Re: 1 in 2 out MIDI ports
Re: 1 in 2 out MIDI ports
- Subject: Re: 1 in 2 out MIDI ports
- From: Doug Wyatt <email@hidden>
- Date: Tue, 18 Feb 2003 14:24:06 -0800
On Monday, Feb 17, 2003, at 08:32 US/Pacific, Jaeho Chang wrote:
We're developing a small MIDI interface with 1 input and 2 output
ports. This interface is working very well with Win XP, but one of 2
output ports is not recognized on Mac OS X. We already made 4 in 4
out, and 8 in 8 out interfaces and they are working very well. So I'm
wondering if inputs and outputs should be always in pairs.
Any idea?
Is there a special thing we have to consider when making a MIDI
interface for Mac OS X?
Herbie: you referred to a bug but I haven't seen one; would you mind
writing one?
Is the problem that the device doesn't appear in Audio MIDI Setup or
API calls to have the correct number of ports, or that the ports are
there and I/O doesn't work?
If the problem is in adding the device to the setup..... the USB class
driver does this:
int nIns = 0, nOuts =0
int *whichCounter = NULL
in the device's configuration descriptor
find the interface descriptor
for each entry in the interface descriptor
if it is an endpoint descriptor
if bEndpointAddress & 0x80
whichCounter = &nIns
else
whichCounter = &nOuts
else if type == 0x25 and first byte is 1 // class-specific endpoint,
general
if whichCounter != NULL
*whichCounter = bNumEmbMIDIJack
int nPorts = max(nIns, nOuts)
for port = 1; port <= nPorts; ++port
add an entity: it has an input if port <= nIns, it has an output if
port <= nOuts
Do you see a flaw in this logic? Or I can look at a dump of your
device's configuration descriptor.
I checked the logic for preparing a device for I/O and I don't see any
obvious problems there either...
Will be glad to investigate given more info.
Thanks,
Doug
--
Doug Wyatt
email@hidden (CoreAudio)
personal: email@hidden
http://www.sonosphere.com
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