process
  * @param[in]     avctx           ptr to the AVCodecContext
  * @return result code: 0 = OK, otherwise - error code
  */
-static int decode_gainc_loc_codes(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
+static int decode_gainc_loc_codes(BitstreamContext *bc, Atrac3pChanUnitCtx *ctx,
                                   int ch_num, int coded_subbands,
                                   AVCodecContext *avctx)
 {
@@ -1215,11 +1216,11 @@ static int decode_gainc_loc_codes(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
     Atrac3pChanParams *chan     = &ctx->channels[ch_num];
     Atrac3pChanParams *ref_chan = &ctx->channels[0];
 
-    switch (get_bits(gb, 2)) { /* switch according to coding mode */
+    switch (bitstream_read(bc, 2)) { /* switch according to coding mode */
     case 0: /* sequence of numbers in ascending order */
         for (sb = 0; sb < coded_subbands; sb++)
             for (i = 0; i < chan->gain_data[sb].num_points; i++)
-                gainc_loc_mode0(gb, ctx, &chan->gain_data[sb], i);
+                gainc_loc_mode0(bc, ctx, &chan->gain_data[sb], i);
         break;
     case 1:
         if (ch_num) {
@@ -1230,8 +1231,8 @@ static int decode_gainc_loc_codes(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
                 ref = &ref_chan->gain_data[sb];
 
                 /* 1st value is vlc-coded modulo delta to master */
-                delta = get_vlc2(gb, gain_vlc_tabs[10].table,
-                                 gain_vlc_tabs[10].bits, 1);
+                delta = bitstream_read_vlc(bc, gain_vlc_tabs[10].table,
+                                           gain_vlc_tabs[10].bits, 1);
                 pred = ref->num_points > 0 ? ref->loc_code[0] : 0;
                 dst->loc_code[0] = (pred + delta) & 0x1F;
 
@@ -1241,19 +1242,19 @@ static int decode_gainc_loc_codes(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
                         /* ascending curve */
                         if (more_than_ref) {
                             delta =
-                                get_vlc2(gb, gain_vlc_tabs[9].table,
-                                         gain_vlc_tabs[9].bits, 1);
+                                bitstream_read_vlc(bc, gain_vlc_tabs[9].table,
+                                                   gain_vlc_tabs[9].bits, 1);
                             dst->loc_code[i] = dst->loc_code[i - 1] + delta;
                         } else {
-                            if (get_bits1(gb))
-                                gainc_loc_mode0(gb, ctx, dst, i);  // direct coding
+                            if (bitstream_read_bit(bc))
+                                gainc_loc_mode0(bc, ctx, dst, i);  // direct coding
                             else
                                 dst->loc_code[i] = ref->loc_code[i];  // clone master
                         }
                     } else { /* descending curve */
                         tab   = more_than_ref ? &gain_vlc_tabs[7]
                                               : &gain_vlc_tabs[10];
-                        delta = get_vlc2(gb, tab->table, tab->bits, 1);
+                        delta = bitstream_read_vlc(bc, tab->table, tab->bits, 1);
                         if (more_than_ref)
                             dst->loc_code[i] = dst->loc_code[i - 1] + delta;
                         else
@@ -1263,7 +1264,7 @@ static int decode_gainc_loc_codes(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
             }
         } else /* VLC delta to previous */
             for (sb = 0; sb < coded_subbands; sb++)
-                gainc_loc_mode1(gb, ctx, &chan->gain_data[sb]);
+                gainc_loc_mode1(bc, ctx, &chan->gain_data[sb]);
         break;
     case 2:
         if (ch_num) {
@@ -1272,8 +1273,8 @@ static int decode_gainc_loc_codes(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
                     continue;
                 dst = &chan->gain_data[sb];
                 ref = &ref_chan->gain_data[sb];
-                if (dst->num_points > ref->num_points || get_bits1(gb))
-                    gainc_loc_mode1(gb, ctx, dst);
+                if (dst->num_points > ref->num_points || bitstream_read_bit(bc))
+                    gainc_loc_mode1(bc, ctx, dst);
                 else /* clone master for the whole subband */
                     for (i = 0; i < chan->gain_data[sb].num_points; i++)
                         dst->loc_code[i] = ref->loc_code[i];
@@ -1281,7 +1282,7 @@ static int decode_gainc_loc_codes(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
         } else {
             /* data for the first subband is coded directly */
             for (i = 0; i < chan->gain_data[0].num_points; i++)
-                gainc_loc_mode0(gb, ctx, &chan->gain_data[0], i);
+                gainc_loc_mode0(bc, ctx, &chan->gain_data[0], i);
 
             for (sb = 1; sb < coded_subbands; sb++) {
                 if (chan->gain_data[sb].num_points <= 0)
@@ -1290,8 +1291,8 @@ static int decode_gainc_loc_codes(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
 
