[FFmpeg-devel] [PATCH v2] avcodec/atrac3plus: reorder channels to match the output layout

[James Almer]

The order in which the channels are coded in the bitstream do not always follow
the native, bitmask-based order of channels both signaled by the WAV container
and forced by this same decoder. This is the case with layouts containing an
LFE channel, as it's always coded last.

Fixes ticket #9964.

Signed-off-by: James Almer <jamrial at gmail.com>
---
 libavcodec/atrac3plusdec.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/libavcodec/atrac3plusdec.c b/libavcodec/atrac3plusdec.c
index ee71645a3c..9e12f21930 100644
--- a/libavcodec/atrac3plusdec.c
+++ b/libavcodec/atrac3plusdec.c
@@ -48,6 +48,17 @@
 #include "atrac.h"
 #include "atrac3plus.h"
 
+static uint8_t channel_map[8][8] = {
+    { 0, },
+    { 0, 1, },
+    { 0, 1, 2, },
+    { 0, 1, 2, 3, },
+    { 0, },
+    { 0, 1, 2, 4, 5, 3, },
+    { 0, 1, 2, 4, 5, 8, 3, },
+    { 0, 1, 2, 4, 5, 9, 10, 3, },
+};
+
 typedef struct ATRAC3PContext {
     GetBitContext gb;
     AVFloatDSPContext *fdsp;
@@ -378,7 +389,7 @@ static int atrac3p_decode_frame(AVCodecContext *avctx, AVFrame *frame,
                           channels_to_process, avctx);
 
         for (i = 0; i < channels_to_process; i++)
-            memcpy(samples_p[out_ch_index + i], ctx->outp_buf[i],
+            memcpy(samples_p[channel_map[frame->ch_layout.nb_channels - 1][out_ch_index + i]], ctx->outp_buf[i],
                    ATRAC3P_FRAME_SAMPLES * sizeof(**samples_p));
 
         ch_block++;
-- 
2.38.1