[FFmpeg-devel] [PATCH v2 2/3] avformat/mpegtsenc: make first_pcr sync with the first valid dts

[lance.lmwang at gmail.com]

On Sun, Oct 25, 2020 at 06:47:27PM +0100, Marton Balint wrote:
> 
> 
> On Sun, 25 Oct 2020, lance.lmwang at gmail.com wrote:
> 
> > On Sun, Oct 25, 2020 at 01:04:11PM +0100, Marton Balint wrote:
> > > 
> > > 
> > > On Thu, 22 Oct 2020, lance.lmwang at gmail.com wrote:
> > > 
> > > > From: Limin Wang <lance.lmwang at gmail.com>
> > > > > now first_pts assume dts will start from zero, if it's not
> > > true(copyts is enable),
> > > > too many null packet will be inserted for cbr output.
> > > > > Please test with below command, you'll get huge test.ts without
> > > the patch:
> > > > ./ffmpeg -y -copyts -i ../fate-suite/mpegts/loewe.ts  -c:v libx264 -x264opts \
> > > >   nal-hrd=cbr:force-cfr=1 -b:v 3500k -minrate 3500k -maxrate 3500k -bufsize \
> > > >   1000k  -c:a mp2 -muxrate 4500k  -vframes 1000 test.ts
> > > > > Signed-off-by: Limin Wang <lance.lmwang at gmail.com>
> > > > ---
> > > > libavformat/mpegtsenc.c | 7 +++++++
> > > > 1 file changed, 7 insertions(+)
> > > > > diff --git a/libavformat/mpegtsenc.c b/libavformat/mpegtsenc.c
> > > > index 5c97d63..415a64e 100644
> > > > --- a/libavformat/mpegtsenc.c
> > > > +++ b/libavformat/mpegtsenc.c
> > > > @@ -81,6 +81,7 @@ typedef struct MpegTSWrite {
> > > >     int64_t pat_period; /* PAT/PMT period in PCR time base */
> > > >     int nb_services;
> > > >     int64_t first_pcr;
> > > > +    int first_dts_check;
> > > 
> > > It is minor nitpicking, but can you rename this to first_dts_checked and
> > > reverse the logic? So this can be 0 by default (so it does not have to be
> > > explicitly initialized), and you set it to 1 after it is checked.
> > 
> > I'm OK for your suggestion for the name, but MpegTSWriteStream have
> > defined a first_pts_check for every stream to check first pts for
> > stream, do you think it's necessary to keep the same style?
> 
> Ok, I see what you mean. I'd rather change that to use reversed logic (and
> past tense) there later. And we should expand that to check if not only pts,
> but the first dts in every stream is also valid.

thanks, will update the patch to fix the name to first_dts_checked and reverse
the logic.

> 
> Regards,
> Marton
> 
> > 
> > > 
> > > Thanks,
> > > Marton
> > > 
> > > >     int64_t next_pcr;
> > > >     int mux_rate; ///< set to 1 when VBR
> > > >     int pes_payload_size;
> > > > @@ -1134,6 +1135,7 @@ static int mpegts_init(AVFormatContext *s)
> > > > >     if (ts->copyts < 1)
> > > >         ts->first_pcr = av_rescale(s->max_delay, PCR_TIME_BASE, AV_TIME_BASE);
> > > > +    ts->first_dts_check = 1;
> > > > >     select_pcr_streams(s);
> > > > > @@ -1688,6 +1690,11 @@ static int
> > > mpegts_write_packet_internal(AVFormatContext *s, AVPacket *pkt)
> > > >         stream_id = side_data[0];
> > > > >     if (ts->copyts < 1) {
> > > > +        if (ts->first_dts_check && dts != AV_NOPTS_VALUE) {
> > > > +            ts->first_pcr += dts * 300;
> > > > +            ts->first_dts_check = 0;
> > > > +        }
> > > > +
> > > >         if (pts != AV_NOPTS_VALUE)
> > > >             pts += delay;
> > > >         if (dts != AV_NOPTS_VALUE)
> > > > -- > 1.8.3.1
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> > 
> > -- 
> > Thanks,
> > Limin Wang
> > _______________________________________________
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-- 
Thanks,
Limin Wang