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

Brad Midgley
2005-08-22T06:15:40Z

Victor

> In the attachment is the patch to support fixed point encoding for

This is great! If everything works I'm going to commit it as-is and we
can tweak it later for 4 subbands etc.

> 8-subband sbc codec. To compie ARM specific version USE_FIXED_ARM should
> be defined (currently in sbc/sbc.c should be in configuration?). It is

If it seems ok, I'd like to just use '#ifdef __arm__' so it's automatic.

> possible I broke your fixed point tables cause I've changed gen_fixed.c,
> but it should be easy fixable.

ok, the change should be fine

> Floating point implementation is optimized too, runs 30% faster on my

wow, nice. Maybe this room for optimization is what Marcel was talking
about.

> AthlonXP. General fixed point (long long) runs slower than floating on
> my PC, which is strange...

interesting

> I do not have HW to test arm specific version
> real time, hope no suprises there, but I could have missed something
> when integrating it into sbc code (it decodes well, but how fast, I will
> try only monday evening).

Ok, I'll load it on gumstix now and give it a try.

> Using a2play needs to tweak 87 magic number, otherwise it drops samples?

yes, this is disappointing. We may need to find another way to get
reliable timing than setitimer.

I did change the first usleep(10) to usleep(1000) and that *may* help
with this problem by ensuring that we always interrupt the usleep
syscall consistently. I don't have my hp headphones (the set that's very
sensitive to timing) handy to test.