[Speex-dev] Noisy sound quality with Blackfin in WB-mode

Bernhard Gerlach bernhard.gerlach at stud.tu-ilmenau.de
Wed Oct 26 08:35:37 PDT 2005

Hello Jean-Marc,

> Could you try mixing the encoders and decoders (encode with one  
> version,
> decode with the other) to see whether the problem is in the  
> encoder, the
> decoder or both.

I tested that,and the results are: The fixedpoint+blackfin encoder  
used together with the fixedpoint-only decoder produces an bad  
sounding file (for all the combinations for quality and complexity I  
mentioned in my previous postings, and also for both WB and UWB mode).
The combination fixedpoint-only encoder together with the fixedpoint 
+blackfin decoder results in good sounding files.

> A couple things worth checking: try with WB quality 5 and 8. Do  
> both of
> these have a problem (they use a different scheme). Also, with Speex,
> it's possible to encode in NB and decode in WB and vice versa.  
> Could you
> try that too? With all this information, I should have a good idea of
> where the problem is.

I tried the WB with 5 and 8 for quality what leads to the same  
results for fixedpoint+blackfin encoder/decoder: bad sounding file.  
Sound was good when quality 5 or 8 was used with fixedpoint-only  

I also tried the --force-XY options supported by the decoder. But I  
couldn't finish the tests til now, because I got files with wrong  
overall playing time entries in the wav-header for some --force- 
options. I'm not finished trying to reproduce this behaviour on a x86/ 
PC. So, unfortunately no results for this so far.

Bernhard Gerlach
Technical University Ilmenau

More information about the Speex-dev mailing list