[opus] Silence causing encoder slowdown on 32 bit architecture

[Jean-Marc Valin]

Indeed, the fix you referenced fixed the hp filter used in audio mode,
but not the one used in voip mode. I just checked in a fix in git. See
if it works for you. Thanks for reporting this.

Cheers,

	Jean-Marc

On 08/12/2013 02:01 PM, D. B. wrote:
> Hi all,
> 
>  
> 
> I noticed some odd behavior with the Opus encoder, and I was wondering
> if this is a known issue.
> 
>  
> 
> First, note that this problem occurs when the Opus encoder is created
> with OPUS_APPLICATION_VOIP, there is no issue if the encoder is created
> with OPUS_APPLICATION_AUDIO.
> 
>  
> 
> If compiled for a 32 bit architecture (i386), the encoder experiences
> significant slowdowns when regular audio is followed by digital silence.
> The size of the encoded frames is also far too big: 128 byes for 20ms of
> pure silence. The problem does not occur if the library was compiled for
> a 64 bit architecture (amd64).
> 
>  
> 
> For example, if a single audio frame (20 ms, 48kHz, mono, 16 bit)
> normally takes less than a millisecond to encode, after hitting the
> digital silence opus_encode() can take up to 30ms to encode a single
> frame. Note that this is longer than the actual frame! Resetting the
> encoder state after each encoded frame can eliminate the slowdown.
> 
>  
> 
> I've tested this with versions 1.0.2, 1.0.3, and a couple of 1.1-beta
> snapshots. The 1.0.x versions experience significant slowdowns. The
> 1.1-beta is faster, but still not as fast as it probably should be. The
> 1.0.x versions were tested on Linux and Windows (same problem on both),
> 1.1-beta was tested only on Linux. Again, when compiled for 64 bit, all
> versions are fine.
> 
>  
> 
> I noticed a recent commit that references something that might be
> related:
> http://git.xiph.org/?p=opus.git;a=commit;h=260474fb81463420adf6acbcfdcac892a4b7c912
> 
> However the changes made in the commit do not seem to affect VOIP. I
> also tried earlier snapshots and the problem is still there (though not
> as bad since it's the 1.1 branch).
> 
>  
> 
> Any ideas as to what is going on? I can provide more information if it
> helps.
> 
>  
> 
> Thanks,
> 
> - DB
> 
>  
> 
> 
> 
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