Merge commit 'f0ccc65bc9ab9ddf1366066395564c71bcc825ee'

* commit 'f0ccc65bc9ab9ddf1366066395564c71bcc825ee':
  ac3dec: Split coupling-specific code from decode_audio_block()

Merged-by: Clément Bœsch <u@pkh.me>

libavcodec/ac3dec.c

@@ -935,79 +935,17 @@ static inline void spx_coordinates(AC3DecodeContext *s)
     }
 }
 
-/**
+static inline int coupling_strategy(AC3DecodeContext *s, int blk,
- * Decode a single audio block from the AC-3 bitstream.
+                                    uint8_t *bit_alloc_stages)
- */
-static int decode_audio_block(AC3DecodeContext *s, int blk)
 {
+    GetBitContext *bc = &s->gbc;
     int fbw_channels = s->fbw_channels;
     int channel_mode = s->channel_mode;
-    int i, bnd, seg, ch, ret;
+    int ch;
-    int different_transforms;
-    int downmix_output;
-    int cpl_in_use;
-    GetBitContext *gbc = &s->gbc;
-    uint8_t bit_alloc_stages[AC3_MAX_CHANNELS] = { 0 };
-
-    /* block switch flags */
-    different_transforms = 0;
-    if (s->block_switch_syntax) {
-        for (ch = 1; ch <= fbw_channels; ch++) {
-            s->block_switch[ch] = get_bits1(gbc);
-            if (ch > 1 && s->block_switch[ch] != s->block_switch[1])
-                different_transforms = 1;
-        }
-    }
-
-    /* dithering flags */
-    if (s->dither_flag_syntax) {
-        for (ch = 1; ch <= fbw_channels; ch++) {
-            s->dither_flag[ch] = get_bits1(gbc);
-        }
-    }
-
-    /* dynamic range */
-    i = !s->channel_mode;
-    do {
-        if (get_bits1(gbc)) {
-            /* Allow asymmetric application of DRC when drc_scale > 1.
-               Amplification of quiet sounds is enhanced */
-            int range_bits = get_bits(gbc, 8);
-            INTFLOAT range = AC3_RANGE(range_bits);
-            if (range_bits <= 127 || s->drc_scale <= 1.0)
-                s->dynamic_range[i] = AC3_DYNAMIC_RANGE(range);
-            else
-                s->dynamic_range[i] = range;
-        } else if (blk == 0) {
-            s->dynamic_range[i] = AC3_DYNAMIC_RANGE1;
-        }
-    } while (i--);
-
-    /* spectral extension strategy */
-    if (s->eac3 && (!blk || get_bits1(gbc))) {
-        s->spx_in_use = get_bits1(gbc);
-        if (s->spx_in_use) {
-            if ((ret = spx_strategy(s, blk)) < 0)
-                return ret;
-        }
-    }
-    if (!s->eac3 || !s->spx_in_use) {
-        s->spx_in_use = 0;
-        for (ch = 1; ch <= fbw_channels; ch++) {
-            s->channel_uses_spx[ch] = 0;
-            s->first_spx_coords[ch] = 1;
-        }
-    }
-
-    /* spectral extension coordinates */
-    if (s->spx_in_use)
-        spx_coordinates(s);
 
-    /* coupling strategy */
-    if (s->eac3 ? s->cpl_strategy_exists[blk] : get_bits1(gbc)) {
     memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
     if (!s->eac3)
-            s->cpl_in_use[blk] = get_bits1(gbc);
+        s->cpl_in_use[blk] = get_bits1(bc);
     if (s->cpl_in_use[blk]) {
         /* coupling in use */
         int cpl_start_subband, cpl_end_subband;
@@ -1018,7 +956,7 @@ static int decode_audio_block(AC3DecodeContext *s, int blk)
         }
 
