oss raw midi emulation

oss raw midi emulation

[Carlos Pita]

Hi!

What should be /dev/midi??   ?
Symlimks to /dev/snd/midiC?D?  ?
Or devices with the correct major/minor numbers specified by the oss manual ?

I'm asking because I need to use snd-virmidi in order to connect pd (which has no support
for alsa midi yet) with muse or vkeybd. So I'm doing:

> modprobe snd-virmidi
> cat /proc/asound/devices
  [...]
  43: [1- 3]: raw midi
  42: [1- 2]: raw midi
  41: [1- 1]: raw midi
  40: [1- 0]: raw midi
> ln -s /dev/snd/midiC1D0 /dev/midi10
> pd -midiindev 11
(with -midiindev N,  pd will open /dev/midiM with M=N-1, just a quirk)
Then I aconnect muse or vkeybd to alsa client VirMIDI 1-0.

It works fine, but is this the right way to do it? For me it was
a matter of trial and error.

Also, debian sarge predefines the following four devices:

crw-rw----  1 root audio 14,  2 2004-10-26 21:40 /dev/midi00
crw-rw----  1 root audio 14, 18 2004-10-26 21:40 /dev/midi01
crw-rw----  1 root audio 14, 34 2004-10-26 21:40 /dev/midi02
crw-rw----  1 root audio 14, 50 2004-10-26 21:40 /dev/midi03

which suggests that /dev/midi?? shouldn't be symlinked as I'm
doing with /dev/midi10.

Thank you.
Regards,
Carlos


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Re: oss raw midi emulation

[Jaroslav Kysela]

On Sun, 28 Nov 2004, Carlos Pita wrote:

> which suggests that /dev/midi?? shouldn't be symlinked as I'm
> doing with /dev/midi10.

No, debian or snddevices script in the driver package does right job.

						Jaroslav

-----
Jaroslav Kysela <perex@suse.cz>
Linux Kernel Sound Maintainer
ALSA Project, SUSE Labs


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Re: oss raw midi emulation

[Carlos Pita]

On Sunday 28 November 2004 12:22, you wrote:
> On Sun, 28 Nov 2004, Carlos Pita wrote:
> 
> > which suggests that /dev/midi?? shouldn't be symlinked as I'm
> > doing with /dev/midi10.
> 
> No, debian or snddevices script in the driver package does right job.

debian sarge only creates /dev/midi00, ..., /dev/midi03. I need the
/dev/midi10, ..., /dev/midi13 ones. Perhaps if I install udev they will
be created when virmidi is loaded (my kernel has hotplug enabled,
but does virmidi send a hotplug add event? I'm really short of
knowledge here).

I think that my current /dev/ fs is a "static" one, since debian udev package
is not installed and devfs fs creation is disabled at boot time. But I don't know
how to be sure. If the /dev/ fs is "static", would snddevices add the
needed /dev/midi10../dev/midi13 files?

Regards,
Carlos


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Re: oss raw midi emulation

[Carlos Pita]

On Sunday 28 November 2004 12:22, you wrote:
> On Sun, 28 Nov 2004, Carlos Pita wrote:
> 
> > which suggests that /dev/midi?? shouldn't be symlinked as I'm
> > doing with /dev/midi10.
> 
> No, debian or snddevices script in the driver package does right job.

debian sarge only creates /dev/midi00, ..., /dev/midi03. I need the
/dev/midi10, ..., /dev/midi13 ones. Perhaps if I install udev they will
be created when virmidi is loaded (my kernel has hotplug enabled,
but does virmidi send a hotplug add event? I'm really short of
knowledge here).

I think that my current /dev/ fs is a "static" one, since debian udev package
is not installed and devfs fs creation is disabled at boot time. But I don't know
how to be sure. If the /dev/ fs is "static", would snddevices add the
needed /dev/midi10../dev/midi13 files?

Regards,
Carlos


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Discover which products truly live up to the hype. Start reading now. 
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Re: oss raw midi emulation

[Takashi Iwai]

At Sun, 28 Nov 2004 12:14:24 -0300,
Carlos Pita wrote:
> 
> Hi!
> 
> What should be /dev/midi??   ?
> Symlimks to /dev/snd/midiC?D?  ?

No, it's an ALSA rawmidi device.  It accepts totally different ioctls,
etc although read/write controls are almost identical.

> Or devices with the correct major/minor numbers specified by the oss manual ?

Yes.  It should be cdev with major 14 & minor (2 + n * 16) 

> I'm asking because I need to use snd-virmidi in order to connect pd (which has no support
> for alsa midi yet) with muse or vkeybd. So I'm doing:
> 
> > modprobe snd-virmidi
> > cat /proc/asound/devices
>   [...]
>   43: [1- 3]: raw midi
>   42: [1- 2]: raw midi
>   41: [1- 1]: raw midi
>   40: [1- 0]: raw midi
> > ln -s /dev/snd/midiC1D0 /dev/midi10
> > pd -midiindev 11
> (with -midiindev N,  pd will open /dev/midiM with M=N-1, just a quirk)
> Then I aconnect muse or vkeybd to alsa client VirMIDI 1-0.
> 
> It works fine, but is this the right way to do it? For me it was
> a matter of trial and error.
> 
> Also, debian sarge predefines the following four devices:
> 
> crw-rw----  1 root audio 14,  2 2004-10-26 21:40 /dev/midi00
> crw-rw----  1 root audio 14, 18 2004-10-26 21:40 /dev/midi01
> crw-rw----  1 root audio 14, 34 2004-10-26 21:40 /dev/midi02
> crw-rw----  1 root audio 14, 50 2004-10-26 21:40 /dev/midi03
> 
> which suggests that /dev/midi?? shouldn't be symlinked as I'm
> doing with /dev/midi10.

No, definitely not.

The device assignment is different between ALSA and OSS.
ALSA assigns multiple devices per card, but OSS has basically no
concept of cards, so the currently OSS emulation assigns up to two
device per card for /dev/midi0? and /dev/amidi0?.

Instead of symlinks, the applications should be able to point
different paths for devices...


Takashi


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