On September 19, 2012 3:18:19 PM Robert Jonsson wrote: Hi Luis
2012/9/19 Luis Garrido <[email protected]> On 09/19/2012 01:42 PM, Florian Jung wrote: > > and if there are disadvantages of jack-midi vs alsa-midi: tell me! > > > > > I am by no means an expert on the subject, but I have the vague > recollection that jack-midi has a couple of disadvantages: > > 1) Makes midi latency dependent on jack's audio buffer size. > 2) Doesn't deal well with big sysex messages. > > > > I see. If that is the case the realtime use case (playing keyboard and listening live) will also have considerable jitter. > I need to test it. > > Robert and Luis are both right. Jack Midi offers the advantage of frame-precision, but with large Jack buffers there is midi latency. And there's nothing you can do about it, just like audio latency, for 'live' playing. With pure Jack midi you could be waiting up to *two* periods - one record and one playback cycle. Not good. A separate ALSA or other timer on the record side offers *some* immunity to this. In theory the latency could be halved - reduced to nothing on the record side but still there's Jack midi playback latency you can't get around. In fact live players using large Jack audio buffers may be better served by using only ALSA for /both/ record and playback. But of course then there's the audio latency... So that's why I argued against completely removing ALSA support. I even spoke of a hybrid system in which we use Jack midi, but at large buffer sizes we automatically choose between Jack and the ALSA or other timer for the best timing. Thus satisfying 'live' realtime performers. So having ALSA and a separate timer is very important. Whether it be ALSA or HP or RTC, it's good to have one. That's why I was so hesitant to force the -A switch, hope it was a good idea... About the sysex: At this point MusE doesn't handle sysex chunking anyway (prints a warning), so it doesn't really matter, but if we ever fix that we'll need to be sure whatever system we use, we can rely on it to deliver large sysexes or at least chunk them, and Jack midi can't do large ones ATM, but there's no reason why the source couldn't just break it up into chunks, Jack can handle that I think. Thanks for the RTC links Robert, I'll try it out. Tim. ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Lmuse-developer mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/lmuse-developer
