[Fluxus] MIDI clock

[Greg]

On 07/12/2010 20:10, Kassen wrote:
> One thing I'd be interested in is using this to sync Fluxa's "(seq )" 
> to other musicians. For that kind of thing we might also need 
> something like a timestamp of when the actual message was received and 
> probably a "latency offset" that we could set on a per-system basis in 
> .fluxus.scm

Interesting. All MIDI messages are time-stamped by RtMidi. The time 
stamp is not used by fluxus' MIDI listener, but it's possible. We have a 
few problems here:
- what's the meaning of this timestamp?
- is this meaning platform-dependent?
- how can we convert this time stamp to a value that can be compared to 
(time)?

I need to experiment...

>     I've also found what I think is a bug in RtMidi :
>
>
>
> Not sure how long ago you send this. In my experience Gary does reply 
> to such issues but sometimes it takes a bit.
11 or 12 days...

> I do find this a bit of a odd error to make by mistake. Couldn't it be 
> that rtMidi was assuming all messages are three bytes? I'm asking 
> because I know that ChucK also uses rtMidi and does that. Sending 1 
> byte messages is possible there (not receiving) but you have to use 
> two padding bytes. That might, of course, be a ChucK issue, not a 
> rtMidi one. I commented on that several times and proposed some 
> possible solutions but didn't get a clear reply.
>
This may be a copy-paste error from another part of the code:

         else if ( status < 0xF3 ) {
           if ( status == 0xF1 && (data->ignoreFlags & 0x02) ) {
             // A MIDI time code message and we're ignoring it.
             size = 0;
             iByte += 3;
           }
           else size = 3;
         }

And not all messages are 3-byte-long:

         if ( status < 0xC0 ) size = 3;
         else if ( status < 0xE0 ) size = 2;
         else if ( status < 0xF0 ) size = 3;
         else if ( status == 0xF0 ) {

Mysterious.

> At any rate; good job!
>

Thanks!

-- 
     G.

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