[Speex-dev] how to fix high freq noise?

Jason Hennigar jhennigar at pantelintl.com
Thu Jan 8 07:47:00 PST 2009

Hi Jean-Marc,

Thanks for the quick response! I am resending this mail hopefully in 
plain text.

The following three version have been tried and all of them have the 
high frequency tones.


I've isolated this down to the Speex encode/decode by sending silence 
(i.e. all zeros) to the encoder and displaying the decoder output in 
addition to recording the audio. The ALSA functionality that I am using 
to receive and transmit audio is not introducing the problem as it works 
correctly when I remove Speex. The problem occurs both on the Blackfin 
537 Stamp board with the AD1836 audio daughter card and with our own 537 

The build configuration settings that I am using are as follows:


Jean-Marc Valin wrote:
> What version did you use. Some older releases had encoder-side issues
> with some times, but that should be fixed now.
> 	Jean-Marc
> Jason Hennigar a écrit :
>> Hi Masakazu,
>> I have reproduced the Speex high frequency noise issue on a Blackfin 537 
>> by sending 'silence' into the Speex fixed point encoder. By recording 
>> the Speex decoder output and plotting the spectrum using Audacity the 
>> following two frequencies.
>> 1596Hz at -31.3dB
>> 3200Hz at -48dB
>> These two frequencies are present in both Narrow Band and Wide Band 
>> modes. I've tried a number of different configurations and these two 
>> frequencies are always present (quality set to 10 or default, the 
>> complexity set to default, perceptual enhancement turned on or off). I 
>> have not determined how to correct this problem but wanted to provide 
>> additional information.
>> Cheers!
>> Jason
>> _______________________________________________
>> Speex-dev mailing list
>> Speex-dev at xiph.org
>> http://lists.xiph.org/mailman/listinfo/speex-dev

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