2011/1/18 Dr. Adrian Wrigley <mail at adrianwrigley.com>: > Hi all, > > I'm now having problems with latency. > > I'm trying to send the analog input on Machine2 to the speakers on > Machine1. ?I'm currenty trying with esd protocol and module-esound-sink > on Macine2. > > (Unfortunately, native tcp protocol doesn't work for me. ?It produces only > silence > or brief bursts of sound unless I am running pavucontrol on Machine2 at the > same time, when it works fine (weird). ?Also, the CPU usage is excessive on > the machine > receiving the audio - about 12%, which then requires fan cooling (650MHz > Pentium laptop). > The latency on native tcp protocol is fine. ?Why is native tcp need 10x the > CPU of esd?) This has to do with resampling to correct for clock drift between the machines. You could try setting a lower quality resampler to save CPU, or disabling resampling all together. > The latency with esd I hear is about 1500ms. ?I'd like under 200ms. > > The three key modules I load on Machine2 are: > > load-module module-alsa-source source_name=wireloop > load-module module-tunnel-sink server=192.168.1.4:16001 > load-module module-loopback source=wireloop sink=tunnel.192.168.1.4 You mentioned ESD before. I fail to see any use of protocol-esound here. Or are you describing two different setups? > My questions: > 1) ?The reported latency of 38 years must reflect a bug!(?) ?Can this be > fixed? > 2) ?Is my configuration for listening to the ALSA source sensible? is there > a better way? Did you try module-rtp-send and module-rtp-recv? > 3) ?Where does my 1.5 second latency come from? ?How can I reduce it? By default pulse tries to wake up as little as possible. This is done by setting a large buffer size. I'm still a little bit confused about your exact setup, so I can't really tell you how to reduce the latency in your case, other than: look at the available module parameters. > 4) ?Why does native tcp protocol (module-tunnel-sink) need pavucontrol > running to work? pavucontrol sets up streams to every sink to monitor audio for its vumeters. For these streams it requests a low latency. That makes the latency for all the streams low. The solution would be to ask pulse for a lower latency for your stream. > A work-around for the moment is to bypass Pulse by running this command on > Machine2 > arecord -f S16_LE -c 2 -r 44100 | /usr/bin/esdcat ? # Lower latency transmit > to Machine1 > > Using Puleaudio adds 1.5 seconds in the path. > > Thanks again for any helpful comments! > -- > Adrian Wrigley Maarten
