Re: [Bluez-devel] Bluetooth headset problems.

James Courtier-Dutton wrote:

Cozza wrote:

quoted

Hi,

I believe that there is a problem with the hci-usb driver. I performed 
some
brief investigations which I posted earlier to this mailing list.

Are you using a USB device? I've used the same code and Bluetooth headset
with a PC card Bluetooth adaptor and everything worked fine.

Both Bluetooth devices use the CSR chipset, but the UART one using the 
BCSP
protocol works whereas the USB one misses half the data packets, as you
suggest.

My earlier message was posted on 20th June, entitled "SCO problem with 
USB
devices" - I'd be interested to see if your problem looks the same. I 
think
it possibly is, from what you've posted.

I haven't yet got around to investigating the problem with the USB 
stack -
but I have the same problem, if it helps! If you are in a rush, then 
PC card
devices seem to work at the moment...

Regards,

Colin

I have made some progress. I can now record audio from the headset 
without it loosing any samples. I.e. I can record 8 bit PCM at 8000hz 
and it sounds fine. Before it was loosing samples and recording at more 
like 4000hz.
Once I get playback to work, I will post a patch to this list.
Cheers
James

If anyone is interested, the fix for recording required 2 urbs for each 
isoc connection. The current cvs only uses 1 urb for isoc connections, 
so the usbcore fills one urb in real time, and then when it is full, 
sends it to hci_usb.c via a callback. Once hci_usb.c has finished with 
the urb it sends it back to the usbcore to get refilled. The problem is 
that while hci_usb.c is processing the urb, usbcore has no urb to put 
real time audio samples in, so it just drops them. If 2 urbs are used, 
if hci_usb.c is processing one, usbcore always has another to place 
samples in. As long as hci_usb.c does not hold on to it's urb for too 
long, all is ok. This fix was discovered by comparing the alsa 
snd-usb-audio driver with the hci_usb.c driver.
I hope to get playback working soon.

Cheers
James



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