AC-3 decoder, soc revision 40, Aug 9 00:10:14 2006 UTC by cloud9

More code cleanup.
Window is now runtime generated.
Fixed the bugs in rematrixing routine and
in Decoding AC3 Bitstreams when coupling is in use.

Still struggling to find out what affects the quality of
the produced sound. Can anybody have a look at the
imdct routines do_imdct_256 and do_imdct_512 and tell me
whether it is the correctly implemented as described in
standard.

Originally committed as revision 9658 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 173 insertions, 174 deletions

diff --git a/libavcodec/ac3dec.c b/libavcodec/ac3dec.c
index c26b8f6700..18328b1fad 100644
--- a/libavcodec/ac3dec.c
+++ b/libavcodec/ac3dec.c
@@ -219,6 +219,51 @@ static inline int16_t dither_int16(dither_state *state)
 
 /* END Mersenne Twister */
 
+/**
+ * Generate a Kaiser Window.
+ */
+static void
+k_window_init(int alpha, double *window, int n, int iter)
+{
+    int j, k;
+    double a, x;
+    a = alpha * M_PI / n;
+    a = a*a;
+    for(k=0; k<n; k++) {
+        x = k * (n - k) * a;
+        window[k] = 1.0;
+        for(j=iter; j>0; j--) {
+            window[k] = (window[k] * x / (j*j)) + 1.0;
+        }
+    }
+}
+
+/**
+ * Generate a Kaiser-Bessel Derived Window.
+ * @param alpha  determines window shape
+ * @param window array to fill with window values
+ * @param n      length of the window
+ * @param iter   number of iterations to use in BesselI0
+ */
+static void
+kbd_window_init(int alpha, double *window, int n, int iter)
+{
+    int k, n2;
+    double *kwindow;
+
+    n2 = n >> 1;
+    kwindow = &window[n2];
+    k_window_init(alpha, kwindow, n2, iter);
+    window[0] = kwindow[0];
+    for(k=1; k<n2; k++) {
+        window[k] = window[k-1] + kwindow[k];
+    }
+    for(k=0; k<n2; k++) {
+        window[k] = sqrt(window[k] / (window[n2-1]+1));
+        window[n-1-k] = window[k];
+    }
+}
+
 static void generate_quantizers_table(int16_t quantizers[], int level, int length)
 {
     int i;
@@ -342,6 +387,9 @@ static void ac3_tables_init(void)
         x_cos2[i] = -cos(alpha);
         x_sin2[i] = -sin(alpha);
     }
+
+    /* Kaiser-Bessel derived window. */
+    kbd_window_init(5, window, 256, 100);
 }
 
 
@@ -374,8 +422,6 @@ static int ac3_parse_sync_info(AC3DecodeContext *ctx)
     GetBitContext *gb = &ctx->gb;
     int frmsizecod, bsid;
 
-    memset (ctx, sizeof (AC3DecodeContext), 0);
-
     skip_bits(gb, 16); //skip the sync_word, sync_info->sync_word = get_bits(gb, 16);
     ctx->crc1 = get_bits(gb, 16);
     ctx->fscod = get_bits(gb, 2);
@@ -471,7 +517,6 @@ static void ac3_parse_bsi(AC3DecodeContext *ctx)
 static int decode_exponents(GetBitContext *gb, int expstr, int ngrps, uint8_t absexp, uint8_t *dexps)
 {
     int exps;
-    av_log(NULL, AV_LOG_INFO, "%d\n", ngrps);
 
     while (ngrps--) {
         exps = get_bits(gb, 7);
@@ -530,7 +575,7 @@ static inline int logadd(int a, int b)
     int c = a - b;
     int address;
 
-    address = FFMIN(ABS(c) >> 1, 255);
+    address = FFMIN((ABS(c) >> 1), 255);
 
     if (c >= 0)
         return (a + latab[address]);
@@ -544,16 +589,16 @@ static inline int calc_lowcomp(int a, int b0, int b1, int bin)
         if ((b0 + 256) == b1)
             a = 384;
         else if (b0 > b1)
-            a = FFMAX(0, a - 64);
+            a = FFMAX(0, (a - 64));
     }
     else if (bin < 20) {
         if ((b0 + 256) == b1)
             a = 320;
         else if (b0 > b1)
-            a = FFMAX(0, a - 64);
+            a = FFMAX(0, (a - 64));
     }
     else
-        a = FFMAX(0, a - 128);
+        a = FFMAX(0, (a - 128));
 
