Add vorbis channel layout support according to those defined in the Vorbis I

specification

Originally committed as revision 20148 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/vorbis.h

@@ -25,6 +25,8 @@
 
 extern const float ff_vorbis_floor1_inverse_db_table[256];
 extern const float * const ff_vorbis_vwin[8];
+extern const uint8_t ff_vorbis_channel_layout_offsets[6][6];
+extern const int64_t ff_vorbis_channel_layouts[7];
 
 typedef struct {
     uint_fast16_t x;

libavcodec/vorbis_data.c

@@ -21,6 +21,25 @@
 #include "dsputil.h"
 #include "vorbis.h"
 
+const uint8_t ff_vorbis_channel_layout_offsets[6][6] = {
+    { 0, },
+    { 0, 1, },
+    { 0, 2, 1, },
+    { 0, 1, 2, 3, },
+    { 0, 2, 1, 3, 4, },
+    { 0, 2, 1, 5, 3, 4, }
+};
+
+const int64_t ff_vorbis_channel_layouts[7] = {
+    CH_LAYOUT_MONO,
+    CH_LAYOUT_STEREO,
+    CH_LAYOUT_SURROUND,
+    CH_LAYOUT_QUAD,
+    CH_LAYOUT_5POINT0_BACK,
+    CH_LAYOUT_5POINT1_BACK,
+    0
+};
+
 DECLARE_ALIGNED_16(static const float, vwin64[32]) = {
     0.0009460463F, 0.0085006468F, 0.0235352254F, 0.0458950567F,
     0.0753351908F, 0.1115073077F, 0.1539457973F, 0.2020557475F,

libavcodec/vorbis_dec.c

@@ -1012,6 +1012,11 @@ static av_cold int vorbis_decode_init(AVCodecContext *avccontext)
         return -1;
     }
 
+    if (vc->audio_channels > 6)
+        avccontext->channel_layout = 0;
+    else
+        avccontext->channel_layout = ff_vorbis_channel_layouts[vc->audio_channels - 1];
+
     avccontext->channels    = vc->audio_channels;
     avccontext->sample_rate = vc->audio_samplerate;
     avccontext->frame_size  = FFMIN(vc->blocksize[0], vc->blocksize[1]) >> 2;
@@ -1643,8 +1648,15 @@ static int vorbis_decode_frame(AVCodecContext *avccontext,
 
     AV_DEBUG("parsed %d bytes %d bits, returned %d samples (*ch*bits) \n", get_bits_count(gb)/8, get_bits_count(gb)%8, len);
 
+    if (vc->audio_channels > 6) {
     for (i = 0; i < vc->audio_channels; i++)
         channel_ptrs[i] = vc->channel_floors + i * len;
+    } else {
+        for (i = 0; i < vc->audio_channels; i++)
+            channel_ptrs[i] = vc->channel_floors +
+                              len * ff_vorbis_channel_layout_offsets[vc->audio_channels - 1][i];
+    }
+
     vc->dsp.float_to_int16_interleave(data, channel_ptrs, len, vc->audio_channels);
     *data_size = len * 2 * vc->audio_channels;
 
@@ -1672,5 +1684,6 @@ AVCodec vorbis_decoder = {
     vorbis_decode_close,
     vorbis_decode_frame,
     .long_name = NULL_IF_CONFIG_SMALL("Vorbis"),
+    .channel_layouts = ff_vorbis_channel_layouts,
 };