Re: [Bluez-devel] AVDTP socket?

Marcel Holtmann
2004-11-17T15:52:33Z

Hi Brad,

> You noticed I have code to open and send a stream. When I send the
> reference sbc streams byte-for-byte, I can hear a signal mixed with a
> lot of noise. But then I don't know what the sbc parameters were for any
> of the reference streams. Maybe it would just work if I knew that.
>
> The reference decoder does not report the sbc parameters and I'm only
> assuming that they have broken up the data and wrapped it in media
> packet headers and sbc headers for a conservative mtu. The reference
> encoder/decoder is undocumented and I didn't figure out how to set
> parameters in the encoder. I don't want to spend any more time trying to
> figure out the reference stuff.

the reference encoder/decoder has some command line options. You will
find them in "A2DP Test v10.pdf". The file format of the *.sbc is also
somewhere described. However I couldn't find it right now, but every
file contains a number of frames and all of them with a SBC header:

struct sbc_frame_header {
uint8_t syncword:8; /* Sync word */
uint8_t subbands:1; /* Subbands */
uint8_t allocation_method:1; /* Allocation method */
uint8_t channel_mode:2; /* Channel mode */
uint8_t blocks:2; /* Blocks */
uint8_t sampling_frequency:2; /* Sampling frequency */
uint8_t bitpool:8; /* Bitpool */
uint8_t crc_check:8; /* CRC check */
} __attribute__ ((packed));

Regards

Marcel

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