On Wed, Jul 17, 2013 at 3:59 PM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > On Tue, 16 Jul 2013, James Stone wrote: > >> Thanks. The patch allows jack to now start at (playback only) 64 >> frames/period. It doesn't work with 32 frames/period though (I think >> you predicted this). This is still a regression from 3.5.0-28, which >> will work with 8 frames/period for playback only. Furthermore, jack >> won't start in duplex at 128 frames/period. It doesn't (yet) tempt me >> to use the 3.8 series kernels for proper audio work. > > Usbmon traces, please (for 3.8 only; I'm willing to believe that 3.5 > works okay). It's difficult to predict the final effect of the > parameters you supply to JACK, because the ALSA layer imposes its own > set of requirements on them. I will send off list again. > > Also, changing the ALSA layer to use a larger minimum pipeline length > might end up fixing all these problems. I'm sure that with the current > code at 64 frames/period, the hardware ends up skipping some frames, > even though the effect may not be audible. Yes - there are definitely missed frames. It sounds crackly. > >> Could there be any other changes to the kernel between 3.5 and 3.8 >> that might be affecting this? > > I don't know. But don't forget also that some of the behaviors you see > now may be a result of the first patch from Clemens (the one that fixes > the problem of the ridiculously large maxpacket values). That patch > may not apply cleanly to the 3.5 kernel, but if it does, finding out > what effects it has could be interesting. OK - I might try this. -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
