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commit ff818b87bf1cfee7a10196e90d0df8de44e9a771 Author: Kacper Michajłow <[email protected]> AuthorDate: Sat Jul 4 20:00:59 2026 +0200 Commit: Kacper Michajłow <[email protected]> CommitDate: Tue Jul 28 17:55:33 2026 +0200 avformat/mpeg: fix demuxing of DVD-Audio LPCM Substream 0xa0 packets without the DVD-Video dynamic range control marker byte were assumed to be MLP, while in DVD-Audio AOBs substream 0xa0 always carries LPCM (MLP uses 0xa1), so hi-res LPCM streams were misdetected and decoded as garbage. Classify them as PCM_DVDA and keep the private stream header in the packet for the decoder to parse, as its length is variable and it carries the audio format. Signed-off-by: Kacper Michajłow <[email protected]> --- libavformat/mpeg.c | 68 +++++++++++++++++++++++++++++++++++++++--------------- 1 file changed, 49 insertions(+), 19 deletions(-) diff --git a/libavformat/mpeg.c b/libavformat/mpeg.c index 29abe329b9..43bbf0ef9f 100644 --- a/libavformat/mpeg.c +++ b/libavformat/mpeg.c @@ -488,6 +488,7 @@ static int mpegps_read_packet(AVFormatContext *s, FFStream *sti; int len, startcode, i, es_type, ret; int pcm_dvd = 0; + int pcm_dvda = 0; int request_probe= 0; enum AVCodecID codec_id = AV_CODEC_ID_NONE; enum AVMediaType type; @@ -503,19 +504,33 @@ redo: goto skip; if (!m->raw_ac3) { - /* audio: skip header */ - avio_skip(s->pb, 3); - len -= 3; - if (startcode >= 0xb0 && startcode <= 0xbf) { - /* MLP/TrueHD audio has a 4-byte header */ - avio_r8(s->pb); - len--; - } else if (startcode >= 0xa0 && startcode <= 0xaf) { - ret = ffio_ensure_seekback(s->pb, 3); + if (startcode >= 0xa0 && startcode <= 0xaf) { + uint8_t header[6]; + + /* Classify the LPCM/MLP substream here; its header is + * skipped at "found" below, once the stream codec is known. */ + if (len < 6) + goto skip; + ret = ffio_ensure_seekback(s->pb, 6); if (ret < 0) return ret; - pcm_dvd = (avio_rb24(s->pb) & 0xFF) == 0x80; - avio_skip(s->pb, -3); + if (avio_read(s->pb, header, 6) != 6) + return AVERROR_INVALIDDATA; + avio_seek(s->pb, -6, SEEK_CUR); + /* DVD-Video LPCM has the dynamic range control byte here, while + * DVD-Audio LPCM and MLP do not. Only substream 0xa0 carries + * LPCM in DVD-Audio AOBs, MLP uses substream 0xa1. */ + pcm_dvd = header[5] == 0x80; + pcm_dvda = startcode == 0xa0 && !pcm_dvd; + } else { + /* audio: skip header */ + avio_skip(s->pb, 3); + len -= 3; + if (startcode >= 0xb0 && startcode <= 0xbf) { + /* MLP/TrueHD audio has a 4-byte header */ + avio_r8(s->pb); + len--; + } } } } @@ -602,7 +617,9 @@ redo: codec_id = AV_CODEC_ID_DTS; } else if (startcode >= 0xa0 && startcode <= 0xaf) { type = AVMEDIA_TYPE_AUDIO; - if (!pcm_dvd) { + if (pcm_dvda) { + codec_id = AV_CODEC_ID_PCM_DVDA; + } else if (!pcm_dvd) { codec_id = AV_CODEC_ID_MLP; } else { codec_id = AV_CODEC_ID_PCM_DVD; @@ -648,13 +665,26 @@ skip: found: if (st->discard >= AVDISCARD_ALL) goto skip; - if (startcode >= 0xa0 && startcode <= 0xaf) { - if (st->codecpar->codec_id == AV_CODEC_ID_MLP) { - if (len < 6) - goto skip; - avio_skip(s->pb, 6); - len -=6; - } + if (startcode >= 0xa0 && startcode <= 0xaf && !m->raw_ac3) { + int header_len = 0; + /* Skip the substream headers of codecs whose decoders do not expect + * them. AV_CODEC_ID_PCM_DVDA parses the header from the packet. */ + if (st->codecpar->codec_id == AV_CODEC_ID_MLP) { + /* 3-byte substream header + 6-byte MLP header */ + header_len = 9; + } else if (st->codecpar->codec_id == AV_CODEC_ID_PCM_DVD) { + header_len = 3; + } + if (len <= header_len) + goto skip; + avio_skip(s->pb, header_len); + len -= header_len; + } else if (startcode >= 0xa0 && startcode <= 0xaf && + st->codecpar->codec_id == AV_CODEC_ID_MLP) { + if (len < 6) + goto skip; + avio_skip(s->pb, 6); + len -= 6; } ret = av_get_packet(s->pb, pkt, len); _______________________________________________ ffmpeg-cvslog mailing list -- [email protected] To unsubscribe send an email to [email protected]
