Merge commit '38389058c3308758c6365abd0f6b45c5e62bb90b'

* commit '38389058c3308758c6365abd0f6b45c5e62bb90b':
  OpenEXR decoder

Conflicts:
	Changelog
	configure
	libavcodec/Makefile
	libavcodec/avcodec.h
	libavcodec/exr.c
	libavcodec/version.h

Merged-by: Michael Niedermayer <michaelni@gmx.at>

1 files changed, 415 insertions, 376 deletions

diff --git a/libavcodec/exr.c b/libavcodec/exr.c
index 77247fcb81..8ee266b7cc 100644
--- a/libavcodec/exr.c
+++ b/libavcodec/exr.c
@@ -32,35 +32,37 @@
 
 #include <zlib.h>
 
-#include "get_bits.h"
+#include "libavutil/imgutils.h"
+#include "libavutil/opt.h"
+
 #include "avcodec.h"
 #include "bytestream.h"
+#include "get_bits.h"
 #include "internal.h"
 #include "mathops.h"
 #include "thread.h"
-#include "libavutil/imgutils.h"
-#include "libavutil/avassert.h"
-#include "libavutil/opt.h"
 
 enum ExrCompr {
-    EXR_RAW   = 0,
-    EXR_RLE   = 1,
-    EXR_ZIP1  = 2,
-    EXR_ZIP16 = 3,
-    EXR_PIZ   = 4,
-    EXR_PXR24 = 5,
-    EXR_B44   = 6,
-    EXR_B44A  = 7,
+    EXR_RAW,
+    EXR_RLE,
+    EXR_ZIP1,
+    EXR_ZIP16,
+    EXR_PIZ,
+    EXR_PXR24,
+    EXR_B44,
+    EXR_B44A,
+    EXR_UNKN,
 };
 
 enum ExrPixelType {
     EXR_UINT,
     EXR_HALF,
-    EXR_FLOAT
+    EXR_FLOAT,
+    EXR_UNKNOWN,
 };
 
 typedef struct EXRChannel {
-    int               xsub, ysub;
+    int xsub, ysub;
     enum ExrPixelType pixel_type;
 } EXRChannel;
 
@@ -76,52 +78,41 @@ typedef struct EXRThreadData {
 } EXRThreadData;
 
 typedef struct EXRContext {
-    AVClass        *class;
+    AVClass *class;
     AVFrame *picture;
-    int compr;
+    AVCodecContext *avctx;
+
+    enum ExrCompr compression;
     enum ExrPixelType pixel_type;
     int channel_offsets[4]; // 0 = red, 1 = green, 2 = blue and 3 = alpha
     const AVPixFmtDescriptor *desc;
 
+    int w, h;
     uint32_t xmax, xmin;
     uint32_t ymax, ymin;
     uint32_t xdelta, ydelta;
-
     int ysize;
 
     uint64_t scan_line_size;
     int scan_lines_per_block;
 
-    const uint8_t *buf, *table;
+    GetByteContext gb;
+    const uint8_t *buf;
     int buf_size;
 
     EXRChannel *channels;
     int nb_channels;
 
     EXRThreadData *thread_data;
-    int thread_data_size;
 
-    const char* layer;
+    const char *layer;
 } EXRContext;
 
-#define OFFSET(x) offsetof(EXRContext, x)
-#define VD AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_DECODING_PARAM
-static const AVOption options[] = {
-    { "layer", "Set the decoding layer",   OFFSET(layer),        AV_OPT_TYPE_STRING, { .str = "" }, 0, 0, VD},
-    { NULL },
-};
-
-static const AVClass exr_class = {
-    .class_name = "EXR",
-    .item_name  = av_default_item_name,
-    .option     = options,
-    .version    = LIBAVUTIL_VERSION_INT,
-};
-
 /**
- * Converts from 32-bit float as uint32_t to uint16_t
+ * Convert from 32-bit float as uint32_t to uint16_t.
  *
  * @param v 32-bit float
+ *
  * @return normalized 16-bit unsigned int
  */
 static inline uint16_t exr_flt2uint(uint32_t v)
@@ -129,7 +120,7 @@ static inline uint16_t exr_flt2uint(uint32_t v)
     unsigned int exp = v >> 23;
     // "HACK": negative values result in exp<  0, so clipping them to 0
     // is also handled by this condition, avoids explicit check for sign bit.
-    if (exp<= 127 + 7 - 24) // we would shift out all bits anyway
+    if (exp <= 127 + 7 - 24) // we would shift out all bits anyway
         return 0;
     if (exp >= 127)
         return 0xffff;
@@ -138,83 +129,32 @@ static inline uint16_t exr_flt2uint(uint32_t v)
 }
 
 /**
- * Converts from 16-bit float as uint16_t to uint16_t
+ * Convert from 16-bit float as uint16_t to uint16_t.
  *
  * @param v 16-bit float
+ *
  * @return normalized 16-bit unsigned int
  */
 static inline uint16_t exr_halflt2uint(uint16_t v)
 {
     unsigned exp = 14 - (v >> 10);
     if (exp >= 14) {
-        if (exp == 14) return (v >> 9) & 1;
-        else           return (v & 0x8000) ? 0 : 0xffff;
+        if (exp == 14)
+            return (v >> 9) & 1;
+        else
+            return (v & 0x8000) ? 0 : 0xffff;
     }
     v <<= 6;
     return (v + (1 << 16)) >> (exp + 1);
 }
 
-/**
- * Gets the size of the header variable
- *
- * @param **buf the current pointer location in the header where
- * the variable data starts
- * @param *buf_end pointer location of the end of the buffer
- * @return size of variable data
- */
-static unsigned int get_header_variable_length(const uint8_t **buf,
-                                               const uint8_t *buf_end)
-{
-    unsigned int variable_buffer_data_size = bytestream_get_le32(buf);
-    if (variable_buffer_data_size >= buf_end - *buf)
-        return 0;
-    return variable_buffer_data_size;
-}
-
-/**
- * Checks if the variable name corresponds with it's data type
- *
- * @param *avctx the AVCodecContext
- * @param **buf the current pointer location in the header where
- * the variable name starts
- * @param *buf_end pointer location of the end of the buffer
- * @param *value_name name of the varible to check
- * @param *value_type type of the varible to check
- * @param minimum_length minimum length of the variable data
- * @param variable_buffer_data_size variable length read from the header
- * after it's checked
- * @return negative if variable is invalid
- */
-static int check_header_variable(AVCodecContext *avctx,
-                                              const uint8_t **buf,
-                                              const uint8_t *buf_end,
-                                              const char *value_name,
-                                              const char *value_type,
-                                              unsigned int minimum_length,
-                                              unsigned int *variable_buffer_data_size)
-{
-    if (buf_end - *buf >= minimum_length && !strcmp(*buf, value_name)) {
-        *buf += strlen(value_name)+1;
-        if (!strcmp(*buf, value_type)) {
-            *buf += strlen(value_type)+1;
-            *variable_buffer_data_size = get_header_variable_length(buf, buf_end);
-            if (!*variable_buffer_data_size)
-                av_log(avctx, AV_LOG_ERROR, "Incomplete header\n");
-            return 1;
-        }
-        *buf -= strlen(value_name)+1;
-        av_log(avctx, AV_LOG_WARNING, "Unknown data type for header variable %s\n", value_name);
-    }
-    return -1;
-}
-
 static void predictor(uint8_t *src, int size)
 {
-    uint8_t *t = src + 1;
+    uint8_t *t    = src + 1;
     uint8_t *stop = src + size;
 