     return a;
 }
@@ -563,17 +608,16 @@ static inline int calc_lowcomp(int a, int b0, int b1, int bin)
  * chnl = 5 coupling channel
  * chnl = 6 lfe channel
  */
-static void do_bit_allocation1(AC3DecodeContext *ctx, int chnl)
+static void do_bit_allocation(AC3DecodeContext *ctx, int chnl)
 {
+    int16_t psd[256], bndpsd[50], excite[50], mask[50], delta;
     int sdecay, fdecay, sgain, dbknee, floor;
-    int lowcomp = 0, fgain = 0, snroffset = 0, fastleak = 0, slowleak = 0;
-    int psd[256], bndpsd[50], excite[50], mask[50], delta;
+    int lowcomp = 0, fgain = 0, snroffset = 0, fastleak = 0, slowleak = 0, do_delta = 0;
     int start = 0, end = 0, bin = 0, i = 0, j = 0, k = 0, lastbin = 0, bndstrt = 0;
     int bndend = 0, begin = 0, deltnseg = 0, band = 0, seg = 0, address = 0;
     int fscod = ctx->fscod;
-    uint8_t *exps, *deltoffst = 0, *deltlen = 0, *deltba = 0;
-    uint8_t *baps;
-    int do_delta = 0;
+    uint8_t *deltoffst = 0, *deltlen = 0, *deltba = 0;
+    uint8_t *exps = 0, *bap = 0;
 
     /* initialization */
     sdecay = sdecaytab[ctx->sdcycod];
@@ -590,8 +634,8 @@ static void do_bit_allocation1(AC3DecodeContext *ctx, int chnl)
         fastleak = (ctx->cplfleak << 8) + 768;
         slowleak = (ctx->cplsleak << 8) + 768;
         exps = ctx->dcplexps;
-        baps = ctx->cplbap;
-        if (ctx->cpldeltbae == AC3_DBASTR_NEW) {
+        bap = ctx->cplbap;
+        if (ctx->cpldeltbae == AC3_DBASTR_NEW || ctx->deltbae == AC3_DBASTR_REUSE) {
             do_delta = 1;
             deltnseg = ctx->cpldeltnseg;
             deltoffst = ctx->cpldeltoffst;
@@ -608,7 +652,7 @@ static void do_bit_allocation1(AC3DecodeContext *ctx, int chnl)
         fgain = fgaintab[ctx->lfefgaincod];
         snroffset = (((ctx->csnroffst - 15) << 4) + ctx->lfefsnroffst) << 2;
         exps = ctx->dlfeexps;
-        baps = ctx->lfebap;
+        bap = ctx->lfebap;
     }
     else {
         start = 0;
@@ -619,8 +663,8 @@ static void do_bit_allocation1(AC3DecodeContext *ctx, int chnl)
         fgain = fgaintab[ctx->fgaincod[chnl]];
         snroffset = (((ctx->csnroffst - 15) << 4) + ctx->fsnroffst[chnl]) << 2;
         exps = ctx->dexps[chnl];
-        baps = ctx->bap[chnl];
-        if (ctx->deltbae[chnl] == AC3_DBASTR_NEW) {
+        bap = ctx->bap[chnl];
+        if (ctx->deltbae[chnl] == AC3_DBASTR_NEW || ctx->deltbae[chnl] == AC3_DBASTR_REUSE) {
             do_delta = 1;
             deltnseg = ctx->deltnseg[chnl];
             deltoffst = ctx->deltoffst[chnl];
@@ -630,13 +674,13 @@ static void do_bit_allocation1(AC3DecodeContext *ctx, int chnl)
     }
 
     for (bin = start; bin < end; bin++) /* exponent mapping into psd */
-        psd[bin] = (3072 - ((int)(exps[bin]) << 7));
+        psd[bin] = (3072 - (exps[bin] << 7));
 
     /* psd integration */
     j = start;
     k = masktab[start];
     do {
-        lastbin = FFMIN(bndtab[k] + bndsz[k], end);
+        lastbin = FFMIN((bndtab[k] + bndsz[k]), end);
         bndpsd[k] = psd[j];
         j++;
         for (i = j; i < lastbin; i++) {
@@ -656,25 +700,25 @@ static void do_bit_allocation1(AC3DecodeContext *ctx, int chnl)
         excite[1] = bndpsd[1] - fgain - lowcomp;
         begin = 7;
         for (bin = 2; bin < 7; bin++) {
-            if (!(chnl == 6 && bin == 6))
+            if ((bndend != 7) || (bin != 6))
                 lowcomp = calc_lowcomp(lowcomp, bndpsd[bin], bndpsd[bin + 1], bin);
             fastleak = bndpsd[bin] - fgain;
             slowleak = bndpsd[bin] - sgain;
             excite[bin] = fastleak - lowcomp;
-            if (!(chnl == 6 && bin == 6))
+            if ((bndend != 7) || (bin != 6))
                 if (bndpsd[bin] <= bndpsd[bin + 1]) {
                     begin = bin + 1;
                     break;
                 }
         }
         for (bin = begin; bin < FFMIN(bndend, 22); bin++) {
-            if (!(chnl == 6 && bin == 6))
+            if ((bndend != 7) || (bin != 6))
                 lowcomp = calc_lowcomp(lowcomp, bndpsd[bin], bndpsd[bin + 1], bin);
             fastleak -= fdecay;
-            fastleak = FFMAX(fastleak, bndpsd[bin] - fgain);
+            fastleak = FFMAX(fastleak, (bndpsd[bin] - fgain));
             slowleak -= sdecay;
-            slowleak = FFMAX(slowleak, bndpsd[bin] - sgain);
-            excite[bin] = FFMAX(fastleak - lowcomp, slowleak);
+            slowleak = FFMAX(slowleak, (bndpsd[bin] - sgain));
+            excite[bin] = FFMAX((fastleak - lowcomp), slowleak);
         }
         begin = 22;
     }
@@ -683,9 +727,9 @@ static void do_bit_allocation1(AC3DecodeContext *ctx, int chnl)
     }
     for (bin = begin; bin < bndend; bin++) {
         fastleak -= fdecay;
-        fastleak = FFMAX(fastleak, bndpsd[bin] - fgain);
+        fastleak = FFMAX(fastleak, (bndpsd[bin] - fgain));
         slowleak -= sdecay;
-        slowleak = FFMAX(slowleak, bndpsd[bin] - sgain);
+        slowleak = FFMAX(slowleak, (bndpsd[bin] - sgain));
         excite[bin] = FFMAX(fastleak, slowleak);
     }
 
