You really only want to perform some video processing functions once -- for example, inverting upside-down video; image stabilization; resizing. The freeware Windows video processing application VirtualDub, now available in an improved and updated version virtualdub2, is lean and fast. By preprocessing in VirtualDub and saving the resulting file, you avoid having your main video editing suite perform the same processing again and again as it renders video. You may even find that VirtualDub is all you need to produce a finished video.

I regularly use VirtualDub as the first step in processing my bicycle videos.

VirtualDub performs most functions using filters. When you click on Filters in VirtualDub's Video menu, a filter dialog box will open. Click on "Add" to see the list of available filters. Then click on a filter in the list to add it. Filter information will appear in the filter dialog box. You may use more than one filter at a time: think of the filter list as a sort of pipeline, working in order from top to bottom of the list. So, for example, you may invert the video image, stabilize it and then adjust color, all in one pass through VirtualDub. Note, though, that any filter which resizes the video, rotates it or performs another geometric alteration must resample it, resulting in some loss of quality. Address more than one function in one step if you can -- for example, the Deshaker image stabilization plugin also can zoom the image, and only resamples once.

Installing VirtualDub is straightforward enough, and instructions are clear: you unzip the program file into the appropriate folder. One hitch is that VirtualDub will generate a shortcut only on the desktop. If you like to use the Start menu (which I do, because the Desktop is usually covered up...) then right-click on the Desktop icon and pin it to the Start menu.

Some filter plug-ins for VirtualDub are available only in 32-bit versions, but the number in the 64-bit version is growing, and this version is faster.

As supplied, VirtualDub has a limited number decoding and re-encoding options, but adding plugins and codecs relieves most of these restrictions. See the ones on the Sourceforge page.

I also recommend the following:

• K-lite codec pack (wide variety of codecs) (free, available here)
• XVid-DivX MPEG4 codec (free, encodes to H264 files, available here)
• AVS4YOU (an excellent and moderately-priced commercial package including a video converter that will fix most problem files that won't play, or play correctly, in other applications.)
  

After you have installed a video codec which will open a file, you may also have to install an audio codec in order to play it. Without the audio codec, you will be able to view still images from any part of the file, but you will get an error message if you try to stream it or process it.

With plugins installed, VirtualDub plays.MP4 files generated by my GoPro Helmet Hero camera and .MOV files from the Contour HD1080. AVS4YOU will usually solve a problem reading a file in VirtualDub (or another application). Examples:

• Some software fails to open the .ASF files produced by the Aiptek Xtreme DVR from helmetcamera.com; other software sees them as recorded at 25 FPS even though they were recorded at 30. They crash VirtualDub with the ASF/WMAcodec. The AVS4YOU converter can make these files accessible in VirtualDub.
• I've found that Insight POV files play at slightly the wrong speed in the Pinnacle Studio editing suite, making synchronizing against other cameras a problem -- and so I convert them in AVS4YOU before doing anything else with them. Note also that this camera scans from bottom to top, of imporance when using image stabliziation software such as Deshaker.

VirtualDub offers input and output panes in which you can see your work. You will of course want to have one of these open to select trim points (see below). The windows zoom only horizontally, not vertically -- producing squished images, and you won't be able to view both the input and output images of HD video at once, unsquished, on any conventional computer screen. You can, however, swap the input and output panes. I recommend turning on only the view you want to see at the moment -- usually, the output. When using filters , you can turn both off to speed the processing. You can turn them on and off during processing to check on your work.

The simplest function of VirtualDub is to trim files -- very useful with bicycle video because it is typical to leave a helmet camera running through an entire ride. The controls are at the bottom of the VirtualDub main window, and simple instructions are in VirtualDub help. You trim a file and save the resulting shorter file. This also is a good exercise to learn VirtualDub fundamentals.

VirtualDub can save only to AVI files. AVI is a standard filetype for video under Windows, and because it supports a variety of compressors including very efficient H.264 MPEG 4 compressors. However: If you use default settings, VirtualDub will produce huge, uncompressed files -- I don't mean the mere 17 GB per hour of an MPEG-2, I mean something on the order of 5 GB per minute. Not only do these files fill up your hard drive on short order, they probably won't even stream properly, because the drive can't read them fast enough.

To get past this problem, select Compressors in the video menu. Then you will see a list of available codecs for output to avi files. I like the XVid/Vidx MPEG-4 codec, because it produces reasonable-sized files and is compatible with a wide variety of software. Unless you save VirtualDub's settings, you will have to choose the compressor every time you open VirtualDub. The one disadvantage compared with uncompressed video is that there will be some loss of video quality through compression. In practice, you can select and configure a codec to produce video which looks just as good as uncompressed video, with 1/10 or less the file size.

AVI produces larger files than .MP4 when using the same compressors, because AVI does not share data among frames. Also, some video software, notably Pinnacle Studio, processes MP$ files much faster than AVI files. Two ways around this are to reprocess the AVI output of Virtualdub into MP4 using AVS4YOU or another software package with this capability, or to install and add-on to VirtualDub, as described here.

To save VirtualDub settings -- including those for filters currently in use -- select 'save processing settings' and save the settings somewhere, You can load them at any time from the file menu . You can also right-click on a shortcut icon, select "properties" and add <space>/s "path-to-the-saved-settings-file" at the end of a shortcut's target path, so it will be loaded automatically. (I thank whoever first posted this information -- I've lost track and can't find it now with a Web search.)

Filters are the top item in the VirtualDub's Video menu. When you click on this, the filter dialog box will open. Click on "Add" to see the list of available filters. Then click on a filter in the list to add it. That will take you back to the main filter window, where its name and related information will appear. Click on the name of the filter in the Filter dialog box to open its own dialog box and configure it.

You may use more than one filter at a time. Processing through filters is in order from top to bottom of the list. So, for example, you may invert the video image and than crop it, all in one pass through VirtualDub.

VirtualDub is supplied with a number of filters by default, but you may add others by copying them into the subfolders in the VirtualDub program folder. Each filter or suite of filters includes instructions on how and where to install it.

As mentioned earlier, some filters are available only for the 32-bit version of VirtualDub. You can have both the 32- and 64-bit versions of VirtualDub installed on your computer. Create different shortcuts to them so you can select one or the other.

I recommend the following extra filters:

VirtualDub Filter Pack -- a collection of over 200 filters

Gunnar Thalin's plugins, including Deshaker -- very fine image stabilization software which is covered on a separate page on this site.

Aside from the built-in help, there is a user-maintained support site at virtualdub.org, Also search online.