     while (t < stop) {
-        int d = (int)t[-1] + (int)t[0] - 128;
+        int d = (int) t[-1] + (int) t[0] - 128;
         t[0] = d;
         ++t;
     }
@@ -224,8 +164,8 @@ static void reorder_pixels(uint8_t *src, uint8_t *dst, int size)
 {
     const int8_t *t1 = src;
     const int8_t *t2 = src + (size + 1) / 2;
-    int8_t *s = dst;
-    int8_t *stop = s + size;
+    int8_t *s        = dst;
+    int8_t *stop     = s + size;
 
     while (1) {
         if (s < stop)
@@ -247,7 +187,7 @@ static int zip_uncompress(const uint8_t *src, int compressed_size,
 
     if (uncompress(td->tmp, &dest_len, src, compressed_size) != Z_OK ||
         dest_len != uncompressed_size)
-        return AVERROR(EINVAL);
+        return AVERROR_INVALIDDATA;
 
     predictor(td->tmp, uncompressed_size);
     reorder_pixels(td->tmp, td->uncompressed_data, uncompressed_size);
@@ -258,11 +198,11 @@ static int zip_uncompress(const uint8_t *src, int compressed_size,
 static int rle_uncompress(const uint8_t *src, int compressed_size,
                           int uncompressed_size, EXRThreadData *td)
 {
-    int8_t *d = (int8_t *)td->tmp;
-    const int8_t *s = (const int8_t *)src;
-    int ssize = compressed_size;
-    int dsize = uncompressed_size;
-    int8_t *dend = d + dsize;
+    uint8_t *d      = td->tmp;
+    const int8_t *s = src;
+    int ssize       = compressed_size;
+    int dsize       = uncompressed_size;
+    uint8_t *dend   = d + dsize;
     int count;
 
     while (ssize > 0) {
@@ -271,9 +211,9 @@ static int rle_uncompress(const uint8_t *src, int compressed_size,
         if (count < 0) {
             count = -count;
 
-            if ((dsize -= count    ) < 0 ||
+            if ((dsize -= count) < 0 ||
                 (ssize -= count + 1) < 0)
-                return -1;
+                return AVERROR_INVALIDDATA;
 
             while (count--)
                 *d++ = *s++;
@@ -281,8 +221,8 @@ static int rle_uncompress(const uint8_t *src, int compressed_size,
             count++;
 
             if ((dsize -= count) < 0 ||
-                (ssize -= 2    ) < 0)
-                return -1;
+                (ssize -= 2) < 0)
+                return AVERROR_INVALIDDATA;
 
             while (count--)
                 *d++ = *s;
@@ -301,16 +241,15 @@ static int rle_uncompress(const uint8_t *src, int compressed_size,
 }
 
 #define USHORT_RANGE (1 << 16)
-#define BITMAP_SIZE (1 << 13)
+#define BITMAP_SIZE  (1 << 13)
 
 static uint16_t reverse_lut(const uint8_t *bitmap, uint16_t *lut)
 {
     int i, k = 0;
 
-    for (i = 0; i < USHORT_RANGE; i++) {
+    for (i = 0; i < USHORT_RANGE; i++)
         if ((i == 0) || (bitmap[i >> 3] & (1 << (i & 7))))
             lut[k++] = i;
-    }
 
     i = k - 1;
 
@@ -331,7 +270,7 @@ static void apply_lut(const uint16_t *lut, uint16_t *dst, int dsize)
 #define HUF_DECBITS 14  // decoding bit size (>= 8)
 
 #define HUF_ENCSIZE ((1 << HUF_ENCBITS) + 1)  // encoding table size
-#define HUF_DECSIZE (1 << HUF_DECBITS)     // decoding table size
+#define HUF_DECSIZE (1 << HUF_DECBITS)        // decoding table size
 #define HUF_DECMASK (HUF_DECSIZE - 1)
 
 typedef struct HufDec {
@@ -352,7 +291,7 @@ static void huf_canonical_code_table(uint64_t *hcode)
     for (i = 58; i > 0; --i) {
         uint64_t nc = ((c + n[i]) >> 1);
         n[i] = c;
-        c = nc;
+        c    = nc;
     }
 
     for (i = 0; i < HUF_ENCSIZE; ++i) {
@@ -388,7 +327,7 @@ static int huf_unpack_enc_table(GetByteContext *gb,
                 hcode[im++] = 0;
 
             im--;
-        } else if (l >= (uint64_t) SHORT_ZEROCODE_RUN) {
+        } else if (l >= SHORT_ZEROCODE_RUN) {
             int zerun = l - SHORT_ZEROCODE_RUN + 2;
 
             if (im + zerun > iM + 1)
@@ -424,7 +363,7 @@ static int huf_build_dec_table(const uint64_t *hcode, int im,
 
             pl->lit++;
 
-            pl->p = av_realloc_f(pl->p, pl->lit, sizeof(int));
+            pl->p = av_realloc(pl->p, pl->lit * sizeof(int));
             if (!pl->p)
                 return AVERROR(ENOMEM);
 
@@ -444,40 +383,42 @@ static int huf_build_dec_table(const uint64_t *hcode, int im,
     return 0;
 }
 
-#define get_char(c, lc, gb) {                   \
-    c = (c << 8) | bytestream2_get_byte(gb);    \
-    lc += 8;                                    \
+#define get_char(c, lc, gb)                                                   \
+{                                                                             \
+        c   = (c << 8) | bytestream2_get_byte(gb);                            \
+        lc += 8;                                                              \
 }
 
-#define get_code(po, rlc, c, lc, gb, out, oe) { \
-    if (po == rlc) {                            \
-        if (lc < 8)                             \
-            get_char(c, lc, gb);                \
-        lc -= 8;                                \
-                                                \
-        cs = c >> lc;                           \
-                                                \
-        if (out + cs > oe)                      \
-            return AVERROR_INVALIDDATA;         \
-                                                \
-        s = out[-1];                            \
-                                                \
-        while (cs-- > 0)                        \
-            *out++ = s;                         \
-    } else if (out < oe) {                      \
-        *out++ = po;                            \
-    } else {                                    \
-        return AVERROR_INVALIDDATA;             \
-    }                                           \
+#define get_code(po, rlc, c, lc, gb, out, oe)                                 \
+{                                                                             \
+        if (po == rlc) {                                                      \
+            if (lc < 8)                                                       \
+                get_char(c, lc, gb);                                          \
+            lc -= 8;                                                          \
+                                                                              \
+            cs = c >> lc;                                                     \
+                                                                              \
+            if (out + cs > oe)                                                \
+                return AVERROR_INVALIDDATA;                                   \
+                                                                              \
+            s = out[-1];                                                      \
+                                                                              \
+            while (cs-- > 0)                                                  \
+                *out++ = s;                                                   \
+        } else if (out < oe) {                                                \
+            *out++ = po;                                                      \
+        } else {                                                              \
+            return AVERROR_INVALIDDATA;                                       \
+        }                                                                     \
 }
 
