[linux-audio-dev] Best-performing Linux-friendly MIDI interfaces?

[Stéphane Letz]

Le 13 juin 05 à 17:05, Jay Vaughan a écrit :

>> Good to see someone other than Grame' guys  try to "push"  
>> MidiShare.... ((:
>>
>
> well, i'm only pushing because i'm using it, and i can't use ALSA.  :)
>
>
>> But Jay, MidiShare cannot help in terms of synchronizing MIDI with
>> audio at the sample level..... MidiShare events are 1 millisecond
>> time stamped.
>>
>
> yes, i understand that now .. i initially mis-understood pd's idea  
> on this, since under OSX, MidiShare is 'sync'ed' using an Audio  
> timer..

You're right. On OSX the MidiShare interrupt source can be derived  
from the audio timing, so that  the MidiShare time will not drift  
form the audio time in case an application has special needs of Midi  
+ audio synchronization. A timer only mode is also available.

This "audio timer mode" is not available of other platforms where it  
was difficult to get audio buffer size (like 64 frames) not "too far   
form the 1 milliscond duration. On OSX with audio timer mode at 64  
frames, the MidiShare interrupt handler is called every 1.45 ms with  
a system that  call the interrupt handler twice every n interrupt  
(don't remember the precise value here...) so that is MidiShare time  
remains correct.


>
> but, it would in fact be interesting if MidiShare had a new 'Audio  
> Event' type added to it, from the standpoint of timestamp'ed  
> events .. thats feasible, i think .. of course, this would only be  
> relevant if one was already using MidiShare, but it would be a nice  
> addition to what I consider a very clean and productive API .. /me  
> goes off to prepare an "AudioShare" patch, heh heh ..

An idea we had some years ago... but even when MidiShare time is  
synchronized with the audio time, a MIDI event still has a time-stamp  
with this 1 interrupt time resolution. We would need a more precise  
time-stamping  to do sample level synchronization.

>
>
>> But well the Linux official API is now ALSA, and the OSX official
>> API  is CoreMidi..... and we have to live with that.
>>
>
> what makes an API 'official' under Linux, anyway?  in my opinion,  
> the old maxim, "use what works" applies .. and ALSA has proven to  
> be a very difficult and annoying thing to get set up and working  
> (witness jwz' recent terror) .. while MidiShare has (for the most  
> part) been smooth and dreamy.
>
> but .. ymmv, yo.
>
> -- 
>
> ;
>
> Jay Vaughan
>
>