[FFmpeg-devel] [PATCH 3/4] mpegts: add fix_teletext_pts mpegts demuxer option

Marton Balint cus at passwd.hu
Mon Jul 29 23:58:45 CEST 2013

On Sun, 28 Jul 2013, Reimar Döffinger wrote:

> On 27.07.2013, at 21:14, Marton Balint <cus at passwd.hu> wrote:
>> The option (if set) overrides teletext packet pts with the PCR of a program
>> which the teletext stream is part of that is not discarded. Using the same
>> teletext PID for multiple programs is possible, therefore we need some kind of
>> heuristics to know which program PCR we should synchronize to. Using the first
>> non-discarded PCR pid among the programs of the teletext stream seemed like a
>> good choice.
> Maybe it would be good to mention that an interpolated pcr (which I believe one of the demuxers has code to calculate) would be more correct?

Good point, I will add a todo into the code and the commit description.

>> +                        if (pkt->dts == AV_NOPTS_VALUE || pkt->dts < pcr) {
>> +                            pkt->pts = pkt->dts = pcr;
> Do you have an example where overwriting a NOPTS is better than just leaving it?

No I don't, I just figured that if the HW decoders ignore the pts, we 
may as well ignore it even if it is unset.

Do you have an example where where keeping it unset makes sense? :)

> Should we have some FATE test(s) for this code?

I'm not (yet) familiar with fate, but obviously it would be nice. However, 
I don't think not having one is a showstopper...


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