                 /* 1st value is vlc-coded modulo delta to the corresponding
                  * value of the previous subband if any or zero */
-                delta = get_vlc2(gb, gain_vlc_tabs[6].table,
-                                 gain_vlc_tabs[6].bits, 1);
+                delta = bitstream_read_vlc(bc, gain_vlc_tabs[6].table,
+                                           gain_vlc_tabs[6].bits, 1);
                 pred             = dst[-1].num_points > 0
                                    ? dst[-1].loc_code[0] : 0;
                 dst->loc_code[0] = (pred + delta) & 0x1F;
@@ -1302,7 +1303,7 @@ static int decode_gainc_loc_codes(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
                      * presence of prediction. */
                     tab = &gain_vlc_tabs[(dst->lev_code[i] > dst->lev_code[i - 1]) *
                                                    2 + more_than_ref + 6];
-                    delta = get_vlc2(gb, tab->table, tab->bits, 1);
+                    delta = bitstream_read_vlc(bc, tab->table, tab->bits, 1);
                     if (more_than_ref)
                         dst->loc_code[i] = dst->loc_code[i - 1] + delta;
                     else
@@ -1316,19 +1317,19 @@ static int decode_gainc_loc_codes(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
             for (sb = 0; sb < coded_subbands; sb++)
                 for (i = 0; i < chan->gain_data[sb].num_points; i++) {
                     if (i >= ref_chan->gain_data[sb].num_points)
-                        gainc_loc_mode0(gb, ctx, &chan->gain_data[sb], i);
+                        gainc_loc_mode0(bc, ctx, &chan->gain_data[sb], i);
                     else
                         chan->gain_data[sb].loc_code[i] =
                             ref_chan->gain_data[sb].loc_code[i];
                 }
         } else { /* shorter delta to min */
-            delta_bits = get_bits(gb, 2) + 1;
-            min_val    = get_bits(gb, 5);
+            delta_bits = bitstream_read(bc, 2) + 1;
+            min_val    = bitstream_read(bc, 5);
 
             for (sb = 0; sb < coded_subbands; sb++)
                 for (i = 0; i < chan->gain_data[sb].num_points; i++)
                     chan->gain_data[sb].loc_code[i] = min_val + i +
-                                                      get_bits(gb, delta_bits);
+                                                      bitstream_read(bc, delta_bits);
         }
         break;
     }
@@ -1353,13 +1354,13 @@ static int decode_gainc_loc_codes(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
 /**
  * Decode gain control data for all channels.
  *
- * @param[in]     gb            the GetBit context
+ * @param[in]     bc            the Bitstream context
  * @param[in,out] ctx           ptr to the channel unit context
  * @param[in]     num_channels  number of channels to process
  * @param[in]     avctx         ptr to the AVCodecContext
  * @return result code: 0 = OK, otherwise - error code
  */
-static int decode_gainc_data(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
+static int decode_gainc_data(BitstreamContext *bc, Atrac3pChanUnitCtx *ctx,
                              int num_channels, AVCodecContext *avctx)
 {
     int ch_num, coded_subbands, sb, ret;
@@ -1368,16 +1369,16 @@ static int decode_gainc_data(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
         memset(ctx->channels[ch_num].gain_data, 0,
                sizeof(*ctx->channels[ch_num].gain_data) * ATRAC3P_SUBBANDS);
 
-        if (get_bits1(gb)) { /* gain control data present? */
-            coded_subbands = get_bits(gb, 4) + 1;
-            if (get_bits1(gb)) /* is high band gain data replication on? */
-                ctx->channels[ch_num].num_gain_subbands = get_bits(gb, 4) + 1;
+        if (bitstream_read_bit(bc)) { /* gain control data present? */
+            coded_subbands = bitstream_read(bc, 4) + 1;
+            if (bitstream_read_bit(bc)) /* is high band gain data replication on? */
+                ctx->channels[ch_num].num_gain_subbands = bitstream_read(bc, 4) + 1;
             else
                 ctx->channels[ch_num].num_gain_subbands = coded_subbands;
 
