| Message ID | 4D821462.9030402@gmail.com |
|---|---|
| State | Superseded |
| Headers | show |
Vladimir Pantelic <vladoman@gmail.com> writes: > Vladimir Pantelic wrote: >> Måns Rullgård wrote: >>> Vladimir Pantelic<vladoman@gmail.com> writes: >> >>>> So, maybe using preroll as start_time is bad, but so is not doing it >>>> as we can see above. I tend to rather follow the spec. >>> >>> The alternative would be to subtract the preroll value from all >>> timestamps in the demuxer and add it back in the muxer. Your patch >>> seems much simpler. >> >> Reading the spec again, I think we should rather subtract the preroll >> in the demuxer: >> >> "...player software *must* subtract the value in the preroll field >> from the play duration and presentation times to calculate their >> actual values..." > > now I set st->start_time to 0 and subtract the preroll, this way we > output 0 based timestamps and prevent ffmpeg.c from guessing the wrong > timestamps. > > From 1c72c47cec36d6548db0f9a622dc2430e5d5bd93 Mon Sep 17 00:00:00 2001 > From: Vladimir Pantelic <vladoman@gmail.com> > Date: Thu, 17 Mar 2011 14:56:14 +0100 > Subject: [PATCH] make ASF demuxer subtract the preroll value and thus output 0 based timestamps > > --- > libavformat/asfdec.c | 3 ++- > 1 files changed, 2 insertions(+), 1 deletions(-) > > diff --git a/libavformat/asfdec.c b/libavformat/asfdec.c > index cbcd576..3d68527 100644 > --- a/libavformat/asfdec.c > +++ b/libavformat/asfdec.c > @@ -236,6 +236,7 @@ static int asf_read_stream_properties(AVFormatContext *s, int64_t size) > if (!asf_st) > return AVERROR(ENOMEM); > st->priv_data = asf_st; > + st->start_time = 0; > start_time = asf->hdr.preroll; > > asf_st->stream_language_index = 128; // invalid stream index means no language info > @@ -960,7 +961,7 @@ static int ff_asf_parse_packet(AVFormatContext *s, AVIOContext *pb, AVPacket *pk > /* new packet */ > av_new_packet(&asf_st->pkt, asf->packet_obj_size); > asf_st->seq = asf->packet_seq; > - asf_st->pkt.dts = asf->packet_frag_timestamp; > + asf_st->pkt.dts = asf->packet_frag_timestamp - asf->hdr.preroll; > asf_st->pkt.stream_index = asf->stream_index; > asf_st->pkt.pos = > asf_st->packet_pos= asf->packet_pos; No PTS? The silly note about ASF in the start_time doxy should still go away.
From 1c72c47cec36d6548db0f9a622dc2430e5d5bd93 Mon Sep 17 00:00:00 2001 From: Vladimir Pantelic <vladoman@gmail.com> Date: Thu, 17 Mar 2011 14:56:14 +0100 Subject: [PATCH] make ASF demuxer subtract the preroll value and thus output 0 based timestamps --- libavformat/asfdec.c | 3 ++- 1 files changed, 2 insertions(+), 1 deletions(-) diff --git a/libavformat/asfdec.c b/libavformat/asfdec.c index cbcd576..3d68527 100644 --- a/libavformat/asfdec.c +++ b/libavformat/asfdec.c @@ -236,6 +236,7 @@ static int asf_read_stream_properties(AVFormatContext *s, int64_t size) if (!asf_st) return AVERROR(ENOMEM); st->priv_data = asf_st; + st->start_time = 0; start_time = asf->hdr.preroll; asf_st->stream_language_index = 128; // invalid stream index means no language info @@ -960,7 +961,7 @@ static int ff_asf_parse_packet(AVFormatContext *s, AVIOContext *pb, AVPacket *pk /* new packet */ av_new_packet(&asf_st->pkt, asf->packet_obj_size); asf_st->seq = asf->packet_seq; - asf_st->pkt.dts = asf->packet_frag_timestamp; + asf_st->pkt.dts = asf->packet_frag_timestamp - asf->hdr.preroll; asf_st->pkt.stream_index = asf->stream_index; asf_st->pkt.pos = asf_st->packet_pos= asf->packet_pos; -- 1.6.0.2