On Wed, 2015-12-02 at 13:40 +0100, Peter Gervai wrote: > Hello, > > I have been fighting with PA and various SIP desktop clients (and the > view is rather > disappointing); it's not your topic anyway. > > However I have been fighting with Linphone with close to no success. I > am pretty sure that > they initialise their streams with buggy values but still the result > may be a bit of PA's fault. > > The effect: I set PA as linphone's output. This results perfect > capture (mic is working fine) but > no sound output: total silence. Even for the ringtone test. > > Watching pavucontrol I see that the channel (sink) is opened and that > it doesn't seem to have > any data to output. Accidentally, however, I pressed the button with > "Built-in Audio Analog Stereo" > and selected the other sink, which is combined for the same, and > immediately the sound started to be > hearable. > > After a long session of wild-guessing whats' what in PA I guess I have > found at least something > analogous with the problem: when the sound is silent paman (pa > manager) says that the > latency is 92777 us which equals to buffer: 0 us + sink: 92777 us. > This "buffer: 0 µs" didn't look quite > promising, and indeed when I have changed sink in pavucontrol (from > normal to combine or vice versa) > the buffer latency pops up to 30000 us or around and the sound starts. > > My guess is - based on the plenthora of PA problems on the net - that > the channel was opened with > some nonsense latency requirement which make PA silent, but why does > it start to work after switching > sinks? Maybe PA was sanitising internal stuff? > > Anyway. First, it would be nice to be able to tell the linphone guys > what they should fix. I'm not > knowledgeable enough in PA for that. > > Second, maybe this "user error" could be prevented by forcing sane > values on channels, or log an > INFORMATIVE warning or something along this line? (I guess that this > is not a "bug" of PA, but maybe > it is.) My guess is that Linphone doesn't initially write any data to the stream, hence the stream buffer is empty and latency is zero. Moving the stream to a different sink probably causes the server to request for more data, and this time Linphone honors the request and audio starts flowing. But that's just wild guessing. -- Tanu
