On Thu, 09 Jun 2016 15:17:53 +0200, Ihar Filipau wrote: > > On 6/9/16, Takashi Iwai <tiwai@xxxxxxx> wrote: > > On Thu, 09 Jun 2016 13:38:19 +0200, > > Ihar Filipau wrote: > >> > >> Hi All! > >> > >> When using the dmix on ARM, the sound comes out garbled, with as if > >> overlapping, increasing-in-number echoes. That happens even with a > >> single aplay instance. > >> > >> In a forum discussion, it was suggested that ARM lacks optimized dmix > >> implementation. But that implies that the generic dmix code is broken, > >> since it is what is used on ARM/etc, but not on i386/amd64. (The forum > >> discussion about my particular issue: > >> http://unix.stackexchange.com/questions/288451/sound-corruption-echo-when-trying-to-use-alsa-dmix > >> ) > >> > >> Does anybody has any suggestions how to fix/avoid the dmix issue on ARM? > > > > This is likely the cache coherency issue. For example, the generic > > dmix code works fine on x86-64 if I modify the ifdef condition (I > > tested now). > > > > Thanks for the test! > > > I suppose the mmap support is broken with your device / driver. > > Does "aplay -Dhw -M --period-size=1024 somefile.wav" work? This > > should show a similar problem. > > > > The command plays the audio perfectly well. Hm, then try to adjust all parameters as same as dmix slave PCM. As default, dmix slave PCM takes 16 x 1024 frames periods, S16_LE format. > The hardware works, and it worked for quite some time now. But > apparently it doesn't support the hardware mixing (I'm not even sure > how to check that, found no documentation) while now we need the audio > playback from two applications. The second applications gets -EBUSY > when trying to open the "default" pcm. I have tried the 'dmix' - e.g. > "aplay -Dplug:dmix somefile.wav" . With that I can open the pcm > multiple times - "for X in 1 2 3 4; do aplay -Dplug:dmix somefile.wav > & ; done" - but the sound is garbled, whether it is a single aplay or > multiple aplays. > > Is there any other way I can debug/trace the alsa to shed light on the > problem I'm having? If the hw works and dmix doesn't even with the very same parameters for a single stream, it can be in the update timing. But it's doubtful, as basically dmix slave is freewheeling... Takashi > > Thanks. > _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
