jon wrote: > On Tue, 2013-04-09 at 21:59 +0200, Clemens Ladisch wrote: >> jon wrote: >>> If I increase the bufchunks value I seem to get larger latency >>> yet the latency values i'm reading always seem to be the same. >> >> Apparently, your program fills the buffer fast enough so that there >> are never too many frames available. I'd guess that if your program >> gets delayed more, by its own computations, by scheduling delays, or >> by increasing the period time, you would see higher values. > > I'm not sure I understand that behaviour at all... I would expect ALSA > to keep the buffer as full as possible not as empty ?
Please note that the number of "available" frames, as returned by snd_pcm_avail(), is the number of sample that your application can write to the buffer. The number of frames available for the device to play is the opposite of that. > If I set the buffer length to say 100ms does ALSA not maintain a 100ms > fill of the buffer only dropping if I don't send samples fast enough, > then re-filling when I do - that is the behaviour I want (and would > expect). And that is exactly what happens. > I am trying to cope with frequent short freezes (30ms or so) making > buffer filling jittery. I want to maintain a cache of about 80ms between > the ALSA write and my ears, If that is what you call latency, then you must subtract the value returned by snd_pcm_avail() from the buffer size. > with ALSA using data from cache during the slower iterations of the > fill loop. How can I do this ? By using a buffer size of about 80 ms. Regards, Clemens ------------------------------------------------------------------------------ Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis & visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter _______________________________________________ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
