26 Jul
2009
26 Jul
'09
8:17 p.m.
Hi,
I'm currently playing with some code that sends SysEx data to ALSA using
RtMidi¹. I get an error reported by the latter one as soon as the size of the
message exceeds 16355 bytes. Unfortunately, I have such SysEx files of two
devices (namely a Waldorf Microwave I and a Digitech Studio Quad).
Can anyone comment whether this is a limitation in ALSA, and in case it is if
there are coding workarounds? AFAIR ALSA splits incoming SysEx-events into
chunks of 256 bytes if necessary. But I obviously overlooked that sending is
much harder when I played with SysEx data the last time :) .
Best regards,
ce
¹ http://www.music.mcgill.ca/~gary/rtmidi/
uname -a
Linux Grandevitesse 2.6.28-11-generic #42-Ubuntu SMP Fri Apr 17 01:57:59 UTC
2009 i686 GNU/Linux
cat /proc/asound/version
Advanced Linux Sound Architecture Driver Version 1.0.18rc3.
rtmidi-1.0.10
27 Jul
27 Jul
6:35 a.m.
Gabriel M. Beddingfield wrote:
Hi :)
on my system it's possible to receive more than 16355 bytes. It might be
hat the TG33 sends "F0 [...] F7" blocks. Should I take a look at this?
Does amidi work for your system?
spinymouse-sudo@64studio:~$ amidi -l
Dir Device Name
IO hw:0,0 TerraTec EWX24/96 MIDI
IO hw:1,0,0 USB Device 0x170b:0x11 MIDI 1
spinymouse-sudo@64studio:~$ amidi -p hw:1,0,0 -t 8 -r
/mnt/music/studio3.0b/SysEx/2009-07-27/YamahaTG33dAlltAll.syx
40981 bytes read
spinymouse-sudo@64studio:~$ ls -Al /mnt/music/studio3.0b/SysEx/2009-07-27
total 44
-rw-r--r-- 1 spinymouse-sudo spinymouse-sudo 40981 2009-07-27 10:27
YamahaTG33dAlltAll.syx
spinymouse-sudo@64studio:~$
Cheers,
Ralf
6:34 a.m.
Christoph Eckert wrote:
This probably exceeds ALSA's sequencer buffer size.
Can anyone comment whether this is a limitation in
ALSA, and in case it is if
there are coding workarounds?
You could increase the sequencer kernel buffer size by calling
snd_seq_client_pool_set_output_pool(). For the RawMIDI buffer, there
is no programmatic way to change the buffer size; you'd have to change
the output_buffer_size parameter of the snd-seq-midi module.
AFAIR ALSA splits incoming SysEx-events into chunks of
256 bytes if
necessary.
This is the RawMIDI->sequencer event converter, which has its own
buffer.
But I obviously overlooked that sending is much harder
when I played
with SysEx data the last time :) .
ALSA's sequencer API (and RtMidi) have been designed for 'real-time'
events that are so small that they do not need much buffering, and that
are scheduled to be sent at some specific time.
When you want to send SysEx messages, you should split them into small
chunks that are scheduled at proper times so that the MIDI bandwidth
is not exceeded. (aplaymidi does something like this if you give it
a .mid file with huge SysExes.)
However, for this it would be easier to use the RawMIDI API, or a tool
like amidi.
Best regards,
Clemens
2 Aug
2 Aug
7:27 a.m.
Hi,
I wanted to avoid using the rawmidi API, as it requires exclusive access to a
MIDI port, so you couldn't send SysEx files to (or receive from) a device while
it still is connected to another app.
I will continue to use RtMidi ATM to get some code written. If I'm pleased
with the code, I will decide how to cope with bigger SysEx events.
Thanks a bunch for all the useful replies!
--
Best regards,
ce
5726
days inactive
5733
days old
linux-audio-dev@lists.linuxaudio.org
4 comments
4 participants
participants (4)
-
Christoph Eckert -
Clemens Ladisch -
Gabriel M. Beddingfield -
Ralf Mardorf