On Fri 28 September 2012 10:37:01 Daniel Mack wrote: > On 28.09.2012 04:55, Jeffrey Barish wrote: > > On Fri 28 September 2012 03:06:22 Daniel Mack wrote: > >> (adding back the mailing list - please don't drop it in replies) > > > > Oops. My bad. > > > >> On 28.09.2012 02:43, Jeffrey Barish wrote: > >>> On Fri 28 September 2012 02:02:05 you wrote: > >>>> On 28.09.2012 01:56, Jeffrey Barish wrote: > >>>>> I am using a USB DAC (HRT Music Streamer II) which operates in > >>>>> asynchronous mode. It works perfectly at sample rates up to 48 kHz. > >>>>> > >>>>> When I go to 88.2 or 96, it works perfectly sometimes. Most of the > >>>>> > >>>>> time I get ticks. When it starts playing without ticks, it will > >>>>> continue to play without ticks to the end of the track. A different > >>>>> USB > >>>>> DAC that operates in isochronous mode is able to play at the high > >>>>> sample > >>>>> rates without problem. > >>>> > >>>> Which kernel are you on? And please post the output of 'lsusb -v'. > >>> > >>> I am on the latest kernel, 3.2.0-31-generic > >> > >> That is not the latest kernel - we're currently close to the final > >> version of 3.6, and the snd-usb driver has seen major overhaul in the > >> last versions. > >> > >> So it would be interesting to know whether you see these effects when > >> > >> running a kernel built from this git: > >> git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git > >> > >> Daniel > > > > You seem to have me confused with someone who knows what he's doing. I > > meant that 3.2.0-31-generic was the latest kernel available from Ubuntu. > > You're proposing what sounds like a worthwhile experiment considering the > > major overhaul to the snd-usb driver, but I've never upgraded a kernel > > except from deb packages, so I'm quaking in my boots just thinking about > > it. Ooh, and I bet you're telling me that I would have to make the > > kernel. More quaking. > You could as well just wait for the next ppa kernel and install that one > form the package once it's there. > > http://kernel.ubuntu.com/~kernel-ppa/mainline/ > > There was unfortunately one small regression in the last versions that I > just fixed, so be sure to wait for one more packaged release or even for > 3.6-final. > > > Out of curiousity, are you aware of any specific characteristics of the > > old > > snd-usb driver that could account for what I am experiencing? > > No, but it would be way easier to have a look into that if it also > happens with the current version :) > > > Daniel Kernel 3.6.2-quantal does the same thing. When I interpose a USB hub between the computer and the USB DAC, the ticks go away. Playback works perfectly at 96 kHz. However, at 88.2 kHz, I now get occasional "blips" (instead of steady "ticks"). These symptoms point to excessive delay in the control feedback loop, probably because of buffers in the driver that are too big. If I wanted to take a look at the source code for the driver to see whether I can find anything, where would I find it? -- Jeffrey Barish ------------------------------------------------------------------------------ Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_sfd2d_oct _______________________________________________ Alsa-user mailing list Alsa-user@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/alsa-user
