[Bluez-devel] sbc synthesis inconsistencies

[Brad Midgley <bmidgley@xmission.com>]

Guys,

Have any of you looked closely at this? It comes straight from the spec 
for a2dp on page 66:


	/* Build a 80 values vector U */
	for (i = 0; i <= 4; i++) {
		for (j = 0; j < 8; j++) {
			state->U[ch][i * 16 + j] = state->V[ch][i * 32 + j];
			state->U[ch][i * 16 + j + 8] = state->V[ch][i * 32 + j + 24];
		}
	}

But isn't this code only populating u[ch][0..63] and not through 79 like 
the comment suggests? So the u[ch][64..79] terms are always 0 right?

This isn't the only thing that looks wrong in the spec. We also have a 
sliding window of v[] values that moves 16 values in each pass. The 
vector is 160 elements long even though the code above never accesses 
anything beyond the 128th value!

It's amazing this stuff even works as poorly specified as it is :(

BTW, in our code it looks like sbc_synthesize_eight was multiplying 
sbc_proto_8_80 by -4 where it should be -8. I changed that in cvs.

Brad


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