-            if ((ret = decode_gainc_npoints(gb, ctx, ch_num, coded_subbands)) < 0 ||
-                (ret = decode_gainc_levels(gb, ctx, ch_num, coded_subbands))  < 0 ||
-                (ret = decode_gainc_loc_codes(gb, ctx, ch_num, coded_subbands, avctx)) < 0)
+            if ((ret = decode_gainc_npoints(bc, ctx, ch_num, coded_subbands)) < 0 ||
+                (ret = decode_gainc_levels(bc, ctx, ch_num, coded_subbands))  < 0 ||
+                (ret = decode_gainc_loc_codes(bc, ctx, ch_num, coded_subbands, avctx)) < 0)
                 return ret;
 
             if (coded_subbands > 0) { /* propagate gain data if requested */
@@ -1396,29 +1397,29 @@ static int decode_gainc_data(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
 /**
  * Decode envelope for all tones of a channel.
  *
- * @param[in]     gb                the GetBit context
+ * @param[in]     bc                the Bitstream context
  * @param[in,out] ctx               ptr to the channel unit context
  * @param[in]     ch_num            channel to process
  * @param[in]     band_has_tones    ptr to an array of per-band-flags:
  *                                  1 - tone data present
  */
-static void decode_tones_envelope(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
+static void decode_tones_envelope(BitstreamContext *bc, Atrac3pChanUnitCtx *ctx,
                                   int ch_num, int band_has_tones[])
 {
     int sb;
     Atrac3pWavesData *dst = ctx->channels[ch_num].tones_info;
     Atrac3pWavesData *ref = ctx->channels[0].tones_info;
 
-    if (!ch_num || !get_bits1(gb)) { /* mode 0: fixed-length coding */
+    if (!ch_num || !bitstream_read_bit(bc)) { /* mode 0: fixed-length coding */
         for (sb = 0; sb < ctx->waves_info->num_tone_bands; sb++) {
             if (!band_has_tones[sb])
                 continue;
-            dst[sb].pend_env.has_start_point = get_bits1(gb);
+            dst[sb].pend_env.has_start_point = bitstream_read_bit(bc);
             dst[sb].pend_env.start_pos       = dst[sb].pend_env.has_start_point
-                                               ? get_bits(gb, 5) : -1;
-            dst[sb].pend_env.has_stop_point  = get_bits1(gb);
+                                               ? bitstream_read(bc, 5) : -1;
+            dst[sb].pend_env.has_stop_point  = bitstream_read_bit(bc);
             dst[sb].pend_env.stop_pos        = dst[sb].pend_env.has_stop_point
-                                               ? get_bits(gb, 5) : 32;
+                                               ? bitstream_read(bc, 5) : 32;
         }
     } else { /* mode 1(slave only): copy master */
         for (sb = 0; sb < ctx->waves_info->num_tone_bands; sb++) {
@@ -1435,7 +1436,7 @@ static void decode_tones_envelope(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
 /**
  * Decode number of tones for each subband of a channel.
  *
- * @param[in]     gb                the GetBit context
+ * @param[in]     bc                the Bitstream context
  * @param[in,out] ctx               ptr to the channel unit context
  * @param[in]     ch_num            channel to process
  * @param[in]     band_has_tones    ptr to an array of per-band-flags:
@@ -1443,7 +1444,7 @@ static void decode_tones_envelope(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
  * @param[in]     avctx             ptr to the AVCodecContext
  * @return result code: 0 = OK, otherwise - error code
  */
-static int decode_band_numwavs(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
+static int decode_band_numwavs(BitstreamContext *bc, Atrac3pChanUnitCtx *ctx,
                                int ch_num, int band_has_tones[],
                                AVCodecContext *avctx)
 {
@@ -1451,25 +1452,25 @@ static int decode_band_numwavs(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
     Atrac3pWavesData *dst = ctx->channels[ch_num].tones_info;
     Atrac3pWavesData *ref = ctx->channels[0].tones_info;
 
