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VirtualDub FAQ
Here some common questions and errors which concern VirtualDub will be discussed along with the answer or most likely solution. However, it might very well be that the answers here are not satisfactory or the solution does not solve the problem you have. In these cases feel free to post a new topic and make it clear that you've already read this topic. Also, when having an error and the solution here does not solve it, give a step-by-step explanation of what you've tried to solve the problem, even if this means just repeating the solution given here. This will help you, because we won't advice you to do things you've already tried, and it will help us removing ambiguities in this FAQ.
To solve any problem you have, make sure you have downloaded the latest version of VirtualDub first, which can be found here.
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Which video-formats are supported by VirtualDub?
VirtualDub gives only full support for AVI-files. The versions before the 1.6.x branch do not support DV type 1 AVIs though. Such AVIs can be converted to DV type 2 with this tool, so that VirtualDub can open them. VirtualDub can also open MPEG1 files, but saving such a file will result in a conversion to AVI. All other formats (e.g. asf, MPEG2, OGM, Matroska) cannot be opened (directly) in VirtualDub. For editing such video-formats other tools are available such as:
- AsfTools
- TMPGEnc (for MPEG1 and 2)
- VirtualDubMod, a modification of VirtualDub for Matroska and OGM, but also AVI. Note that VirtualDubMod is not actively developed anymore and is therefor stuck in the 1.5.10 stage. Matroska support is also outdated for it.
- VirtualDub-MPEG2, adds VOB and MPEG2 opening functionality to VirtualDub (opening only!).
Remember that AVI is a container that usually holds one video stream and one audio stream. To open the file, VirtualDub needs codecs to decompress (read) these streams. Codecs are third party applications: they aren't delivered with VirtualDub nor the AVI-file. This means you will have to download codecs separately. Also note that VirtualDub can only make use of Video for Windows (VfW) codecs; DirectShow-filters are not compatible with VirtualDub.
For version 1.7.6 and higher there is an input plug-in system. For a few formats plugins have already been written, including a general DirectShow plug-in. Links to various plugins can be found here.
When appending with direct stream copy, the file size of the target file is much larger than the sum of the seperate files. Why?
VirtualDub checks for segmented AVIs and will append them automatically when opening the first file. For example, if you have three files with the same prefix and numbers behind it (e.g. file1.avi, file2.avi and file3.avi) VirtualDub will detect this and open all segments accordingly. In the file opening screen there is an option in the lower left corner called "Automatically load linked segments", that toggles this behaviour on or off. As answer to the question: make sure files don't get appended multiple times by first automatic appending and then manual appending afterwards.
When I try to save my AVI nothing happens!
Make sure the check-box in the lower left corner of the 'save AVI'-dialog is unchecked. Otherwise your save will be added to the job list instead.
VirtualDub crashed while in capture mode, and now everytime I try to enter capture mode it crashes again.
Hold down SHIFT while selecting Capture AVI. This will open the capture mode without preloading a driver.
I'm using the 64 bit version of VirtualDub, but when installing codecs they don't appear in the list of available compressors.
The 64 bit version of VirtualDub requires 64 bit codecs, but not many are available. A solution is to simply use the 32 bit version of VirtualDub. This will run fine on a 64 bit OS.
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List of common errors and warnings in VirtualDub:
VBR audio stream detected: VirtualDub has detected an improper VBR audio encoding in the source AVI file and will rewrite the header with standard CBR values during processing for compatibility. This may introduce up to #### ms of skew from the video stream. If this is unacceptable decompress the *entire* audio stream to an uncompressed WAV file and recompress with a constant bit-rate encoder. (bit rate: ###.# +/- ##.# kbps)
As dealt with in this topic.
VirtualDub does not support VBR audio in AVI. It will re-write some headers so the VBR stream will be read as CBR, but this will usually cause desynch (as the warning indicates). There are several ways of dealing with this:
1. Ignore the message and do a remux with AVIMux GUI after you processed the file with VirtualDub. AMG does handle VBR audio and writes appropriate headers.
2. Use VirtualDubMod, and answer "no" when asked to re-write the headers.
3. Decompress the stream to an uncompressed WAV file and compress again using VirtualDub. This will introduce quality loss.
Update: Versions 1.8.0 and higher do support reading AND writing of VBR MP3 with correct synch.
