[opus] Stereo voice not being retained

[Orestes Zoupanos]

Also, check out the "Bitrate Scalability" demo at
www.opus-codec.org/examples/ to get a feel of what happens at what bitrate.
E.g. for your 16kbps you should expect a mono output, low-passed at 6KHz...

On 25/11/2015 18:49, Orestes Zoupanos wrote:
> Hey Kevin!
>
> Once you start dropping under (I think) 32kbps, the codec naturally
> starts losing stereo separation for the benefit of quality.
> If you really want perfect stereo at 16kbps CBR (this is horrifically
> low in my opinion) you might be better off splitting the audio and
> encoding each part at 8kbps CBR.
> Or, there may be a magic "enforce 100% stereo" one could pass?
> (doesn't look like it at
> https://mf4.xiph.org/jenkins/view/opus/job/opus-tools/ws/man/opusenc.html)
>
> You can always ask stuff at the #opus channel at
> https://webchat.freenode.net/
>
> On 16/11/2015 17:37, Honeyager, Kevin S. wrote:
>>
>> Hello,
>>
>>  
>>
>> I’ve been using Opus on an STM32 M4 platform for speech coding in
>> mono mode.  I thought I’d try stereo for grins to see if I can handle
>> the CPU load, and I’m getting a return code of -1 from
>> opus_decode_float (using CBR and 40ms frames).
>>
>>  
>>
>> I decided to try the opusenc and opusdec tools to just see how the
>> command line apps would behave.  I am getting decoded audio, but I am
>> losing the stereo separation.  My test file has speech obtained with
>> a Tascam Recorder, and I spoke directly into each mic individually. 
>> I can clearly hear the stereo separation in the recorded audio. I do
>> not hear any stereo separation once I encode from wav and decode back
>> to wav.     My encoding command line is “opusenc --hard-cbr --bitrate
>> 16.000 --complexity 10 --framesize 20 stereo_voice.wav temp.opus”. 
>> My decoding script is: “opusdec  --force-wav temp.opus decode.wav”. 
>> Opusenc reports that my encoded file is 2 channels (coupled) and
>> opusdec reports that my file is 2 channels.  Can someone tell me how
>> to retain my stereo separation?  If I can’t get stereo separation
>> from the codec, there’s no point in me investigating the error return
>> in my ARM application.
>>
>>  
>>
>> Kevin
>>
>> 	
>>
>> * *
>>
>> * *
>>
>>  
>>
>>  
>>
>>  
>>
>>
>>
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>
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>
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