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? Takashi _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
