[Bluez-devel] Nokia 770 and bluetooth audio

[Bluez-devel] Nokia 770 and bluetooth audio

[Brad Midgley]

Guys,

Has Nokia gotten a dev unit to Marcel or anyone? I think the biggest 
missing piece with this awesome little device will be bluetooth audio. 
Unfortunately it will be a step back in terms of polish and convenience 
from symbian since we're basically still working with prototype audio 
drivers in linux.

Has Nokia promised bluetooth audio when they deliver voip next year? 
They'd be a great partner for straightening things out in our drivers...

Brad


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Re: [Bluez-devel] Nokia 770 and bluetooth audio

[Marcel Holtmann]

Hi Brad,

> Has Nokia gotten a dev unit to Marcel or anyone? I think the biggest 
> missing piece with this awesome little device will be bluetooth audio. 
> Unfortunately it will be a step back in terms of polish and convenience 
> from symbian since we're basically still working with prototype audio 
> drivers in linux.
> 
> Has Nokia promised bluetooth audio when they deliver voip next year? 
> They'd be a great partner for straightening things out in our drivers...

if I am not mistaken, then the integration into GStreamer will solve all
the problems. However we need a good SBC encoder for this first. May you
wanna give an update on its current status.

Regards

Marcel




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Re: [Bluez-devel] Nokia 770 and bluetooth audio

[Brad Midgley]

Marcel

> if I am not mistaken, then the integration into GStreamer will solve all
> the problems. However we need a good SBC encoder for this first. May you
> wanna give an update on its current status.

Victor's changes to our encoder give reasonable performance on arm (<10% 
of cpu on an arm9 400mhz I think). It uses 64-bit integer math and we 
expect there is room for even more optimization using a lossier 32-bit 
version (the 32-bit stuff is stubbed out but disabled for now since it's 
incomplete)

In addition to switching to integer ops, Victor unrolled loops and 
reworked some of the tables so less stuff has to be computed at runtime.

Real-world testing and dev work remain, so if someone has one of these 
Nokias already, please pipe up so we can give the encoder a workout.

Brad


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Re: [Bluez-devel] Nokia 770 and bluetooth audio

[Marcel Holtmann]

Hi Brad,

> > if I am not mistaken, then the integration into GStreamer will solve all
> > the problems. However we need a good SBC encoder for this first. May you
> > wanna give an update on its current status.
> 
> Victor's changes to our encoder give reasonable performance on arm (<10% 
> of cpu on an arm9 400mhz I think). It uses 64-bit integer math and we 
> expect there is room for even more optimization using a lossier 32-bit 
> version (the 32-bit stuff is stubbed out but disabled for now since it's 
> incomplete)

from what other people told me about SBC, a 32-bit version will be
enough for good quality audio.

> In addition to switching to integer ops, Victor unrolled loops and 
> reworked some of the tables so less stuff has to be computed at runtime.

I also heard that there are a lot of possible optimizations, because the
example code in the specification sucks totally.

Regards

Marcel




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Re: [Bluez-devel] Nokia 770 and bluetooth audio

[Victor Shchebatyuk]

Hi all,

It would be nice to have at least a piece of advise from those
mysterious people who tell all those things about the optimization :)

I belive that 32-bit is enough (I saw it working in some other
implementations with excellent sound quality), but it shouldn't be done
in the straight forward way as it is done now. I'm going to look at it
in the nearest future anyway...

I've looked only at the filter-bank code, what is outside probably can
me improved...

Regards,
    Victor.

On Sun, 2005-10-09 at 11:14 +0200, Marcel Holtmann wrote:
> Hi Brad,
> 
> > > if I am not mistaken, then the integration into GStreamer will solve all
> > > the problems. However we need a good SBC encoder for this first. May you
> > > wanna give an update on its current status.
> > 
> > Victor's changes to our encoder give reasonable performance on arm (<10% 
> > of cpu on an arm9 400mhz I think). It uses 64-bit integer math and we 
> > expect there is room for even more optimization using a lossier 32-bit 
> > version (the 32-bit stuff is stubbed out but disabled for now since it's 
> > incomplete)
> 
> from what other people told me about SBC, a 32-bit version will be
> enough for good quality audio.
> 
> > In addition to switching to integer ops, Victor unrolled loops and 
> > reworked some of the tables so less stuff has to be computed at runtime.
> 
> I also heard that there are a lot of possible optimizations, because the
> example code in the specification sucks totally.
> 
> Regards
> 
> Marcel
> 
> 
> 
> 
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Re: [Bluez-devel] Nokia 770 and bluetooth audio

[Marcel Holtmann]

Hi Victor,

> It would be nice to have at least a piece of advise from those
> mysterious people who tell all those things about the optimization :)

the comment from one of the CSR guys should include a really big hint
from what I heard. However I am not a codec expert.

Regards

Marcel




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Re: [Bluez-devel] Nokia 770 and bluetooth audio

[Brad Midgley]

Victor

> It would be nice to have at least a piece of advise from those
> mysterious people who tell all those things about the optimization :)

as far as the algorithm goes, I decided for the decoder that there were 
basically two paths you could go down for optimizing:

  - keep the shifting of values around in each pass and unroll the loops 
(in this case referencing the tables is optimized by the compiler to 
literal values so unrolling eliminates an array access)

  - eliminate the shifting of values and don't unroll the loop, just 
simplify the array index computations (the table access is different in 
each pass depending on where the data would have been shifted around to 
so unrolling is no win)

I ended up moving 8-subbands to the latter and I will move 4 too.

For the decoder it's moot since anyone serious about decoding will be 
doing it in CSR silicon, but there may be a parallel in the encoder.

Brad


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