Re: [Bluez-devel] AVDTP socket?

Brad Midgley
2004-11-14T07:54:13Z

Marcel

Argh... I'm stuck again. the avdtp_set_configuration command goes out
but reading the response just blocks. I'm not sure what is wrong... I send:

00 -> header = request
03 -> AVDTP_SET_CONFIGURATION
04 -> acp_seid = 1
04 -> int_seid = 1 (how should I choose the int_seid?)
01 -> service category = media transport
00 -> length of service capabilities = 0
07 -> capability type = media codec
06 -> bytes remaining? not sure if this is right.
00 -> media type = audio media type
00 -> media codec type = SBC
22 -> 44.1khz stereo
15 -> 16-byte blocks, 8 subbands, "loudness" allocation
02 -> min bitpool
fa -> max bitpool

a2play.c in cvs contains the code I'm trying...

Brad

Marcel Holtmann wrote:
> Hi Brad,
>
>
>>>>The accept looks like this byte-for-byte:
>>>>
>>>>02 -> response accept
>>>>02 -> AVDT_GET_CAPABILITIES
>>>>01 -> category = media transport
>>>>00 -> length of service capabilities = 0
>>>>07 -> 7 'elements' follow
>>>>06 -> elements[0]
>>>>00 ->
>>>>00 ->
>>>>ff ->
>>>>ff ->
>>>>02 ->
>>>>fa -> elements[6]
>>
>>>this should be the codec specific part. Look at A2DP for more details.
>>
>>It doesn't totally seem to match up. The last 4 bytes seem to be the
>>capabilities of SBC (p.20 of a2dp)
>>
>>ff -> supports all sampling frequencies, channel modes
>>ff -> supports all block lengths, subbands, allocation methods
>>02 -> minimum bitpool val
>>fa -> max bitpool val
>>
>>I can't find where the first 06, 00, 00 fit. Also, does the seid=1 in
>>the avdtp_discover accept correspond to only supporting SBC? I wasn't
>>expecting to know the supported codecs until after the first
>>avdt_get_capabilities.
>
>
> I looked it up and the GET_CAPABILITIES response you get back contains
> two block. The first is the "media transport" with 0 bytes of additional
> information and the second is the "media codec" part with 6 bytes of
> codec specific information.
>
> 0x01 = media transport
> 0x07 = media codec
>
> The first 0x00 represents the "media type" and the second the "media
> codec type". And this means "audio" and "SBC". And the rest is SBC
> specific as you already recognized.
>
> Regards
>
> Marcel
>
>
>
>
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