Re: [Bluez-devel] audio problems with a2play

Henryk Plötz
2004-11-23T06:06:21Z

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Moin,

Am Mon, 22 Nov 2004 20:49:05 -0700 schrieb Brad Midgley:

> Are you saying the problem is in a2play or in hcidump?

Both are doing the same wrong thing.

> I don't know the "real" mapping between the indexed settings in the
> sbc file format and the bitmapped settings/capabilities we use with
> the a2dp protocol.

It's on page 20 of the A2DP spec where it says, for example, that the
first byte of the codec specific information elements for SBC encodes
the sampling frequency in the upper half of the byte and the channel
mode in the lower half. The first byte that a2play sends for
sbc_test_01.sbc (which is 48 kHz mono) is 0x81, so bits 7 (0x80) and 0
(0x01) are set. Bit 7 set means 16 kHz (section 4.3.2.1), bit 0 set
means joint stereo (section 4.3.2.2). The correct value for this byte
would be 0x18 (bits 4 and 3 set).

Similarly the second byte (currently 0x86) should be 0x1a (bits 4, 3 and
1 set).

> Are these backwards then?

Most of them are, with the notable exception of the allocation_method.

--
Henryk Plötz
Grüße aus Berlin
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