[mythtv] [mythtv-commits] mythtv commit: r24454 by jyavenard

[Colin Guthrie]

'Twas brillig, and mythtv at cvs.mythtv.org at 06/05/10 09:44 did gyre and
gimble:
> An alternative is to unconditionally increase the buffer with"
> echo 512 > /proc/asound/card1/pcm7p/sub0/prealloc

Purely for reference, if a distro ships with PulseAudio, then they
generally include this following kernel patch:

http://svn.mandriva.com/cgi-bin/viewvc.cgi/packages/cooker/kernel/current/PATCHES/patches/sound-alsa-hda_intel-prealloc-4mb-dmabuffer.patch?view=markup

(same as:
http://cvs.fedoraproject.org/viewvc/rpms/kernel/devel/hda_intel-prealloc-4mb-dmabuffer.patch?view=markup)

I believe Ubuntu also does this but I don't follow their development too
closely.

This increases the DMA buffer to 4meg on HDA class hardware. This allows
for larger audio buffers which mean PulseAudio can get the 2s+ latency
that is desirable for playing audio/video on mobile devices to save power.

i.e. on my system:
[colin at jimmy boot]$ cat /proc/asound/card0/pcm0p/sub0/prealloc
4096
[colin at jimmy boot]$ cat /proc/asound/card0/pcm1p/sub0/prealloc
4096

-- 

Colin Guthrie
myth(at)colin.guthr.ie
http://colin.guthr.ie/

Day Job:
  Tribalogic Limited [http://www.tribalogic.net/]
Open Source:
  Mandriva Linux Contributor [http://www.mandriva.com/]
  PulseAudio Hacker [http://www.pulseaudio.org/]
  Trac Hacker [http://trac.edgewall.org/]