[linux-dvb] Re: Linux DVB API 4 Q's

[Rob.McConnell@Zarlink.Com]

> > Ahh, maybe if we implement your DVB_DMX_SET_PID_FILTER with an array of
> > PIDs to set and start immediately using the DVB_DMX_IMMEDIATE_START
flag,
> > we can nicely obtain this requirement.
> >
> > Do these ideas sound reasonable?

> If I were to implement it I would go with your last proposal.

> But I am not convinced that your requirement is reasonable. If you
> do a few ADD_PID or DEL_PID calls in succession, they would
> typically be only microseconds apart (possibly a few milliseconds
> if the system load is high). Why is that a problem?

From a Q.A. point of view, the audio and video should not be out by greater
than 10ms (in terms of audio lagging behind the video). Can we really
guarantee this requirement between successive system calls?  What happens
if you execute the first system call to setup the video PID and when it
exits the scheduler decides to execute some other process that could be
very time consuming?  We may not get back to setting up the audio or
subtitle PID for quite some time later.  Don't forget that we are not
running on 1GHz+ uProcessors, but rather more like 100MHz+.  If we can
setup the video/audio/subtitle PIDs all in one go, then at least we
wouldn't have this worry.

Rob :^)






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