[vlc-devel] [RFC PATCH 0/9] Fixing A/V dejitter with high latency devices

[Thomas Guillem]

On Fri, Dec 11, 2020, at 10:54, Steve Lhomme wrote:
> On 2020-12-11 10:37, Thomas Guillem wrote:
> > 
> > 
> > On Fri, Dec 11, 2020, at 10:20, Steve Lhomme wrote:
> >> On 2020-12-10 20:14, Thomas Guillem wrote:
> >>>
> >>>
> >>> On Thu, Dec 10, 2020, at 18:35, Francois Cartegnie wrote:
> >>>> Le 10/12/2020 à 18:10, Thomas Guillem a écrit :
> >>>>>
> >>>>> 2/ Add a callback to the master clock that will fetch the aout delay.
> >>>>> This callback could be triggered by the vout before displaying a frame.
> >>>>
> >>>> That means trigger condition is generally when converting the first non
> >>>> master stream timestamp ?
> >>>
> >>> Indeed, so if the vout is early (audio not ready), the time_get() callback won't return a valid delay and the vout will use the monotonic clock. Then it will wait for the frame display time with vlc_clock_Wait(). This waiting function should take care of polling the last delay before returning.
> >>
> >> Shouldn't it just return INT64_MAX (which should have a proper
> >> name/define) ? In that case the vout considers it's paused.
> > 
> > And when there is no audio?
> 
> Isn't the master clock different in that case ?

Audio can be stopped or started during this phase, we should never assume that audio is always present or not.
So, if you wait in the vout, you should wait via vlc_clock_Wait in order to be signalled when a audio stream is started and/or when the audio delay is known.

> 
> >>
> >> IMO, contrary to what is done now, the first frame should not be
> >> displayed ASAP but when its time has come. A file could start with 5s of
> >> audio and then the video starts. There's no reason the first frame
> >> should be shown when the source intentionally didn't have something to
> >> display.
> > 
> > I agree but I think it is independent of this patch set.
> 
> If the goal is to avoid frame drops at the beginning, maybe not.

Sorry, I don't see how it relates to the current issue.

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