Re: [Bluez-devel] AVDTP socket?

[Marcel Holtmann <marcel@holtmann.org>]

Hi Brad,

> > 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));
> 
> I tried reading this from the header but I get nonsensical results like 
> "3" for frequency. Only one bit is supposed to be specified in fields 
> like frequency, so the headset (rightly) rejects the set_config.

I think you have to convert it first. I don't know why the SBC example
files have this header. From my sniffs of the AVDTP media channel I
haven't seen this header data anywhere. So it is somekind of SBC file
format. Try this conversion:

static char *sf2str(uint8_t sf)
{
        switch (sf) {
        case 0:
                return "16 kHz";
        case 1:
                return "32 kHz";
        case 2:
                return "44.1 kHz";
        case 3:
                return "48 kHz";
        }
}

static char *cm2str(uint8_t cm)
{
        switch (cm) {
        case 0:
                return "Mono";
        case 1:
                return "Dual channel";
        case 2:
                return "Stereo";
        case 3:
                return "Joint stereo";
        }
}

Regards

Marcel




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