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The Problem
The following VBR audio error message appears
when opening a media file in VirtulDub, causing audio/video desynch after
the file encoding.

Only VirtualDubMod
allows to ignore this issue with the No button.
The Cause
This message appears when opening video files
with variable bitrate (VBR) audio streams. The
AVI file format specification
does not support VBR audio streams natively, therefore, despite of being
able to playback such files properly, problems appear when trying to work with the audio streams of these files,
such as being unable to properly encode or convert the audio stream(s) from the file.
The Solution
The solution to this problem has 3 steps and will permanently fix errors in the audio stream from your file:
1. Completely extract the audio stream into
an uncompressed WAV file (keeping the original audio format)
2. Convert the created WAV file to a constant bitrate (CBR) MP3 file
3. Finally, replace the original audio stream from the media file with
the fixed MP3 encoded file
All this can be done with VirtualDubMod as explained here:
Open the video file in
VirtualDubMod, and answer No
to the question regarding VBR audio. Under the Video menu, select
Direct stream copy. Go to Streams > Stream list.

If your media file is an
MKV or OGM container file, additional audio or subtitle streams will appear here.
In the streams window, right click on the
audio stream to extract and select Full processing mode in the
popup menu, then right click again and select Conversion. Configure
the conversion options as shown below:

These settings are 100% compatible
with the audio format required for VCD.
Click OK and then Save WAV
to extract the audio into an uncompressed WAV file. This can require up
to 1.2 GB of free space for an audio length of 2 hours. Notice that you will need to
have installed the required audio decompressor to properly extract certain audio formats such as AC3.
Once extracted the audio, we must replace
the file's audio stream with the extracted WAV file, and compress it using
the MPEG Layer-3 codec (constant bitrate). All this can be done in one
step:
Back to Streams > Stream list, disable
the current audio stream by double clicking it. Click Add and choose
the previously extracted WAV file. Right click on this new audio stream
and select Full processing mode. Once again right click on it,
and select Compression.
The audio codec selection window will show
up. Chose the MPEG Layer 3 codec and
a bitrate value between 96 and 256 kbps at 44100 Hz, remember a higher
bitrate will increase the output file size.
Finally click OK on both windows and
go to File > Save as AVI. If your original file was an AVI, make
sure to select the AVI item from the file types drop-down
box, if it was an MKV or OGM with additional streams, select either OGM
or MKV to preserve all the audio and subtitle streams.
Ensure you have selected the Direct stream copy mode at the
Video menu, since we must only recompress the audio stream(s) and
not the video.
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