[Bluez-devel] A2DP Profile Certification

[Bluez-devel] A2DP Profile Certification

[Frédéric DALLEAU]

Hi Brad,

I've just read the "Profile ICS for A2DP" that provides information on =

what is mandatory in order to get this profile certified.
We are only concerned about A2DP Source features and the ICS requires =

the following.

- Initiate Connection Establishment,
- Initiate Start Streaming,
- Initiate Connection Release,
- Start Audio Stream,
- SBC encoder,
- Accept Connection Establishment,
- Accept Start Streaming,
- Accept Connection Release.

- An entry must also appear in SDP records.

The five first points are already provided by the bluetooth-alsa plugin.
Do you have an idea of what can be done in order to satisfy the other =

requirements?

Thank you,
Fr=E9d=E9ric



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Re: [Bluez-devel] A2DP Profile Certification

[Brad Midgley]

Fr=E9d=E9ric

> - Accept Connection Establishment,
> - Accept Start Streaming,
> - Accept Connection Release.

see a2recv for these. it implements the a2dp sink. there is not any sort
of special connection with alsa for this, but i'm not sure it makes
sense since this runs more like a daemon and just sends any audio that
comes in to the speakers.

> - An entry must also appear in SDP records.

sdptool add A2SNK

brad


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Re: [Bluez-devel] A2DP Profile Certification

[Frédéric DALLEAU]

Hi brad,

We must be very careful here : The ICS says the Source must accept =

connection establishment, this is different from the sink role because =

the source will accept the connection and then send its audio stream!

As you said, I'm not sure it makes sense, and I can't figure how to test =

it. But I believe a typical scenario would be the following :

- you listen a2dp music from your pc (source) on the headphone (sink).
- someone call your mobile.
- you answer the call so the headphone tell the source to stop a2dp.
- while you talk, the source send audio data to /dev/null.
- when you hangup, the headphone will tell your computer to send the =

music again.

Fr=E9d=E9ric



Brad Midgley a =E9crit :

>Fr=E9d=E9ric
>
>  =

>
>>- Accept Connection Establishment,
>>- Accept Start Streaming,
>>- Accept Connection Release.
>>    =

>>
>
>see a2recv for these. it implements the a2dp sink. there is not any sort
>of special connection with alsa for this, but i'm not sure it makes
>sense since this runs more like a daemon and just sends any audio that
>comes in to the speakers.
>
>  =

>
>>- An entry must also appear in SDP records.
>>    =

>>
>
>sdptool add A2SNK
>
>brad
>
>
>_______________________________________________
>Bluez-devel mailing list
>Bluez-devel@lists.sourceforge.net
>https://lists.sourceforge.net/lists/listinfo/bluez-devel
>  =

>



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Re: [Bluez-devel] A2DP Profile Certification

[Brad Midgley]

Fr=E9d=E9ric

> We must be very careful here : The ICS says the Source must accept =

> connection establishment, this is different from the sink role because =

> the source will accept the connection and then send its audio stream!

ok. yes, we're missing a lot of stuff here that we need to handle.

we need to use "sdptool add A2SRC" to advertise the source. we need to
listen for new connections and keep listening on the control connection
during playback (maybe in another thread)

the alsa plugin can't just block audio writes when the stream is
stopped. most alsa clients do not have a separate transmission thread,
so the ui will lock up. the way to handle it is to use dbus to tell the
audio app to pause if possible.

there is a lot of overlap with avrcp here, so we should make it easy to
work that in too.

brad


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Re: [Bluez-devel] A2DP Profile Certification

[Marcel Holtmann]

Hi Brad,

> > We must be very careful here : The ICS says the Source must accept 
> > connection establishment, this is different from the sink role because 
> > the source will accept the connection and then send its audio stream!
> 
> ok. yes, we're missing a lot of stuff here that we need to handle.
> 
> we need to use "sdptool add A2SRC" to advertise the source. we need to
> listen for new connections and keep listening on the control connection
> during playback (maybe in another thread)
> 
> the alsa plugin can't just block audio writes when the stream is
> stopped. most alsa clients do not have a separate transmission thread,
> so the ui will lock up. the way to handle it is to use dbus to tell the
> audio app to pause if possible.
> 
> there is a lot of overlap with avrcp here, so we should make it easy to
> work that in too.

it might be a good idea to integrate everything into a deamon and only
have a stupid ALSA plugin that sends us the PCM data.

Regards

Marcel




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Re: [Bluez-devel] A2DP Profile Certification

[Brad Midgley]

Fr=E9d=E9ric,

>> We must be very careful here : The ICS says the Source must accept =

>> connection establishment, this is different from the sink role because =

>> the source will accept the connection and then send its audio stream!
> =

> ok. yes, we're missing a lot of stuff here that we need to handle.

I put code in a2play so it will listen on the control link for
suspend/resume from a2dp headset (*if* you use -p for pthreads). This
should be a decent model for getting it into the alsa plugin if you want
to look at that.

This is how we find out a combo headset is taking a voice call.

Frankly it may be messy getting those signals to the media player. It
would be easier to make the alsa plugin just throw away audio it gets
while the set wants things suspended.

We're still missing something here... we don't listen for new control
connections from the set. You could look at a2recv.c for code that will
listen for new connections. This will be more complicated since you may
want to use dbus to start up the media player in response.

