[PD] Getting Sysex output to work on Linux

Martin Peach martin.peach at sympatico.ca
Tue Jun 3 06:14:07 CEST 2008

So I tried
[240, 1, 247(
on Pd 0-42-0test1 and the message shows up on the MIDI plug.
It also works to send one byte at a time.
But with Pd0.40.3-extended20080324 it doesn't work, although [noteout] 
and [ctlout] work fine.
This is with ALSA-MIDI and Jack.

PSPunch wrote:
> Does anyone have any opinion on the specs suggested by Martin?
> Should [sysexout] behave in this manner, or would it be more suitable to 
> make this a new object rather than over write the conventional object 
> for compatibility?
> I have no idea if I will be skilled to fix this in the near future, but 
> I really would love to see some of my MIDI controllers in action.
> --
> David Shimamoto
>> PSPunch wrote:
>>> Martin,
>>>> I'm looking at the source code in svn, assuming you use [midiout] to 
>>>> send sysex.
>>>> The midiout object has one method, for floats : midiout_float(), in 
>>>> x_midi.c, line 681.
>>>> It just calls outmidi_byte() in s_midi.c, line 239. If Pd was 
>>>> compiled with USEAPI_ALSA defined, then outmidi_byte calls 
>>>> sys_alsa_putmidibyte() in s_midi_alsa.c line 234, otherwise it calls 
>>>> sys_putmidibyte() in s_midi_oss.c line 182.
>>> Do you mean that theoretically, Pd + ALSA MIDI should be working?
>>> hmmm...
>> Well it looks like it should but I just tried with a scope on the cable 
>> and got messages using [noteout] but nothing using [midiout] with alsa 
>> midi and jack. I tried sending bytes singly and in comma-separated 
>> messages as well as just lists. Nothing comes out.
>>> According to IOhannes,
>>>> the problem is rather, that ALSA sequencer does not support MIDI in a
>>>> way Pd would like it, mainly: no raw midi.
>> Yes, it looks like the ALSA function  being called expects a complete 
>> sysex message but instead it's getting one byte at a time. I guess Pd 
>> should buffer the message until it gets an F7 (End of Exclusive) and 
>> then send the whole thing as one packet. Not too difficult except for 
>> anticipating what the the maximum message size is going to be. Maybe a 
>> [sysexout] object that takes lists of bytes (and inserts the F0 and F7) 
>> is in order...
>>> Also I think one of the recent posts which I cannot locate now,
>>> mentioned that it was just a matter of Pd using a function in ALSA API
>>> other than what is used at the moment.
>> Well I think it's better to send a complete sysex packet, otherwise it 
>> could be trashed by a noteout or similar that occurs before the F7 goes 
>> out. Really Pd should buffer the packet and only then send it to ALSA.
>> Martin
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