-    mode = get_bits(gb, ch_num + 1);
+    mode = bitstream_read(bc, ch_num + 1);
     switch (mode) {
     case 0: /** fixed-length coding */
         for (sb = 0; sb < ctx->waves_info->num_tone_bands; sb++)
             if (band_has_tones[sb])
-                dst[sb].num_wavs = get_bits(gb, 4);
+                dst[sb].num_wavs = bitstream_read(bc, 4);
         break;
     case 1: /** variable-length coding */
         for (sb = 0; sb < ctx->waves_info->num_tone_bands; sb++)
             if (band_has_tones[sb])
                 dst[sb].num_wavs =
-                    get_vlc2(gb, tone_vlc_tabs[1].table,
-                             tone_vlc_tabs[1].bits, 1);
+                    bitstream_read_vlc(bc, tone_vlc_tabs[1].table,
+                                       tone_vlc_tabs[1].bits, 1);
         break;
     case 2: /** VLC modulo delta to master (slave only) */
         for (sb = 0; sb < ctx->waves_info->num_tone_bands; sb++)
             if (band_has_tones[sb]) {
-                delta = get_vlc2(gb, tone_vlc_tabs[2].table,
-                                 tone_vlc_tabs[2].bits, 1);
+                delta = bitstream_read_vlc(bc, tone_vlc_tabs[2].table,
+                                           tone_vlc_tabs[2].bits, 1);
                 delta = sign_extend(delta, 3);
                 dst[sb].num_wavs = (ref[sb].num_wavs + delta) & 0xF;
             }
@@ -1501,13 +1502,13 @@ static int decode_band_numwavs(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
 /**
  * Decode frequency information for each subband of a channel.
  *
- * @param[in]     gb                the GetBit context
+ * @param[in]     bc                the Bitstream context
  * @param[in,out] ctx               ptr to the channel unit context
  * @param[in]     ch_num            channel to process
  * @param[in]     band_has_tones    ptr to an array of per-band-flags:
  *                                  1 - tone data present
  */
-static void decode_tones_frequency(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
+static void decode_tones_frequency(BitstreamContext *bc, Atrac3pChanUnitCtx *ctx,
                                    int ch_num, int band_has_tones[])
 {
     int sb, i, direction, nbits, pred, delta;
@@ -1515,26 +1516,26 @@ static void decode_tones_frequency(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
     Atrac3pWavesData *dst = ctx->channels[ch_num].tones_info;
     Atrac3pWavesData *ref = ctx->channels[0].tones_info;
 
