Merge commit 'a5ebe5d1'

* commit 'a5ebe5d1':
  ac3dec: Split spx-specific code from decode_audio_block()
Merged-by: Clément Bœsch <u@pkh.me>

libavcodec/ac3dec.c

@@ -801,76 +801,28 @@ static void decode_band_structure(GetBitContext *gbc, int blk, int eac3,
         memcpy(band_sizes, bnd_sz, n_bands);
 }
 
-/**
- * Decode a single audio block from the AC-3 bitstream.
- */
-static int decode_audio_block(AC3DecodeContext *s, int blk)
+static inline int spx_strategy(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;
-    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) {
     int dst_start_freq, dst_end_freq, src_start_freq,
-                start_subband, end_subband;
+        start_subband, end_subband, ch;
 
     /* determine which channels use spx */
     if (s->channel_mode == AC3_CHMODE_MONO) {
         s->channel_uses_spx[1] = 1;
     } else {
         for (ch = 1; ch <= fbw_channels; ch++)
-                    s->channel_uses_spx[ch] = get_bits1(gbc);
+            s->channel_uses_spx[ch] = get_bits1(bc);
     }
 
     /* get the frequency bins of the spx copy region and the spx start
        and end subbands */
-            dst_start_freq = get_bits(gbc, 2);
-            start_subband  = get_bits(gbc, 3) + 2;
+    dst_start_freq = get_bits(bc, 2);
+    start_subband  = get_bits(bc, 3) + 2;
     if (start_subband > 7)
         start_subband += start_subband - 7;
-            end_subband    = get_bits(gbc, 3) + 5;
+    end_subband    = get_bits(bc, 3) + 5;
 #if USE_FIXED
     s->spx_dst_end_freq = end_freq_inv_tab[end_subband-5];
 #endif
@@ -897,32 +849,29 @@ static int decode_audio_block(AC3DecodeContext *s, int blk)
     if (!USE_FIXED)
         s->spx_dst_end_freq   = dst_end_freq;
 
-            decode_band_structure(gbc, blk, s->eac3, 0,
+    decode_band_structure(bc, blk, s->eac3, 0,
                           start_subband, end_subband,
                           ff_eac3_default_spx_band_struct,
                           &s->num_spx_bands,
                           s->spx_band_sizes);
-        }
-    }
-    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;
-        }
-    }
+    return 0;
+}
+
+static inline void spx_coordinates(AC3DecodeContext *s)
+{
+    GetBitContext *bc = &s->gbc;
+    int fbw_channels = s->fbw_channels;
+    int ch, bnd;
 
-    /* spectral extension coordinates */
-    if (s->spx_in_use) {
     for (ch = 1; ch <= fbw_channels; ch++) {
         if (s->channel_uses_spx[ch]) {
-                if (s->first_spx_coords[ch] || get_bits1(gbc)) {
+            if (s->first_spx_coords[ch] || get_bits1(bc)) {
                 INTFLOAT spx_blend;
                 int bin, master_spx_coord;
 
                 s->first_spx_coords[ch] = 0;
-                    spx_blend = AC3_SPX_BLEND(get_bits(gbc, 5));
-                    master_spx_coord = get_bits(gbc, 2) * 3;
+                spx_blend = AC3_SPX_BLEND(get_bits(bc, 5));
+                master_spx_coord = get_bits(bc, 2) * 3;
 
                 bin = s->spx_src_start_freq;
                 for (bnd = 0; bnd < s->num_spx_bands; bnd++) {
@@ -961,8 +910,8 @@ static int decode_audio_block(AC3DecodeContext *s, int blk)
                     bin += bandsize;
 
                     /* decode spx coordinates */
-                        spx_coord_exp  = get_bits(gbc, 4);
-                        spx_coord_mant = get_bits(gbc, 2);
+                    spx_coord_exp  = get_bits(bc, 4);
+                    spx_coord_mant = get_bits(bc, 2);
                     if (spx_coord_exp == 15) spx_coord_mant <<= 1;
                     else                     spx_coord_mant += 4;
                     spx_coord_mant <<= (25 - spx_coord_exp - master_spx_coord);
@@ -984,8 +933,76 @@ static int decode_audio_block(AC3DecodeContext *s, int blk)
             s->first_spx_coords[ch] = 1;
         }
     }
+}
+
+/**
+ * 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)) {
         memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);