When attempting to upstream this MythTV change in September 2022, it was
recommended to
use AV_CHANNEL_ORDER_CUSTOM with two AV_CHAN_FRONT_CENTER channels. See
https://patchwork.ffmpeg.org/project/ffmpeg/patch/20220921192611.3241-1-scott.the....@gmail.com/
---
libavcodec/audiotoolboxdec.c | 4 ++--
libavcodec/mpegaudio_parser.c | 12 +++++++++---
libavcodec/mpegaudiodecheader.c | 4 +++-
libavcodec/mpegaudiodecheader.h | 2 +-
tests/ref/fate/pva-demux | 2 +-
5 files changed, 16 insertions(+), 8 deletions(-)
diff --git a/libavcodec/audiotoolboxdec.c b/libavcodec/audiotoolboxdec.c
index 0f7ce8e4eb..d279d7bbc4 100644
--- a/libavcodec/audiotoolboxdec.c
+++ b/libavcodec/audiotoolboxdec.c
@@ -346,10 +346,10 @@ static av_cold int ffat_create_decoder(AVCodecContext
*avctx,
avctx->codec_id == AV_CODEC_ID_MP2 ||
avctx->codec_id == AV_CODEC_ID_MP3)) {
enum AVCodecID codec_id;
- int bit_rate;
+ int bit_rate, dual_mono;
if (ff_mpa_decode_header(AV_RB32(pkt->data), &avctx->sample_rate,
&in_format.mChannelsPerFrame,
&avctx->frame_size,
- &bit_rate, &codec_id) < 0)
+ &bit_rate, &codec_id, &dual_mono) < 0)
return AVERROR_INVALIDDATA;
avctx->bit_rate = bit_rate;
in_format.mSampleRate = avctx->sample_rate;
diff --git a/libavcodec/mpegaudio_parser.c b/libavcodec/mpegaudio_parser.c
index d54366f10a..d1a4ee6434 100644
--- a/libavcodec/mpegaudio_parser.c
+++ b/libavcodec/mpegaudio_parser.c
@@ -65,12 +65,12 @@ static int mpegaudio_parse(AVCodecParserContext *s1,
}
}else{
while(i<buf_size){
- int ret, sr, channels, bit_rate, frame_size;
+ int ret, sr, channels, bit_rate, frame_size, dual_mono;
enum AVCodecID codec_id = avctx->codec_id;
state= (state<<8) + buf[i++];
- ret = ff_mpa_decode_header(state, &sr, &channels, &frame_size,
&bit_rate, &codec_id);
+ ret = ff_mpa_decode_header(state, &sr, &channels, &frame_size,
&bit_rate, &codec_id, &dual_mono);
if (ret < 4) {
if (i > 4)
s->header_count = -2;
@@ -85,7 +85,13 @@ static int mpegaudio_parse(AVCodecParserContext *s1,
if (s->header_count > header_threshold) {
avctx->sample_rate= sr;
av_channel_layout_uninit(&avctx->ch_layout);
- av_channel_layout_default(&avctx->ch_layout, channels);
+ if (dual_mono) {
+ av_channel_layout_custom_init(&avctx->ch_layout,
2);
+ avctx->ch_layout.u.map[0].id =
AV_CHAN_FRONT_CENTER;
+ avctx->ch_layout.u.map[1].id =
AV_CHAN_FRONT_CENTER;
+ } else {
+ av_channel_layout_default(&avctx->ch_layout,
channels);
+ }
s1->duration = frame_size;
avctx->codec_id = codec_id;
if (s->no_bitrate || !avctx->bit_rate) {
diff --git a/libavcodec/mpegaudiodecheader.c b/libavcodec/mpegaudiodecheader.c
index ef63befbf4..5cbfdcb677 100644
--- a/libavcodec/mpegaudiodecheader.c
+++ b/libavcodec/mpegaudiodecheader.c
@@ -117,7 +117,7 @@ int avpriv_mpegaudio_decode_header(MPADecodeHeader *s,
uint32_t header)
return 0;
}
-int ff_mpa_decode_header(uint32_t head, int *sample_rate, int *channels, int
*frame_size, int *bit_rate, enum AVCodecID *codec_id)
+int ff_mpa_decode_header(uint32_t head, int *sample_rate, int *channels, int
*frame_size, int *bit_rate, enum AVCodecID *codec_id, int *dual_mono)
{
MPADecodeHeader s1, *s = &s1;
@@ -148,5 +148,7 @@ int ff_mpa_decode_header(uint32_t head, int *sample_rate,
int *channels, int *fr
*sample_rate = s->sample_rate;
*channels = s->nb_channels;
*bit_rate = s->bit_rate;
+ *dual_mono = (s->mode == MPA_DUAL);
+
return s->frame_size;
}
diff --git a/libavcodec/mpegaudiodecheader.h b/libavcodec/mpegaudiodecheader.h
index ed5d1f3b33..e599d287f7 100644
--- a/libavcodec/mpegaudiodecheader.h
+++ b/libavcodec/mpegaudiodecheader.h
@@ -56,7 +56,7 @@ int avpriv_mpegaudio_decode_header(MPADecodeHeader *s,
uint32_t header);
/* useful helper to get MPEG audio stream info. Return -1 if error in
header, otherwise the coded frame size in bytes */
int ff_mpa_decode_header(uint32_t head, int *sample_rate,
- int *channels, int *frame_size, int *bitrate, enum
AVCodecID *codec_id);
+ int *channels, int *frame_size, int *bitrate, enum
AVCodecID *codec_id, int *dual_mono);
/* fast header check for resync */
static inline int ff_mpa_check_header(uint32_t header){
diff --git a/tests/ref/fate/pva-demux b/tests/ref/fate/pva-demux
index 5c0e1c1ea0..2749ea9f07 100644
--- a/tests/ref/fate/pva-demux
+++ b/tests/ref/fate/pva-demux
@@ -7,7 +7,7 @@
#media_type 1: audio
#codec_id 1: mp2
#sample_rate 1: 48000
-#channel_layout_name 1: stereo
+#channel_layout_name 1: 2 channels (FC+FC)
1, 0, 0, 2160, 384, 0x071abcc8
1, 2160, 2160, 2160, 384, 0x31c9aee0
1, 4320, 4320, 2160, 384, 0xa50eaa94
--
2.43.0
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