OK... that's really quite strange indeed. FWIW the 'mmap' alsa code, as far as I know, is only selected for RME devices. I don't have any of those handy so have little way to check any of this on my end. It was written by Winfried Ritsch a decade or more ago :)
Miller > > Made a latency test with pd's own latency testing patch > /usr/local/lib/pd/doc/7.stuff/tools/latency.pd > > -alsa -rt -audiobuf 2 -channels 18 on an HDSPe card with Multiface and > a loopback analogue cable gives 6.5ms, which I consider great! > > Interestingly Pd gives this latency value regardless of setting > -audiobuf to values 1-6, which I suppose is because of rounding this > value to something usable by the dsp part. Pd also reports on startup > "...buffer_time 2902 us opened" > "using mmap audio interface" > > Now what is weird, is that I can't get clean audio under alsa with any > values larger than -audiobuf 6. The sound is very distorted. > > Using the -oss emulation and -rt, clean audio is available for values larger > than -audiobuf 2 such as: > > -audiobuf 3 with measured latency of 7.9ms (Pd choses blocksze 56) > -audiobuf 5 with measured latency of 9.4ms (Pd choses blocksze 56) > -audiobuf 6 with measured latency of 10.9ms (Pd choses blocksze 56) > and so on. > > Oh this is on a Debian system running kernel 3.2.0-4-rt-amd64 > > Nice that Pd can do so low latencies, but that's a strange thing about alsa > though... > > > > best, P > > > > _______________________________________________ > > [email protected] mailing list > > UNSUBSCRIBE and account-management -> > > http://lists.puredata.info/listinfo/pd-list > > _______________________________________________ > [email protected] mailing list > UNSUBSCRIBE and account-management -> > http://lists.puredata.info/listinfo/pd-list _______________________________________________ [email protected] mailing list UNSUBSCRIBE and account-management -> http://lists.puredata.info/listinfo/pd-list
