#262: Pulseaudio should switch sample rates when possible
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Reporter: Florob | Owner: lennart
Type: defect | Status: closed
Priority: normal | Milestone:
Component: daemon | Severity: normal
Resolution: wontfix | Keywords:
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Comment (by lennart):
Dude, we ask ALSA for a 44100hz by default, and also ask it to not give us
anything that is not native to the hardware. Then, we take whatever ALSA
gives us, which might be different from 44100hz. Could be 48khz or
whatever.
What I was referring to is that we won't do on-the-fly sample rate
switching. You are always welcome to configure PA via default-sample-rate=
option in daemon.conf to a different sampling rate.
But again: PA will *not* default to any "artificial" sampling rate. We try
our best to convince ALSA to hand us only *native* sampling rates.
Florob: Resampling won't cause you stuttering music. Not on any hardware
that is newer than 10 years. However, if we'd switch sampling rates all
the times when a new client connects and requests a different rate and
have to close and reopen the audio device for that then you would
certainly hear that as nasty drop outs. Just think of this case: you play
two streams at the same time. First you start one with 8khz sampling rate.
When it is half way through you start one at 44khz. In the world you are
requesting we'd first open the audio device in 8khz and as soon as the
second stream starts to close it and reopen it in 44khz. You will
certainly hear that, the first stream will be interrupted for a short
time! So in short: what you are requesting will cause bad sound quality.
In summary, what you guys are requesting doesn't make sense.
In PA 0.9.11 we will probably ship an SSE optimized version of the Speex
resampler. Then you probably won't be able to even notice the CPU load.
I'll then also change the default sampling rate to 48khz, which is what
dmix did already.
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Ticket URL: <http://www.pulseaudio.org/ticket/262#comment:4>
PulseAudio <http://pulseaudio.org/>
The PulseAudio Sound Server
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