On Mon, 2012-03-26 at 23:54 -0500, Steven Elliott wrote: > I use tvtime (an open source TV application) to watch TV on my Fedora 16 > system. As some of you may know forwarding audio from the sound card > built into the TV tuner card to the primary sound card is not done by > tvtime. There are various ways of forwarding the audio including SoX, > module-loopback, etc. but I've had the best luck (least latency) using > pacat in a manner similar to what this webpage describes: > > http://thelinuxexperiment.com/guinea-pigs/tyler-b/fix-pulseaudio-loopback-delay/ > > But with a change that I've made to pacat that I'd like to share in case > it's helpful. Since I've posted the above I've refined my patch a bit, which I've attached, but I've also explored an additional cause of latency in the PulseAudio server. I've found that, if for some reason, there is an underrun the watermark or latency is increased via increase_watermark() in alsa-source.c and alsa-sink.c. That probably makes sense in a lot of cases, but in the case of watching TV via tvtime I'd rather suffer a fleeting glitch due to underrun than a longer lasting A/V sync issue. I don't think the attached "pulseaudio-limited-watermark-experimental.diff" patch is ideal which why I marked it "experimental". Consequently I'm curious if there is potential for it to evolve into a submitable patch. Should the 50 msec limit that I've imposed in fix_tsched_watermark() be configurable? Would it be preferable to decrease the watermark more aggressively in decrease_watermark()? -- ------------------------------------------------------------------------ | Steven Elliott | http://selliott.org | selliott4 at austin.rr.com | ------------------------------------------------------------------------ -------------- next part -------------- A non-text attachment was scrubbed... Name: pacat-drain-experimental.diff Type: text/x-patch Size: 4898 bytes Desc: not available URL: <http://lists.freedesktop.org/archives/pulseaudio-discuss/attachments/20120519/b94734cf/attachment.bin> -------------- next part -------------- A non-text attachment was scrubbed... Name: pulseaudio-limited-watermark-experimental.diff Type: text/x-patch Size: 2931 bytes Desc: not available URL: <http://lists.freedesktop.org/archives/pulseaudio-discuss/attachments/20120519/b94734cf/attachment-0001.bin>