 static int huf_decode(const uint64_t *hcode, const HufDec *hdecod,
                       GetByteContext *gb, int nbits,
                       int rlc, int no, uint16_t *out)
 {
-    uint64_t c = 0;
-    uint16_t *outb = out;
-    uint16_t *oe = out + no;
+    uint64_t c        = 0;
+    uint16_t *outb    = out;
+    uint16_t *oe      = out + no;
     const uint8_t *ie = gb->buffer + (nbits + 7) / 8; // input byte size
     uint8_t cs, s;
     int i, lc = 0;
@@ -486,7 +427,7 @@ static int huf_decode(const uint64_t *hcode, const HufDec *hdecod,
         get_char(c, lc, gb);
 
         while (lc >= HUF_DECBITS) {
-            const HufDec pl = hdecod[(c >> (lc-HUF_DECBITS)) & HUF_DECMASK];
+            const HufDec pl = hdecod[(c >> (lc - HUF_DECBITS)) & HUF_DECMASK];
 
             if (pl.len) {
                 lc -= pl.len;
@@ -519,7 +460,7 @@ static int huf_decode(const uint64_t *hcode, const HufDec *hdecod,
         }
     }
 
-    i = (8 - nbits) & 7;
+    i   = (8 - nbits) & 7;
     c >>= i;
     lc -= i;
 
@@ -549,8 +490,8 @@ static int huf_uncompress(GetByteContext *gb,
     int ret, i;
 
     src_size = bytestream2_get_le32(gb);
-    im = bytestream2_get_le32(gb);
-    iM = bytestream2_get_le32(gb);
+    im       = bytestream2_get_le32(gb);
+    iM       = bytestream2_get_le32(gb);
     bytestream2_skip(gb, 4);
     nBits = bytestream2_get_le32(gb);
     if (im < 0 || im >= HUF_ENCSIZE ||
@@ -560,8 +501,8 @@ static int huf_uncompress(GetByteContext *gb,
 
     bytestream2_skip(gb, 4);
 
-    freq = av_calloc(HUF_ENCSIZE, sizeof(*freq));
-    hdec = av_calloc(HUF_DECSIZE, sizeof(*hdec));
+    freq = av_mallocz_array(HUF_ENCSIZE, sizeof(*freq));
+    hdec = av_mallocz_array(HUF_DECSIZE, sizeof(*hdec));
     if (!freq || !hdec) {
         ret = AVERROR(ENOMEM);
         goto fail;
@@ -580,10 +521,9 @@ static int huf_uncompress(GetByteContext *gb,
     ret = huf_decode(freq, hdec, gb, nBits, iM, dst_size, dst);
 
 fail:
-    for (i = 0; i < HUF_DECSIZE; i++) {
+    for (i = 0; i < HUF_DECSIZE; i++)
         if (hdec)
             av_freep(&hdec[i].p);
-    }
 
     av_free(freq);
     av_free(hdec);
@@ -595,8 +535,8 @@ static inline void wdec14(uint16_t l, uint16_t h, uint16_t *a, uint16_t *b)
 {
     int16_t ls = l;
     int16_t hs = h;
-    int hi = hs;
-    int ai = ls + (hi & 1) + (hi >> 1);
+    int hi     = hs;
+    int ai     = ls + (hi & 1) + (hi >> 1);
     int16_t as = ai;
     int16_t bs = ai - hi;
 
@@ -605,13 +545,13 @@ static inline void wdec14(uint16_t l, uint16_t h, uint16_t *a, uint16_t *b)
 }
 
 #define NBITS      16
-#define A_OFFSET  (1 << (NBITS  - 1))
+#define A_OFFSET  (1 << (NBITS - 1))
 #define MOD_MASK  ((1 << NBITS) - 1)
 
 static inline void wdec16(uint16_t l, uint16_t h, uint16_t *a, uint16_t *b)
 {
-    int m = l;
-    int d = h;
+    int m  = l;
+    int d  = h;
     int bb = (m - (d >> 1)) & MOD_MASK;
     int aa = (d + bb - A_OFFSET) & MOD_MASK;
     *b = bb;
@@ -622,8 +562,8 @@ static void wav_decode(uint16_t *in, int nx, int ox,
                        int ny, int oy, uint16_t mx)
 {
     int w14 = (mx < (1 << 14));
-    int n = (nx > ny) ? ny: nx;
-    int p = 1;
+    int n   = (nx > ny) ? ny : nx;
+    int p   = 1;
     int p2;
 
     while (p <= n)
@@ -647,19 +587,19 @@ static void wav_decode(uint16_t *in, int nx, int ox,
             uint16_t *ex = py + ox * (nx - p2);
 
             for (; px <= ex; px += ox2) {
-                uint16_t *p01 = px  + ox1;
-                uint16_t *p10 = px  + oy1;
+                uint16_t *p01 = px + ox1;
+                uint16_t *p10 = px + oy1;
                 uint16_t *p11 = p10 + ox1;
 
                 if (w14) {
-                    wdec14(*px,  *p10, &i00, &i10);
+                    wdec14(*px, *p10, &i00, &i10);
                     wdec14(*p01, *p11, &i01, &i11);
-                    wdec14(i00, i01, px,  p01);
+                    wdec14(i00, i01, px, p01);
                     wdec14(i10, i11, p10, p11);
                 } else {
-                    wdec16(*px,  *p10, &i00, &i10);
+                    wdec16(*px, *p10, &i00, &i10);
                     wdec16(*p01, *p11, &i01, &i11);
-                    wdec16(i00, i01, px,  p01);
+                    wdec16(i00, i01, px, p01);
                     wdec16(i10, i11, p10, p11);
                 }
             }
@@ -692,25 +632,30 @@ static void wav_decode(uint16_t *in, int nx, int ox,
             }
         }
 
-        p2 = p;
+        p2  = p;
         p >>= 1;
     }
 }
 
-static int piz_uncompress(EXRContext *s, const uint8_t *src, int ssize, int dsize, EXRThreadData *td)
+static int piz_uncompress(EXRContext *s, const uint8_t *src, int ssize,
+                          int dsize, EXRThreadData *td)
 {
     GetByteContext gb;
     uint16_t maxval, min_non_zero, max_non_zero;
-    uint16_t *ptr, *tmp = (uint16_t *)td->tmp;
-    int8_t *out;
+    uint16_t *ptr;
+    uint16_t *tmp = (uint16_t *)td->tmp;
+    uint8_t *out;
     int ret, i, j;
 
     if (!td->bitmap)
         td->bitmap = av_malloc(BITMAP_SIZE);
     if (!td->lut)
         td->lut = av_malloc(1 << 17);
-    if (!td->bitmap || !td->lut)
+    if (!td->bitmap || !td->lut) {
+        av_free(td->bitmap);
+        av_free(td->lut);
         return AVERROR(ENOMEM);
+    }
 
     bytestream2_init(&gb, src, ssize);
     min_non_zero = bytestream2_get_le16(&gb);
@@ -727,7 +672,7 @@ static int piz_uncompress(EXRContext *s, const uint8_t *src, int ssize, int dsiz
 
     maxval = reverse_lut(td->bitmap, td->lut);
 
