[speex-dev] testenc and snr calculation
Jean-Marc.Valin at USherbrooke.ca
Mon Sep 1 14:31:49 PDT 2003
Actually, the SNR calculation in testenc has been broken for a while.
The reason for taking the last frame was that the codec would introduce
a one-frame latency. I changed that to half a frame (10 ms) a while ago
and never updated testenc.
Le lun 01/09/2003 à 13:12, Mike Dunn a écrit :
> Hi all,
> I'm new to the group. I'm looking at the speex code with an eye towards
> maybe helping out with either codec optimization or fixed-point
> implementation, The SNR calculation in testenc.c and testenc_uwb.c
> doesn't make sense to me. The code is
> float enoise=0, esig=0, snr;
> for (i=0;i<FRAME_SIZE;i++)
> esig += bak2[i]*bak2[i];
> snr = 10*log10((esig+1)/(enoise+1));
> printf ("real SNR = %f\n", snr);
> But what I see from the rest of the code is that bak2 contains the
> previous input frame, and input contains the current input frame. So
> each enoise calculation is the square of the difference between input
> sample from the last frame and the current frame???
> I have the latest version from CVS. I think this code has changed in
> the past few months, because I see different code in Christian Buchner's
> modified code, downloaded from his site at openacm.org.
> Hope this question isn't too dumb :-)
> Mike Dunn
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Jean-Marc Valin, M.Sc.A., ing. jr.
Université de Sherbrooke, Québec, Canada
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