[alsa-devel] RawMIDI behaviour with MidiFace 4x4

[Clemens Ladisch]

Ricard Wanderlof wrote:
> On Sat, 7 Mar 2015, Kalvas, Taneli wrote:
>> I am developing a patch librarian for a synthesizer. Because the
>> communication happens with Midi sysex and timing is not relevant I chose
>> RawMIDI interface and not the alsa sequencer. The problem I have
>> encountered is that writing to the midi port with snd_rawmidi_write()
>> seems to broken. The function accepts any size of data block and claims
>> to have sent everything. In reality only a part of the message is sent.
>> For a large block size I can see the activity light blinking for
>> fraction of a second. This happens both in blocking and non-blocking
>> mode. I would expect the snd_rawmidi_write() to accept only a part of
>> the message.
>
> Can't help with rawmidi, but I can at least report that my experience
> using the sequencer interface has been that it is rather straightforward
> to use, even if just using it to send and transmit sysex data, even when
> the data is longer than 300 bytes.

If the data is larger than the RawMIDI buffer size (4096 bytes), the
sequencer does not wait (like snd_rawmidi_write() would do), but just
drops data.


Regards,
Clemens