-    ret = huf_uncompress(&gb, tmp, dsize / sizeof(int16_t));
+    ret = huf_uncompress(&gb, tmp, dsize / sizeof(uint16_t));
     if (ret)
         return ret;
 
@@ -737,20 +682,20 @@ static int piz_uncompress(EXRContext *s, const uint8_t *src, int ssize, int dsiz
         int size = channel->pixel_type;
 
         for (j = 0; j < size; j++)
-            wav_decode(ptr + j, s->xdelta, size, s->ysize, s->xdelta * size, maxval);
+            wav_decode(ptr + j, s->xdelta, size, s->ysize,
+                       s->xdelta * size, maxval);
         ptr += s->xdelta * s->ysize * size;
     }
 
-    apply_lut(td->lut, tmp, dsize / sizeof(int16_t));
+    apply_lut(td->lut, tmp, dsize / sizeof(uint16_t));
 
     out = td->uncompressed_data;
-    for (i = 0; i < s->ysize; i++) {
+    for (i = 0; i < s->ysize; i++)
         for (j = 0; j < s->nb_channels; j++) {
             uint16_t *in = tmp + j * s->xdelta * s->ysize + i * s->xdelta;
             memcpy(out, in, s->xdelta * 2);
             out += s->xdelta * 2;
         }
-    }
 
     return 0;
 }
@@ -766,10 +711,10 @@ static int pxr24_uncompress(EXRContext *s, const uint8_t *src,
 
     if (uncompress(td->tmp, &dest_len, src, compressed_size) != Z_OK ||
         dest_len != uncompressed_size)
-        return AVERROR(EINVAL);
+        return AVERROR_INVALIDDATA;
 
     out = td->uncompressed_data;
-    for (i = 0; i < s->ysize; i++) {
+    for (i = 0; i < s->ysize; i++)
         for (c = 0; c < s->nb_channels; c++) {
             EXRChannel *channel = &s->channels[c];
             const uint8_t *ptr[4];
@@ -780,12 +725,12 @@ static int pxr24_uncompress(EXRContext *s, const uint8_t *src,
                 ptr[0] = in;
                 ptr[1] = ptr[0] + s->xdelta;
                 ptr[2] = ptr[1] + s->xdelta;
-                in = ptr[2] + s->xdelta;
+                in     = ptr[2] + s->xdelta;
 
                 for (j = 0; j < s->xdelta; ++j) {
                     uint32_t diff = (*(ptr[0]++) << 24) |
                                     (*(ptr[1]++) << 16) |
-                                    (*(ptr[2]++) <<  8);
+                                    (*(ptr[2]++) << 8);
                     pixel += diff;
                     bytestream_put_le32(&out, pixel);
                 }
@@ -793,7 +738,7 @@ static int pxr24_uncompress(EXRContext *s, const uint8_t *src,
             case EXR_HALF:
                 ptr[0] = in;
                 ptr[1] = ptr[0] + s->xdelta;
-                in = ptr[1] + s->xdelta;
+                in     = ptr[1] + s->xdelta;
                 for (j = 0; j < s->xdelta; j++) {
                     uint32_t diff = (*(ptr[0]++) << 8) | *(ptr[1]++);
 
@@ -802,10 +747,9 @@ static int pxr24_uncompress(EXRContext *s, const uint8_t *src,
                 }
                 break;
             default:
-                av_assert1(0);
+                return AVERROR_INVALIDDATA;
             }
         }
-    }
 
     return 0;
 }
@@ -822,19 +766,19 @@ static int decode_block(AVCodecContext *avctx, void *tdata,
     uint32_t xdelta = s->xdelta;
     uint16_t *ptr_x;
     uint8_t *ptr;
-    int32_t data_size, line;
+    uint32_t data_size, line;
     const uint8_t *src;
     int axmax = (avctx->width - (s->xmax + 1)) * 2 * s->desc->nb_components;
     int bxmin = s->xmin * 2 * s->desc->nb_components;
     int i, x, buf_size = s->buf_size;
-    int av_unused ret;
+    int ret;
 
-    line_offset = AV_RL64(s->table + jobnr * 8);
+    line_offset = AV_RL64(s->gb.buffer + jobnr * 8);
     // Check if the buffer has the required bytes needed from the offset
     if (line_offset > buf_size - 8)
         return AVERROR_INVALIDDATA;
 
-    src = buf + line_offset + 8;
+    src  = buf + line_offset + 8;
     line = AV_RL32(src - 8);
     if (line < s->ymin || line > s->ymax)
         return AVERROR_INVALIDDATA;
@@ -843,22 +787,24 @@ static int decode_block(AVCodecContext *avctx, void *tdata,
     if (data_size <= 0 || data_size > buf_size)
         return AVERROR_INVALIDDATA;
 
-    s->ysize = FFMIN(s->scan_lines_per_block, s->ymax - line + 1);
+    s->ysize          = FFMIN(s->scan_lines_per_block, s->ymax - line + 1);
     uncompressed_size = s->scan_line_size * s->ysize;
-    if ((s->compr == EXR_RAW && (data_size != uncompressed_size ||
+    if ((s->compression == EXR_RAW && (data_size != uncompressed_size ||
                                  line_offset > buf_size - uncompressed_size)) ||
-        (s->compr != EXR_RAW && (data_size > uncompressed_size ||
+        (s->compression != EXR_RAW && (data_size > uncompressed_size ||
                                  line_offset > buf_size - data_size))) {
         return AVERROR_INVALIDDATA;
     }
 
     if (data_size < uncompressed_size) {
-        av_fast_padded_malloc(&td->uncompressed_data, &td->uncompressed_size, uncompressed_size);
+        av_fast_padded_malloc(&td->uncompressed_data,
+                              &td->uncompressed_size, uncompressed_size);
         av_fast_padded_malloc(&td->tmp, &td->tmp_size, uncompressed_size);
         if (!td->uncompressed_data || !td->tmp)
             return AVERROR(ENOMEM);
 
-        switch (s->compr) {
+        ret = AVERROR_INVALIDDATA;
+        switch (s->compression) {
         case EXR_ZIP1:
         case EXR_ZIP16:
             ret = zip_uncompress(src, data_size, uncompressed_size, td);
@@ -872,7 +818,10 @@ static int decode_block(AVCodecContext *avctx, void *tdata,
         case EXR_RLE:
             ret = rle_uncompress(src, data_size, uncompressed_size, td);
         }
-
+        if (ret < 0) {
+            av_log(avctx, AV_LOG_ERROR, "decode_block() failed.\n");
+            return ret;
+        }
         src = td->uncompressed_data;
     }
 