@@ -700,12 +744,12 @@ static void do_bit_allocation1(AC3DecodeContext *ctx, int chnl)
     if (do_delta) {
         band = 0;
         for (seg = 0; seg < deltnseg + 1; seg++) {
-            band += (int)(deltoffst[seg]);
-            if ((int)(deltba[seg]) >= 4)
-                delta = ((int)(deltba[seg]) - 3) << 7;
+            band += deltoffst[seg];
+            if (deltba[seg] >= 4)
+                delta = (deltba[seg] - 3) << 7;
             else
-                delta = ((int)(deltba[seg]) - 4) << 7;
-            for (k = 0; k < (int)(deltlen[seg]); k++) {
+                delta = (deltba[seg] - 4) << 7;
+            for (k = 0; k < deltlen[seg]; k++) {
                 mask[band] += delta;
                 band++;
             }
@@ -716,7 +760,7 @@ static void do_bit_allocation1(AC3DecodeContext *ctx, int chnl)
     i = start;
     j = masktab[start];
     do {
-        lastbin = FFMIN(bndtab[j] + bndsz[j], end);
+        lastbin = FFMIN((bndtab[j] + bndsz[j]), end);
         mask[j] -= snroffset;
         mask[j] -= floor;
         if (mask[j] < 0)
@@ -725,48 +769,28 @@ static void do_bit_allocation1(AC3DecodeContext *ctx, int chnl)
         mask[j] += floor;
         for (k = i; k < lastbin; k++) {
             address = (psd[i] - mask[j]) >> 5;
-            address = FFMIN(63, FFMAX(0, address));
-            baps[i] = baptab[address];
+            address = FFMIN(63, (FFMAX(0, address)));
+            bap[i] = baptab[address];
             i++;
         }
         j++;
     } while (end > lastbin);
 }
 
-static void do_bit_allocation(AC3DecodeContext *ctx, int flags)
+/* Check if snroffsets are zero. */
+static int is_snr_offsets_zero(AC3DecodeContext *ctx)
 {
-    int i, zerosnroffst = 1;
-
-    if (!flags) /* bit allocation is not required */
-        return;
+    int i;
 
-    /* Check if snroffsets are zero. */
-    if ((ctx->csnroffst) || (ctx->chincpl && ctx->cplfsnroffst) ||
+    if ((ctx->csnroffst) || (ctx->cplinu && ctx->cplfsnroffst) ||
             (ctx->lfeon && ctx->lfefsnroffst))
-        zerosnroffst = 0;
-    if (zerosnroffst)
-        for (i = 0; i < ctx->nfchans; i++)
-            if (ctx->fsnroffst[i]) {
-                zerosnroffst = 0;
-                break;
-            }
-
-    if (zerosnroffst) {
-        memset(ctx->cplbap, 0, sizeof (ctx->cplbap));
-        for (i = 0; i < ctx->nfchans; i++)
-            memset(ctx->bap[i], 0, sizeof (ctx->bap[i]));
-        memset(ctx->lfebap, 0, sizeof (ctx->lfebap));
-        return;
-    }
+        return 0;
 
-    /* perform bit allocation */
-    if (ctx->cplinu && (flags & 64))
-        do_bit_allocation1(ctx, 5);
     for (i = 0; i < ctx->nfchans; i++)
-        if (flags & (1 << i))
-            do_bit_allocation1(ctx, i);
-    if (ctx->lfeon && (flags & 32))
-        do_bit_allocation1(ctx, 6);
+        if (ctx->fsnroffst[i])
+            return 0;
+
+    return 1;
 }
 
 typedef struct { /* grouped mantissas for 3-level 5-leve and 11-level quantization */
@@ -776,7 +800,6 @@ typedef struct { /* grouped mantissas for 3-level 5-leve and 11-level quantizati
     int l3ptr;
     int l5ptr;
     int l11ptr;
-    int bits;
 } mant_groups;
 