-    if (!ch_num || !get_bits1(gb)) { /* mode 0: fixed-length coding */
+    if (!ch_num || !bitstream_read_bit(bc)) { /* mode 0: fixed-length coding */
         for (sb = 0; sb < ctx->waves_info->num_tone_bands; sb++) {
             if (!band_has_tones[sb] || !dst[sb].num_wavs)
                 continue;
             iwav      = &ctx->waves_info->waves[dst[sb].start_index];
-            direction = (dst[sb].num_wavs > 1) ? get_bits1(gb) : 0;
+            direction = (dst[sb].num_wavs > 1) ? bitstream_read_bit(bc) : 0;
             if (direction) { /** packed numbers in descending order */
                 if (dst[sb].num_wavs)
-                    iwav[dst[sb].num_wavs - 1].freq_index = get_bits(gb, 10);
+                    iwav[dst[sb].num_wavs - 1].freq_index = bitstream_read(bc, 10);
                 for (i = dst[sb].num_wavs - 2; i >= 0 ; i--) {
                     nbits = av_log2(iwav[i+1].freq_index) + 1;
-                    iwav[i].freq_index = get_bits(gb, nbits);
+                    iwav[i].freq_index = bitstream_read(bc, nbits);
                 }
             } else { /** packed numbers in ascending order */
                 for (i = 0; i < dst[sb].num_wavs; i++) {
                     if (!i || iwav[i - 1].freq_index < 512)
-                        iwav[i].freq_index = get_bits(gb, 10);
+                        iwav[i].freq_index = bitstream_read(bc, 10);
                     else {
                         nbits = av_log2(1023 - iwav[i - 1].freq_index) + 1;
-                        iwav[i].freq_index = get_bits(gb, nbits) +
+                        iwav[i].freq_index = bitstream_read(bc, nbits) +
                                              1024 - (1 << nbits);
                     }
                 }
@@ -1547,8 +1548,8 @@ static void decode_tones_frequency(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
             iwav = &ctx->waves_info->waves[ref[sb].start_index];
             owav = &ctx->waves_info->waves[dst[sb].start_index];
             for (i = 0; i < dst[sb].num_wavs; i++) {
-                delta = get_vlc2(gb, tone_vlc_tabs[6].table,
-                                 tone_vlc_tabs[6].bits, 1);
+                delta = bitstream_read_vlc(bc, tone_vlc_tabs[6].table,
+                                           tone_vlc_tabs[6].bits, 1);
                 delta = sign_extend(delta, 8);
                 pred  = (i < ref[sb].num_wavs) ? iwav[i].freq_index :
                         (ref[sb].num_wavs ? iwav[ref[sb].num_wavs - 1].freq_index : 0);
@@ -1561,13 +1562,13 @@ static void decode_tones_frequency(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
 /**
  * Decode amplitude information for each subband of a channel.
  *
- * @param[in]     gb                the GetBit context
+ * @param[in]     bc                the Bitstream context
  * @param[in,out] ctx               ptr to the channel unit context
  * @param[in]     ch_num            channel to process
  * @param[in]     band_has_tones    ptr to an array of per-band-flags:
  *                                  1 - tone data present
  */
-static void decode_tones_amplitude(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
+static void decode_tones_amplitude(BitstreamContext *bc, Atrac3pChanUnitCtx *ctx,
                                    int ch_num, int band_has_tones[])
 {
     int mode, sb, j, i, diff, maxdiff, fi, delta, pred;
@@ -1601,7 +1602,7 @@ static void decode_tones_amplitude(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
         }
     }
 
-    mode = get_bits(gb, ch_num + 1);
+    mode = bitstream_read(bc, ch_num + 1);
 
     switch (mode) {
     case 0: /** fixed-length coding */
@@ -1610,9 +1611,9 @@ static void decode_tones_amplitude(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
                 continue;
             if (ctx->waves_info->amplitude_mode)
                 for (i = 0; i < dst[sb].num_wavs; i++)
-                    ctx->waves_info->waves[dst[sb].start_index + i].amp_sf = get_bits(gb, 6);
+                    ctx->waves_info->waves[dst[sb].start_index + i].amp_sf = bitstream_read(bc, 6);
             else
-                ctx->waves_info->waves[dst[sb].start_index].amp_sf = get_bits(gb, 6);
+                ctx->waves_info->waves[dst[sb].start_index].amp_sf = bitstream_read(bc, 6);
         }
         break;
     case 1: /** min + VLC delta */
@@ -1622,12 +1623,12 @@ static void decode_tones_amplitude(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
             if (ctx->waves_info->amplitude_mode)
                 for (i = 0; i < dst[sb].num_wavs; i++)
                     ctx->waves_info->waves[dst[sb].start_index + i].amp_sf =
-                        get_vlc2(gb, tone_vlc_tabs[3].table,
-                                 tone_vlc_tabs[3].bits, 1) + 20;
+                        bitstream_read_vlc(bc, tone_vlc_tabs[3].table,
+                                           tone_vlc_tabs[3].bits, 1) + 20;
             else
                 ctx->waves_info->waves[dst[sb].start_index].amp_sf =
-                    get_vlc2(gb, tone_vlc_tabs[4].table,
-                             tone_vlc_tabs[4].bits, 1) + 24;
+                    bitstream_read_vlc(bc, tone_vlc_tabs[4].table,
+                                       tone_vlc_tabs[4].bits, 1) + 24;
         }
         break;
     case 2: /** VLC modulo delta to master (slave only) */
@@ -1635,8 +1636,8 @@ static void decode_tones_amplitude(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
             if (!band_has_tones[sb] || !dst[sb].num_wavs)
                 continue;
             for (i = 0; i < dst[sb].num_wavs; i++) {
-                delta = get_vlc2(gb, tone_vlc_tabs[5].table,
-                                 tone_vlc_tabs[5].bits, 1);
+                delta = bitstream_read_vlc(bc, tone_vlc_tabs[5].table,
+                                           tone_vlc_tabs[5].bits, 1);
                 delta = sign_extend(delta, 5);
                 pred  = refwaves[dst[sb].start_index + i] >= 0 ?
                         ctx->waves_info->waves[refwaves[dst[sb].start_index + i]].amp_sf : 34;
@@ -1661,13 +1662,13 @@ static void decode_tones_amplitude(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
 /**
  * Decode phase information for each subband of a channel.
  *
- * @param[in]     gb                the GetBit context
+ * @param[in]     bc                the Bitstream context
  * @param[in,out] ctx               ptr to the channel unit context
  * @param[in]     ch_num            channel to process
  * @param[in]     band_has_tones    ptr to an array of per-band-flags:
  *                                  1 - tone data present
  */
-static void decode_tones_phase(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
+static void decode_tones_phase(BitstreamContext *bc, Atrac3pChanUnitCtx *ctx,
                                int ch_num, int band_has_tones[])
 {
     int sb, i;
@@ -1679,20 +1680,20 @@ static void decode_tones_phase(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
             continue;
         wparam = &ctx->waves_info->waves[dst[sb].start_index];
         for (i = 0; i < dst[sb].num_wavs; i++)
-            wparam[i].phase_index = get_bits(gb, 5);
+            wparam[i].phase_index = bitstream_read(bc, 5);
     }
 }
 
