Message-ID: <426BA787.9060202@xmission.com>
From: Brad Midgley <bmidgley@xmission.com>
MIME-Version: 1.0
To: bluez-devel@lists.sourceforge.net
Subject: Re: [Bluez-devel] Comments about the Logitech/HP stereo headphones
References: <1114345112.10706.64.camel@pegasus>
In-Reply-To: <1114345112.10706.64.camel@pegasus>
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Date: Sun, 24 Apr 2005 08:04:55 -0600

Marcel

This all sounds very good and I feel like a dope for getting rid of my 
bluetake headset when I had only ordered, but not received, a 
replacement. I'm still waiting for my itech. :(

> So what I have done so far is that I extended the pcm_a2dp ALSA plugin
> in the utils CVS repository with the ability to cache the connection.

btsco now fires up the connection on demand and drops it immediately 
after the close. we are going to need caching too. I noticed my phone 
holds the connection open for about 3-5 seconds after it uses it.

> To fully support all A2DP headphones (including Logitech/HP) this plugin
> needs a AVDTP implementation. I have a hacked one on my development
> system and it works fine with the GCT headphones. The code is a little
> bit messy, but in general it works. It is fully event driven and so it
> deprecates the idea of the AVDTP library. It is a lot easier to do it
> directly inside the plugin. I need to cleanup the code and submit it to
> the CVS when there is a little bit more time.

I am excited to see this!

> all about the timing. The perfect thing now would be if we can tell ALSA
> to time everything for us. Problem is that I am not an audio expert and
> also not an ALSA expert. Maybe the SBC encoder should return/store the
> time the SBC frame is encoded for.

I think alsa should help us out here. If I have to learn more about the 
alsa api to help, I will do it.

Doing a2dp inside an alsa plugin is clearly the right way. Thomas was 
saying that requiring alsa-lib was not good for embedded. I'm working on 
an xscale board now and I do have to use a precious 700k of limited 
flash for alsa-lib, but the alternative is to write something into the 
kernel that would never be accepted by Linus.

Brad


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