Re: Is BT_VOICE_TRANSPARENT correctly defined?

[Luiz Augusto von Dentz <luiz.dentz@gmail.com>]

Hi Pali,

On Fri, Jun 7, 2019 at 4:43 PM Pali Rohár <pali.rohar@gmail.com> wrote:
>
> On Sunday 19 May 2019 12:18:54 Pali Rohár wrote:
> > Hello!
> >
> > Now I'm looking at BT_VOICE_TRANSPARENT definition which comes from file
> > include/net/bluetooth/bluetooth.h and it has value 0x0003. It is really
> > correct? Because it means following format:
> >
> >   Linear Coding, 8-bit without padding bits, 1's complement
> >
> > I think that usage of 1's complement is not easy as there is no C type
> > which matches it. Should not it be 2's complement or rather Unsigned
> > type?
> >
> > Seems that main usage of BT_VOICE_TRANSPARENT is mSBC codec and I doubt
> > that it uses 1's complement signed format (specially as it should be
> > modification of SBC codec which encode bytes as unsigned type).
> >
> > There is another define BT_VOICE_CVSD_16BIT with value 0x0060 which
> > seems to be correct as it means Linear Coding, 16-bit without padding
> > bits, 2's complement and encoded by CVSD codec.
>
> Hello, can somebody look at this BT_VOICE_TRANSPARENT definition and
> verify that it really should be defined as unsigned or 2's complement?

Are you talking about these:

https://elixir.bootlin.com/linux/latest/source/include/net/bluetooth/bluetooth.h#L119

Which is used in ofono:

https://github.com/DynamicDevices/ofono/blob/master/src/handsfree-audio.c#L93

Afaik these values work as intended with mSBC/WBS.

-- 
Luiz Augusto von Dentz