Speex dev - Oct 2005 - Noisy sound quality with Blackfin in WB-mode

Hi Jean-Marc,
> Can you confirm I'm understanding everything correctly? You encode  
> with
> the same encoder and then decode with either A) blackfin assembly and
> fixed-point or B) fixed-point only on Blackfin. Then A) sounds bad and
> B) sounds good. If you do the same in narrowband, it sounds OK. Is  
> that
> correct? If that's the case, it's *probably* some kind of bug
and/or
Yes, that's right, except one thing: I always use the blackfin 
+fixedpoint optimized encoder *and* decoder or the fixedpoint-only  
optimized encoder *and* decoder at one time.  And I do every encoding/ 
decoding on the Blackfin.

> invalid assumption in the blackfin assembly. Could you check if that
> happens on all wideband modes (and none of the narrowband modes)?  
> Also,
> testing with 1.1.10 would help (in case I broke something in svn).
I rechecked the issue with the following combinations with the 1.1.11- 
svn version:
NB-Mode (8kHz):
Complexity = 1, Quality = 1, 5, 9
Complexity = 5, Quality = 1, 5, 9
Complexity = 9, Quality = 1, 5, 9

I also checked the above combinations for the WB (16 KHz) and UWB- 
Mode (32kHz). And I checked everything with 1.1.10 version, too, as  
you suggested.  I checked by encoding+decoding a test speech sample  
for each mode with fixed+blackfin optimizations and by comparing the  
resulting file to the fixed-only-optimized encoded+decoded version of  
the speech sample.

Results: The strange sound persists in all WB and UWB combinations,  
no matter if its the 1.1.11-svn or the 1.1.10 version. No difference  
between blackfin+fixed and fixed-only in NB modes. The sound is  
getting even worse when comparing WB to UWB modes. Also sound seems  
to get worse with raising quality values.


Hope that helps,

Bernhard Gerlach
Technical University Ilmenau
Germany

Hi Bernhard,
> Yes, that's right, except one thing: I always use the blackfin 
> +fixedpoint optimized encoder *and* decoder or the fixedpoint-only  
> optimized encoder *and* decoder at one time.  And I do every encoding/ 
> decoding on the Blackfin.
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.
> Results: The strange sound persists in all WB and UWB combinations,  
> no matter if its the 1.1.11-svn or the 1.1.10 version. No difference  
> between blackfin+fixed and fixed-only in NB modes. The sound is  
> getting even worse when comparing WB to UWB modes. Also sound seems  
> to get worse with raising quality values.
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.

Thanks,

	Jean-Marc

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  
encoder/decoder.

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
Germany