 /**
  * Decode tones info for all channels.
  *
- * @param[in]     gb            the GetBit context
+ * @param[in]     bc            the Bitstream context
  * @param[in,out] ctx           ptr to the channel unit context
  * @param[in]     num_channels  number of channels to process
  * @param[in]     avctx         ptr to the AVCodecContext
  * @return result code: 0 = OK, otherwise - error code
  */
-static int decode_tones_info(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
+static int decode_tones_info(BitstreamContext *bc, Atrac3pChanUnitCtx *ctx,
                              int num_channels, AVCodecContext *avctx)
 {
     int ch_num, i, ret;
@@ -1702,26 +1703,26 @@ static int decode_tones_info(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
         memset(ctx->channels[ch_num].tones_info, 0,
                sizeof(*ctx->channels[ch_num].tones_info) * ATRAC3P_SUBBANDS);
 
-    ctx->waves_info->tones_present = get_bits1(gb);
+    ctx->waves_info->tones_present = bitstream_read_bit(bc);
     if (!ctx->waves_info->tones_present)
         return 0;
 
     memset(ctx->waves_info->waves, 0, sizeof(ctx->waves_info->waves));
 
-    ctx->waves_info->amplitude_mode = get_bits1(gb);
+    ctx->waves_info->amplitude_mode = bitstream_read_bit(bc);
     if (!ctx->waves_info->amplitude_mode) {
         avpriv_report_missing_feature(avctx, "GHA amplitude mode 0");
         return AVERROR_PATCHWELCOME;
     }
 
     ctx->waves_info->num_tone_bands =
-        get_vlc2(gb, tone_vlc_tabs[0].table,
-                 tone_vlc_tabs[0].bits, 1) + 1;
+        bitstream_read_vlc(bc, tone_vlc_tabs[0].table,
+                           tone_vlc_tabs[0].bits, 1) + 1;
 
     if (num_channels == 2) {
-        get_subband_flags(gb, ctx->waves_info->tone_sharing, ctx->waves_info->num_tone_bands);
-        get_subband_flags(gb, ctx->waves_info->tone_master,  ctx->waves_info->num_tone_bands);
-        if (get_subband_flags(gb, ctx->waves_info->phase_shift,
+        get_subband_flags(bc, ctx->waves_info->tone_sharing, ctx->waves_info->num_tone_bands);
+        get_subband_flags(bc, ctx->waves_info->tone_master,  ctx->waves_info->num_tone_bands);
+        if (get_subband_flags(bc, ctx->waves_info->phase_shift,
                               ctx->waves_info->num_tone_bands)) {
             avpriv_report_missing_feature(avctx, "GHA Phase shifting");
             return AVERROR_PATCHWELCOME;
@@ -1734,14 +1735,14 @@ static int decode_tones_info(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
         for (i = 0; i < ctx->waves_info->num_tone_bands; i++)
             band_has_tones[i] = !ch_num ? 1 : !ctx->waves_info->tone_sharing[i];
 
