Hello alsa-devel,
I'm trying to build bit-perfect music playback box using Olinuxino board and EMU 0404 USB sound card running MPD. I have wide collection of lossless songs with different sampling rates - from 44100 to 192000. I set MPD config to play sound via correct alsa device and it works, however whenever I start play song with different sampling rate - MPD (or ALSA?) 'forgets' to switch sampling rate frequency and I hear buzzing sound instead of music. If I run alsamixer and manually switch there sampling rate - it plays OK until I select song with again different sampling rate. It seems I'm not first with such a problem, here is same complain with a workadound: http://murga-linux.com/puppy/viewtopic.php?p=745547#745547
Currently I'm running sunxi Linux kernel: 3.4.90, but same bug reproduced when I used Raspberry PI with kernel 3.6.11 ALSA's version: cat /proc/asound/version Advanced Linux Sound Architecture Driver Version 1.0.25. Seems I was able to fix this on my system, but not sure if this fix is correct, here is diff:
--- quirks.c Fri Jul 18 01:20:16 2014 +++ quirks.c Sun Jul 20 00:20:49 2014 @@ -723,7 +723,8 @@ static void set_format_emu_quirk(struct * by playback substream */ if (subs->direction == SNDRV_PCM_STREAM_PLAYBACK) { - if (subs->stream->substream[SNDRV_PCM_STREAM_CAPTURE].interface != -1) + if (subs->stream->substream[SNDRV_PCM_STREAM_CAPTURE].interface != -1 && + subs->stream->substream[SNDRV_PCM_STREAM_CAPTURE].running) return; }