Re: [Bluez-devel] SCO & btsco

[Steven Singer <steven.singer@csr.com>]

Luca Pizzamiglio wrote:
> bt specification says that bluetooth supports three audio formats:
> - CVSD
> - u-law
> - a-law

That's not what the BT spec says, you need to read it more carefully.

BT supports 3 *air* formats: u-law, A-law and CVSD, however, that's
irrelevant as far as interfacing with the chip is concerned as the
chip will transcode to and from those formats from and to the HCI
format (aka the input format).

BT supports the following HCI formats:

  2's complement linear
  1's complement linear
  sign-magnitude
  unsigned (some devices only)
  u-law
  A-law

The linear formats can be 8 bit, 16 bit or 9..15 bit right aligned
in a 16 bit word.

The default format - 0x0060 - is CVSD on the air and 16 bit 2's
complement linear signed on the wire as the output of hciconfig
clearly states.

Always keep the air format set to CVSD (as the two sides need to agree
on the air format in order to be able to make a connection and most,
if not all, Bluetooth devices are set up for CVSD). Make the HCI
format whatever your program supports.

	- Steven
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