[vlc-devel] [PATCH 03/13] es_out: add the ES_OUT_SET_FIRST_PCR control

[Rémi Denis-Courmont]

Le torstaina 22. elokuuta 2019, 12.00.25 EEST Thomas Guillem a écrit :
> On Wed, Aug 21, 2019, at 19:16, Rémi Denis-Courmont wrote:
> > Le keskiviikkona 21. elokuuta 2019, 17.13.54 EEST Thomas Guillem a écrit :
> > > In order to check if a module need this control, one should check the
> > > DEMUX_GET_TIME implementation for a subtraction with a first_pcr member.
> > 
> > That does not sound right. AFAIK, some demuxers use 0 and some 1 as their
> > start timestamp, but this seems to assume always 0.
> 
> Ah yes, I could set it to 1 by default then.
> 
> Is having a possible off by 10^-6 us conceivable in the case the demuxer
> origin is not 1 ?

I don't know. We'd better fix VLC_TS_0 to be zero (and remove it) as was 
originally planned by Laurent.

spatch should be able to spot the remaining bogus PTS/DTS zero test.

> > As for the TS demuxer, I think its current time has nothing to do with the
> > PCR whatsoever.
> 
> Ah ?
> 
> In demux/mpeg/ts.c:
>     case DEMUX_GET_TIME:
>          ...
>         *va_arg( args, vlc_tick_t * ) = FROM_SCALE(i_pcr -
> p_pmt->pcr.i_first);
> 
> Ah you saying the FIRST_PCR naming is not correct ? What do you propose
> then?

No, I'm saying that that snippet from the TS demuxer is not systematically 
used, as this patch assumes.

-- 
Реми Дёни-Курмон
http://www.remlab.net/