Hi Josh, 'Twas brillig, and Joshua Redstone at 16/07/11 18:50 did gyre and gimble: > I'm running pulseaudio 0.9.22-24-g67d18 on Ubuntu 11.04, with a source > at "s16le 2ch 44100Hz" and a USB card that is configured the same way. > I see CPU usage at 25% - I would have thought that if the source/sink > sample rates are identical and there is nothing else going on in the > system, that pulseaudio would have no sample conversion work to do. > Is there a setting to get more info on what it's doing? I've tried > 'pulseaudio -vv' and I see: ...sniped... > D: alsa-util.c: rate : 44100 > D: alsa-util.c: exact rate : 44100 (44100/1) > > and later on, when I play a stream: > > I: sink-input.c: Created input 0 "ALSA Playback" on > alsa_output.usb-Burr-Brown_from_TI_USB_Audio_CODEC-00-default.analog-stereo > with sample spec s16le 2ch 44100Hz and channel map > front-left,front-right > I: sink-input.c: media.name <http://media.name> = "ALSA Playback" > I: sink-input.c: application.name <http://application.name> = > "ALSA plug-in [chrome]" > I: sink-input.c: native-protocol.peer = "TCP/IP client from > 192.168.0.200:46969 <http://192.168.0.200:46969>" > > It seems like they match up exactly, or am I missing something? This is interesting..... The rates match up directly but it seems you are using TCP for communications. This means that the client application (Chrome in this case) is talking over a network socket to the daemon. This method is inefficient if you don't *have* to use it like this. In a typical setup PA client and server will both be run by the same user. When this happens, the client can talk to the server via a local domain socket which is more efficient. But more importantly than TCP vs. local domain, one of the key things the latter enables is SHM data transfer. Rather than copying audio data over the "wire" to the server, SHM, allows the client to just share it's memory space with the server allowing for lower overhead. I suspect you are using padevchooser which is basically cocking this all up. This is one of the many reasons we deprecated padevchooser many years ago and do not recommend it's usage. I still wouldn't expect such high CPU usage rates, so perhaps PA is waking up more than it needs to to service your USB speakers still, but getting a proper connection working is a good first step all the same. Col -- Colin Guthrie gmane(at)colin.guthr.ie http://colin.guthr.ie/ Day Job: Tribalogic Limited [http://www.tribalogic.net/] Open Source: Mageia Contributor [http://www.mageia.org/] PulseAudio Hacker [http://www.pulseaudio.org/] Trac Hacker [http://trac.edgewall.org/]