@@ -883,7 +832,9 @@ static int decode_block(AVCodecContext *avctx, void *tdata,
         channel_buffer[3] = src + xdelta * s->channel_offsets[3];
 
     ptr = p->data[0] + line * p->linesize[0];
-    for (i = 0; i < s->scan_lines_per_block && line + i <= s->ymax; i++, ptr += p->linesize[0]) {
+    for (i = 0;
+         i < s->scan_lines_per_block && line + i <= s->ymax;
+         i++, ptr += p->linesize[0]) {
         const uint8_t *r, *g, *b, *a;
 
         r = channel_buffer[0];
@@ -892,7 +843,7 @@ static int decode_block(AVCodecContext *avctx, void *tdata,
         if (channel_buffer[3])
             a = channel_buffer[3];
 
-        ptr_x = (uint16_t *)ptr;
+        ptr_x = (uint16_t *) ptr;
 
         // Zero out the start if xmin is not 0
         memset(ptr_x, 0, bxmin);
@@ -930,256 +881,296 @@ static int decode_block(AVCodecContext *avctx, void *tdata,
     return 0;
 }
 
-static int decode_frame(AVCodecContext *avctx,
-                        void *data,
-                        int *got_frame,
-                        AVPacket *avpkt)
+/**
+ * Check if the variable name corresponds to its data type.
+ *
+ * @param s              the EXRContext
+ * @param value_name     name of the variable to check
+ * @param value_type     type of the variable to check
+ * @param minimum_length minimum length of the variable data
+ *
+ * @return bytes to read containing variable data
+ *         -1 if variable is not found
+ *         0 if buffer ended prematurely
+ */
+static int check_header_variable(EXRContext *s,
+                                 const char *value_name,
+                                 const char *value_type,
+                                 unsigned int minimum_length)
 {
-    const uint8_t *buf      = avpkt->data;
-    unsigned int   buf_size = avpkt->size;
-    const uint8_t *buf_end  = buf + buf_size;
-
-    EXRContext *const s = avctx->priv_data;
-    ThreadFrame frame = { .f = data };
-    AVFrame *picture  = data;
-    uint8_t *ptr;
-
-    int i, y, magic_number, version, flags, ret;
-    int w = 0;
-    int h = 0;
+    int var_size = -1;
+
+    if (bytestream2_get_bytes_left(&s->gb) >= minimum_length &&
+        !strcmp(s->gb.buffer, value_name)) {
+        // found value_name, jump to value_type (null terminated strings)
+        s->gb.buffer += strlen(value_name) + 1;
+        if (!strcmp(s->gb.buffer, value_type)) {
+            s->gb.buffer += strlen(value_type) + 1;
+            var_size = bytestream2_get_le32(&s->gb);
+            // don't go read past boundaries
+            if (var_size > bytestream2_get_bytes_left(&s->gb))
+                var_size = 0;
+        } else {
+            // value_type not found, reset the buffer
+            s->gb.buffer -= strlen(value_name) + 1;
+            av_log(s->avctx, AV_LOG_WARNING,
+                   "Unknown data type %s for header variable %s.\n",
+                   value_type, value_name);
+        }
+    }
 
-    int out_line_size;
-    int scan_line_blocks;
+    return var_size;
+}
 
-    unsigned int current_channel_offset = 0;
+static int decode_header(EXRContext *s)
+{
+    int current_channel_offset = 0;
+    int magic_number, version, flags, i;
 
-    s->xmin = ~0;
-    s->xmax = ~0;
-    s->ymin = ~0;
-    s->ymax = ~0;
-    s->xdelta = ~0;
-    s->ydelta = ~0;
-    s->channel_offsets[0] = -1;
-    s->channel_offsets[1] = -1;
-    s->channel_offsets[2] = -1;
-    s->channel_offsets[3] = -1;
-    s->pixel_type = -1;
-    s->nb_channels = 0;
-    s->compr = -1;
-    s->buf = buf;
-    s->buf_size = buf_size;
-
-    if (buf_size < 10) {
-        av_log(avctx, AV_LOG_ERROR, "Too short header to parse\n");
+    if (bytestream2_get_bytes_left(&s->gb) < 10) {
+        av_log(s->avctx, AV_LOG_ERROR, "Header too short to parse.\n");
         return AVERROR_INVALIDDATA;
     }
 
-    magic_number = bytestream_get_le32(&buf);
-    if (magic_number != 20000630) { // As per documentation of OpenEXR it's supposed to be int 20000630 little-endian
-        av_log(avctx, AV_LOG_ERROR, "Wrong magic number %d\n", magic_number);
+    magic_number = bytestream2_get_le32(&s->gb);
+    if (magic_number != 20000630) {
+        /* As per documentation of OpenEXR, it is supposed to be
+         * int 20000630 little-endian */
+        av_log(s->avctx, AV_LOG_ERROR, "Wrong magic number %d.\n", magic_number);
         return AVERROR_INVALIDDATA;
     }
 
-    version = bytestream_get_byte(&buf);
+    version = bytestream2_get_byte(&s->gb);
     if (version != 2) {
-        avpriv_report_missing_feature(avctx, "Version %d", version);
+        avpriv_report_missing_feature(s->avctx, "Version %d", version);
         return AVERROR_PATCHWELCOME;
     }
 
-    flags = bytestream_get_le24(&buf);
-    if (flags & 0x2) {
-        avpriv_report_missing_feature(avctx, "Tile support");
+    flags = bytestream2_get_le24(&s->gb);
+    if (flags & 0x02) {
+        avpriv_report_missing_feature(s->avctx, "Tile support");
         return AVERROR_PATCHWELCOME;
     }
 
     // Parse the header
-    while (buf < buf_end && buf[0]) {
-        unsigned int variable_buffer_data_size;
-        // Process the channel list
-        if (check_header_variable(avctx, &buf, buf_end, "channels", "chlist", 38, &variable_buffer_data_size) >= 0) {
-            const uint8_t *channel_list_end;
-            if (!variable_buffer_data_size)
+    while (bytestream2_get_bytes_left(&s->gb) > 0 && *s->gb.buffer) {
+        int var_size;
+        if ((var_size = check_header_variable(s, "channels",
+                                              "chlist", 38)) >= 0) {
+            GetByteContext ch_gb;
+            if (!var_size)
                 return AVERROR_INVALIDDATA;
 
-            channel_list_end = buf + variable_buffer_data_size;
-            while (channel_list_end - buf >= 19) {
+            bytestream2_init(&ch_gb, s->gb.buffer, var_size);
+
+            while (bytestream2_get_bytes_left(&ch_gb) >= 19) {
                 EXRChannel *channel;
                 enum ExrPixelType current_pixel_type;
                 int channel_index = -1;
                 int xsub, ysub;
 
-                const char* b = buf;
-
-                if ( strcmp( s->layer, "" ) != 0 ) {
-                    if ( strncmp( b, s->layer, strlen(s->layer) ) == 0 ) {
-                        b += strlen(s->layer);
-                        if ( *b == '.' ) ++b;   /* skip dot if not given */
-                        av_log( avctx, AV_LOG_INFO, "Layer %s.%s matched\n",
-                               s->layer, b );
+                if (strcmp(s->layer, "") != 0) {
+                    if (strncmp(ch_gb.buffer, s->layer, strlen(s->layer)) == 0) {
+                        ch_gb.buffer += strlen(s->layer);
+                        if (*ch_gb.buffer == '.')
+                            ch_gb.buffer++;         /* skip dot if not given */
+                        av_log(s->avctx, AV_LOG_INFO,
+                               "Layer %s.%s matched.\n", s->layer, ch_gb.buffer);
                     }
                 }
 
