[AG-TECH] Fw: Test to get better XAP settings

Natalia Costas Lago natalia at cesga.es
Wed Dec 22 02:09:47 CST 2004

Hi again,

The main problem we have is that we arent able to get complete full duplex, that means.. that from time to time the sound seems to vanish, we have an even worse effect when two people (each one from each site) try to speak at the same time.. when this occurs the sound of one of the nodes starts to decrease and being distorted. When the mics of one of the sites are muted, there's no problem with the sound coming from the other. 

It is quite an annoying problem so we are not happy with the current configuration.

I'll go through all ur advices in order to get a good audio levels, maybe that's the origin of the problem.

  ----- Original Message ----- 
  From: Osland, CD (Chris) 
  To: 'Natalia Costas Lago' ; ag-tech 
  Sent: Monday, December 20, 2004 1:15 PM
  Subject: RE: [AG-TECH] Fw: Test to get better XAP settings

  This is written in a bit of a hurry and without the software in front of me but basically ...

  Mute the feed to your speakers.

  For each mic {

      set the coarse gain as necessary (usually the -50 or is it -55 dB)
      turn its meter on and adjust fine gain on the mic until loudish
          speaking gets it above the halfway (0 dB) mark while normal
          speaking has it just below
      turn off AGC (in my opinion)
      turn off gating if you're going to be in a small or medium meeting
          but arguably leave it on if you're in a monster meeting
      make sure echo cancellation is on and the reference is to the
          feed to your speakers

  Now go to the Outputs frame and turn on the meter of the feed to the
  audio computer.  Adjust its gain until it is like the mics' (just below 0 dB
  for normal speech, just above for loud speaking).

  Now go to RAT and get it so that normal speaking is usually green with
  a few yellows, and loud speaking just occasionally hits a red.  Make sure
  RAT silence suppression is OFF - let the Gentner do everything or it
  will get confused and sulk.

  Now turn your speakers back on and, in RAT, get the incoming level
  from a trusted source into the same region (green/yellow normal, yellow/red

  Now back to the Gentner and look at the Line input from the computer - get
  that straddling 0 dB as above.

  Now go to the Outputs frame and get the same result on the output(s)
  feeding the speakers.

  Finally go the the speakers (if active) or amps (if passive) and set the sound
  level to a comfortable level; if you have a sound level meter 70 dBA on
  A-weighting is conventional.

  Never be in a hurry to adjust audio when you first get into a venue; the echo
  canceller takes time to settle (say 2 mins) so let things ride for that amount
  of time while you get seating, lighting and camera angles sorted out, THEN
  fix the audio if there's still a problem.



  Chris Osland                                               Office tel: +44 (0) 1235 446565 
  Digital Media and Access Grid                          Medialab tel: +44 (0) 1235 446459 
  BIT Department                                     Access Grid room tel: +44 (0) 1235 445666 
  e-mail:   C.D.Osland at rl.ac.uk                                       Fax: +44 (0) 1235 445597 
  CCLRC Rutherford Appleton Laboratory (Bldg. R18) 
  Chilton, DIDCOT, Oxon OX11 0QX, UK 
  [The contents of this email are confidential and are for the use of the intended recipient only.
  If you are not the intended recipient do not take any action on it or show it to anyone else,
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    -----Original Message-----
    From: owner-ag-tech at mcs.anl.gov [mailto:owner-ag-tech at mcs.anl.gov]On Behalf Of Natalia Costas Lago
    Sent: 20 December 2004 10:25
    To: ag-tech
    Subject: [AG-TECH] Fw: Test to get better XAP settings

    I had to resend this email.. it doesnt reach the list!! Maybe with this second try?

    ----- Original Message ----- 
    From: Natalia Costas Lago 
    To: ag-tech 
    Sent: Monday, December 20, 2004 11:04 AM
    Subject: Test to get better XAP settings


    I need someone to help me to improve my XAP settings for a better audio quality.. anyone out there? Or just to help me.. I can try to guess the better ones...

    Thanx in advance,

    Kind regards,

    Natalia Costas Lago
    email: natalia at cesga.es
    Centro de Supercomputacion de Galicia (CESGA)
    Avenida de Vigo, s/n Campus Sur 
    15706 Santiago de Compostela - SPAIN
    Tel:   +34  981 56 98 10 
    Fax:  +34  981 59 46 16
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