Fix libvorbis encoding with more than 2 channels

Fixes issue 1325.

Patch by James Darnley, james dot darnley at gmail

Originally committed as revision 23818 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/Makefile

@@ -540,7 +540,7 @@ OBJS-$(CONFIG_LIBSCHROEDINGER_ENCODER)    += libschroedingerenc.o \
                                              libdirac_libschro.o
 OBJS-$(CONFIG_LIBSPEEX_DECODER)           += libspeexdec.o
 OBJS-$(CONFIG_LIBTHEORA_ENCODER)          += libtheoraenc.o
-OBJS-$(CONFIG_LIBVORBIS_ENCODER)          += libvorbis.o
+OBJS-$(CONFIG_LIBVORBIS_ENCODER)          += libvorbis.o vorbis_data.o
 OBJS-$(CONFIG_LIBVPX_DECODER)             += libvpxdec.o
 OBJS-$(CONFIG_LIBVPX_ENCODER)             += libvpxenc.o
 OBJS-$(CONFIG_LIBX264_ENCODER)            += libx264.o

libavcodec/libvorbis.c

@@ -28,6 +28,7 @@
 
 #include "avcodec.h"
 #include "bytestream.h"
+#include "vorbis.h"
 
 #undef NDEBUG
 #include <assert.h>
@@ -146,16 +147,14 @@ static int oggvorbis_encode_frame(AVCodecContext *avccontext,
     if(data) {
         int samples = OGGVORBIS_FRAME_SIZE;
         float **buffer ;
+        int c, channels = context->vi.channels;
 
         buffer = vorbis_analysis_buffer(&context->vd, samples) ;
-        if(context->vi.channels == 1) {
+        for (c = 0; c < channels; c++) {
+            int co = (channels > 8) ? c :
+                ff_vorbis_encoding_channel_layout_offsets[channels-1][c];
             for(l = 0 ; l < samples ; l++)
-                buffer[0][l]=audio[l]/32768.f;
+                buffer[c][l]=audio[l*channels+co]/32768.f;
-        } else {
-            for(l = 0 ; l < samples ; l++){
-                buffer[0][l]=audio[l*2]/32768.f;
-                buffer[1][l]=audio[l*2+1]/32768.f;
-            }
         }
         vorbis_analysis_wrote(&context->vd, samples) ;
     } else {

libavcodec/vorbis.h

@@ -26,6 +26,7 @@
 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[8][8];
+extern const uint8_t ff_vorbis_encoding_channel_layout_offsets[8][8];
 extern const int64_t ff_vorbis_channel_layouts[9];
 
 typedef struct {

libavcodec/vorbis_data.c

@@ -32,6 +32,17 @@ const uint8_t ff_vorbis_channel_layout_offsets[8][8] = {
     { 0, 2, 1, 7, 5, 6, 3, 4},
 };
 
+const uint8_t ff_vorbis_encoding_channel_layout_offsets[8][8] = {
+    { 0, },
+    { 0, 1, },
+    { 0, 2, 1, },
+    { 0, 1, 2, 3, },
+    { 0, 2, 1, 3, 4, },
+    { 0, 2, 1, 4, 5, 3, },
+    { 0, 2, 1, 5, 6, 4, 3, },
+    { 0, 2, 1, 6, 7, 4, 5, 3 }
+};
+
 const int64_t ff_vorbis_channel_layouts[9] = {
     CH_LAYOUT_MONO,
     CH_LAYOUT_STEREO,