-
-                if (!strcmp(b, "R")||!strcmp(b, "X")||!strcmp(b,"U"))
+                if (!strcmp(ch_gb.buffer, "R") ||
+                    !strcmp(ch_gb.buffer, "X") ||
+                    !strcmp(ch_gb.buffer, "U"))
                     channel_index = 0;
-                else if (!strcmp(b, "G")||!strcmp(b, "Y")||!strcmp(b,"V"))
+                else if (!strcmp(ch_gb.buffer, "G") ||
+                         !strcmp(ch_gb.buffer, "Y") ||
+                         !strcmp(ch_gb.buffer, "V"))
                     channel_index = 1;
-                else if (!strcmp(b, "B")||!strcmp(b, "Z")||!strcmp(b,"W"))
+                else if (!strcmp(ch_gb.buffer, "B") ||
+                         !strcmp(ch_gb.buffer, "Z") ||
+                         !strcmp(ch_gb.buffer, "W"))
                     channel_index = 2;
-                else if (!strcmp(b, "A"))
+                else if (!strcmp(ch_gb.buffer, "A"))
                     channel_index = 3;
                 else
-                    av_log(avctx, AV_LOG_WARNING, "Unsupported channel %.256s\n", buf);
+                    av_log(s->avctx, AV_LOG_WARNING,
+                           "Unsupported channel %.256s.\n", ch_gb.buffer);
 
-                while (bytestream_get_byte(&buf) && buf < channel_list_end)
-                    continue; /* skip */
+                /* skip until you get a 0 */
+                while (bytestream2_get_bytes_left(&ch_gb) > 0 &&
+                       bytestream2_get_byte(&ch_gb))
+                    continue;
 
-                if (channel_list_end - * &buf < 4) {
-                    av_log(avctx, AV_LOG_ERROR, "Incomplete header\n");
+                if (bytestream2_get_bytes_left(&ch_gb) < 4) {
+                    av_log(s->avctx, AV_LOG_ERROR, "Incomplete header.\n");
                     return AVERROR_INVALIDDATA;
                 }
 
-                current_pixel_type = bytestream_get_le32(&buf);
-                if (current_pixel_type > 2) {
-                    av_log(avctx, AV_LOG_ERROR, "Unknown pixel type\n");
-                    return AVERROR_INVALIDDATA;
+                current_pixel_type = bytestream2_get_le32(&ch_gb);
+                if (current_pixel_type >= EXR_UNKNOWN) {
+                    avpriv_report_missing_feature(s->avctx,
+                                                  "Pixel type %d.\n",
+                                                  current_pixel_type);
+                    return AVERROR_PATCHWELCOME;
                 }
 
-                buf += 4;
-                xsub = bytestream_get_le32(&buf);
-                ysub = bytestream_get_le32(&buf);
+                bytestream2_skip(&ch_gb, 4);
+                xsub = bytestream2_get_le32(&ch_gb);
+                ysub = bytestream2_get_le32(&ch_gb);
                 if (xsub != 1 || ysub != 1) {
-                    avpriv_report_missing_feature(avctx, "Subsampling %dx%d", xsub, ysub);
+                    avpriv_report_missing_feature(s->avctx,
+                                                  "Subsampling %dx%d",
+                                                  xsub, ysub);
                     return AVERROR_PATCHWELCOME;
                 }
 
                 if (channel_index >= 0) {
-                    if (s->pixel_type != -1 && s->pixel_type != current_pixel_type) {
-                        av_log(avctx, AV_LOG_ERROR, "RGB channels not of the same depth\n");
+                    if (s->pixel_type != EXR_UNKNOWN &&
+                        s->pixel_type != current_pixel_type) {
+                        av_log(s->avctx, AV_LOG_ERROR,
+                               "RGB channels not of the same depth.\n");
                         return AVERROR_INVALIDDATA;
                     }
-                    s->pixel_type = current_pixel_type;
+                    s->pixel_type                     = current_pixel_type;
                     s->channel_offsets[channel_index] = current_channel_offset;
                 }
 
-                s->channels = av_realloc_f(s->channels, ++s->nb_channels, sizeof(EXRChannel));
+                s->channels = av_realloc(s->channels,
+                                         ++s->nb_channels * sizeof(EXRChannel));
                 if (!s->channels)
                     return AVERROR(ENOMEM);
-                channel = &s->channels[s->nb_channels - 1];
+                channel             = &s->channels[s->nb_channels - 1];
                 channel->pixel_type = current_pixel_type;
-                channel->xsub = xsub;
-                channel->ysub = ysub;
+                channel->xsub       = xsub;
+                channel->ysub       = ysub;
 
                 current_channel_offset += 1 << current_pixel_type;
             }
 
             /* Check if all channels are set with an offset or if the channels
              * are causing an overflow  */
-
             if (FFMIN3(s->channel_offsets[0],
                        s->channel_offsets[1],
                        s->channel_offsets[2]) < 0) {
                 if (s->channel_offsets[0] < 0)
-                    av_log(avctx, AV_LOG_ERROR, "Missing red channel\n");
+                    av_log(s->avctx, AV_LOG_ERROR, "Missing red channel.\n");
                 if (s->channel_offsets[1] < 0)
-                    av_log(avctx, AV_LOG_ERROR, "Missing green channel\n");
+                    av_log(s->avctx, AV_LOG_ERROR, "Missing green channel.\n");
                 if (s->channel_offsets[2] < 0)
-                    av_log(avctx, AV_LOG_ERROR, "Missing blue channel\n");
+                    av_log(s->avctx, AV_LOG_ERROR, "Missing blue channel.\n");
                 return AVERROR_INVALIDDATA;
             }
 
-            buf = channel_list_end;
+            // skip one last byte and update main gb
+            s->gb.buffer = ch_gb.buffer + 1;
             continue;
-        } else if (check_header_variable(avctx, &buf, buf_end, "dataWindow", "box2i", 31, &variable_buffer_data_size) >= 0) {
-            if (!variable_buffer_data_size)
+        } else if ((var_size = check_header_variable(s, "dataWindow", "box2i",
+                                                     31)) >= 0) {
+            if (!var_size)
                 return AVERROR_INVALIDDATA;
 
-            s->xmin = AV_RL32(buf);
-            s->ymin = AV_RL32(buf + 4);
-            s->xmax = AV_RL32(buf + 8);
-            s->ymax = AV_RL32(buf + 12);
+            s->xmin   = bytestream2_get_le32(&s->gb);
+            s->ymin   = bytestream2_get_le32(&s->gb);
+            s->xmax   = bytestream2_get_le32(&s->gb);
+            s->ymax   = bytestream2_get_le32(&s->gb);
             s->xdelta = (s->xmax - s->xmin) + 1;
             s->ydelta = (s->ymax - s->ymin) + 1;
 