 #define TRANSFORM_COEFF(tc, m, e, f) (tc) = (m) * (f)[(e)]
@@ -789,13 +812,11 @@ typedef struct { /* grouped mantissas for 3-level 5-leve and 11-level quantizati
 static int get_transform_coeffs_cpling(AC3DecodeContext *ctx, mant_groups *m)
 {
     GetBitContext *gb = &ctx->gb;
-    int ch, bin, start, end, cplbndstrc, bnd, gcode, tbap;
+    int ch, start, end, cplbndstrc, bnd, gcode, tbap;
     float cplcos[5], cplcoeff;
     uint8_t *exps = ctx->dcplexps;
     uint8_t *bap = ctx->cplbap;
 
-    int bits_consumed = m->bits;
-
     cplbndstrc = ctx->cplbndstrc;
     start = ctx->cplstrtmant;
     bnd = 0;
@@ -815,9 +836,9 @@ static int get_transform_coeffs_cpling(AC3DecodeContext *ctx, mant_groups *m)
             tbap = bap[start];
             switch(tbap) {
                 case 0:
-                    for (ch = 0; ch < ctx->nfchans; ctx++)
+                    for (ch = 0; ch < ctx->nfchans; ch++)
                         if (((ctx->chincpl) >> ch) & 1) {
-                            if (((ctx->dithflag) >> ch) & 1) {
+                            if (!(((ctx->dithflag) >> ch) & 1)) {
                                 TRANSFORM_COEFF(cplcoeff, dither_int16(&ctx->dith_state), exps[start], scale_factors);
                                 ctx->transform_coeffs[ch + 1][start] = cplcoeff * cplcos[ch];
                             } else
@@ -828,13 +849,10 @@ static int get_transform_coeffs_cpling(AC3DecodeContext *ctx, mant_groups *m)
                 case 1:
                     if (m->l3ptr > 2) {
                         gcode = get_bits(gb, 5);
-                        /*if (gcode > 26)
-                            return -1;*/
                         m->l3_quantizers[0] = l3_quantizers_1[gcode];
                         m->l3_quantizers[1] = l3_quantizers_2[gcode];
                         m->l3_quantizers[2] = l3_quantizers_3[gcode];
                         m->l3ptr = 0;
-                        m->bits += 5;
                     }
                     TRANSFORM_COEFF(cplcoeff, m->l3_quantizers[m->l3ptr++], exps[start], scale_factors);
                     break;
@@ -842,89 +860,84 @@ static int get_transform_coeffs_cpling(AC3DecodeContext *ctx, mant_groups *m)
                 case 2:
                     if (m->l5ptr > 2) {
                         gcode = get_bits(gb, 7);
-                        /*if (gcode > 124)
-                            return -1;*/
                         m->l5_quantizers[0] = l5_quantizers_1[gcode];
                         m->l5_quantizers[1] = l5_quantizers_2[gcode];
                         m->l5_quantizers[2] = l5_quantizers_3[gcode];
                         m->l5ptr = 0;
-                        m->bits += 7;
                     }
                     TRANSFORM_COEFF(cplcoeff, m->l5_quantizers[m->l5ptr++], exps[start], scale_factors);
                     break;
 
                 case 3:
-                    gcode = get_bits(gb, 3);
-                    /*if (gcode > 6)
-                        return -1;*/
-                    m->bits += 3;
-                    TRANSFORM_COEFF(cplcoeff, l7_quantizers[gcode], exps[start], scale_factors);
+                    TRANSFORM_COEFF(cplcoeff, l7_quantizers[get_bits(gb, 3)], exps[start], scale_factors);
                     break;
 
                 case 4:
                     if (m->l11ptr > 1) {
                         gcode = get_bits(gb, 7);
-                        /*if (gcode > 120)
-                            return -1;*/
                         m->l11_quantizers[0] = l11_quantizers_1[gcode];
                         m->l11_quantizers[1] = l11_quantizers_2[gcode];
                         m->l11ptr = 0;
-                        m->bits += 7;
                     }
                     TRANSFORM_COEFF(cplcoeff, m->l11_quantizers[m->l11ptr++], exps[start], scale_factors);
                     break;
 
                 case 5:
-                    gcode = get_bits(gb, 4);
-                    /*if (gcode > 14)
-                        return -1;*/
-                    m->bits += 4;
-                    TRANSFORM_COEFF(cplcoeff, l15_quantizers[gcode], exps[start], scale_factors);
+                    TRANSFORM_COEFF(cplcoeff, l15_quantizers[get_bits(gb, 4)], exps[start], scale_factors);
                     break;
 
                 default:
-                    m->bits += qntztab[bap[bin]];
                     TRANSFORM_COEFF(cplcoeff, get_bits(gb, qntztab[tbap]) << (16 - qntztab[tbap]),
-                            exps[bin], scale_factors);
+                            exps[start], scale_factors);
             }
             for (ch = 0; ch < ctx->nfchans; ch++)
                 if ((ctx->chincpl >> ch) & 1)
-                    ctx->transform_coeffs[ch][bin] = cplcoeff * cplcos[ch];
+                    ctx->transform_coeffs[ch + 1][start] = cplcoeff * cplcos[ch];
             start++;
         }
     }
 
