status of usb audio driver

[Takashi Iwai <tiwai@suse.de>]

Hi,

snd-usb-audio is a bit updated.
i borrowed a usb microphone and found that there was a deadlock at
exit of capture.  now it's fixed.
the source codes have more comments and readable (hopefully).

most of debug messages have been moved to snd_printdd().  that is,
to show such debug messages, you'll need to configure alsa-driver with
--with-debug=detect.  if your usb device doesn't work try this, and
send me the output of kernel messages together with the output of
lsusb.

the co-existence problem with oss audio module can be fixed by adding
an entry to /etc/hotplug/blacklist.  the file would be dependent on
the distribution, though.

18/20/24bit formats are not supported yet (if 3-byte format).


so far, i have no plan to port the usb midi driver for alsa, since
there is already a usb midi daemon (see alsa-devel archive).
not like an audio device, the access timing to a midi device is not so
critical.  in the case of audio device, we have to send continuous
packets at each 1ms, sometimes even with a sync pipe.  unfortunately,
this is fairly difficult to be implemented on the current framework of
usbdevfs.  on the contrary, midi can be relatively easily done on
usbdevfs.

however, i'm not sure about the latency over usbdevfs.  if the latency
is too bad, i have to change my mind...


btw, from tomorrow i'll be at LinuxTag at Karlsruhe.
answers will be delayed until the next week.


ciao,

Takashi

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