-            buf += variable_buffer_data_size;
             continue;
-        } else if (check_header_variable(avctx, &buf, buf_end, "displayWindow", "box2i", 34, &variable_buffer_data_size) >= 0) {
-            if (!variable_buffer_data_size)
+        } else if ((var_size = check_header_variable(s, "displayWindow",
+                                                     "box2i", 34)) >= 0) {
+            if (!var_size)
                 return AVERROR_INVALIDDATA;
 
-            w = AV_RL32(buf + 8) + 1;
-            h = AV_RL32(buf + 12) + 1;
+            bytestream2_skip(&s->gb, 8);
+            s->w = bytestream2_get_le32(&s->gb) + 1;
+            s->h = bytestream2_get_le32(&s->gb) + 1;
 
-            buf += variable_buffer_data_size;
             continue;
-        } else if (check_header_variable(avctx, &buf, buf_end, "lineOrder", "lineOrder", 25, &variable_buffer_data_size) >= 0) {
-            if (!variable_buffer_data_size)
+        } else if ((var_size = check_header_variable(s, "lineOrder",
+                                                     "lineOrder", 25)) >= 0) {
+            int line_order;
+            if (!var_size)
                 return AVERROR_INVALIDDATA;
 
-            av_log(avctx, AV_LOG_DEBUG, "line order : %d\n", *buf);
-            if (*buf > 2) {
-                av_log(avctx, AV_LOG_ERROR, "Unknown line order\n");
+            line_order = bytestream2_get_byte(&s->gb);
+            av_log(s->avctx, AV_LOG_DEBUG, "line order: %d.\n", line_order);
+            if (line_order > 2) {
+                av_log(s->avctx, AV_LOG_ERROR, "Unknown line order.\n");
                 return AVERROR_INVALIDDATA;
             }
 
-            buf += variable_buffer_data_size;
             continue;
-        } else if (check_header_variable(avctx, &buf, buf_end, "pixelAspectRatio", "float", 31, &variable_buffer_data_size) >= 0) {
-            if (!variable_buffer_data_size)
+        } else if ((var_size = check_header_variable(s, "pixelAspectRatio",
+                                                     "float", 31)) >= 0) {
+            if (!var_size)
                 return AVERROR_INVALIDDATA;
 
-            avctx->sample_aspect_ratio = av_d2q(av_int2float(AV_RL32(buf)), 255);
+            s->avctx->sample_aspect_ratio =
+                av_d2q(av_int2float(bytestream2_get_le32(&s->gb)), 255);
 
-            buf += variable_buffer_data_size;
             continue;
-        } else if (check_header_variable(avctx, &buf, buf_end, "compression", "compression", 29, &variable_buffer_data_size) >= 0) {
-            if (!variable_buffer_data_size)
+        } else if ((var_size = check_header_variable(s, "compression",
+                                                     "compression", 29)) >= 0) {
+            if (!var_size)
                 return AVERROR_INVALIDDATA;
 
-            if (s->compr == -1)
-                s->compr = *buf;
+            if (s->compression == EXR_UNKN)
+                s->compression = bytestream2_get_byte(&s->gb);
             else
-                av_log(avctx, AV_LOG_WARNING, "Found more than one compression attribute\n");
+                av_log(s->avctx, AV_LOG_WARNING,
+                       "Found more than one compression attribute.\n");
 
-            buf += variable_buffer_data_size;
             continue;
         }
 
-        // Check if there is enough bytes for a header
-        if (buf_end - buf <= 9) {
-            av_log(avctx, AV_LOG_ERROR, "Incomplete header\n");
+        // Check if there are enough bytes for a header
+        if (bytestream2_get_bytes_left(&s->gb) <= 9) {
+            av_log(s->avctx, AV_LOG_ERROR, "Incomplete header\n");
             return AVERROR_INVALIDDATA;
         }
 
         // Process unknown variables
-        for (i = 0; i < 2; i++) {
-            // Skip variable name/type
-            while (++buf < buf_end)
-                if (buf[0] == 0x0)
-                    break;
-        }
-        buf++;
+        for (i = 0; i < 2; i++) // value_name and value_type
+            while (bytestream2_get_byte(&s->gb) != 0);
+
         // Skip variable length
-        if (buf_end - buf >= 5) {
-            variable_buffer_data_size = get_header_variable_length(&buf, buf_end);
-            if (!variable_buffer_data_size) {
-                av_log(avctx, AV_LOG_ERROR, "Incomplete header\n");
-                return AVERROR_INVALIDDATA;
-            }
-            buf += variable_buffer_data_size;
-        }
+        bytestream2_skip(&s->gb, bytestream2_get_le32(&s->gb));
     }
 
-    if (s->compr == -1) {
-        av_log(avctx, AV_LOG_ERROR, "Missing compression attribute\n");
+    if (s->compression == EXR_UNKN) {
+        av_log(s->avctx, AV_LOG_ERROR, "Missing compression attribute.\n");
         return AVERROR_INVALIDDATA;
     }
+    s->scan_line_size = s->xdelta * current_channel_offset;
 
-    if (buf >= buf_end) {
-        av_log(avctx, AV_LOG_ERROR, "Incomplete frame\n");
+    if (bytestream2_get_bytes_left(&s->gb) <= 0) {
+        av_log(s->avctx, AV_LOG_ERROR, "Incomplete frame.\n");
         return AVERROR_INVALIDDATA;
     }
-    buf++;
+
+    // aaand we are done
+    bytestream2_skip(&s->gb, 1);
+    return 0;
+}
+
+static int decode_frame(AVCodecContext *avctx, void *data,
+                        int *got_frame, AVPacket *avpkt)
+{
+    EXRContext *s = avctx->priv_data;
+    ThreadFrame frame = { .f = data };
+    AVFrame *picture = data;
+    uint8_t *ptr;
+
+    int y, ret;
+    int out_line_size;
+    int scan_line_blocks;
+
+    bytestream2_init(&s->gb, avpkt->data, avpkt->size);
+
+    if ((ret = decode_header(s)) < 0)
+        return ret;
 
     switch (s->pixel_type) {
     case EXR_FLOAT:
@@ -1193,11 +1184,11 @@ static int decode_frame(AVCodecContext *avctx,
         avpriv_request_sample(avctx, "32-bit unsigned int");
         return AVERROR_PATCHWELCOME;
     default:
-        av_log(avctx, AV_LOG_ERROR, "Missing channel list\n");
+        av_log(avctx, AV_LOG_ERROR, "Missing channel list.\n");
         return AVERROR_INVALIDDATA;
     }
 
-    switch (s->compr) {
+    switch (s->compression) {
     case EXR_RAW:
     case EXR_RLE:
     case EXR_ZIP1:
@@ -1211,49 +1202,41 @@ static int decode_frame(AVCodecContext *avctx,
         s->scan_lines_per_block = 32;
         break;
     default:
-        avpriv_report_missing_feature(avctx, "Compression %d", s->compr);
+        avpriv_report_missing_feature(avctx, "Compression %d", s->compression);
         return AVERROR_PATCHWELCOME;
     }
 