-    bits_consumed = m->bits - bits_consumed;
-    av_log(NULL, AV_LOG_INFO, "\tbits consumed by coupling = %d\n", bits_consumed);
-
     return 0;
 }
 
 /* Get the transform coefficients for particular channel */
-static int get_transform_coeffs_ch(uint8_t *exps, uint8_t *bap, float chcoeff,
-        float *coeffs, int start, int end, int dith_flag, GetBitContext *gb,
-        dither_state *state, mant_groups *m)
+static int get_transform_coeffs_ch(AC3DecodeContext *ctx, int ch_index, mant_groups *m)
 {
-    int i;
-    int gcode;
-    int tbap;
+    GetBitContext *gb = &ctx->gb;
+    int i, gcode, tbap, dithflag, end;
+    uint8_t *exps;
+    uint8_t *bap;
+    float *coeffs;
     float factors[25];
 
-    int bits_consumed = m->bits;
-
     for (i = 0; i < 25; i++)
-        factors[i] = scale_factors[i] * chcoeff;
+        factors[i] = scale_factors[i] * ctx->chcoeffs[ch_index];
+
+    if (ch_index != -1) { /* fbw channels */
+        dithflag = (ctx->dithflag >> ch_index) & 1;
+        exps = ctx->dexps[ch_index];
+        bap = ctx->bap[ch_index];
+        coeffs = ctx->transform_coeffs[ch_index + 1];
+        end = ctx->endmant[ch_index];
+    } else if (ch_index == -1) {
+        dithflag = 0;
+        exps = ctx->dlfeexps;
+        bap = ctx->lfebap;
+        coeffs = ctx->transform_coeffs[0];
+        end = 7;
+    }
 
-    for (i = start; i < end; i++) {
+
+    for (i = 0; i < end; i++) {
         tbap = bap[i];
         switch (tbap) {
             case 0:
-                if (!dith_flag) {
+                if (dithflag) {
                     coeffs[i] = 0;
                     continue;
                 }
                 else {
-                    TRANSFORM_COEFF(coeffs[i], dither_int16(state), exps[i], factors);
+                    TRANSFORM_COEFF(coeffs[i], dither_int16(&ctx->dith_state), exps[i], factors);
                     coeffs[i] *= LEVEL_PLUS_3DB;
                     continue;
                 }
@@ -932,13 +945,10 @@ static int get_transform_coeffs_ch(uint8_t *exps, uint8_t *bap, float chcoeff,
             case 1:
                 if (m->l3ptr > 2) {
                     gcode = get_bits(gb, 5);
-                    /*if (gcode > 26)
-                        return -1;*/
                     m->l3_quantizers[0] = l3_quantizers_1[gcode];
                     m->l3_quantizers[1] = l3_quantizers_2[gcode];
                     m->l3_quantizers[2] = l3_quantizers_3[gcode];
                     m->l3ptr = 0;
-                    m->bits += 5;
                 }
                 TRANSFORM_COEFF(coeffs[i], m->l3_quantizers[m->l3ptr++], exps[i], factors);
                 continue;
@@ -946,56 +956,38 @@ static int get_transform_coeffs_ch(uint8_t *exps, uint8_t *bap, float chcoeff,
             case 2:
                 if (m->l5ptr > 2) {
                     gcode = get_bits(gb, 7);
-                    /*if (gcode > 124)
-                        return -1;*/
                     m->l5_quantizers[0] = l5_quantizers_1[gcode];
                     m->l5_quantizers[1] = l5_quantizers_2[gcode];
                     m->l5_quantizers[2] = l5_quantizers_3[gcode];
                     m->l5ptr = 0;
-                    m->bits += 7;
                 }
                 TRANSFORM_COEFF(coeffs[i], m->l5_quantizers[m->l5ptr++], exps[i], factors);
                 continue;
 
             case 3:
-                gcode = get_bits(gb, 3);
-                /*if (gcode > 6)
-                    return -1; */
-                m->bits += 3;
-                TRANSFORM_COEFF(coeffs[i], l7_quantizers[gcode], exps[i], factors);
+                TRANSFORM_COEFF(coeffs[i], l7_quantizers[get_bits(gb, 3)], exps[i], factors);
                 continue;
 
