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lavf/dv: do not set video timebase more than once

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Current code will call avpriv_set_pts_info() for each video frame,
possibly setting a different timebase if the stream framerate changes.
This violates API conventions, as the timebase is supposed to stay
constant after stream creation.

Change the demuxer to set a single timebase that is fine enough to
handle all supported DV framerates.

The seek tests change slightly because the new timebase is more
granular.
This commit is contained in:
Anton Khirnov
2022-08-24 10:27:09 +02:00
parent 5617465916
commit c7a852b638
8 changed files with 91 additions and 60 deletions
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36
libavformat/dv.c
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@@ -69,6 +69,8 @@ struct DVDemuxContext {
uint8_t audio_buf[4][8192];
int ach;
int frames;
int64_t next_pts_video;
};
static inline uint16_t dv_audio_12to16(uint16_t sample)
@@ -314,8 +316,6 @@ static int dv_extract_video_info(DVDemuxContext *c, const uint8_t *frame)
par = c->vst->codecpar;
avpriv_set_pts_info(c->vst, 64, c->sys->time_base.num,
c->sys->time_base.den);
c->vst->avg_frame_rate = av_inv_q(c->vst->time_base);
/* finding out SAR is a little bit messy */
@@ -360,6 +360,8 @@ static int dv_init_demux(AVFormatContext *s, DVDemuxContext *c)
c->vst->codecpar->bit_rate = 25000000;
c->vst->start_time = 0;
avpriv_set_pts_info(c->vst, 64, 1, DV_TIMESCALE_VIDEO);
/* Audio streams are added later as they are encountered. */
s->ctx_flags |= AVFMTCTX_NOHEADER;
@@ -463,7 +465,10 @@ int avpriv_dv_produce_packet(DVDemuxContext *c, AVPacket *pkt,
pkt->size = size;
pkt->flags |= AV_PKT_FLAG_KEY;
pkt->stream_index = c->vst->index;
pkt->pts = c->frames;
pkt->pts = c->next_pts_video;
pkt->duration = av_rescale_q(1, c->sys->time_base, c->vst->time_base);
c->next_pts_video += pkt->duration;
}
c->frames++;
@@ -472,28 +477,34 @@ int avpriv_dv_produce_packet(DVDemuxContext *c, AVPacket *pkt,
}
static int64_t dv_frame_offset(AVFormatContext *s, DVDemuxContext *c,
int64_t timestamp, int flags)
int64_t *timestamp)
{
// FIXME: sys may be wrong if last dv_read_packet() failed (buffer is junk)
FFFormatContext *const si = ffformatcontext(s);
const int frame_size = c->sys->frame_size;
int64_t frame_count = av_rescale_q(*timestamp, c->vst->time_base, c->sys->time_base);
int64_t offset;
int64_t size = avio_size(s->pb) - si->data_offset;
int64_t max_offset = ((size - 1) / frame_size) * frame_size;
offset = frame_size * timestamp;
offset = frame_size * frame_count;
if (size >= 0 && offset > max_offset)
offset = max_offset;
else if (offset < 0)
offset = 0;
*timestamp = av_rescale_q(offset / frame_size, c->sys->time_base, c->vst->time_base);
return offset + si->data_offset;
}
void ff_dv_offset_reset(DVDemuxContext *c, int64_t frame_offset)
void ff_dv_ts_reset(DVDemuxContext *c, int64_t ts)
{
c->frames = frame_offset;
c->frames = !c->sys ? 0 :
av_rescale_q(ts, c->vst->time_base, c->sys->time_base);
c->next_pts_video = ts;
c->audio_pkt[0].size = c->audio_pkt[1].size = 0;
c->audio_pkt[2].size = c->audio_pkt[3].size = 0;
}
@@ -618,12 +629,19 @@ static int dv_read_seek(AVFormatContext *s, int stream_index,
{
RawDVContext *r = s->priv_data;
DVDemuxContext *c = &r->dv_demux;
int64_t offset = dv_frame_offset(s, c, timestamp, flags);
int64_t offset;
// seek using the video stream
if (stream_index != c->vst->index)
timestamp = av_rescale_q(timestamp, s->streams[stream_index]->time_base,
c->vst->time_base);
offset = dv_frame_offset(s, c, &timestamp);
if (avio_seek(s->pb, offset, SEEK_SET) < 0)
return -1;
ff_dv_offset_reset(c, offset / c->sys->frame_size);
ff_dv_ts_reset(c, timestamp);
return 0;
}