#187 WavSource doesnt work with certain avi files using pcm sound

[eddified]

Zip file with media exhibiting problem can be found at (13 MB): http://bishops.sytes.net/avisynth_audio_problem/soundDropsOut.zip

Problem:
using WavSource doesn't work on certain AVI files, not sure why.
The problem is that the sound completely drops out after a second (or so).
All of the movies taken with the Canon PowerShot SD1000 have this same problem. All I'm doing in the avisynth script is WavSource("file"), that's it. When testing it, the sound will be heard, but only for a very short amount of time (about a second), and then only silence is heard for the rest of the file. All AVI Movies taken with my Canon PowerShot A640 do not have this problem, but all movies taken with the PowerShot SD1000 DO have the problem. The movies taken by these cameras are very similar in terms of file size, video codec, audio codec, etc.. but with different audio characteristics.

tested on avisynth 2.5.7, and 2.5.8 alpha 2

In the zip are two avi files, one that works (MVI_0261__ok.AVI), and one that doesnt (MVI_0709__bug.AVI). They can be downloaded here: http://bishops.sytes.net/avisynth_audio_problem/soundDropsOut.zip

SIMILARITIES w/ BOTH FILES:
.AVI extension
video: motion JPEG @ 640 x 480
audio: PCM

DIFFERENCES between FILES:
audio rate differences :
MVI_0709__bug.AVI : 44100 Hz, 16 bit
MVI_0261__ok.AVI : 11024 Hz, 8 bit

container info differences : (according to GSpot Codec Information Appliance software, http://www.headbands.com/gspot/ [has nothing to do with its name, it is software that shows you information about video files like what video and audio codecs are used, etc.] )
MVI_0709__bug.AVI : OpenDML (AVI v2.0)
MVI_0261__ok.AVI : AVI v1.0

source differences:
MVI_0709__bug.AVI : Canon PowerShot SD1000 (ultra compact)
MVI_0261__ok.AVI : Canon PowerShot A640 (not sure what this would be classified as... but i know it's much larger than the SD1000 ultra compact)

[Ian Brabham]

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The file MVI_0709__bug.AVI has an irregular IDX1 structure, where only the very first chunk of the audio stream is indexed. The current WAVSource() code requires all audio chunks to be indexed.

Use VirtualDub in DirectStreamCopy mode (audio and video) to copy the streams and write a compatible IDX1 structure into a new file.