2006-06-28 09:34:07

by I-Chung Chane

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Subject: Re: [Bluez-devel] A2DP a2play and a2recv

Hi, Mayank:

Thanks for reply. can a2play run on OSS too?

I ported BlueZ on an embeded ARM7 running at 80 MHz.
I also try a2recv on embeded board with sound chip using OSS
driver. Printout looks ok, but can't hear anything:

---------------------------------------------------------------------
> ./a2recv

Connected [imtu 672, omtu 672, flush_to 65535]
Connected
Sent Stream End Point Discovery Response

Sent the get capabilities responseChannels=2, speed=44100channel_mode = 2 alloca tion_method = 2 subbands = 1 block_length = 1 min_bitpool = 2 max_bitpool = 250

Sent a Set configurations response

Received an open stream command

Sent open stream confirm

Connected [imtu 672, omtu 672, flush_to 65535]
ConnectedGot stream fd

Sent start stream confirm
------------------------------------------------------------------------------

Is CPU (ARM7 @80MHz) powerful enough to run a2recv ?

Thanks a lot for help,

Chane
----- Original Message -----
From: Mayank Batra
To: BlueZ development
Sent: Wednesday, June 28, 2006 11:49 AM
Subject: Re: [Bluez-devel] A2DP a2play and a2recv


Hi Chane,


On 6/28/06, I-Chung Chane <[email protected]> wrote:

I'm trying Bluetooth-ALSA Project (A2DP part). I wonder does a2play and a2recv need
ALSA to make it work? Can they work with sound card using OSS driver?

a2recv will work with OSS driver. It will accept an incoming A2DP connection and then bind to your /dev/dsp.

Regards,
Mayank








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2006-06-29 07:20:17

by Mayank Batra

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Subject: Re: [Bluez-devel] A2DP a2play and a2recv

Hi Chane,

On 6/29/06, Mayank Batra <[email protected]> wrote:
>
> Hi Chane,
>
> On 6/28/06, I-Chung Chane <[email protected]> wrote:
>
> > Is CPU (ARM7 @80MHz) powerful enough to run a2recv ?
> >
>
> On second thoughts, I think it is not fast enough. So please use fixed
> point calculations in libsbc.a
> In fact I tried the floating point library with a2play on my ARM9 platform
> (~100MHz) yesterday. And it was probably too much for it. The CPU load was
> too high.
>

Just to confirm, I ran a2play on my ARM9 platform just now.
It works fine when I use fixed point libsbc.
But if I use floating point, it is terrible.

Hope that helps.

Regards,
Mayank


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2006-06-29 03:23:28

by Mayank Batra

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Subject: Re: [Bluez-devel] A2DP a2play and a2recv

Hi Chane,

On 6/28/06, I-Chung Chane <[email protected]> wrote:
>
> Is CPU (ARM7 @80MHz) powerful enough to run a2recv ?
>

On second thoughts, I think it is not fast enough. So please use fixed point
calculations in libsbc.a
In fact I tried the floating point library with a2play on my ARM9 platform
(~100MHz) yesterday. And it was probably too much for it. The CPU load was
too high.

Regards,
Mayank


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2006-06-28 15:24:31

by Brad Midgley

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Subject: Re: [Bluez-devel] A2DP a2play and a2recv

guys

first off, make sure you configure with --enable-fixed so you get the
fixed-point sbc library.

> Thanks for reply. can a2play run on OSS too?

not directly.

if you know what you're doing, you could use dynamic loading tricks to
make writes to /dev/dsp go to custom code based on a2play.

it would be easier to modify the audio apps themselves. you may be able
to do that on your embedded platform.

> I ported BlueZ on an embeded ARM7 running at 80 MHz.
> I also try a2recv on embeded board with sound chip using OSS
> driver. Printout looks ok, but can't hear anything:

it could be the cpu is too busy or the oss writes aren't right. I'm not
sure 80Mhz is fast enough.

There are a couple more sbc optimizations in the list of things to do.

- rework encoder to avoid moving values around (follow model from decoder)
- use a log2 table for byte integer scale factors calculation (sum log2
results for high and low bytes)
- fill bitpool by 16 bits instead of one at a time in bits
allocation/bitpool generation

Brad

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2006-06-28 09:57:58

by Mayank Batra

[permalink] [raw]
Subject: Re: [Bluez-devel] A2DP a2play and a2recv

Hi Chane,

On 6/28/06, I-Chung Chane <[email protected]> wrote:
>
> Thanks for reply. can a2play run on OSS too?
>

I am not very sure of a2play's design now.


> I ported BlueZ on an embeded ARM7 running at 80 MHz.
> I also try a2recv on embeded board with sound chip using OSS
> driver. Printout looks ok, but can't hear anything:
>
> ---------------------------------------------------------------------
> > ./a2recv
>
> Connected [imtu 672, omtu 672, flush_to 65535]
> Connected
> Sent Stream End Point Discovery Response
>
> Sent the get capabilities responseChannels=2, speed=44100channel_mode = 2
> alloca tion_method = 2 subbands = 1 block_length = 1 min_bitpool = 2
> max_bitpool = 250
>
> Sent a Set configurations response
>
> Received an open stream command
>
> Sent open stream confirm
>
> Connected [imtu 672, omtu 672, flush_to 65535]
> ConnectedGot stream fd
>
> Sent start stream confirm
>
> ------------------------------------------------------------------------------
>
>

The above logs are OK. It means that the A2DP source is streaming to your
target device.
The only reason that you do not hear anything can be an endian problem.
Maybe the endian type in which the SBC is decoded is different from the one
that your device supports.
Don't you even hear any noise?
By the way are you using the latest version of a2recv?


Is CPU (ARM7 @80MHz) powerful enough to run a2recv ?
>

I think it should be powerful enough.

Regards,
Mayank


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