Re: [Bluez-users] step by step - how to get your bluetooth stereo headset fully working with the bluez software stack under linux

[Jelle de Jong <jelledejong@powercraft.nl>]

Brad Midgley wrote:
>  Jelle
> 
>>  I got some kind of bandwidth issue with bluez. When I use my bluetooth
>>  headset and mouse at the same time, the audio gets interrupted. Both
>>  devices are master connections, if the headset is connected as slave,
>>  the connection is totally unusable, every other bluetooth event will
>>  make the audio stop in this case.
>>  - So how can we fix the bandwidth priority/distribution system with bluez?
> 
> since the computer's adapter is master on all the connections, it
> shouldn't be a bandwidth/scatternet issue.
> 
> Someone found a background process was starting up bt scans regularly
> that tanked a2dp streams but it doesn't sound like that is happening
> to you.
> 
> I did notice quite a while ago that the nvidia driver would interrupt
> a2dp while scrolling or moving windows. It must work some evil like
> disabling interrupts for long periods. But that would happen even with
> a wired mouse.
> 
> Do you have anything special with low-latency or other kernel process
> scheduler options?
> 
>>  When I play audio from a dvd, there is a little glitch in some of the
>>  audio frequency's, I think there is an issue with the sbc codec it
>>  appears only in some audio frequency circumstances.
>>  - Can we create a freq spectrum sweep to test the sdc codec on some
>>  glitches?
> 
> I suspect some less conservative encoder settings would help here, but
> if you have an audio clip you can share, I'd be able to hear for
> myself.
> 
>>  When playing audio, it gets buffered, and when you hit the pause key the
>>  media should stop directly. The buffer is also a source for some major
>>  audio video synchronization issues that I have encountered. hitting
>>  pause and play resets the buffer, but it keeps getting out of sync after
>>  some time.
> 
> the delay when using the gstreamer plugin should be more consistent and shorter.
> 
> that's good to hear it basically works in windows... early a2dp
> hardware had an inherent delay problem.
> 
>>  I can't get two audio streams to mix and play at the same time on one
>>  bluetooth device.
>>  - Can we get support for multiple audio streams mixing together for the
>>  same bluetooth device?
> 
> that will be one of the benefits of a native pulse plugin when it's
> written. the old school way to do this is dmix, but it will result in
> more confusion and delay.
> 
> it might be possible to coax pulse to use the gstreamer plugins. this
> setup would give you mixing and more stability. I would only try this
> with native pulse clients.
> 

a. I use the default kernel of debian sid, no low-latency kernel and my 
system is an asus eeepc with all intel chips, except for the atheros 
wireless chipset.

b. I will try to create an audio sample for you.

c. It fully 100% works under that other operating system: 
http://imagebin.ca/view/CEtNv9zN.html


ok, so to summary:

development and testing focus of bluez is: native pulse audio system 
with gstreamer multimedia backend.

xine and alsa do not work very well.... and for now there will be no 
attempts to fix this...?

1. How can we make bluez reserve 278kbps for an a2dp headset?

2. How can we make bluez force all a2dp headsets to become master 
instead of slave?

3. How can we make bluez continue to sent data to the headset even when 
a new bluetooth devices connects.

4. Will pulse and gstreamer and bluez be able to work on a 200 MHz ARM 
system.... please keep things usable for embedded devices...

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