[pulseaudio-discuss] Bluetooth aptX codec

[Pali Rohár]

On Thursday 09 August 2018 16:39:09 ValdikSS wrote:
> 0xFF 0x000A 0x0103 — Unknown codec found on Bose QuietComfort QC35 II

"The CSR True Wireless Stereo v3 Codec ID for SBC."

> Value hex dump: 07 06 00 00 ff ff 02 35

From information which I have, info payload is just embedded AVDTP media
capability buffer.

07 - AVDTP_SERVICE_MEDIA_CODEC
06 - length

00 - AVDTP_MEDIA_TYPE_AUDIO

00 - A2DP_CODEC_SBC
ff - SBC_CHANNEL_MODE_JOINT_STEREO | SBC_CHANNEL_MODE_STEREO |
     SBC_CHANNEL_MODE_DUAL_CHANNEL | SBC_CHANNEL_MODE_MONO |
     SBC_SAMPLING_FREQ_48000 | SBC_SAMPLING_FREQ_44100 |
     SBC_SAMPLING_FREQ_32000 | SBC_SAMPLING_FREQ_16000
ff - SBC_BLOCK_LENGTH_4 | SBC_BLOCK_LENGTH_8 |
     SBC_BLOCK_LENGTH_12 | SBC_BLOCK_LENGTH_16 |
     SBC_SUBBANDS_4 | SBC_SUBBANDS_8
     SBC_ALLOCATION_SNR | SBC_ALLOCATION_LOUDNESS
02 - min bitpool
35 - max bitpool

So it matches SBC definition buffer as expected.

> 0xFF 0x000A 0x0104 — Unknown codec found on Bose QuietComfort QC35 II

"The CSR True Wireless Stereo v3 Codec ID for AAC."

> Value hex dump: 07 08 00 02 c0 ff 8c 84 e2 00

Again, it should be embedded AVDTP media capability buffer.

07 - AVDTP_SERVICE_MEDIA_CODEC
08 - length

00 - AVDTP_MEDIA_TYPE_AUDIO

02 - A2DP_CODEC_MPEG24
c0 - AAC_OBJECT_TYPE_MPEG2_AAC_LC | AAC_OBJECT_TYPE_MPEG4_AAC_LTP |
     AAC_OBJECT_TYPE_MPEG4_AAC_SCA
ff 8c - frequences: all; channels: all
84 e2 00 - VBR; bitrate: 320000

So also MPEG2/4 AAC buffer is correct.


Moreover there also exist these codecs:

0xFF 0x000A 0x0105 - The CSR True Wireless Stereo v3 Codec ID for MP3.
0xFF 0x000A 0x0106 - The CSR True Wireless Stereo v3 Codec ID for AptX.

And again capability buffer should contain embedded AVDTP media
capability buffer for MPEG1 (with Layyer 3) and for aptX.

-- 
Pali Rohár
pali.rohar at gmail.com
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 195 bytes
Desc: not available
URL: <https://lists.freedesktop.org/archives/pulseaudio-discuss/attachments/20181219/f894be15/attachment.sig>