Video Editing FAQ

I'm an active contributor on the Unofficial VirtualDub Support Forums. There seem to be several questions that pop up over and over again. To avoid having to give the same answers again and again, I've deviced to write up this little FAQ list with those answers. If you have a question you think should be on here, send me some e-mail.

Table of contents

Combining two or more AVI files into one

This question seems to be asked by far the most often... Anyway, here's how to do it:

First, make sure all your files have the same type of compression, video framerate, sound bitrate and samplerate etc. If the files don't have identical settings, VirtualDub cannot join them and you first need to convert the files so they match eachother.

Once your AVIs match, start by loading the first into VirtualDub. Then, load the second by selecting "Append AVI segment..." from the file menu. If your files are sequentally number, you dont have to repeat this step for the other files, just check the box "Autodetect additional segments by filename" and be done. If not, you'll have to repeat the append for each segment you need to add.

Now, everything should be in place. Check the video preview to make sure everything is as you want it, cut out stuff you don't need etc. If you're not applying any filters, you will probably want to set "Direct Stream Copy" in the video menu as this saves you from a lengthy recompression cycle and probably degradation in quality.

Done that? Okay, all you need to do now is save to a new file. Select "Save as AVI" from the file menu and specify a filename.

Too many dropped frames on cards with a Conexant/Brooktree Bt848/Bt849/Bt878/Bt879 chipset

If you have one of these cards and have attempted to capture to, for instance, SVCD resolution (PAL: 480x576, NTSC: 480x480), you may experience an inordinate number of dropped frames (50% or even more is not uncommon), even though your CPU usage is acceptably low (below 80% should be fine). If this happens, try increasing the capture resolution to the maximum. On my system, I have found that capturing at 480x576, 704x576 or even 720x576 sometimes drops about 50% of frames, depending on the source material. Capturing at 768x576 (which is only available using VirtualDub's "Set custom video format" dialog), works quite well, however. I get about 10 dropped frames per hour. Resize the video after capture.

Philips SAA713x vs. VirtualDub

Recently, many people have been posting messages about not being able to use VirtualDub to capture full resolution video with Philips SAA713x based cards, especially under Windows XP. Especially common is error message 418. Since capture video with this combo pretty much every day, I assure you it is possible. It's not all that difficult, although it does require some small sacrifice on your part (nothing major -- you won't get blood over your keyboard and you won't need any incense or small animals): you will lose the ability to use the video overlay functionality of the board. Here's what you ought to do:

  1. Create a system restore point -- this will allow you to revert your system to its current working condition in case you do manage to mess up anything. From the start menu, go to "All programs", "Accessories", "System Tools" and select "System Restore". Creating the restore point should be self-explanatory.
  2. If you don't need (or want) to update your drivers, skip to step 7.
  3. Get the latest drivers for your card. You might want to try the FlyVideo driver. These are intended for the LifeView FlyVideo series of cards, but will most likely work with other SAA713x based chipsets. I have confirmed compatibility with the E-tech TV Card, for instance.
  4. Don't install them just yet, but remove the old drivers (if any), first. Personally, I have 3 capture cards in my system (don't ask me why) and have found it best to remove their drivers as well. To remove the drivers:
    1. Start device manager. There's several ways to get there, but most people prefer to to "Control Panel", double-click "System", choose the "Hardware" tab and click "Device Manager".
    2. Expand the "Sound, video and game controllers" section.
    3. Right-click on the TV Tuner (named something like "LifeView FlyVideo WDM TV Tuner" or "TV Capture Card WDM TV Tuner", and select "Uninstall". The uninstall process should be self-explanatory.
    4. Repeat for the capture device ("LifeView FlyVideo WDM Video Capture" or similar).
    5. Reboot your system. In theory, you should be done now, but I've found that the drivers don't always get removed fully, so:
    6. Start the registry editor (select "Run" from the start menu and type "regedit", then click OK).
    7. Locate the key HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4D36E96C-E325-11CE-BFC1-08002BE10318} and expand it. This will have a series of numbered subkeys. Each time you click on a subkey, the right-hand pane will be updated to display its contents. Take a look at the "DriverDesc" value. There, you'll may likely find that some of them have the same name as the devices you removed from device manager. When you get to those, delete the entire subkey (In my case, that would mean deleting the 0020 and 0033 subkeys).
    8. Reboot your system again.
    9. Remove the following files (assuming you have Windows installed to C:\Windows):
      • C:\Windows\System32\Drivers\PhTVTune.sys
      • C:\Windows\System32\Drivers\Cap7134.sys
  5. Okay, now, install the new drivers. If Windows complains about digital driver signing, ignore it.
  6. Once the drivers are fully installed, reboot your system.
  7. Run the registry editor, and locate the key HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4D36E96C-E325-11CE-BFC1-08002BE10318} and expand it. This will have a series of numbered subkeys. Each time you click on a subkey, the right-hand pane will be updated to display its contents. Take a look at the "DriverDesc" value. One of them will have the value "LifeView FlyVideo WDM Video Capture". Once you've found the appropriate subkey, expand it and find the subkey "Parameters". There should be a DWORD value called "CapPreviewEnabled". Set that to 0.
  8. Reboot your system, yet again.
  9. Now, start VirtualDub. Go to capture mode. VirtualDub may complain about not being able to find a capture driver. When that happens, it will bring up the "Video Source" window. If you don't get any errors, bring it up manually by hitting 'S' or selecting "Source" from the "Video" menu.
  10. Make sure the list title "Select a Video Device" has your card in it and select that. Click OK. Ignore any errors you get. Close VirtualDub.
  11. Run the registry editor, and go to the key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\VfWWDM Mapper, right-click it, select "Permissions" from the context menu. Deny "Full Control" to everyone, including the system itself. This forces the VfW-WDM-wrapper to rebuild its list of devices every time it is used, which fixes a situation where the system claims your capture device is already in use, when it clearly isn't.
  12. Start VirtualDub, use the "Set custom video format" dialog to set your capture resolution to whatever you need (I use 768x576) and capture.

Not all of these steps are necessary in all cases, but they won't hurt.

The list of video codecs does not show all codecs you have installed

Run the registry editor, and go to the key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Drivers32. You'll see a list of values containing FOURCC references and CODECs, such as VIDC.IYUV --> "iyuv_32.dll" and vidc.iv50 --> "ir50_32.dll". Look for any values that have no data associated with them (except the "default" value, of course). Delete those values.

Capturing to DivX or with compressed audio?

Please don't. Instead, capture to a lossless format, like Huffyuv and with uncompressed audio. After you're done capturing, compress to whatever format you want. This will also allow you to do other processing, such getting rid of commercial breaks, applying filters for resizing the video and noise reduction off-line. This'll take a bit longer, but it means your final video will be of the highest possible quality.

Windows refuses to delete an AVI, saying it is "in use"

This seems to happen with Windows XP especially (possibly other versions as well). It is caused by the little thumb-nail picture of the first frame which you see in the left-hand pane of the explorer window if you have the folder tasks enabled (this used to be called "view as web-page"). Even if you haven't enabled this, the thumb-nail is still generated. As it is being generated, Windows has the file open and therefore in use. The solution is simple: if you want the thumbnail enabled, simply wait a few seconds as it is being generated and then delete the AVI file (just try a few times). If you don't need the thumbnail, then you can disable it in the registry by clearing the Default value found at HKEY_CLASSES_ROOT\SystemFileAssociations\.avi\shellex\PropertyHandler.

If you don't feel comfortable editing the registry, you can use my read-made .REG files to either disable or re-enable the thumbnail from Windows explorer.