[Bluez-devel] SCO transparent transmission

[Bluez-devel] SCO transparent transmission

[Israel Guío]

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Hi.

I'm trying to write an app for voice transmission between two laptops. When
using CVSD, the communication performs ok. However, I would need to transmit
the PCM samples in a transparent mode, for after receiving a voice frame, I
must process the samples.

I have read in Bluetooth 2.0 specification that this can be done, for
example, with 0x0063 as voice settings. I have tried it with my Bluetooth
2.0+EDR dongles but it doesn't work properly. I transmit continuously a
frame with values 0x01 through 0x30, but in the receiver side and using
hcidump, I see that a brust of 0 is inserted in the middle of some frames
and there are hops in the sequence. For instance, I send 0x00 0x01 0x02 0x03
0x04 .... 0x29 0x30, but I receive 0x2e 0x2f 0x30 0x00 0x01 0x02 0x2f 0x30
0x00 0x01.....

Have any of you tested it? Is there any solution to make what I try?

Thanks.

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Re: [Bluez-devel] SCO transparent transmission

[Sowmya Gattupalli]

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Hey Israel,
How did u use CVSD when transmitting over sco?? U mean u used some sort of
function to convert the voice you input from /dev/dsp into CVSD codec??
Can u also throw some light on CVSD and SCO... I mean how are u transmitting
the packets over SCO??

Soumya

On 4/4/06, Israel Guío <israzar@gmail.com> wrote:
>
> Hi.
>
> I'm trying to write an app for voice transmission between two laptops.
> When using CVSD, the communication performs ok. However, I would need to
> transmit the PCM samples in a transparent mode, for after receiving a voice
> frame, I must process the samples.
>
> I have read in Bluetooth 2.0 specification that this can be done, for
> example, with 0x0063 as voice settings. I have tried it with my Bluetooth
> 2.0+EDR dongles but it doesn't work properly. I transmit continuously a
> frame with values 0x01 through 0x30, but in the receiver side and using
> hcidump, I see that a brust of 0 is inserted in the middle of some frames
> and there are hops in the sequence. For instance, I send 0x00 0x01 0x02 0x03
> 0x04 .... 0x29 0x30, but I receive 0x2e 0x2f 0x30 0x00 0x01 0x02 0x2f 0x30
> 0x00 0x01.....
>
> Have any of you tested it? Is there any solution to make what I try?
>
> Thanks.
>

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Re: [Bluez-devel] SCO transparent transmission

[Steven Singer]

Sowmya Gattupalli wrote:
> On 4/4/06, Israel Gu=EDo <israzar@gmail.com> wrote:
>> example, with 0x0063 as voice settings. I have tried it with my Blueto=
oth
> How did u use CVSD when transmitting over sco?? [...]

He was quite clear that he'd used voice settigns 0x0063. The last two
bits indicate transparent coding and not CVSD.

Israel, you need to be sure you're sending data at exactly the right
average data rate. SCO links are synchronous and if you don't provide
data at exactly the right rate then something somewhere in the
system will have to insert or delete samples.

It would also be helpful if you stated what chip and firmware version
you were using.

	- Steven
--=20


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Re: [Bluez-devel] SCO transparent transmission

[Sowmya Gattupalli]

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Hey Steven...
For a CSR USB chip when the SCO mapping is over HCI is it possible to change
the voice settings to send PCM samples over the air?

On 4/7/06, Steven Singer <steven.singer@csr.com> wrote:
>
> Sowmya Gattupalli wrote:
> > On 4/4/06, Israel Guío <israzar@gmail.com> wrote:
> >> example, with 0x0063 as voice settings. I have tried it with my
> Bluetooth
> > How did u use CVSD when transmitting over sco?? [...]
>
> He was quite clear that he'd used voice settigns 0x0063. The last two
> bits indicate transparent coding and not CVSD.
>
> Israel, you need to be sure you're sending data at exactly the right
> average data rate. SCO links are synchronous and if you don't provide
> data at exactly the right rate then something somewhere in the
> system will have to insert or delete samples.
>
> It would also be helpful if you stated what chip and firmware version
> you were using.
>
>         - Steven
> --
>
>
> To access the latest news from CSR copy this link into a web browser:
> http://www.csr.com/email_sig.php
>
>
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