-        decode_tones_envelope(gb, ctx, ch_num, band_has_tones);
-        if ((ret = decode_band_numwavs(gb, ctx, ch_num, band_has_tones,
+        decode_tones_envelope(bc, ctx, ch_num, band_has_tones);
+        if ((ret = decode_band_numwavs(bc, ctx, ch_num, band_has_tones,
                                        avctx)) < 0)
             return ret;
 
-        decode_tones_frequency(gb, ctx, ch_num, band_has_tones);
-        decode_tones_amplitude(gb, ctx, ch_num, band_has_tones);
-        decode_tones_phase(gb, ctx, ch_num, band_has_tones);
+        decode_tones_frequency(bc, ctx, ch_num, band_has_tones);
+        decode_tones_amplitude(bc, ctx, ch_num, band_has_tones);
+        decode_tones_phase(bc, ctx, ch_num, band_has_tones);
     }
 
     if (num_channels == 2) {
@@ -1758,13 +1759,13 @@ static int decode_tones_info(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
     return 0;
 }
 
-int ff_atrac3p_decode_channel_unit(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
+int ff_atrac3p_decode_channel_unit(BitstreamContext *bc, Atrac3pChanUnitCtx *ctx,
                                    int num_channels, AVCodecContext *avctx)
 {
     int ret;
 
     /* parse sound header */
-    ctx->num_quant_units = get_bits(gb, 5) + 1;
+    ctx->num_quant_units = bitstream_read(bc, 5) + 1;
     if (ctx->num_quant_units > 28 && ctx->num_quant_units < 32) {
         av_log(avctx, AV_LOG_ERROR,
                "Invalid number of quantization units: %d!\n",
@@ -1772,10 +1773,10 @@ int ff_atrac3p_decode_channel_unit(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
         return AVERROR_INVALIDDATA;
     }
 
-    ctx->mute_flag = get_bits1(gb);
+    ctx->mute_flag = bitstream_read_bit(bc);
 
     /* decode various sound parameters */
-    if ((ret = decode_quant_wordlen(gb, ctx, num_channels, avctx)) < 0)
+    if ((ret = decode_quant_wordlen(bc, ctx, num_channels, avctx)) < 0)
         return ret;
 
     ctx->num_subbands       = atrac3p_qu_to_subband[ctx->num_quant_units - 1] + 1;
@@ -1783,32 +1784,32 @@ int ff_atrac3p_decode_channel_unit(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
                               ? atrac3p_qu_to_subband[ctx->used_quant_units - 1] + 1
                               : 0;
 
-    if ((ret = decode_scale_factors(gb, ctx, num_channels, avctx)) < 0)
+    if ((ret = decode_scale_factors(bc, ctx, num_channels, avctx)) < 0)
         return ret;
 
-    if ((ret = decode_code_table_indexes(gb, ctx, num_channels, avctx)) < 0)
+    if ((ret = decode_code_table_indexes(bc, ctx, num_channels, avctx)) < 0)
         return ret;
 
-    decode_spectrum(gb, ctx, num_channels, avctx);
+    decode_spectrum(bc, ctx, num_channels, avctx);
 
     if (num_channels == 2) {
-        get_subband_flags(gb, ctx->swap_channels, ctx->num_coded_subbands);
-        get_subband_flags(gb, ctx->negate_coeffs, ctx->num_coded_subbands);
+        get_subband_flags(bc, ctx->swap_channels, ctx->num_coded_subbands);
+        get_subband_flags(bc, ctx->negate_coeffs, ctx->num_coded_subbands);
     }
 
-    decode_window_shape(gb, ctx, num_channels);
+    decode_window_shape(bc, ctx, num_channels);
 
-    if ((ret = decode_gainc_data(gb, ctx, num_channels, avctx)) < 0)
+    if ((ret = decode_gainc_data(bc, ctx, num_channels, avctx)) < 0)
         return ret;
 
-    if ((ret = decode_tones_info(gb, ctx, num_channels, avctx)) < 0)
+    if ((ret = decode_tones_info(bc, ctx, num_channels, avctx)) < 0)
         return ret;
 