-    // Verify the xmin, xmax, ymin, ymax and xdelta before setting the actual image size
-    if (s->xmin > s->xmax ||
-        s->ymin > s->ymax ||
+    /* Verify the xmin, xmax, ymin, ymax and xdelta before setting
+     * the actual image size. */
+    if (s->xmin > s->xmax                  ||
+        s->ymin > s->ymax                  ||
         s->xdelta != s->xmax - s->xmin + 1 ||
-        s->xmax >= w || s->ymax >= h) {
-        av_log(avctx, AV_LOG_ERROR, "Wrong sizing or missing size information\n");
+        s->xmax >= s->w                    ||
+        s->ymax >= s->h) {
+        av_log(avctx, AV_LOG_ERROR, "Wrong or missing size information.\n");
         return AVERROR_INVALIDDATA;
     }
 
-    if ((ret = ff_set_dimensions(avctx, w, h)) < 0)
+    if ((ret = ff_set_dimensions(avctx, s->w, s->h)) < 0)
         return ret;
 
-    s->desc = av_pix_fmt_desc_get(avctx->pix_fmt);
-    out_line_size = avctx->width * 2 * s->desc->nb_components;
-    s->scan_line_size = s->xdelta * current_channel_offset;
-    scan_line_blocks = (s->ydelta + s->scan_lines_per_block - 1) / s->scan_lines_per_block;
-
-    if (s->compr != EXR_RAW) {
-        size_t thread_data_size, prev_size;
-        EXRThreadData *m;
-
-        prev_size = s->thread_data_size;
-        if (av_size_mult(avctx->thread_count, sizeof(EXRThreadData), &thread_data_size))
-            return AVERROR(EINVAL);
-
-        m = av_fast_realloc(s->thread_data, &s->thread_data_size, thread_data_size);
-        if (!m)
-            return AVERROR(ENOMEM);
-        s->thread_data = m;
-        memset(s->thread_data + prev_size, 0, s->thread_data_size - prev_size);
-    }
+    s->desc          = av_pix_fmt_desc_get(avctx->pix_fmt);
+    if (!s->desc)
+        return AVERROR_INVALIDDATA;
+    out_line_size    = avctx->width * 2 * s->desc->nb_components;
+    scan_line_blocks = (s->ydelta + s->scan_lines_per_block - 1) /
+                       s->scan_lines_per_block;
 
     if ((ret = ff_thread_get_buffer(avctx, &frame, 0)) < 0)
         return ret;
 
-    if (buf_end - buf < scan_line_blocks * 8)
+    if (bytestream2_get_bytes_left(&s->gb) < scan_line_blocks * 8)
         return AVERROR_INVALIDDATA;
-    s->table = buf;
-    ptr = picture->data[0];
+
+    // save pointer we are going to use in decode_block
+    s->buf      = avpkt->data;
+    s->buf_size = avpkt->size;
+    ptr         = picture->data[0];
 
     // Zero out the start if ymin is not 0
     for (y = 0; y < s->ymin; y++) {
@@ -1273,15 +1256,54 @@ static int decode_frame(AVCodecContext *avctx,
     picture->pict_type = AV_PICTURE_TYPE_I;
     *got_frame = 1;
 
-    return buf_size;
+    return avpkt->size;
+}
+
+static av_cold int decode_init(AVCodecContext *avctx)
+{
+    EXRContext *s = avctx->priv_data;
+
+    s->avctx              = avctx;
+    s->xmin               = ~0;
+    s->xmax               = ~0;
+    s->ymin               = ~0;
+    s->ymax               = ~0;
+    s->xdelta             = ~0;
+    s->ydelta             = ~0;
+    s->channel_offsets[0] = -1;
+    s->channel_offsets[1] = -1;
+    s->channel_offsets[2] = -1;
+    s->channel_offsets[3] = -1;
+    s->pixel_type         = EXR_UNKNOWN;
+    s->compression        = EXR_UNKN;
+    s->nb_channels        = 0;
+    s->w                  = 0;
+    s->h                  = 0;
+
+    // allocate thread data, used for non EXR_RAW compreesion types
+    s->thread_data = av_mallocz_array(avctx->thread_count, sizeof(EXRThreadData));
+    if (!s->thread_data)
+        return AVERROR_INVALIDDATA;
+
+    return 0;
+}
+
+static int decode_init_thread_copy(AVCodecContext *avctx)
+{    EXRContext *s = avctx->priv_data;
+
+    // allocate thread data, used for non EXR_RAW compreesion types
+    s->thread_data = av_mallocz_array(avctx->thread_count, sizeof(EXRThreadData));
+    if (!s->thread_data)
+        return AVERROR_INVALIDDATA;
+
+    return 0;
 }
 
 static av_cold int decode_end(AVCodecContext *avctx)
 {
     EXRContext *s = avctx->priv_data;
     int i;
-
-    for (i = 0; i < s->thread_data_size / sizeof(EXRThreadData); i++) {
+    for (i = 0; i < avctx->thread_count; i++) {
         EXRThreadData *td = &s->thread_data[i];
         av_freep(&td->uncompressed_data);
         av_freep(&td->tmp);
@@ -1290,20 +1312,37 @@ static av_cold int decode_end(AVCodecContext *avctx)
     }
 
     av_freep(&s->thread_data);
-    s->thread_data_size = 0;
     av_freep(&s->channels);
 
     return 0;
 }
 
+#define OFFSET(x) offsetof(EXRContext, x)
+#define VD AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_DECODING_PARAM
+static const AVOption options[] = {
+    { "layer", "Set the decoding layer", OFFSET(layer),
+        AV_OPT_TYPE_STRING, { .str = "" }, 0, 0, VD },
+    { NULL },
+};
+
+static const AVClass exr_class = {
+    .class_name = "EXR",
+    .item_name  = av_default_item_name,
+    .option     = options,
+    .version    = LIBAVUTIL_VERSION_INT,
+};
+
 AVCodec ff_exr_decoder = {
-    .name               = "exr",
-    .long_name          = NULL_IF_CONFIG_SMALL("OpenEXR image"),
-    .type               = AVMEDIA_TYPE_VIDEO,
-    .id                 = AV_CODEC_ID_EXR,
-    .priv_data_size     = sizeof(EXRContext),
-    .close              = decode_end,
-    .decode             = decode_frame,
-    .capabilities       = CODEC_CAP_DR1 | CODEC_CAP_FRAME_THREADS | CODEC_CAP_SLICE_THREADS,
-    .priv_class         = &exr_class,
+    .name             = "exr",
+    .long_name        = NULL_IF_CONFIG_SMALL("OpenEXR image"),
+    .type             = AVMEDIA_TYPE_VIDEO,
+    .id               = AV_CODEC_ID_EXR,
+    .priv_data_size   = sizeof(EXRContext),
+    .init             = decode_init,
+    .init_thread_copy = ONLY_IF_THREADS_ENABLED(decode_init_thread_copy),
+    .close            = decode_end,
+    .decode           = decode_frame,
+    .capabilities     = CODEC_CAP_DR1 | CODEC_CAP_FRAME_THREADS |
+                        CODEC_CAP_SLICE_THREADS,
+    .priv_class       = &exr_class,
 };