Re: [Bluez-devel] sbc and fixed-point progress

Brad Midgley
2005-08-27T03:01:30Z

Victor

> The _anamatrix8[] and _sbc_proto_8[] are extracted from anamatrix8[][]
> and sbc_proto_8_80[].
> Basically what I did is, made loop unrolling, then the rearanged
> resulting code minimizing the number of multiplies

wow. you the man as they say.

FYI I stubbed in the fixed-point 4 subband stuff for now but I'd
eventually like to see it in there. Curently it may not behave right
when you build with USE_FIXED and then encode with 4 subbands (it tries
to use floating point)

I don't know if you've used 4 subbands much, but it sounds quite
respectable and it would allow us to scale down to some of the
smallest/slowest embedded processors out there (memory permitting).

> P.S. There is a bug in general code of SUB64 (not much influencing the
> final result). I'll check in fix this weeken and also I did some
> cleaning up of my code and added arm assembly for ADD64, SUB64. I still
> plan to modify joint stereo code in sbc_pack_frame() (as there are some
> floating point ops still remain there) sbc_init() (and a2play) to accept
> encoder parameters like nr. of subbands, bit pool and so on.

you probably saw that a2play has some rough options for encoder params,
jut the -t (thrifty) flag.

> P.P.S. I'm also thinking to merge floating point and fixed point filter
> code, so USE_FIXED will decide which macro to use floating or fixed
> (general|arm). Btw, I also think it is quite easy to implement 32 bit
> version this way.

nice