[vlc-devel] [PATCH 08/17] es_out: use the input_clock as a master source of vlc_clock

[Thomas Guillem]

Ping

On Fri, Feb 19, 2021, at 09:38, Thomas Guillem wrote:
> Thanks for this review, you raise an important point. Let me enumerate 
> what my patch set is changing and what could be discussed.
> 
>  - 1/ We add back the input (PCR) as clock master, disabled by default. 
> This feature is likely to be used by advanced users.
> 
>  - 2/ We now use the input clock to calculate the pts_delay for the 
> Output. When converting the first PTS, the master ES will use the input 
> clock to convert its PTS. Once the master ES is started, (the first 
> vlc_clock_Update() is called), it won't use the input clock anymore.
> 
> The pts_delay calculated by this new way is now the same as what we 
> were doing in VLC 3.0 (you can easily see it by comparing the starting 
> differed logs in pulse audio). When we added the clock, we tried to 
> emulate this calculation via vlc_clock_main_SetFirstPcr() and 
> vlc_clock_main_SetInputDejitter() but the results are not exactly the 
> same.
> 
> - 3/ If there is no master, the input clock is used as master (like in VLC 3.0).
> 
> 
> I think the points 1/ and 2/ are valid. What do you think?
> 
> As for 3/, we can do it differently:
>  - All ES types can be the master (but the audio is in priority).
>  - Use to the current monotonic fallback when there is no audio by 
> default. The "--clock-master" option will have 3 options: master_audio, 
> input, monotonic.
> 
> Thanks for your time!
> 
> 
> On Wed, Feb 17, 2021, at 20:52, Rémi Denis-Courmont wrote:
> > Le maanantaina 15. helmikuuta 2021, 12.15.03 EET Thomas Guillem a écrit :
> > > There is now always a master clock, the input one or the audio one.
> > 
> > That assertion does not make much sense.
> > 
> > The input can only provide a clock if it is paced, which is not usually the 
> > case, at least not for regular files. And even when it is, it might be much too 
> > coarse/irregular to be useful (though we can leave that later determination to 
> > the user).
> > 
> > -- 
> > Rémi Denis-Courmont
> > http://www.remlab.net/
> > 
> > 
> > 
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