     /* decode global noise info */
-    ctx->noise_present = get_bits1(gb);
+    ctx->noise_present = bitstream_read_bit(bc);
     if (ctx->noise_present) {
-        ctx->noise_level_index = get_bits(gb, 4);
-        ctx->noise_table_index = get_bits(gb, 4);
+        ctx->noise_level_index = bitstream_read(bc, 4);
+        ctx->noise_table_index = bitstream_read(bc, 4);
     }
 
     return 0;
diff --git a/libavcodec/atrac3plus.h b/libavcodec/atrac3plus.h
index e56c4441b6..cca399adab 100644
--- a/libavcodec/atrac3plus.h
+++ b/libavcodec/atrac3plus.h
@@ -31,10 +31,11 @@
 #include <stdint.h>
 
 #include "libavutil/float_dsp.h"
+
 #include "atrac.h"
+#include "bitstream.h"
 #include "avcodec.h"
 #include "fft.h"
-#include "get_bits.h"
 
 /** Global unit sizes */
 #define ATRAC3P_SUBBANDS        16  ///< number of PQF subbands
@@ -163,13 +164,13 @@ void ff_atrac3p_init_vlcs(AVCodec *codec);
 /**
  * Decode bitstream data of a channel unit.
  *
- * @param[in]     gb            the GetBit context
+ * @param[in]     bc            the Bitstream context
  * @param[in,out] ctx           ptr to the channel unit context
  * @param[in]     num_channels  number of channels to process
  * @param[in]     avctx         ptr to the AVCodecContext
  * @return result code: 0 = OK, otherwise - error code
  */
-int  ff_atrac3p_decode_channel_unit(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
+int  ff_atrac3p_decode_channel_unit(BitstreamContext *bc, Atrac3pChanUnitCtx *ctx,
                                     int num_channels, AVCodecContext *avctx);
 
 /**
diff --git a/libavcodec/atrac3plusdec.c b/libavcodec/atrac3plusdec.c
index 4a742c159e..17774d5657 100644
--- a/libavcodec/atrac3plusdec.c
+++ b/libavcodec/atrac3plusdec.c
@@ -39,14 +39,15 @@
 
 #include "libavutil/channel_layout.h"
 #include "libavutil/float_dsp.h"
+
 #include "avcodec.h"
-#include "get_bits.h"
+#include "bitstream.h"
 #include "internal.h"
 #include "atrac.h"
 #include "atrac3plus.h"
 
 typedef struct ATRAC3PContext {
-    GetBitContext gb;
+    BitstreamContext bc;
     AVFloatDSPContext fdsp;
 
     DECLARE_ALIGNED(32, float, samples)[2][ATRAC3P_FRAME_SAMPLES];  ///< quantized MDCT spectrum
@@ -334,16 +335,16 @@ static int atrac3p_decode_frame(AVCodecContext *avctx, void *data,
         return ret;
     }
 
-    if ((ret = init_get_bits8(&ctx->gb, avpkt->data, avpkt->size)) < 0)
+    if ((ret = bitstream_init8(&ctx->bc, avpkt->data, avpkt->size)) < 0)
         return ret;
 
-    if (get_bits1(&ctx->gb)) {
+    if (bitstream_read_bit(&ctx->bc)) {
         av_log(avctx, AV_LOG_ERROR, "Invalid start bit!\n");
         return AVERROR_INVALIDDATA;
     }
 
-    while (get_bits_left(&ctx->gb) >= 2 &&
-           (ch_unit_id = get_bits(&ctx->gb, 2)) != CH_UNIT_TERMINATOR) {
+    while (bitstream_bits_left(&ctx->bc) >= 2 &&
+           (ch_unit_id = bitstream_read(&ctx->bc, 2)) != CH_UNIT_TERMINATOR) {
         if (ch_unit_id == CH_UNIT_EXTENSION) {
             avpriv_report_missing_feature(avctx, "Channel unit extension");
             return AVERROR_PATCHWELCOME;
@@ -358,7 +359,7 @@ static int atrac3p_decode_frame(AVCodecContext *avctx, void *data,
         ctx->ch_units[ch_block].unit_type = ch_unit_id;
         channels_to_process               = ch_unit_id + 1;
 
-        if ((ret = ff_atrac3p_decode_channel_unit(&ctx->gb,
+        if ((ret = ff_atrac3p_decode_channel_unit(&ctx->bc,
                                                   &ctx->ch_units[ch_block],
                                                   channels_to_process,
                                                   avctx)) < 0)