[AG-TECH] RAT audio quality - Alternative codecs?

[Piers O'Hanlon]

2009/9/22 Henry Hernando Caballero Corzo <hh.caballero921 at uniandes.edu.co>:
> You're right Lloyd; using a headset highly increases the quality of sound in
> a conference. Indeed, we typically recommend this kind of setup to our
> users.
>
> Sometimes though, they just don't have a headset at hand, or they just want
> to use their mere laptop so other people in their office can listen to the
> discussion and eventually take part of it.
>
> This kind of setup (rather hostile for any conferencing solution) led us to
> think, could RAT itself overcome this kind of issues? thus originating the
> idea to eventually integrate higher-end codecs (which are known to
> successfully deal with these problems).
>
Any 'higher-end' codecs don't provide for echo cancellation - they
only provide for better quality and/or better bit rate. Although Skype
and Xiph/Speex systems contain echo cancellers they are seperate
entities and are not part of the codec (e.g. SILK and Speex). It is
certainly possible to integrate the Speex Echo (libsppexdsp) canceller
to RAT.

Piers.

> Regards,
>
> Henry.
>
> Lloyd Pearson wrote:
>>
>> Hello Henry,
>>
>> Have you tested with the academic using a headset microphone and
>> earphones?
>>
>> The use of a headset severely reduces (but doesn’t eliminate!) the
>> transference of sound from the incoming to the outgoing.
>>
>> Some laptops’ microphones can be very good at picking up fan noise, HD
>> noise, keystroke noise etc, so a headset can be preferable.
>>
>> Most echo cancellers can be significantly affected by the acoustic
>> environment, and any movement of the academic would change the acoustic
>> parameters of his environment. It is not uncommon for many reputable echo
>> cancellers to take several seconds to stabilise when a hand or object is
>> moved close to a microphone or the microphone position is moved.
>>
>> Changing the volume of the laptop speakers or gain of the laptop
>> microphone can give big clues about the cause of an echo or other noise.
>> Another useful tip is to hold the mouse pointer over a participant’s name in
>> the RAT window and press the scroll wheel. This will mute their audio coming
>> in to you, and place a line through their name. Press the scroll wheel again
>> to unmute them. As a general rule, if you hear echo, mute each participant
>> in turn until the echo disappears. You will usually only hear single echos
>> if other nodes are causing them. However sustained echo (when the same word
>> echos several times) may be caused by yourself!
>>
>> Good luck.
>>
>> Regards,
>>
>> Lloyd Pearson
>>
>> AVCC Operator
>>
>> University of Otago
>>
>> Ph +64 3 479 8997
>>
>> /lloyd.pearson at otago.ac.nz <mailto:lloyd.pearson at otago.ac.nz>/
>>
>> *From:* ag-tech-bounces at lists.mcs.anl.gov
>> [mailto:ag-tech-bounces at lists.mcs.anl.gov] *On Behalf Of *Henry Hernando
>> Caballero Corzo
>> *Sent:* Tuesday, 22 September 2009 4:38 p.m.
>> *To:* ag-tech at lists.mcs.anl.gov
>> *Subject:* [AG-TECH] RAT audio quality - Alternative codecs?
>>
>> Hi everyone,
>>
>> Hope you can advise me in the following issue.
>>
>> Scenario:
>>
>> Say we're holding a videoconference which joins people from two different
>> types of nodes:
>>
>> -A conference room with an adequate AG node setup (audio equipment for
>> echo cancelling (ClearOne RAV 600), ambient microphone, high-end speakers,
>> etc.)
>>
>> -A "casual participant" (an academic who joins the conference from his
>> workplace and uses his personal AG-equipped laptop sporting integrated
>> microphone and speakers)
>>
>> Then a lot of -predictible- problems related to audio arise. Audio quality
>> can degrade so badly (enormous echo and noise) that ends up ruining the
>> meeting. We certainly know we're dealing with a "non-recommendable"
>> scenario, but the fact is, we need it to work.
>>
>> First question:
>>
>> 1. How do you guys deal with this kind of setups? (if there's some way)
>>
>> Going deeper in this issue, I -almost inevitably- turned my eyes on RAT.
>> Even though RAT works well under controlled setups, We certainly expect it
>> to perform much better when used in uncontrolled environments like the
>> described above. So, there're some more questions to ask:
>>
>> 3. Is RAT lacking important features like: ultra-wideband sampling, echo
>> cancelling, noise suppression, active voice detection, discontinuous
>> transmission (among others) ?
>>
>> 4. Or it's all about tweaking with RAT options? (some of the above
>> features seem to be included, not sure if they work well though)
>>
>> 5. What about Speex[1] and/or SILK[2] codecs? Would it be feasible to
>> integrate these codecs to the Access Grid?
>>
>> * I'm aware of this development[3], which is part of a contribution from
>> NCHC. It involves the integration of Speex into RAT, but I'm really not sure
>> if these features are included in the current version of RAT that ships with
>> the latest AG release
>>
>> * SILK claims excellent voicecall quality and the truth is, Skype can in
>> fact deal with our "problematic setup" with absolutely no problem
>>
>> Thanks in advance!
>>
>> Henry Caballero
>>
>> ----------------
>>
>> AG node administrator - Universidad de los Andes
>> (http://ag-mox.uniandes.edu.co)
>>
>> [1] http://speex.org/
>> [2] https://developer.skype.com/silk
>>
>> [3] http://www.nchc.org.tw/en/core_content/download.php?FILE_ID=152
>>
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