[FFmpeg-devel] [PATCH] ALSA for libavdevice
Thu Dec 25 11:29:16 CET 2008
On date Sunday 2008-12-21 21:12:35 +0100, Michael Niedermayer encoded:
> On Sun, Dec 21, 2008 at 08:10:37PM +0100, Luca wrote:
> > Hi,
> > sorry for the delayed response
> > On Fri, 2008-12-19 at 10:59 +0100, Nicolas George wrote:
> > > L'octidi 28 frimaire, an CCXVII, Luca Abeni a ?crit :
> > > > So, it seems to me that the alsa library is still not stable enough for
> > > > what concerns the snd_pcm_htimestamp() function. :(
> > >
> > > All I can say is that it works at home (Debian Testing).
> > Well, I tested various ubuntu installations, but none of them provides
> > snd_pcm_htimestamp(). I've been able to compile the new alsa code only
> > on debian unstable... I tested it on various different machines with
> > different audio cards, but snd_pcm_htimestamp() always blocks and ffmpeg
> > hangs.
> > > Remotely testing ALSA programs is not easy.
> > I know... I suppose this problem depends on the ALSA library version,
> > but also on the driver (and on the hardware).
> > > I guess that means we will have to fall back to the av_gettime-based
> > > timestamp, probably with a call to know the delay to ensure A-V sync.
> > Well, I think that a configure test for snd_pcm_htimestamp() (or for the
> > proper libasound2 version) is surely needed to avoid breaking
> > compilation.
> > A fallback solution based on gettime+compensation would be even
> > better...
> > > Shall I work on a filtering function and submit it as a prerequisite patch?
> > I do not know... I hope a alsa input with proper checking for the right
> > alsa version can be accepted first, but this is up to Michael.
> if its possible to test if snd_pcm_htimestamp() is working in configure
> (that would require detecting that it hanged ...)
> alternatively if someone happens to know which version/driver/hw works ...
> if neither of these then i dont see how we could add snd_pcm_htimestamp()
> based input support
Maybe complaining upstream could help, if we get it fixed then we just
have to check for some ALSA version, rather than put random magik in
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