         /* check for enhanced coupling */
-            if (s->eac3 && get_bits1(gbc)) {
+        if (s->eac3 && get_bits1(bc)) {
             /* TODO: parse enhanced coupling strategy info */
             avpriv_request_sample(s->avctx, "Enhanced coupling");
             return AVERROR_PATCHWELCOME;
@@ -1030,17 +968,17 @@ static int decode_audio_block(AC3DecodeContext *s, int blk)
             s->channel_in_cpl[2] = 1;
         } else {
             for (ch = 1; ch <= fbw_channels; ch++)
-                    s->channel_in_cpl[ch] = get_bits1(gbc);
+                s->channel_in_cpl[ch] = get_bits1(bc);
         }
 
         /* phase flags in use */
         if (channel_mode == AC3_CHMODE_STEREO)
-                s->phase_flags_in_use = get_bits1(gbc);
+            s->phase_flags_in_use = get_bits1(bc);
 
         /* coupling frequency range */
-            cpl_start_subband = get_bits(gbc, 4);
+        cpl_start_subband = get_bits(bc, 4);
         cpl_end_subband = s->spx_in_use ? (s->spx_src_start_freq - 37) / 12 :
-                                              get_bits(gbc, 4) + 3;
+                                          get_bits(bc, 4) + 3;
         if (cpl_start_subband >= cpl_end_subband) {
             av_log(s->avctx, AV_LOG_ERROR, "invalid coupling range (%d >= %d)\n",
                    cpl_start_subband, cpl_end_subband);
@@ -1049,7 +987,7 @@ static int decode_audio_block(AC3DecodeContext *s, int blk)
         s->start_freq[CPL_CH] = cpl_start_subband * 12 + 37;
         s->end_freq[CPL_CH]   = cpl_end_subband   * 12 + 37;
 
-            decode_band_structure(gbc, blk, s->eac3, 0, cpl_start_subband,
+        decode_band_structure(bc, blk, s->eac3, 0, cpl_start_subband,
                               cpl_end_subband,
                               ff_eac3_default_cpl_band_struct,
                               &s->num_cpl_bands, s->cpl_band_sizes);
@@ -1062,31 +1000,27 @@ static int decode_audio_block(AC3DecodeContext *s, int blk)
         s->first_cpl_leak = s->eac3;
         s->phase_flags_in_use = 0;
     }
-    } else if (!s->eac3) {
-        if (!blk) {
-            av_log(s->avctx, AV_LOG_ERROR, "new coupling strategy must "
-                   "be present in block 0\n");
-            return AVERROR_INVALIDDATA;
-        } else {
-            s->cpl_in_use[blk] = s->cpl_in_use[blk-1];
-        }
-    }
-    cpl_in_use = s->cpl_in_use[blk];
 
-    /* coupling coordinates */
+    return 0;
-    if (cpl_in_use) {
+}
+
+static inline int coupling_coordinates(AC3DecodeContext *s, int blk)
+{
+    GetBitContext *bc = &s->gbc;
+    int fbw_channels = s->fbw_channels;
+    int ch, bnd;
     int cpl_coords_exist = 0;
 
