Re: [alsa-devel] Help requested: new HSS1394 MIDI back-end

["Sean M. Pappalardo - D.J. Pegasus" <spappalardo@mixxx.org>]

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On 05/30/2012 06:51 AM, Clemens Ladisch wrote:
> Sean M. Pappalardo - D.J. Pegasus wrote:
>> It works perfectly with the SCS.1m!! The .1d works, but some of
>> the non-standard data it sends appears to be getting corrupted. In
>> particular, the device sends four-byte platter messages that start with
>> 0xF9 and the remaining three can range from 0x00 to 0xFF.
>
> This is not MIDI. Into what MIDI messages should
> the driver convert this?

It shouldn't convert it at all. Just deliver it as-is in a single 
four-byte message, if possible. (0xF9 is a valid, if undefined, MIDI 
status. They're using it kind of like SYSEX only without the terminating 
byte, likely for efficiency on the wire.)

> Is this documented anywhere?

It's documented in the SCS.1 MIDI spec which is attached. (See the 
record encoder doc.) In looking at that again, I will also need the 
ability to use the HSS1394 SendUserControl function to set the device's 
timers, and that is definitely not MIDI at all. (Sorry, I forgot about 
that since I wrote Mixxx's HSS1394 code awhile ago.) I wonder if it 
would be a good idea to define a special SYSEX message that the SCS1x 
driver would interpret and convert to a call to that function? That 
wouldn't be future-proof but it is MIDI-compatible.

Sincerely,
Sean M. Pappalardo
"D.J. Pegasus"
Mixxx Developer - Controller Specialist

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