linuxaudio.org

On Mon, Jul 18, 2011 at 08:52:55PM +1000, Erik de Castro Lopo wrote:
> For instance in Secret Rabbit Code (my code), all data entering

quoted text
> and leaving the converter plus the actual filter coefficients are

> stored as 32 bit floats. However, the inner loop which does the

> multiply accumulate (similar to what is done when mixing) does:

>

>     double result = 0.0 ;

>

>     for ( ..... )

>         sum += coeff [k] * data [k] ;

>

> Specifically all the inputs are 32 bit floats, but all intermediate

> results are 64 bit.

In the case they would probably be even if the sum was declared

float - it's very likely that the intermediate result will be

stored in a FP register anyway. OTOH there are compiler options

that would force it to single precision even in that case.
Zita-resampler does this a little bit different: it calculates

the sum from the start and end of the filter (where the very small

coefficients are) and working towards the center.
Ciao,
--

FA
_______________________________________________

Linux-audio-user mailing list

Linux-audio-user@lists.linuxaudio.org

http://lists.linuxaudio.org/listinfo/linux-audio-user