PR #24280 opened by Yalda URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/24280 Patch URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/24280.patch
Resolves audio drop outs in very early generation DVD-R/ROM discs. This filtering was originally added to smooth out seeking and chapter cutpoints, but after robust testing (>1000 discs), it was discovered that certain encoders from 1997-era did produce valid AC3 streams this way. Beside the point, it is an archival accuracy concern. Signed-off-by: Yalda <[email protected]> # Summary of changes Briefly describe what this PR does and why. <!-- If this PR requires new FATE test samples, attach them to the PR and list their target paths below (relative to the fate-suite root). Attached filenames must match the sample's filename: ```fate-samples # e.g. vorbis/new-sample.ogg ``` --> >From 49058b577c11ab37b9dcc4de3c749e3ae49beea9 Mon Sep 17 00:00:00 2001 From: Yalda <[email protected]> Date: Sat, 7 Mar 2026 19:35:37 -0600 Subject: [PATCH] avformat/dvdvideodec: do not drop out-of-order AC3 packets Resolves audio drop outs in very early generation DVD-R/ROM discs. This filtering was originally added to smooth out seeking and chapter cutpoints, but after robust testing (>1000 discs), it was discovered that certain encoders from 1997-era did produce valid AC3 streams this way. Beside the point, it is an archival accuracy concern. Signed-off-by: Yalda <[email protected]> --- libavformat/dvdvideodec.c | 24 ++---------------------- 1 file changed, 2 insertions(+), 22 deletions(-) diff --git a/libavformat/dvdvideodec.c b/libavformat/dvdvideodec.c index 1e397e3bf5..14c878ff6c 100644 --- a/libavformat/dvdvideodec.c +++ b/libavformat/dvdvideodec.c @@ -168,7 +168,6 @@ typedef struct DVDVideoDemuxContext { int nb_angles; /* number of angles in the current title */ int play_started; /* signal that playback has started */ DVDVideoPlaybackState play_state; /* the active playback state */ - int64_t *prev_pts; /* track the previous PTS emitted per stream */ int64_t pts_offset; /* PTS discontinuity offset (ex. VOB change) */ int seek_warned; /* signal that we warned about seeking limits */ int subdemux_reset; /* signal that subdemuxer should be reset */ @@ -1580,7 +1579,7 @@ static int dvdvideo_read_header(AVFormatContext *s) (ret = dvdvideo_subdemux_open(s)) < 0) return ret; - goto end_ready; + return 0; } if (c->opt_pgc && (c->opt_chapter_start > 1 || c->opt_chapter_end > 0 || c->opt_preindex)) { @@ -1617,14 +1616,6 @@ static int dvdvideo_read_header(AVFormatContext *s) (ret = dvdvideo_subdemux_open(s)) < 0) return ret; -end_ready: - c->prev_pts = av_malloc(s->nb_streams * sizeof(int64_t)); - if (!c->prev_pts) - return AVERROR(ENOMEM); - - for (int i = 0; i < s->nb_streams; i++) - c->prev_pts[i] = AV_NOPTS_VALUE; - return 0; } @@ -1685,13 +1676,10 @@ static int dvdvideo_read_packet(AVFormatContext *s, AVPacket *pkt) if (pkt->pts < 0) goto discard; - /* clean up after DVD muxers which end seamless PGs on duplicate or partial AC3 samples */ + /* clean up after DVD muxers which end seamless PGs on partial AC3 samples */ if (st_subdemux->codecpar->codec_type == AVMEDIA_TYPE_AUDIO && st_subdemux->codecpar->codec_id == AV_CODEC_ID_AC3) { - if (pkt->pts <= c->prev_pts[pkt->stream_index]) - goto discard; - ret = av_ac3_parse_header(pkt->buf->data, pkt->size, &ac3_bitstream_id, &ac3_frame_size); @@ -1704,8 +1692,6 @@ static int dvdvideo_read_packet(AVFormatContext *s, AVPacket *pkt) pkt->stream_index, pkt->pts, pkt->dts, c->pts_offset, c->first_pts); - c->prev_pts[pkt->stream_index] = pkt->pts; - return 0; discard: @@ -1713,9 +1699,6 @@ discard: "Discarding frame @ st=%d pts=%" PRId64 " dts=%" PRId64 " is_key=%d st_mapped=%d\n", st_mapped ? pkt->stream_index : -1, pkt->pts, pkt->dts, is_key, st_mapped); - if (st_mapped) - c->prev_pts[pkt->stream_index] = pkt->pts; - return FFERROR_REDO; } @@ -1732,9 +1715,6 @@ static int dvdvideo_close(AVFormatContext *s) dvdvideo_ifo_close(s); - if (c->prev_pts) - av_freep(&c->prev_pts); - return 0; } -- 2.52.0 _______________________________________________ ffmpeg-devel mailing list -- [email protected] To unsubscribe send an email to [email protected]
