Native sample rate and speaker configuration

[Rudd-O]

At the moment PA hotplug module starts all sinks with a rather conservative channel model and sample rate: stereo 44100 Hz. It would be best if PA could autodetect the best features of the card and start the sink with them.

[lennart]

We could easily do this, however this would then require resampling for almost all cases, since the vast majority of audio still is in 44100hz. Since our resampler is not as fast as I would like it to be people would most likely start complaining.

My plan is to increase the default to 48khz as soon as we have an SSE resampler in place (which will happen very likely very soon).

[lennart]

Oh, and for the speaker configuration: most soundcards do surround sound sound these days, however only a minority has surround speakers attached. Unfortunately we cannot auto detect what kind of speaker set is attached. Thus we will make this selectable in pavucontrol eventually, but still default to stereo.

[fackamato]

Has there been any change to this? I know in Ubuntu Intrepid pulseaudio (0.9.10-2ubuntu8) doesn't use the sound card's capabilities by default. Also, it's true that most sound files are 44.1kHz, but then again most sound cards have an internal sampling rate of 48000Hz, which means it goes 44.1 source > PA 44.1 > card (internal 44.1 > 48k resampling). If we set PA for 48k, it would be awesome when playing DVDs for example (48k all the way through), and for MP3 etc it would be 44.1k > 48k > 48k. Don't know which is better, resampling on the card or in software? My guess is that software resampling would be more accurate (I've no idea on the performance penalty though).

Or I might be talking out of my rear.., not sure. Any updates?

[lennart]

Thre's now a feature that allows easy selection of the speaker configuration during runtime. (Look for set-card-profile for more information)

Also, we fix the sample rate used by PA to what the hardware can do, hence unlike what you suggest needless resampling does not take place.

If the sound card can do 44khz we use that, but if it cannot we take what is suggested instead, looking first for higher and then for lower sampling frequencies.