Re: [Bluez-devel] Continued SCO audio issues...

[Marcel Holtmann <marcel@holtmann.org>]

Hi Rob,

> I posted a while back about having some issues getting SCO audio to work 
> on some Compulab em-x270 boards. Well, we're still not there, but we've 
> tried a lot more things. I'm going to describe the problem in some more 
> detail now in the hopes that somebody here can help point me in a 
> direction to get this working.
> 
> Symptoms:
> 
>   - Everything involved (bt headset, ALSA, aplay/mplayer/pulseaudio, 
> etc) seems to think everything is working.
>   - No sound comes out of the headset. We hear a hissing from the 
> headset during actual audio playback (or when I have pulseaudio talking 
> to it via 'module-alsa-sink' and the sink is not suspended).
> 
> Config(s) Tested:
> 
>  - Kernels: 2.6.23, 2.6.26, 2.6.27
>  - Bluez: 3.26, 3.36, 4.12, 4.18
>  - ALSA drivers: as shipped w/ kernels above
> 
> We've been through about every possible combination of the above. We've 
> tried hci_usb and btusb. We've tested with 3 models of bt headset and 2 
> development boards. For some reason, the ONLY place I can make SCO audio 
> work is under a stock Ubuntu 8.10 (which uses Bluez 4.12, kernel 2.6.27, 
> and ALSA 1.0.17 for the record).
> 
> I'm stumped. Here is some sample output from various pieces as we try to 
> play a file. Right now we're using Bluez 3.36 (getting 4.x running on 
> this platform was a bit of a PITA and was somewhat unstable so we backed 
> out to what currently ships with openembedded)
> 
> We've tried with separate USB dongles (using the same chipset, that 
> works under Ubuntu 8.10) so it's not the onboard BT chipset...
> 
> # hciconfig hci0 version
> hci0:    Type: USB
>     BD Address: 00:02:5B:00:A5:A5 ACL MTU: 310:10 SCO MTU: 64:8
>     HCI Ver: 2.0 (0x3) HCI Rev: 0xc5c LMP Ver: 2.0 (0x3) LMP Subver: 0xc5c
>     Manufacturer: Cambridge Silicon Radio (10)
> 
> # hciconfig hci0 revision
> hci0:    Type: USB
>     BD Address: 00:02:5B:00:A5:A5 ACL MTU: 310:10 SCO MTU: 64:8
>     Unified 21e
>     Chip version: BlueCore4-ROM
>     Max key size: 128 bit
>     SCO mapping:  PCM

you never thought that routing the SCO packets via the chips internal
PCM (instead of HCI) might be a problem if you wanna use ALSA?

Regards

Marcel



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