             case 4:
                 if (m->l11ptr > 1) {
                     gcode = get_bits(gb, 7);
-                    /*if (gcode > 120)
-                        return -1;*/
                     m->l11_quantizers[0] = l11_quantizers_1[gcode];
                     m->l11_quantizers[1] = l11_quantizers_2[gcode];
                     m->l11ptr = 0;
-                    m->bits += 7;
                 }
                 TRANSFORM_COEFF(coeffs[i], m->l11_quantizers[m->l11ptr++], exps[i], factors);
                 continue;
 
             case 5:
-                gcode = get_bits(gb, 4);
-                /*if (gcode > 14)
-                    return -1;*/
-                m->bits += 4;
-                TRANSFORM_COEFF(coeffs[i], l15_quantizers[gcode], exps[i], factors);
+                TRANSFORM_COEFF(coeffs[i], l15_quantizers[get_bits(gb, 4)], exps[i], factors);
                 continue;
 
             default:
-                m->bits += qntztab[bap[i]];
                 TRANSFORM_COEFF(coeffs[i], get_bits(gb, qntztab[tbap]) << (16 - qntztab[tbap]), exps[i], factors);
                 continue;
         }
     }
 
-    bits_consumed = m->bits - bits_consumed;
-    av_log(NULL, AV_LOG_INFO, "\tbits consumed by channel = %d\n", bits_consumed);
-
     return 0;
 }
 
@@ -1003,17 +995,13 @@ static int get_transform_coeffs(AC3DecodeContext * ctx)
 {
     int i, end;
     int got_cplchan = 0;
-    int dithflag = 0;
     mant_groups m;
 
     m.l3ptr = m.l5ptr = m.l11ptr = 3;
-    m.bits = 0;
 
     for (i = 0; i < ctx->nfchans; i++) {
-        dithflag = (ctx->dithflag >> i) & 1;
         /* transform coefficients for individual channel */
-        if (get_transform_coeffs_ch(ctx->dexps[i], ctx->bap[i], ctx->chcoeffs[i], ctx->transform_coeffs[i + 1],
-                    0, ctx->endmant[i], dithflag, &ctx->gb, &ctx->dith_state, &m))
+        if (get_transform_coeffs_ch(ctx, i, &m))
             return -1;
         /* tranform coefficients for coupling channels */
         if ((ctx->chincpl >> i) & 1)  {
@@ -1032,15 +1020,13 @@ static int get_transform_coeffs(AC3DecodeContext * ctx)
         while(++end < 256);
     }
     if (ctx->lfeon) {
-        if (get_transform_coeffs_ch(ctx->dlfeexps, ctx->lfebap, 1.0f, ctx->transform_coeffs[0], 0, 7, 0, &ctx->gb, &ctx->dith_state, &m))
+        if (get_transform_coeffs_ch(ctx, -1, &m))
                 return -1;
         for (i = 7; i < 256; i++) {
             ctx->transform_coeffs[0][i] = 0;
         }
     }
 
-    av_log(NULL, AV_LOG_INFO, "bits consumed by get_transform_coeffs = %d\n", m.bits);
-
     return 0;
 }
 
@@ -1059,22 +1045,27 @@ static void do_rematrixing1(AC3DecodeContext *ctx, int start, int end)
 
 static void do_rematrixing(AC3DecodeContext *ctx)
 {
-    uint8_t bnd1 = 13, bnd2 = 25, bnd3 = 37, bnd4 = 61;
-    uint8_t bndend;
+    int bnd1 = 13, bnd2 = 25, bnd3 = 37, bnd4 = 61;
+    int end, bndend;
+
+    end = FFMIN(ctx->endmant[0], ctx->endmant[1]);
 
-    bndend = FFMIN(ctx->endmant[0], ctx->endmant[1]);
     if (ctx->rematflg & 1)
         do_rematrixing1(ctx, bnd1, bnd2);
+
     if (ctx->rematflg & 2)
         do_rematrixing1(ctx, bnd2, bnd3);
-    if (ctx->rematflg & 4) {
-        if (ctx->cplbegf > 0 && ctx->cplbegf <= 2 && (ctx->chincpl))
+
+    bndend = bnd4;
+    if (bndend > end) {
+        bndend = end;
+        if (ctx->rematflg & 4)
             do_rematrixing1(ctx, bnd3, bndend);
-        else {
+    } else {
+        if (ctx->rematflg & 4)
             do_rematrixing1(ctx, bnd3, bnd4);
-            if (ctx->rematflg & 8)
-                do_rematrixing1(ctx, bnd4, bndend);
-        }
+        if (ctx->rematflg & 8)
+            do_rematrixing1(ctx, bnd4, end);
     }
 }
 