Brad


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Re: [Bluez-devel] A2DP Profile Certification

[Frédéric DALLEAU]

Hi brad,

>I put code in a2play so it will listen on the control link for
>suspend/resume from a2dp headset (*if* you use -p for pthreads). This
>should be a decent model for getting it into the alsa plugin if you want
>to look at that.
>  =

>
I will have a look by the end of the week.

>This is how we find out a combo headset is taking a voice call.
>  =

>
I noticed that my headset stopped streaming when pressing the main =

button and didn't get back playing after pressing the button again.
Is that what you mean?

>Frankly it may be messy getting those signals to the media player. It
>would be easier to make the alsa plugin just throw away audio it gets
>while the set wants things suspended.
>  =

>
Yes for sure, and it's not bad IMHO, you would not like your speaker do =

some sound if you answer a phone call!

>We're still missing something here... we don't listen for new control
>connections from the set. You could look at a2recv.c for code that will
>listen for new connections. This will be more complicated since you may
>want to use dbus to start up the media player in response.
>  =

>
I was wondering how to generate such connections? Simply switch on the =

headset? Any ideas?

Fr=E9d=E9ric.



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Re: [Bluez-devel] A2DP Profile Certification

[Brad Midgley]

Fr=E9d=E9ric

>> This is how we find out a combo headset is taking a voice call.
>>  =

> I noticed that my headset stopped streaming when pressing the main =

> button and didn't get back playing after pressing the button again.
> Is that what you mean?

yes this should cover that scenario.

>> We're still missing something here... we don't listen for new control
>> connections from the set. You could look at a2recv.c for code that will
>> listen for new connections. This will be more complicated since you may
>> want to use dbus to start up the media player in response.
>>
> I was wondering how to generate such connections? Simply switch on the =

> headset? Any ideas?

the play button on an avrcp set? i was surprised to find when I ran
"sdptool add AVRTG" then avrecv that the play button did not cause the
set to connect to avrecv. maybe it's really trying to start up a one of
these plain a2dp connection (or maybe not doing anything :)

brad


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Re: [Bluez-devel] A2DP Profile Certification

[Frédéric DALLEAU]

Hi brad

>"sdptool add AVRTG" then avrecv that the play button did not cause the
>set to connect to avrecv. maybe it's really trying to start up a one of
>these plain a2dp connection (or maybe not doing anything :)
>  =

>
Yes, sdptool add A2SRC followed by hcidump shows an incoming connection!

I suppose the following log shows there is no L2CAP listening socket on =

PSM 25.

 > ACL data: handle 43 flags 0x02 dlen 12
    L2CAP(s): Connect req: psm 25 scid 0x0040
< ACL data: handle 43 flags 0x02 dlen 16
    L2CAP(s): Connect rsp: dcid 0x0000 scid 0x0040 result 2 status 0
      Connection refused - PSM not supported
 > HCI Event: Number of Completed Packets (0x13) plen 5
 > HCI Event: Remote Name Req Complete (0x07) plen 255
 > HCI Event: Disconn Complete (0x05) plen 4


Fr=E9d=E9ric.



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Re: [Bluez-devel] A2DP Profile Certification

[Frédéric DALLEAU]

Hi brad,

I've been looking at what you did in a2play.

>>I put code in a2play so it will listen on the control link for
>>suspend/resume from a2dp headset (*if* you use -p for pthreads). This
>>should be a decent model for getting it into the alsa plugin if you want
>>to look at that.
>>    =

>>
>I will have a look by the end of the week.
>  =

>

I used -p options but I have some problems :
When reading /dev/rtc, I always read 0x8C0 and I only get 50 read per =

sec. If you strip the low byte, it's 8 ticks but the sbc data is 23 ms =

long (190 ticks). So decreasing the tick count to 0 nefore sending data =

takes nearly one second and I have intermittent sound. I fixed it by =

commenting out the "while(ticks <=3D 0)" line, I also tried smaller rtc =

frequency without success. Why not use gettimeofday?

>>This is how we find out a combo headset is taking a voice call.
>>
> noticed that my headset stopped streaming when pressing the main =

>button and didn't get back playing after pressing the button again.
>Is that what you mean?
>  =

>
I don't receive control commands when doing this. What model do you use?

>>We're still missing something here... we don't listen for new control
>>connections from the set. You could look at a2recv.c for code that will
>>listen for new connections. This will be more complicated since you may
>>want to use dbus to start up the media player in response.
>>    =

>>
>I was wondering how to generate such connections? Simply switch on the =

>headset? Any ideas?
>  =

>
Last but not least, I receive the frame sent by the headset but it is a =

2 byte "0x00 0x01". Is does not look like a stream_cmd. And only one of =

my heasets sends data.

plus the weather is bad, sad day...

Fr=E9d=E9ric.



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Re: [Bluez-devel] A2DP Profile Certification

[Brad Midgley]

Fr=E9d=E9ric

> frequency without success. Why not use gettimeofday?

Yeah... I would like to change the rtc stuff to gettimeofday and usleep.

> I don't receive control commands when doing this. What model do you use?

I've only tried it with an itech r35. I have a bluetake iphono mini
kicking around somewhere that I intend to try.

I keep an avrecv running whenever I do stuff like this just in case the
set is trying to use that route.

> Last but not least, I receive the frame sent by the headset but it is a =

> 2 byte "0x00 0x01". Is does not look like a stream_cmd. And only one of =

> my heasets sends data.
> =

> plus the weather is bad, sad day...

So you wrote code to listen on psm 25?

I think the best way to test that part of things is to have a2play run
in a listen mode when it's executed without a bt addr.

Brad

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