[Flac-dev] Re: Reg. FLAC decoding

[Josh Coalson]

--- Joe Steeve <joesteeve at zodiactorp.com> wrote:

> Sorry for the delay in getting back to you., I was working on
> something
> else and just now got FLAC to work.
> 
> Ok., FLAC files are playing now :) Cheers. There is a slight noise
> happening in the background., which i'm figuring out. I hope that
> it'll
> be solved soon. However, i wanted to know if there are any ARM
> specific
> optimizations that can be done. The processor is a 166MHz processor.
> Do
> you think it is ok?

we don't have any ARM optimizations yet, just x86 and ppc. but
yes, FLAC__lpc_restore_signal() will give the most bang for the
buck and is the easiest (it's just a multiply-accumulate-shift
loop).

    unsigned i, j;
    FLAC__int32 sum;
    for(i = 0; i < data_len; i++) {
        sum = 0;
        for(j = 0; j < order; j++)
            sum += qlp_coeff[j] * data[i-j-1];
        data[i] = residual[i] + (sum >> lp_quantization);
    }

the next would probably be FLAC__fixed_restore_signal(), which
is also easy, and FLAC__bitbuffer_read_rice_signed_block(),
which is unfortunately complicated.

Josh



	
		
__________________________________ 
Yahoo! Mail - PC Magazine Editors' Choice 2005 
http://mail.yahoo.com