WARNING: Nothing to output, b-frame decoder lag
First of all, this is not a message of VirtualDub, but from the XviD decoder. It means you created (or, God forbid, downloaded) a file that was encoded without "packed bit stream". It only affects the first (few) frame(s) as you can see when playing the file. If you want to use "direct stream copy" with the file, you can safely ignore this warning. If you want to re-encode the file, it is best to delete the frames that have this warning message on them (otherwise they will show up in your re-encoded video).
The source image format is not acceptable (error code -2)
There are three main causes for this to happen:
1. You are trying to compress a video in a format that is not supported by the codec. This will usually mean that the frame height and width are incorrect or that the color depth is not valid. To see what restrictions there are for a codec go to video-->compression and select the codec. The codec restrictions will now appear in a box right of the middle in this window.
2. It happens when trying to play the file in VirtualDub. This is the result of a codec that is trying to decompress a video stream, which it actually cannot handle. This shouldn't be happening, but there are a few codecs (e.g. Panasonic DV) that will try to decompress anything they can get their hands on. Check the file info in VirtualDub and look up the codec used for decompression. Then uninstall/disable this codec and open the file again and see if it plays. It might be possible that with opening the file you will get another type of error message, which will be dealt with below.
3. This error is also common with DivX and can have two main possible causes for it. First of all, it is recommended that in the advanced setting of the DivX config, you disable "Do not prompt with errors and warnings". Why this setting is not disabled by default I don't know, complain to DivX about it. If you now start your encode again an error message will appear. Usually there are problems with the logfile or the dimensions of your video are not correct. With DivX hardware profiles enabled, there are maximum resolutions you can encode with (e.g. 720x576 is the maximum res for the Home Theatre profile). It could also be that you have issues as described at number 1.
Couldn't locate decompressor for format 'XXXX" (unknown). VirtualDub requires a Video for Windows (VFW) compatible codec to decompress video. DirectShow codecs, such as those used by Windows Media Player are not suitable.
This error message will appear when VirtualDub cannot find an appropriate codec to decompress the video. To figure out what codec you need there are programs like GSpot and AVIcodec. You can also look up the FOURCC (that's what those four letters 'XXXX' are called) yourself at www.fourcc.org. Here is a page that provides links to the most commonly used codecs. Note that sometimes GSpot or AVIcodec will tell you that you can open the file while still getting this error in VirtualDub. But as the error message already indicates: only VfW codecs can be used for VirtualDub.
No audio decompressor could be found to decompress the source audio format
This will happen when you don’t have an Audio Compression Manager (ACM) for your audio. Again, DirectShow-filters will not work with VirtualDub. The best thing to do is check the file info in VirtualDub and look for the audio tag. Most likely it will be 'tag 2000', which means AC3-audio. For this you can download the AC3ACM.zip from fcchandler. If you encounter another tag you can check for example with the audio codecs list of GSpot to which codec that tag belongs.
No video frames found in MPEG-file
Most likely you are trying to open a MPEG2 file in VirtualDub, which it can't handle. Try opening the file with the MPEG2 input plug-in from fcchandler. For simple editing (cutting, merging) it’s best to use the MPEG-tools from TMPGEnc so you don't have to re-encode the file.
Cannot detect type of file c:\filename.xxx
You are trying to open a file-type that is not supported by VirtualDub. Remember that VirtualDub only can open AVI files and MPEG1 files. Even if the extension is .avi, this doesn't necessarily mean the file is a genuine AVI. Sometimes people give the file a different extension when renaming the file. Try opening it in VirtualDubMod, maybe it’s an OGM or Matroska file, or try opening it in your player and look in the properties to find out what format it’s in.
Error initializing audio stream compression: The requested conversion is not possible.
You have chosen an audio compression that is not directly compatible with the audio channeled to the encoder by VirtualDub. Go to audio ---> conversion and make sure the right conversion factors are filled in. For example if you have an ac3 stream with 6 channels and try to encode to MP3 with 2 channels, you will have to convert to stereo in this menu. Another thing that commonly has to be changed is the sampling rate (e.g. 16000 Hz). Make sure that in the conversion menu you fill in the same sampling rate as you have selected in the audio compression menu.
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If you have a question or problem that is not discussed here, try and use the search function of this board. If that doesn't help you, feel free to post a new topic with your question.
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useful links:
VirtualDub, Input plugins and filters, AviSynth, AVI-Mux GUI, AC3ACM by fcchandler, VirtualDub FAQ |
