On 11/14/2024 1:37 AM, Scott Theisen wrote:
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;
Kind of sucks we have used FC to represent mono for so long that we can't cleanly introduce a new channel that's strictly mono (with no speaker location implied) and give it meaningful use.
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