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

Hi Anisse,

> Besides the DAC and AA filters, you cannot expect that every loudspeaker, 
> headset, earplug, microphone out there to have a flat frequency response 
> regardless of if it is a VoIP application or something else. Specifying a 
> frequency mask helps in reducing some of the variability and uncertainty 
> due to these and other external factors.

Most of your external factors depend on the listening setup, but are otherwise
constant over all tests.  So how can you possibly mitigate the "variability
and uncertainty" with frequency masks that are _constant_ over all setups, and
which -for unclear reasons- depend on the (bandwidth of the) listening
test?

best,
koen.

----- Original Message -----
From: "Anisse Taleb" <anisse.taleb@huawei.com>
To: "Koen Vos" <koen.vos@skype.net>
Cc: codec@ietf.org
Sent: Tuesday, April 19, 2011 2:16:49 AM
Subject: RE: [codec] draft test and processing plan for the IETF Codec

Dear Koen,

Let's mimic the real world as closely as possible :-).

Besides the DAC and AA filters, you cannot expect that every loudspeaker, headset, earplug, microphone out there to have a flat frequency response regardless of if it is a VoIP application or something else. Specifying a frequency mask helps in reducing some of the variability and uncertainty due to these and other external factors.

That aside, I am not against revisiting these in getting something that all agree on. 

Kind regards,
/Anisse
> -----Original Message-----
> From: Koen Vos [mailto:koen.vos@skype.net]
> Sent: Saturday, April 16, 2011 7:04 AM
> To: Anisse Taleb
> Cc: codec@ietf.org
> 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.
> 
> best,
> koen.
> 
> 
> ----- Original Message -----
> From: "Anisse Taleb" <anisse.taleb@huawei.com>
> To: codec@ietf.org
> Sent: Wednesday, April 13, 2011 12:32:00 AM
> Subject: [codec] draft test and processing plan for the IETF Codec
> 
> Hi,
> 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,
> /Anisse
> (From La Jolla - San Diego).
> 
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