On Fri, 13.06.08 15:06, Jaroslav Kysela (perex@xxxxxxxx) wrote: > The comment for snd_pcm_delay() in alsa-lib is clear and it's what James > wrote. If only one app interprets this wrongly, then I agree it would be > better not to change original meaning. > > Then we have snd_pcm_avail_update(). Although it is stated in comment that > this function is useless for non-mmap mode, it's quite clear that returns > number of available frames to be handled (r/w) by application. > > The easiest method would be just to remove "useless for non-mmap" from > comments for snd_pcm_avail_update() and suggest to application developers: > > 1) overall latency is returned by snd_pcm_delay() > 2) ring buffer filling is controlled by snd_pcm_avail_update(), for > non-mmap access is usage of this function optional > > As mentioned, it will need to fix some drivers mixing software output FIFO > with ring buffer (USB, PCMCIA).. > > Opinions? Sounds good to me, on first sight. Hmm, however, there is one thing I'd still need for PulseAudio: I'd like to know when (in time units) the playback buffer would underrun from now on if I don't write anything anymore. For the USB driver at least this happens much earlier than just calculating (buffer_size - snd_pcm_avail_update()) and transforming that into time units, because the USB driver seems to remove a block at a time from the playback buffer, and hence it will signal the XRUN much earlier then the aforementioned value. To fix this I'd need to know what this granularity is. If I knew that I could fix my sleep time accordingly. In short: I need some kind of granularity information about snd_pcm_avail_update() but I must admit that right now I am not actually sure which parameter would be the best one to know about. Lennart -- Lennart Poettering Red Hat, Inc. lennart [at] poettering [dot] net ICQ# 11060553 http://0pointer.net/lennart/ GnuPG 0x1A015CC4 _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
