BEEPFIX - DV audio dropout fixer

 
 

This program will go through the audio portion of a digital video encoded AVI file looking for audio dropouts characteristic of DV (those PCM values of -32768).  Dropouts are replaced with values interpolated from the surrounding good data.
 

How to Use

beepfix is a Windows console application (i.e. not a GUI).  To use it, you must open an MS-DOS prompt from within Windows and use as follows:
beepfix in.avi out.avi
where in.avi is the AVI file you are trying to fix.  out.avi will be a new AVI file (audio only) with the corrected audio.  You can then use Premier to composite the new audio track in place of the old one.

This has only been tested under Windows 95.  I would be interested to hear if it also works under Windows 98 or Windows NT.
 

Example

D:\>beepfix p5b.avi c:out.avi
Number of channels: 2
Samples per second: 48000
Avg bytes per second: 192000
Block alignment: 4
Bits per sample: 16
Clip is 6062280 samples long
samples checked: 5924538 (97.7% done), dropouts left=715, right=715
Total samples: 6062280, total drops left=715, right=715
Longest span of dropped audio:
   Left:     2 samples
   Right:    1 samples


Looking at this, of 6062280 audio samples, 715 were dropped in each of the left and right channels (it's a little unusual for the drops to be equivalent).  The longest span section gives you an idea of the worst case of how many consecutive samples were dropped for each channel.  Obviously, the longer the span, the more interpolation needs to be done.  I haven't actually seens drops longer than 2 consecutive samples.
 

Caveats

Some DV equipment has a habit of just sending you muted audio (PCM values = 0) when things get really bad.  This software doesn't detect or correct for that.

Where is it?

You can ftp the software from:   http://www.slb.org/download/beepfix.exe

If you have comments or suggestions, email me at scott@slb.org

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