[Speex-dev] Resampler saturation

Stephane Lesage stephane.lesage at ateis-international.com
Fri Jun 12 09:21:50 PDT 2009

Hi Jean-Marc,
I use the resampler to convert various sampling frequencies to 48 kHz on my Blackfin platform (fixed-point)

48K -> 16K speex -> 48K chain does not sound very good compared to plain 16K.
But the main issue is when processing loud signals, I have truncation (and not clipping/saturation)
I could hear it and see it with various music and speech messages. See example.png.

I also ran a test with a chirp signal -> see chirp-resample.png.

The original signal amplitude is 0.8 or 26214.
After 2x upsampling, the peak level is about 30000 -> 114 % !!!
(plus the output is kinda weird)

Is this a bug ? Is it possible to fix it ?
(I use version speex 1.2beta2, because newer versions just don't work on my platform) 

Best regards.

Stéphane LESAGE
ATEIS International
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