     for (ch = 1; ch <= fbw_channels; ch++) {
         if (s->channel_in_cpl[ch]) {
-                if ((s->eac3 && s->first_cpl_coords[ch]) || get_bits1(gbc)) {
+            if ((s->eac3 && s->first_cpl_coords[ch]) || get_bits1(bc)) {
                 int master_cpl_coord, cpl_coord_exp, cpl_coord_mant;
                 s->first_cpl_coords[ch] = 0;
                 cpl_coords_exist = 1;
-                    master_cpl_coord = 3 * get_bits(gbc, 2);
+                master_cpl_coord = 3 * get_bits(bc, 2);
                 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
-                        cpl_coord_exp = get_bits(gbc, 4);
+                    cpl_coord_exp  = get_bits(bc, 4);
-                        cpl_coord_mant = get_bits(gbc, 4);
+                    cpl_coord_mant = get_bits(bc, 4);
                     if (cpl_coord_exp == 15)
                         s->cpl_coords[ch][bnd] = cpl_coord_mant << 22;
                     else
@@ -1104,11 +1038,102 @@ static int decode_audio_block(AC3DecodeContext *s, int blk)
         }
     }
     /* phase flags */
-        if (channel_mode == AC3_CHMODE_STEREO && cpl_coords_exist) {
+    if (s->channel_mode == AC3_CHMODE_STEREO && cpl_coords_exist) {
         for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
-                s->phase_flags[bnd] = s->phase_flags_in_use? get_bits1(gbc) : 0;
+            s->phase_flags[bnd] = s->phase_flags_in_use ? get_bits1(bc) : 0;
+        }
+    }
+
+    return 0;
+}
+
+/**
+ * Decode a single audio block from the AC-3 bitstream.
+ */
+static int decode_audio_block(AC3DecodeContext *s, int blk)
+{
+    int fbw_channels = s->fbw_channels;
+    int channel_mode = s->channel_mode;
+    int i, bnd, seg, ch, ret;
+    int different_transforms;
+    int downmix_output;
+    int cpl_in_use;
+    GetBitContext *gbc = &s->gbc;
+    uint8_t bit_alloc_stages[AC3_MAX_CHANNELS] = { 0 };
+
+    /* block switch flags */
+    different_transforms = 0;
+    if (s->block_switch_syntax) {
+        for (ch = 1; ch <= fbw_channels; ch++) {
+            s->block_switch[ch] = get_bits1(gbc);
+            if (ch > 1 && s->block_switch[ch] != s->block_switch[1])
+                different_transforms = 1;
+        }
+    }
+
+    /* dithering flags */
+    if (s->dither_flag_syntax) {
+        for (ch = 1; ch <= fbw_channels; ch++) {
+            s->dither_flag[ch] = get_bits1(gbc);
+        }
+    }
+
+    /* dynamic range */
+    i = !s->channel_mode;
+    do {
+        if (get_bits1(gbc)) {
+            /* Allow asymmetric application of DRC when drc_scale > 1.
+               Amplification of quiet sounds is enhanced */
+            int range_bits = get_bits(gbc, 8);
+            INTFLOAT range = AC3_RANGE(range_bits);
+            if (range_bits <= 127 || s->drc_scale <= 1.0)
+                s->dynamic_range[i] = AC3_DYNAMIC_RANGE(range);
+            else
+                s->dynamic_range[i] = range;
+        } else if (blk == 0) {
+            s->dynamic_range[i] = AC3_DYNAMIC_RANGE1;
+        }
+    } while (i--);
+
+    /* spectral extension strategy */
+    if (s->eac3 && (!blk || get_bits1(gbc))) {
+        s->spx_in_use = get_bits1(gbc);
+        if (s->spx_in_use) {
+            if ((ret = spx_strategy(s, blk)) < 0)
+                return ret;
+        }
+    }
+    if (!s->eac3 || !s->spx_in_use) {
+        s->spx_in_use = 0;
+        for (ch = 1; ch <= fbw_channels; ch++) {
+            s->channel_uses_spx[ch] = 0;
+            s->first_spx_coords[ch] = 1;
         }
     }
+
+    /* spectral extension coordinates */
+    if (s->spx_in_use)
+        spx_coordinates(s);
+
+    /* coupling strategy */
+    if (s->eac3 ? s->cpl_strategy_exists[blk] : get_bits1(gbc)) {
+        if ((ret = coupling_strategy(s, blk, bit_alloc_stages)) < 0)
+            return ret;
+    } else if (!s->eac3) {
+        if (!blk) {
+            av_log(s->avctx, AV_LOG_ERROR, "new coupling strategy must "
+                   "be present in block 0\n");
+            return AVERROR_INVALIDDATA;
+        } else {
+            s->cpl_in_use[blk] = s->cpl_in_use[blk-1];
+        }
+    }
+    cpl_in_use = s->cpl_in_use[blk];
+
+    /* coupling coordinates */
+    if (cpl_in_use) {
+        if ((ret = coupling_coordinates(s, blk)) < 0)
+            return ret;
     }
 
     /* stereo rematrixing strategy and band structure */