On 11/11/14, 4:06 PM, Marcus van Dam wrote: > Hi, > > Today I ran into an issue regarding alternate-sample-rate. Hooking up my > 16/48 DAC, I was hoping to play back some 48Khz FLAC files. > With the defaults of: > default-sample-rate = 44100 > alternate-sample-rate = 48000 > This should be possible, PA should switch sample rates to 48000. > > At this time I had `pavucontrol` open to switch the source to the right > sink, and adjust the volume. Using `pacmd list-sinks | grep sample` I > noticed that the sample rate is not changing, however if I flip output > profiles on the sink with pavucontrol it does. > > Tracing the whole thing back it seems to come down to the following; > `pavucontrol` opens a source on the soundcard. Directly at startup of > `pavucontrol`: > source-output.c: Created output 0 "Peak detect" on > alsa_output.usb-Burr-Brown_from_TI_USB_Audio_DAC-00-DAC.iec958-stereo.monitor > with sample spec float32le 1ch 25Hz and channel map mono > source-output.c: media.name = "Peak detect" > source-output.c: application.name = "PulseAudio Volume Control" > > Sample rate on startup is "s16le 2ch 44100Hz" as usual. > > Now if I start the 48Khz source (mplayer: AO: [pulse] 48000Hz 2ch s16le > (2 bytes per sample)) the sample rate of the sink stays the same. With > the following in the debug log: > source.c: Cannot update rate, SOURCE_IS_RUNNING, will keep using 44100 Hz > > I've read that _not_ switching sample rates on a sink with has streams > connected is expected behavior. However `pavucontrol` does not show any > streams connected, and only its internal "Peak detect" is connected to > the sink with no way to kick that one out. > > Switching the profiles seems to temporary remove the sink, kicking even > the "Peak detect" out and therefore switching to 48Khz, but then again, > never back down to 44.1Khz. > > So is this a little known caveat, did I encounter a bug, or is there a > better way to control PA keeping the alternate-sample-rate functionality? If you are already running pavucontrol, chances a source becomes active to show the vu-meter on the 'input devices' tab. you should double-check with pacmd list-sources. In general pavucontrol is known to get in the way to sink/source reconfiguration (and prevent them from going to idle due to the vumeter) -Pierre
