----- Original Message ---- > From: Takashi Iwai <tiwai@xxxxxxx> > To: Eran Ben-Avi <eranpublic@xxxxxxxxx> > Cc: alsa-devel@xxxxxxxxxxxxxxxx > Sent: Monday, June 22, 2009 7:41:19 PM > Subject: Re: Noisy USB audio stream using MPlayer > > At Mon, 22 Jun 2009 01:17:25 -0700 (PDT), > Eran Ben-Avi wrote: > > > > > > Hi, > > > > I encountered some issue with my USB audio device and couldn't find any > similar issue in previous mailing lists, any help will be appreciated. > > When playing an audio stream using MPlayer Ver1.0rc2-4.1.2 (tried different > sample rates 44K, 48K and different files WAV , MP3) using my Creative SB0271 > USB device on ARM based system(Marvell Kirkwood SoC) and kernel 2.6.22.18, I > hear an interfering constant noise additionally to the original audio stream. > > At the beginning I heard this noise also when I used aplay(for WAV) but after > I reinstalled the ALSA-LIB and ALSA-UTILS(version 1.0.14rc4), the aplay suddenly > started to work smooth. > > I tested different USB audio device(AKM) but got same noisy results. > > Another piece of information I can provide is that increasing the CPU > utilization eliminates the noise completely - maybe a timing issue ??? > > Could it be the cache coherency? > The usb-audio driver uses vmalloc'ed buffers as intermediate buffers, > and they can be exposed to user-space via mmap. > > Does the problem disappears when you disable mmap support by > commenting out SNDRV_PCM_INFO_MMAP* in snd_usb_hardware info field? When I disabled the mmap support I got the following messages while running the mplayer: [AO_ALSA] alsa-lib: pcm_direct.c:874:(snd_pcm_direct_initialize_slave) slave plugin does not support mmap interleaved or mmap noninterleaved access [AO_ALSA] alsa-lib: pcm_dmix.c:876:(snd_pcm_dmix_open) unable to initialize slave [AO_ALSA] Playback open error: Invalid argument Opening /dev/dvb/adapter0/audio0 DVB AUDIO DEVICE: No such file or directory seems like ALSA-LIB doesn't really like it. Thanks, Eran > > > Takashi > _______________________________________________ > Alsa-devel mailing list > Alsa-devel@xxxxxxxxxxxxxxxx > http://mailman.alsa-project.org/mailman/listinfo/alsa-devel _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
