Re: Midi data transmission protocol

Hi there,

Just to review the situation about midi cables:

The speed of midi transmission through cables
can only be varied by introducing a new protocol
as has been done with the newer USB midi protocols.

It's not like internet communications where you can
send the data at any rate supported by the hardware - midi
data has to be sent at a fixed rate set by the protocol.

The midi data transmission protocol operates at 31,250 bits per
second, and each byte has two extra redundant error correction
bits added so 10 bits get sent per byte.

So that makes it 3125 bytes per second, or about 320 microseconds
per byte. Three bytes take about a millisecond to transmit through
a cable. That's all fixed. A manufacturer can't make their equipment
to send the data any faster as that would mean it no longer conforms
to the protocol. Only if they support one of the newer faster
midi protocols, that's the only way to go to achieve faster
transmission.

Some links:

http://music.dartmouth.edu/~wowem/hardware/midi.html

http://www.mtsu.edu/~dsmitche/rim419/midi/HTMLs/MIDIIN~1.HTM

However for midi data transmission between programs on the same
computer, there is no midi cable to send it through and instead
you use the windows operating system (at least if using Windows) to send
the data and that operates at a far faster rate, which
also seems to depend only on the number of midi events
sent - seems to send the data at a particular number of events
per millisecond (which may vary depending on computer speed
perhaps), the number of bytes in each message seems
to be irrelevant - a 128 note midi tuning sysex gets sent
as quickly from one program to another on a single
computer as a single note on message.

Robert

Hi Robert,

Thank you for the clarification.
But the main problem of many hardware is caused
by an old fashioned and poor CPU or / and
its ancient operating system.

Please reflect, that most of the "big" companies
don't update a specific product as long as it will be
produced.

Best

Werner

-----Urspr�ngliche Nachricht-----
Von: Robert Walker [mailto:robertwalker@ntlworld.com]
Gesendet: Dienstag, 12. Oktober 2004 17:09
An: tuning@yahoogroups.com
Betreff: [tuning] Re: Midi data transmission protocol

Hi there,

Just to review the situation about midi cables:

The speed of midi transmission through cables
can only be varied by introducing a new protocol
as has been done with the newer USB midi protocols.

It's not like internet communications where you can
send the data at any rate supported by the hardware - midi
data has to be sent at a fixed rate set by the protocol.

The midi data transmission protocol operates at 31,250 bits per
second, and each byte has two extra redundant error correction
bits added so 10 bits get sent per byte.

So that makes it 3125 bytes per second, or about 320 microseconds
per byte. Three bytes take about a millisecond to transmit through
a cable. That's all fixed. A manufacturer can't make their equipment
to send the data any faster as that would mean it no longer conforms
to the protocol. Only if they support one of the newer faster
midi protocols, that's the only way to go to achieve faster
transmission.

Some links:

http://music.dartmouth.edu/~wowem/hardware/midi.html

http://www.mtsu.edu/~dsmitche/rim419/midi/HTMLs/MIDIIN~1.HTM

However for midi data transmission between programs on the same
computer, there is no midi cable to send it through and instead
you use the windows operating system (at least if using Windows) to send
the data and that operates at a far faster rate, which
also seems to depend only on the number of midi events
sent - seems to send the data at a particular number of events
per millisecond (which may vary depending on computer speed
perhaps), the number of bytes in each message seems
to be irrelevant - a 128 note midi tuning sysex gets sent
as quickly from one program to another on a single
computer as a single note on message.

Robert

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