On Thu, 19 Jul 2018 09:50:09 +0200, <twischer@xxxxxxxxxxxxxx> wrote: > > From: Laxmi Devi <ldevi@xxxxxxxxxxxxxx> > > There is a higher Xrun probability whenever the ALSA period is not a > multiple of the JACKd period and the ALSA buffer is only twice the period. > Allowing ALSA buffers of min. 3x period is not a good solution because this > would increase the latency. > > As an example in case of ALSA is using a period of 11 frames and JACK a > period of 12 frames and a buffer of 22 frames (2x ALSA period) is used: > - The buffer is filled and contains 22 frames > - JACK is reading 12 frames. Buffer is only containing 10 frames > - Now, ALSA has to be scheduled exactly after the last JACK read and > before the next read. Otherwise we will get an Xrun > In case of ALSA is using a multiple period of JACK, JACK can always read > 2 periods before an Xrun if the buffer was full. > > In case of ALSA is using a period of 12 frames and JACK a period of 11 > frames and a buffer of 24 frames (2x ALSA period) is used: > - The buffer is filled and contains 24 frames > - JACK is reading 11 frames. Buffer is now containing 13 frames. But ALSA > can still not write to the buffer > - JACK reads 11 additional frames. Buffer contains 2 frames > - Now, ALSA has to be scheduled exactly after the last JACK read and > before the next read. Otherwise we will get an Xrun > In case of ALSA is using a multiple period of JACK, ALSA can always write > to the buffer as long as the buffer is filled with less or equal of half > of buffer. > > Therefore this patch enforces an ALSA period which is always a multiple > of the JACKd period. > > Signed-off-by: Laxmi Devi <ldevi@xxxxxxxxxxxxxx> > Signed-off-by: Timo Wischer <twischer@xxxxxxxxxxxxxx> Applied now. Thanks. Takashi _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
