[opus] High Frequency Hiss with Opus at 48 kbit/s

Jean-Marc Valin jmvalin at jmvalin.ca
Thu Sep 4 10:51:24 PDT 2014

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Hi Andreas,

I listened to the .opus file you included and considering the bitrate,
I don't see anything wrong. This is a pretty low bitrate for fullband
stereo music. I haven't listened to the .wma file and it's possible it
may sound better, but then it might very well sound worse on another
sample. We're just not yet at the point of having good quality at 48 kb/s.



On 10/08/14 08:01 AM, Andreas Stöckel wrote:
> Hi to everybody.
> First of all I hope this is the right place to discuss such an 
> (nitpicky) issue.
> I've just been testing the current Opus release and for mere
> curiosity compared its performance to WMAPro with CD quality music
> at low bitrates (48 kbit/s).
> While Opus generally does a very good job, I found one particular 
> example (a high pitched chorale) where Opus produces some strange 
> high-frequency hiss/resonance, whereas WMAPro does not seem to
> have this issue (although it audibly seems to change the bitrate
> after a few seconds). The hiss is (at some extend) already present
> in the original file, yet Opus seems to amplify it.
> You can find the example uploaded here (please ignore the
> certificate warning):
> https://somweyr.de/public/opus_test.tar
> The files were produced using the following command lines:
>> opusenc --bitrate 48 test.wav test.opus
>> wine xWMAEncode.exe -b 48000 test.wav test.wma
> opusenc version is opusenc opus-tools 0.1.9 (using libopus 1.1)
> I used ffplay (version 2.1.5) for playback.
> Is there any way I can tweak opusenc to not show this behavior
> (except for lowpass filtering/downsampling), or is this a bug/a
> general issue with the encoder at this bitrate and high frequency
> noise being present in the input?
> Greetings and thank you for your excellent work, Andreas 
> _______________________________________________ opus mailing list 
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