@@ -1118,7 +1109,7 @@ static void get_downmix_coeffs(AC3DecodeContext *ctx)
                 case AC3_OUTPUT_MONO:
                     ctx->chcoeffs[0] *= LEVEL_MINUS_3DB;
                     ctx->chcoeffs[2] *= LEVEL_MINUS_3DB;
-                    ctx->chcoeffs[1] *= clev * LEVEL_PLUS_3DB;
+                    ctx->chcoeffs[1] *= (clev * LEVEL_PLUS_3DB);
                     break;
                 case AC3_OUTPUT_STEREO:
                     ctx->chcoeffs[1] *= clev;
@@ -1561,14 +1552,13 @@ static void do_imdct_256(FFTContext *fft_ctx, float *coeffs, float *output,
         CMUL(z2[k].re, z2[k].im, x2[n4 - 2 * k - 1], x2[2 * k], x_cos2[k], x_sin2[k]);
     }
 
-    /* Permutation needed before calling ff_fft_calc. */
-    ff_fft_permute(fft_ctx, z1);
-    ff_fft_permute(fft_ctx, z2);
-
     /* N/8 pointe complex IFFT. */
+    ff_fft_permute(fft_ctx, z1);
     ff_fft_calc(fft_ctx, z1);
+    ff_fft_permute(fft_ctx, z2);
     ff_fft_calc(fft_ctx, z2);
 
+
     /* Post IFFT Complex Multiply Step. */
     for (k = 0; k < n8; k++) {
         CMUL(z1[k].re, z1[k].im, z1[k].re, z1[k].im, x_cos2[k], x_sin2[k]);
@@ -1646,11 +1636,12 @@ static inline void do_imdct(AC3DecodeContext *ctx)
         do_imdct_512(&ctx->fft_128, ctx->transform_coeffs[0], ctx->output[0],
                 ctx->delay[0], ctx->tmp_imdct, ctx->tmp_output);
     }
-    for (i = 0; i < ctx->nfchans + 1; i++) {
-        if (!(((ctx->blksw) >> i) & 1)) {
+    for (i = 0; i < ctx->nfchans; i++) {
+        if (!((ctx->blksw >> i) & 1)) {
             do_imdct_512(&ctx->fft_128, ctx->transform_coeffs[i + 1], ctx->output[i + 1],
                     ctx->delay[i + 1], ctx->tmp_imdct, ctx->tmp_output);
         } else {
+            av_log(NULL, AV_LOG_INFO, "block switching enabled.\n");
             do_imdct_256(&ctx->fft_64, ctx->transform_coeffs[i + 1], ctx->output[i + 1],
                     ctx->delay[i + 1], ctx->tmp_imdct, ctx->tmp_output);
         }
@@ -1664,9 +1655,9 @@ static int ac3_parse_audio_block(AC3DecodeContext * ctx)
     int i, bnd, rbnd, seg, grpsize;
     GetBitContext *gb = &ctx->gb;
     int bit_alloc_flags = 0;
-    float drange, tmpco;
+    float drange;
     uint8_t *dexps;
-    int mstrcplco, cplcoexp, cplcomant, sbnd, cplbndstrc;
+    int mstrcplco, cplcoexp, cplcomant;
     int dynrng, chbwcod, ngrps, cplabsexp, skipl;
 
     for (i = 0; i < 5; i++)
@@ -1695,14 +1686,12 @@ static int ac3_parse_audio_block(AC3DecodeContext * ctx)
 
     if (get_bits1(gb)) { /* coupling strategy */
         ctx->cplinu = get_bits1(gb);
+        ctx->cplbndstrc = 0;
+        ctx->chincpl = 0;
         if (ctx->cplinu) { /* coupling in use */
-            ctx->chincpl = 0;
             for (i = 0; i < nfchans; i++)
                 ctx->chincpl |= get_bits1(gb) << i;
 
-            if (acmod == 0x00 || acmod == 0x01) //atleast two shared channels required
-                return -1;
-
             if (acmod == 0x02)
                 ctx->phsflginu = get_bits1(gb); //phase flag in use
 
@@ -1717,7 +1706,6 @@ static int ac3_parse_audio_block(AC3DecodeContext * ctx)
             ctx->ncplbnd = ctx->ncplsubnd = 3 + ctx->cplendf - ctx->cplbegf;
             ctx->cplstrtmant = ctx->cplbegf * 12 + 37;
             ctx->cplendmant = ctx->cplendf * 12 + 73;
-            ctx->cplbndstrc = 0;
             for (i = 0; i < ctx->ncplsubnd - 1; i++) /* coupling band structure */
                 if (get_bits1(gb)) {
                     ctx->cplbndstrc |= 1 << i;
@@ -1732,9 +1720,8 @@ static int ac3_parse_audio_block(AC3DecodeContext * ctx)
         for (i = 0; i < nfchans; i++)
             if ((ctx->chincpl) >> i & 1)
                 if (get_bits1(gb)) { /* coupling co-ordinates */
-                    ctx->cplcoe = 1;
+                    ctx->cplcoe |= 1 << i;
                     mstrcplco = 3 * get_bits(gb, 2);
-                    cplbndstrc = ctx->cplbndstrc;
                     for (bnd = 0; bnd < ctx->ncplbnd; bnd++) {
                         cplcoexp = get_bits(gb, 4);
                         cplcomant = get_bits(gb, 4);
@@ -1746,7 +1733,7 @@ static int ac3_parse_audio_block(AC3DecodeContext * ctx)
                     }
                 }
 
