At Mon, 29 Dec 2008 23:22:54 +0000, mike start wrote: > > I've been having difficulty getting an ews88MT (ice1712 chipset) to work > in full duplex using the jack audio server (jackd). Capture only mode > works fine, even down to 64 samples latency, Playback only mode works > fine down to 64 samples latency. Duplex mode causes 'xruns' at even > 2048 samples latency. Looking at the interrupt handler, if I add some > diagnostics to tell me the difference between the capture and playback > DMA counters timing out I see what appears to be clock drift between the > playback and capture halves of the ice1712. I also added some debug > messages to show what sample rate the alsa driver was setting the > hardware to and it agrees with the rate set in my jackd invocation > (jackd -R -d alsa -n 2 -p 1024 - r 48000 -d hw:0,0) > Also adding diagnostics to jackd to show the time spent in poll waiting > for the capture and playback interrupts shows that they start in sync > and gradually drift until an 'xrun' occurs when they are '-p' samples > apart. According to the ice1712 data sheet the 'professional' > multitrack part of this chip (the part my soundcard is using) runs its > inputs and outputs from the same master clock so I'm puzzled as to why > they are drifting. I'm puzzled, too. Not only clock but also sample rates are shared (must be identical) both for playback and capture on ICE1712... > Does anybody have any more information relating to > the ews88mt? - I think the drivers are working fine but the problems > are being caused by the capture and playback not being quite in sync > which renders it almost useless for professional recording. Anyone have > any suggestions? How did you check the DMA counter value? From the raw register read or on jackd? Takashi _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
