Re: [codec] draft test and processing plan for the IETF Codec

David Virette <> Mon, 18 April 2011 20:41 UTC

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Date: Mon, 18 Apr 2011 22:41:44 +0200
From: David Virette <>
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To: 'Koen Vos' <>, 'Anisse Taleb' <>
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Subject: Re: [codec] draft test and processing plan for the IETF Codec
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Hi Koen,
I agree that for narrowband, in VoIP applications the 300-3400 Hz IRS filter
is not used and I think the 300-4000 was a typo in the test plan, this
should have been 50-4000Hz. This will be corrected in the next version. For
the super-wideband, if I understood correctly, the input signal from OPUS
will be sampled at 24 kHz. And I don't see the point to test it against the
super-wideband as defined in ITU-T. This comparison is part of the
At the same time, as pointed out by Jean-Marc, for some bitrates it is
better to use a full band mode rather than super-wideband. In that case, if
no full band reference codec can operate at the same bitrate, I think that
the final comparison will be done against a super-wideband reference codec
operating at the same bitrate. As all the super-wideband and full band codec
will be tested in the same experiments, all these comparisons will be
Best regards,

-----Original Message-----
From: [] On Behalf Of
Koen Vos
Sent: samedi 16 avril 2011 07:04
To: Anisse Taleb
Subject: Re: [codec] draft test and processing plan for the IETF Codec

Hi Anisse,

I noticed your plan tests with band-limited signals: Narrowband signals are 
filtered from 300-4000 Hz, Wideband from 50-7000 Hz, Superwideband from 
50-14000 Hz.

However, VoIP applications have no such band-pass filters (which degrade 
quality and add complexity).  So results will be more informative to the WG 
and potential adopters of the codec if the testing avoids band-pass 
filtering as well.  We want test conditions to mimic the real world as 
closely as possible. 

Instead of band-pass filtering, tests on speech could use a simple high-pass

filter with a cutoff around 50 Hz, as many VoIP applications do indeed have 
such a filter.  


----- Original Message -----
From: "Anisse Taleb" <>
Sent: Wednesday, April 13, 2011 12:32:00 AM
Subject: [codec] draft test and processing plan for the IETF Codec

Please find attached a first draft of a test plan of the IETF codec (Opus). 
The proposal does not claim to be complete, there are still many missing
things, e.g. tandeming cases, tests with delay jitter, dtx etc. Consider it
as a starting point for discussion where everyone is welcome to contribute
in a constructive manner. Further updates are planned, but let's see first
some initial comments.

The attachment is a pdf version, please let me know if you would like to see
another format and I would be glad to oblige.

Comments and additions are welcome!

Kind regards,
(From La Jolla - San Diego).

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