Clicks?

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Clicks?

Roger B
I just used Audacity to record an hour long teaching session using a
lavaliere microphone
by audio-technica and an edirol sound card onto my laptop. It was a vast
improvement over
what we had been doing. But I found 6-8 truncated words in the
recording.  I suspect that
I need a buffer in Audacity or a larger buffer than is present in the
program.  How do I
control the buffer or does Audacity have a buffer that I can set and if
so what is the
optimum setting?
 
Any help would be appreciated.
 
Roger b.


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Re: Clicks?

Gale Andrews

    | From Roger B <[hidden email]>
    | Sun, 28 May 2006 17:48:51 -0500
    | I just used Audacity to record an hour long teaching session using a
    | lavaliere microphone by audio-technica and an edirol sound card
    | onto my laptop. It was a vast improvement over what we had been
    | doing. But I found 6-8 truncated words in the recording.  I suspect
    |  that I need a buffer in Audacity or a larger buffer than is present
    | in the  program.  How do I  control the buffer or does Audacity have
    | a buffer that I can set and if  so what is the optimum setting?

Where this problem occurs is there a flat line (silence) or a large spike
suggesting noise (as implied by your subject header)?

Unlike some programs Audacity does not write a continuous stream of data
to disc when recording but buffers the recorded data and writes it as an
individual .au file in its temporary folder every 6 -10 seconds. This makes for
rapid editing and navigation even in long tracks but requires that the input
and the output keep up with each other or dropouts or duplications can
occur in the recorded track. The forthcoming 1.3.1. Beta version does have
a buffer adjustment for recording latency which may help with synchronisation
problems but to avoid the type of problems you have had you probably need to
investigate updating the soundcard drivers and resolving possible hardware or
resources issues which when done, almost always solve these problems.

I have pasted in these suggestions below. Updating the soundcard drivers and
enabling DMA if you are on Windows or Linux is very important as this
dramatically increases the rate of data reading and writing and reduces the
amount of processing power needed to do so.

Gale Andrews

********************************************************************


Here are some general tips on avoiding recording problems.  

    * Close all other programs while recording. Be aware of background virus
scanners and other system tray programs. Norton, Sophos and other anti-virus
products scan each file as it is opened and closed by default. On a slow computer
this scanning can affect recording as it takes too long.

    * Reduce the recording bit depth to 16 bit from 32 bit (the default). This is
set under File > Preferences on the Quality tab. Reducing the bit depth halves
the amount of data stored and the time taken to write it to the disk.

    *  Don't record stereo unless you have to. Stereo requires your machine to
handle twice as much data. A single instrument or solo vocal track should usually
be recorded mono. You can position it in the stereo mix later.

    * Turn off "Auto-scroll while playing". This stops the display re-drawing as the
recording is made. Stopping this reduces the amount of processing the display uses,
freeing power for recording. This is set under File > Preferences on the Interface
tab.

    * Zoom out to the whole length you will be recording

    * Disable the recording level meter in Audacity Preferences > Interface as this
will conserve  resources on  a slower computer

    * Defragment your hard drive (only affects Windows users). This increases the
speed your computer can read and write information at by ensuring that files are
kept close together in a logical manner.
   
    *Windows 2000/XP users can try increasing the priority of Audacity in
Task Manager. On GNU/Linux you can run as root (back up everything
first and not recommended unless you are on a standalone machine)        

    * Make sure (Windows/Linux) that DMA mode is enabled for your
       hard drive  -  see
http://www-users.york.ac.uk/~raa110/audacity/AudacityHelp.html#DMA

   *Try to avoid interrupt sharing for your soundcard  

   * Update your hardware drivers to avoid conflicts and get better hardware
performance. Key targets are:

          o Sound Card. This is also a common cause of crashes, especially during
          recording
          o Video (Display) Card
          o Hard Drive controller - This is especially important for RAID and other
          high performance controllers.

   * If you have audio equipment such as microphones or amplifier close to the
computer, consider moving them apart, altering the grounding so that the
PC is not grounded together with the audio equipment, and using high quality
shielded audio cable, to prevent extraneous noises from the equipment or
the computer seeping into the recording.    






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Re: Clicks?

JhonX
thank you for all those tips to record better!

but still, shouldn't there be just a basic setting under Preferences to change the buffer size?
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Re: Clicks?

Gale
Administrator
Beta Audacity has a buffer size setting in the Audacity preferences.


Gale