Topic: Crackles on pressing play when using many midi outputs

Viewing 5 posts - 1 through 5 (of 5 total)
  • August 21, 2010 at 14:37 #2346
    swindus
    Participant

    I’m using a Moto MIDI Express with 8 midi outputs. All outputs are enabled in Podium controlling my hardware devices, no midi clock is sent. When I press play Podium sends some midi messages (all notes off, cc default values?) to all the enabled outputs one after another and this results in a crackling noise on start playing. The driver report of Podium shows one or more buffer underruns. When I disable all midi outputs or just use one or two of them all is running fine.

    Is there a way to disable the midi messages sent to the outputs on play?

    August 23, 2010 at 13:46 #19269
    Zynewave
    Keymaster

    Podium sends the “all notes off”, “reset all controllers” and “all sound off” control change messages to each MIDI channel. That’s 8 ports * 16 channels * 9 bytes = 1152 bytes. Quite a lot when the MIDI transmission speed is about 3K bytes per second. The MIDI server operates at a high priority, so that can explain why it is stealing time from the audio driver. I could optimize this, so that only the channels that are actually used on the tracks will be reset.

    Can you get rid of the crackles by increasing the ASIO buffer size?

    August 23, 2010 at 16:06 #19270
    swindus
    Participant

    No, still crackles with a buffer size of 1024 or 2048. Usually I use a buffer of 256.

    August 24, 2010 at 02:06 #19272
    Zynewave
    Keymaster

    Try the new 2.36 beta7. The reset messages are now only sent to MIDI channels that previously have received MIDI messages.

    August 24, 2010 at 05:14 #19276
    swindus
    Participant

    Thanks! Works great so far. Let’s see what happens when I use some of the external MIDI devices at the same time. Maybe there is a need for an option to disable those messages completely.

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