[opus] Stereo channel separation

Jean-Marc Valin jmvalin at jmvalin.ca
Mon Apr 7 13:16:11 PDT 2014

The bleed-over is actually possible with CELT because at low bitrates,
the encoder will deliberately reduce the stereo image to reduce the
coding noise. For 48 kHz/20 ms, the image reduction occurs below about
40 kbps. Any bitrate above that shouldn't have any leakage.


On 07/04/14 03:10 PM, Timothy B. Terriberry wrote:
> O'Connor, Kevin wrote:
>> Is this bleedover expected? I found an older copy of opus-tools (0.1.6, libopus 1.0.2) and it does not appear to
>> have the bleedover between channels, so I think this was introduced in 1.0.3 or 1.1.
> This bleed-over should not be possible with the CELT layer (_especially_ 
> not during silence), but it is possible with the SILK layer. 1.1 added 
> automatic speech detection, so it is possible that this is caused by 
> switching to SILK in places 1.0.2 would have defaulted to CELT based on 
> your bitrate.
> Can you reproduce the issue when you encode with
>    --set-ctl-int 4000=2051
> ?
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