-        if (acmod == 0x02 && ctx->phsflginu && ctx->cplcoe)
+        if (acmod == 0x02 && ctx->phsflginu && (ctx->cplcoe & 1 || ctx->cplcoe & 2))
             for (bnd = 0; bnd < ctx->ncplbnd; bnd++)
                 if (get_bits1(gb))
                     ctx->cplco[1][bnd] = -ctx->cplco[1][bnd];
@@ -1789,12 +1776,11 @@ static int ac3_parse_audio_block(AC3DecodeContext * ctx)
                     return -1;
                 }
                 ctx->endmant[i] = chbwcod * 3 + 73;
-                av_log(NULL, AV_LOG_INFO, "i = %d \t chbwcod = %d \t endmant = %d\n", i, chbwcod, ctx->endmant[i]);
             }
         }
 
     if (ctx->cplexpstr != AC3_EXPSTR_REUSE) {/* coupling exponents */
-        bit_alloc_flags |= 64;
+        bit_alloc_flags = 64;
         cplabsexp = get_bits(gb, 4) << 1;
         ngrps = (ctx->cplendmant - ctx->cplstrtmant) / (3 << (ctx->cplexpstr - 1));
         if (decode_exponents(gb, ctx->cplexpstr, ngrps, cplabsexp, ctx->dcplexps + ctx->cplstrtmant)) {
@@ -1827,7 +1813,7 @@ static int ac3_parse_audio_block(AC3DecodeContext * ctx)
     }
 
     if (get_bits1(gb)) { /* bit allocation information */
-        bit_alloc_flags |= 127;
+        bit_alloc_flags = 127;
         ctx->sdcycod = get_bits(gb, 2);
         ctx->fdcycod = get_bits(gb, 2);
         ctx->sgaincod = get_bits(gb, 2);
@@ -1836,7 +1822,7 @@ static int ac3_parse_audio_block(AC3DecodeContext * ctx)
     }
 
     if (get_bits1(gb)) { /* snroffset */
-        bit_alloc_flags |= 127;
+        bit_alloc_flags = 127;
         ctx->csnroffst = get_bits(gb, 6);
         if (ctx->cplinu) { /* couling fine snr offset and fast gain code */
             ctx->cplfsnroffst = get_bits(gb, 4);
@@ -1852,8 +1838,6 @@ static int ac3_parse_audio_block(AC3DecodeContext * ctx)
         }
     }
 
-    ctx->cplfleak = 0;
-    ctx->cplsleak = 0;
     if (ctx->cplinu && get_bits1(gb)) { /* coupling leak information */
         bit_alloc_flags |= 64;
         ctx->cplfleak = get_bits(gb, 3);
@@ -1861,7 +1845,7 @@ static int ac3_parse_audio_block(AC3DecodeContext * ctx)
     }
 
     if (get_bits1(gb)) { /* delta bit allocation information */
-        bit_alloc_flags |= 127;
+        bit_alloc_flags = 127;
 
         if (ctx->cplinu) {
             ctx->cpldeltbae = get_bits(gb, 2);
@@ -1900,7 +1884,22 @@ static int ac3_parse_audio_block(AC3DecodeContext * ctx)
             }
     }
 
-    do_bit_allocation (ctx, bit_alloc_flags); /* perform the bit allocation */
+    if (bit_alloc_flags) {
+        if (is_snr_offsets_zero(ctx)) {
+            memset(ctx->cplbap, 0, sizeof (ctx->cplbap));
+            memset(ctx->lfebap, 0, sizeof (ctx->lfebap));
+            for (i = 0; i < nfchans; i++)
+                memset(ctx->bap[i], 0, sizeof(ctx->bap[i]));
+        } else {
+            if (ctx->chincpl && (bit_alloc_flags & 64))
+                do_bit_allocation(ctx, 5);
+            for (i = 0; i < nfchans; i++)
+                if ((bit_alloc_flags >> i) & 1)
+                    do_bit_allocation(ctx, i);
+            if (ctx->lfeon && (bit_alloc_flags & 32))
+                do_bit_allocation(ctx, 6);
+        }
+    }
 
     if (get_bits1(gb)) { /* unused dummy data */
         skipl = get_bits(gb, 9);
@@ -1918,7 +1917,7 @@ static int ac3_parse_audio_block(AC3DecodeContext * ctx)
         dump_floats("channel transform coefficients", 10, ctx->transform_coeffs[i + 1], BLOCK_SIZE);*/
 
     /* recover coefficients if rematrixing is in use */
-    if (ctx->rematflg)
+    if (ctx->rematstr)
         do_rematrixing(ctx);
 
     do_imdct(ctx);