linuxaudio.org

Crypto wrote:

quoted text
> I am currently using two external MIDI devices that connect to my notebook via

> an external USB MIDI adaptor (a nice Edirol UM2).

> [...]

> And now there is a problem: as I have connected the two devices to the IN port

> the application (or the driver of the MIDI port) has to do MIDI merging. But

> something is wrong with the merging, if the running status device's data

> bytes have to be merged with the second device's data stream.

Please note that neither the USB MIDI protocol nor ALSA's sequencer

messages can use running status.
That IN port is an ALSA sequencer port, isn't it?
Does the data look correct when you view it with aseqdump?
> 1.) Which part is actually responsible for the MIDI merging of two or more

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> output devices into one input device? Is it the driver of the port or is it

> the application, that is in the end receiving the MIDI data stream?

Each ALSA sequencer input port has a queue of messages; ALSA

automatically puts messages into this queue in the correct order.
> 2.) Is it illegal to connect two output devices to one input port?
No.
> 3.) If I should need some kind of virtual MIDI multiplexing/demultiplexing

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> driver: which one should I chose?

Connecting one port to several other ports works without a separate

device.
In certain situations, you might want to use the MIDI Through device.
Best regards,

Clemens

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