Ogg vorbis performance.
hozer at hozed.org
Fri Jul 18 06:40:44 CEST 2008
> It should have essentially zero overhead when properly configured, and
> when its not doing anything fancy. I don't think these performance
> problems are fundamental.
Don't think, benchmark :) There are a ton of non-obvious reasons one
approach might seem just fine but really suck. (cache alignments, tlb
misses, ctx switch overhead)
> >For power and performance reasons on a cell phone, I think anything a
> >sound server does would be much better done in the kernel-level ALSA
> >drivers. The only downside I can see to this approach whether the
> >in-kernel bluetooth audio drivers are any good.
> Kernel-level software resampling should be just as expensive as
> userspace resampling... Pulseaudio does seem to do some soft-realtime
> stuff and adds a bit of device transparency.
> >Last I tried bluetooth-audio on my laptop I had to run a userspace
> I have no idea what would happen with Alsa if you tried to transfer a
> call between the speaker and the bluetooth set. I think pulseaudio can
> handle this sort of thing correctly.
All my whining aside, seamless speaker->bluetooth handoff seems to be a
'must-have' feature. Although I would like to hear a good reason why the
kernel shouldn't be in charge of that.
> >Speaking of which.. do we have any way to measure the power consumption
> >of playing a reference .ogg file without special hardware? Are the
> >built-in battery charge management counters good enough?
> Good question. :) Also, pulseaudio may be preventing the sound card and
> cpu from falling asleep, even when no sounds are being played. From
> what I can tell, it's been configured to never go idle.
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