[wdmaudiodev] MIDI-usb packets Zero padded using WinXP SP2 generic audio-usb drivers
- From: Bruno PILLET <bruno.pillet@xxxxxxxxxxx>
- To: wdmaudiodev@xxxxxxxxxxxxx
- Date: Wed, 19 Jul 2006 18:26:20 +0200
Hi,
I am developing a usb midi controlleur, and have a strange behavior with
windows XP sp2 Midi usb generic driver. I use a cypress FX2/FX2PL usb
high speed chip.
-> Every Usb Midi packet sent is filled with zeros until the size of
the OUT endpoint. So the bandwidth of the connection is wasted, and the
endpoint byte counter point to the size of the buffer instead of the
size of the message itself.
I check with both hardware and software USB analyser.
It does not append on Mac OSx!
So does anybody already noticed such a kind of behavior? Is it normal?
Do you have any suggestion to deal with it.
A workaround to determine real packets length is to stop counting on the
first USB command egal to zero(not already used in USB spec), but my
main concern is the waste of bandwidth because my device is also an
audio device with 10 in and 2 out channels.
Regards,
Bruno
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