[maemo-developers] DSP SBC debugging

[From: Simon Pickering]

Hi all,

I've moved to Diablo as it uses bluez-utils-3.28 which has the same  
API as version 2.32 on which I based the DSP code. Patching the DSP  
SBC encoder into bluez-utils 2.38 I can use sbcenc (good sign) so I  
tried to play music from mplayer using the a2dp tools produced by  
johnx to set it up.

I get the following error message:

(none):/home/user/MyDocs/.sounds# a2dp enable
(none):/home/user/MyDocs/.sounds# mplayer Moby-In_My_Heart.mp3
MPlayer 1.0rc1-maemo.27.n8x0 (C) 2000-2006 MPlayer Team
CPU: ARM
Internet Tablet OS version: RX-34+RX-44+RX-48_DIABLO_4.2008.22-8_PR_MR0

[MENU] Can't open menu config file: /root/.mplayer/menu.conf
Menu inited: /etc/mplayer/menu.conf

Playing Moby-In_My_Heart.mp3.

Audio file file format detected.
==========================================================================
Trying to force audio codec driver family dspmp3...
Opening audio decoder: [dspmp3] MP3 audio pass-through for Nokia  
770/N800 (fake decoder)
ADecoder preinit failed :(
ADecoder init failed :(
Trying to force audio codec driver family libmad...
Opening audio decoder: [libmad] libmad mpeg audio decoder
AUDIO: 44100 Hz, 2 ch, s16le, 128.0 kbit/9.07% (ratio: 16000->176400)
Selected audio codec: [mad] afm: libmad (libMAD MPEG layer 1-2-3)
==========================================================================
DEBUG: _snd_pcm_bluetooth_open: Bluetooth PCM plugin (Playback)
DEBUG: audioservice_send: sending BT_GETCAPABILITIES_REQ
DEBUG: audioservice_recv: trying to receive msg from audio service...
DEBUG: audioservice_recv: Received BT_GETCAPABILITIES_RSP
alsa-lib: pcm_bluetooth.c:1589:(bluetooth_init) BT_GETCAPABILITIES  
failed : Input/output error(5)
alsa-init: playback open error: Input/output error
Could not open/initialize audio device -> no sound.
Audio: no sound
Video: no video


Exiting... (End of file)
(none):/home/user/MyDocs/.sounds#


Note that I've uncommented the #define ENABLE_DEBUG line in  
pcm_bluetooth.c to get some more info out. I have tried following the  
code back from bluetooth_init(), where the error occurs, but can't  
work out where/why it should occur (the code ends in an IPC and I  
don't know enough about the code to know where it goes to/from). I'd  
be very grateful for some advice/help in debugging this problem.

If you'd like to test for yourself (and you probably need to be  
running Diablo for package compatibility), the ARM code which should  
be substituted into the bluez-utils-*/sbc directory can be found in  
the Garage svn under dsp-sbc/mk2/arm/ and a binary DSP task can be  
found here:  
http://people.bath.ac.uk/enpsgp/nokia770/dsp/sbc/sbcenc.o.diablo.rename-me  
(rename to sbcenc.o and place in /lib/dsp/modules/) to go with the  
sbcenc.cmd file which can be found in dsp-sbc/mk2/dsp/ (again place  
this file in /lib/dsp/modules/)

You will need to add an entry line to the /lib/dsp/dsp_dld_avs.conf  
file like this:
sbcenc <tab> _task_sbcenc <tab> 1 <tab> /lib/dsp/modules/sbcenc.o  
<tab> /lib/dsp/modules/sbcenc.cmd

Then restart the dsp_dld to reload the conf file (by simply running  
"dsp_dld" in a terminal). DSP output can be seen in dmesg.

A compiled bluez-utils can also be found here:
http://people.bath.ac.uk/enpsgp/nokia770/dsp/sbc/bluez-utils_3.28-0osso4_armel.deb

Thanks,


Simon