Well, I had the same problem when I tried to open some AVIs with VirtualDub, and, after several days of searching and trying, I finally found the ONLY 100% EFFECTIVE SOLUTION. That stuff about decompressing and recompressing doesnâ€™t work: after the whole process it loses sync between video and audio.
First of all, letâ€™s understand the problem:
You have an AVI file whichâ€™s audio is encoded with VBR (Variable Bit Rate). This is very frequently used, but is not â€œtechnically correctâ€ for AVI files. VirtualDub suggests decompressing the audio and recompressing it with CBR (Constant Bit Rate). This, no matter which way you do it, which program you use, which BitRate you choose, wonâ€™t work. You will never get sync between Audio and Video.
Thereâ€™s a program called VirtualDubMod. Itâ€™s a variation of VirtualDub, with a lot of great add-ons, but still has this same problem: canâ€™t handle files with VBR without losing sync. Thereâ€™s another program called NanDub. Itâ€™s another variation of VirtualDub specially designed to work with files with VBR. It doesnâ€™t alert anything when you open the file. The problem is that it just doesnâ€™t work: when trying to save the file, although youâ€™ve already selected the desired compression, it doesnâ€™t compress anything and writes entire raw video data. This generates a file of approximately 80 GB. Not to mention that IT DOESNâ€™T WRITE ANY AUDIO DATA AT ALL. Maybe itâ€™s my fault, but itâ€™s a lot different and harder to use than VirtualDub. Searching a lot more, I discovered that an earlier version of VirtualDubMod (the first variation I mentioned) has a checkbox in the lower left corner of the â€œOpen Video Fileâ€ dialogue that reads â€œNanDub VBR MP3 compatibility modeâ€. I canâ€™t imagine why they left out this option in newer versions. So, to sum up, you need VirtualDubMod 22.214.171.124
Download it from http://downloads.sourceforge.net/virtualdubmod/VirtualDubMod_1_4_11_2.zip?modtime=1038182400&big_mirror=0
As you might have already guessed, problems donâ€™t stop here: VirtualDubMod has always been distributed in two packages: one for the program files and another for the DLL files. And also, as an option, an â€œALL INCLUSIVEâ€ package, which includes both. But the problem is that they discontinued the DLL package as well as the â€œALL INCLUSIVEâ€ for older versions, so, if you download and install from the url I gave you, it wonâ€™t work yet. You need to get the DLLs from a newer version. Download it from http://downloads.sourceforge.net/virtualdubmod/VirtualDubMod_1_5_10_2_All_inclusive.zip?modtime=1125529938&big_mirror=0
Now extract all files from the 126.96.36.199 version (the firs link) into a folder. Then, extract all DLL files from the 188.8.131.52 version (second link) to the same folder. MORE PROBLEMS: the older version uses some DLL files that the newer doesnâ€™t, so you need to get them from somewhere else. These files are libpng.dll and zlib.dll.
You can get them from these addresses (these are the versions that work with this program, it took me a while to find them, because they are also older versions, and newer versions wonâ€™t work with VirtualDubMod 184.108.40.206, so donâ€™t try getting them from other addresses):
They are both within zip files, so you need to open the files you downloaded and extract both DLL files into VirtualDubMod folder.
Congratulations!!! You did it! Finally! Now, open VirtualDubMod, choose File>Open video file. Check the â€œNanDub VBR MP3 compatibility modeâ€ checkbox before selecting the file, and then just open the file you want. You should know that you canâ€™t change anything about the audio stream (compression, conversion, etc) or it will lose sync. Be sure that â€œDirect Stream Copyâ€ is selected in the Audio menu. Thatâ€™s it. You can do whatever you want to the video stream without losing sync in an AVI file with VBR audio encoding. Itâ€™s also possible that you wonâ€™t hear any audio when playing the opened video file in VirtualDubMod, but it will be perfect when you save it and open it with a Video Player such as Windows Media Player, DivX Player, or any other.
Hope it helps, I couldnâ€™t find this solution anywhere, I had to discover it myself, so read this and you wonâ€™t have to go to so much trouble as I did. Greetings,