2006-05-10 15:13:10

by javier labella

[permalink] [raw]
Subject: [Bluez-devel] A2DP and VDP for BlueZ

>Hi,
> I've visited bluetooth-alsa.sf.net and the project is very
>interesting bu=
>t
> I think that the profile's implementation is based on SCO channels.
>If I'=
>m
> making a mistake I apologize for it. On the other hand, I've read the
>A2D=
>P
> profile specification and I think that an implementation should uses
>ACL
> channels: "The Advanced Audio Distribution Profile (A2DP) defines the
> protocols and procedures that realize distribution of audio content
>of
> high-quality in mono or stereo on ACL channels (Introduction of
>Advanced
> Audio Distribution Profile Specification)" So I'd like to develop an
> implementation using ACL channels instead of SCO channels.
>
> I'd like to know if you're interested in include this implementation
in
> the BlueZ stack too.
> Thanks.
>
>
> Javier.
>
>Javier,
>I think that you did not read the page bluetooth-alsa.sf.net
>completely.
>Both SCO and ACL implementations have been done.
>Maybe you can add some new feature to the existing A2DP. (a2play or
>pcm_a2dp).
>I think support for the mp3 codec (making a choice at run time between
>SBC
>and MP3 codec) could be handy.
>Also, the A2DP spec mentions briefly about RTP. Nobody has looked into
>that
>till now.
>Regards
>Mayank
>
>
>
>it may not be all that clear but the project has two parts, sco and
>a2dp.
>an a2dp stream can be sent to a stereo headset using the application
>a2play. there are also some test apps for avrcp in av*.c in case that's
>interesting to you.
>brad

Hi

Thank you very much for your comments. I was wrong. I've already seen the A2DP's implementation over ACL channels in the page bluetooth-alsa.sf.net.

On the other hand, I'd like to know if you had studied the Video Distribution Profile (VDP). At first, my objetives were to develop the A2DP or, if it was already implemented, the VDP. Therefore, I'm interested in knowing if you have implemented something similar to a2play for A2DP.

Regards.
Javier



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2006-05-11 03:37:18

by Mayank Batra

[permalink] [raw]
Subject: Re: [Bluez-devel] A2DP and VDP for BlueZ

Javier,


> >Thank you very much for your comments. I was wrong. I've already seen the
> A2DP's implementation over ACL channels in the page >bluetooth-alsa.sf.net<http://bluetooth-alsa.sf.net/>
> .
>
> >On the other hand, I'd like to know if you had studied the Video
> Distribution Profile (VDP). At first, my objetives were to develop the
>
>A2DP or, if it was already implemented, the VDP. Therefore, I'm
> interested in knowing if you have implemented something similar to >a2play
> for A2DP.
>
>

VDP also makes use of AVDTP, thus it is pretty much the same, protocol wise.
So connection establishment in case of 'vplay' / 'vrecv' should be more or
less the same as in a2play/a2recv.
Only difference might be the sink capabilities.
So you'll only have to read stuff about the H.263 codec.
To begin with you can directly send the encoded file and later on try
encoding video taken from a webcam to h.263 and then stream.

Mayank


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2006-05-10 15:38:05

by Brad Midgley

[permalink] [raw]
Subject: Re: [Bluez-devel] A2DP and VDP for BlueZ

javier

> On the other hand, I'd like to know if you had studied the Video
> Distribution Profile (VDP). At first, my objetives were to develop the
> A2DP or, if it was already implemented, the VDP. Therefore, I'm
> interested in knowing if you have implemented something similar to
> a2play for A2DP.

I have not read much about vdp. At least it uses a common codec (h.263)
so you won't have to write codec code I think.

There are no vdp devices out there so you would have to write the sender
and the receiver to see results.

I would suggest you write your stuff as a new app "vplay" that is
modeled after a2play (and vrecv modeled after a2recv).

Brad


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