On 2011-03-19 17:45, Philip J?genstedt wrote: > Hi PulseAudionauts, > > I've been meaning to experiment a bit with low-latency voice codecs > and naturally want to add as little latency as possible to what is > imposed by the codec on both capture and playback. (My guess is that > the latency added would be between min(capture_latency, > playback_latency) and capture_latency+playback_latency, depending on > how well capture end and playback begin are synchronized.) > > Q: Does it matters for latency if I program against ALSA or PulseAudio? Well, that kind of depends on what scale you're on. If you need latencies under say - and this is just a qualified guess - ~ 10-20 ms, you'll need to program against ALSA or Jack. Above that and you'll be good with PulseAudio. > This is assuming a setup like on Ubuntu, where the default ALSA device > is using a PulseAudio backend. (Portability and code complexity may > favor one solution or the other, but that's not what I'm asking.) When I say program against ALSA above, I mean directly against an ALSA sound card, i e bypassing Pulseaudio. As for if ALSA plugin -> PulseAudio -> ALSA -> HW gives worse latency than PulseAudio -> ALSA -> HW, I don't think that matters much. -- David Henningsson, Canonical Ltd. http://launchpad.net/~diwic
