[MPlayer-dev-eng] [PATCH] reduce latency for ao_pulse

[Dan Oscarsson]

On 2010-07-14 at 18:50 +0200 Reimar Döffinger wrote:
> > If you enable autosync mplayer drops frames to keep up with the faulty
> > ao driver.
> 
> No, -framedrop does that. If autosync without -framedrop does that it would
> be a bug.
> 

Yes, you are right. I was looking at the status line and forgot that
even though it output dropped frames - the frames are only dropped if
framedrop is active.

Maybe the status line output should be changed so it only shows dropped
frames if they really are dropped?

> > It is the audio that is the problem, not the video.
> 
> I repeat: autosync was explicitly designed for broken audio drivers, which
> is exactly this case. It may not actually implement to detect and work
> for this case, and I am not sure it is possible to do this reasonably
> successfully.

Yes, you are right. I have looked at the code for autosync but it was
not easy to understand. Will have a deeper look at it.

> 
> > My patch
> > changes so pulseaudio works much better without needing autosync.
> 
> Well, it also does nothing to avoid similar issues that I suspect other
> aos like SDL and possibly OSS have, seems to rely on pulseaudio internals
> that might change with unknown effects on our code and will continue to
> cause higher CPU load and higher power usage due to more frequent wakeups
> even if the bug is eventually fixed.

I have been running through the oss driver without any bad effects. But,
yes you may be right. Pulseaudio is not easy to understand (but neither
is mplayer in some parts).
 
> Do you have a link to a pulseaudio bug report so we have at least a chance
> to notice if it is ever fixed?

No, tried to get the developers to explain why it was not working as I
expected but got no good answer. So I more or less gave up trying to get
pulseaudio to be fixed. I will see if I can try to get them to look at
the problem.

   Dan