In the guides here and here I talk about using the VirtualDub internal filters, namely the resize and sharpen filters. But you can also use external filters. I use the ffdshow filters. What is ffdshow, you ask? Here’s the quote from the ffdshow sourceforge page
ffdshow tryouts is a DirectShow and Video for Windows codec with support for a wide range of audio and video formats, such as Xvid, DivX, and H.264. It includes a powerful filter set that can enhance the video quality – with filters for resizing, deinterlacing, and displaying subtitles – as well as audio quality through normalization, down-/upmixing, and resampling.
First of all, you’ll need to download the latest ffdshow codec. Although it’s “safer” to always use the latest stable builds, in this case however I’d recommend always using the latest SVN builds. Because they are updated way more often including the filters. The latest SVN build, as of the time writing this article was 2011-01-19. Even the SVN builds are subdivided in 3 areas:
Start installing the ffdshow codec now. You’ll be asked what you want to install. This
is your choice:
After that leave the rest of the settings as they are and continue finishing the codec installation. After the installation a file named ffvdub.vdf should be inside your VirtualDub/Plugins folder:
Now we can start using the ffdshow filter in VirtualDub. Start up VirtualDub, open a video file, then add the filter:
Now the important part: VirtualDub processes the selected filters in their order. Meaning squentially. This is very important because it affects your quality especially in connection with watermarks. Say such as if we were using the filters in this order:
What happens is this: First a watermark is slapped on a frame, then this frame including the watermark is sharpened and after that the sharpened frame including the watermark is resized.
This is not what we want. Why? Imagine you have a watermark 100*100 pixel small. This image is first slapped on each frame, then it is sharpened and then it is resized. You don’t want that. You want the watermark to maintain its original size and quality. So the ideal filter order would be:
Resize the frame, sharpen the frame and insert original, unedited watermark. Let’s take a look at the selected filters.
ffdshow filter: Resize It’s pretty much straightforward. Enable resize, choose “Specify horizontal and vertical size” and enter the numbers you want to resize it to. It’s 1280720 for 720p HD and 19201080 for 1080p HD.
If you’re resizing down or up from a 4:3 resolution, remember to enable “Keep original aspect ratio” under Aspect ratio. Otherwise the end-result will look over-stretched/-squeezed. If you’re resizing down or up from a 16:10 resolution, you could ignore this option. The end-result won’t look too bad. But check it out yourself to make sure!
ffdshow filter: Sharpen Sharpen is a bit trickier, and a lot different from VirtualDub’s internal one. In fact there are 5 different sharpening algorithms, I haven’t experience with them all, but I’ve made best experiences with “msharpen”. Enable “high quality”.
Sadly I can’t give you ballpark figures like in the previous guides because this filter works very different. I’ll do my best to try to explain how it works. There are 2 sliders: Strength (1-127) and Threshold (0-255).
Strength dictates how strong it should sharpen. Threshold dictates how much of the frame should be sharpened. A Threshold of 0 means everything (every pixel) in the frame will be sharpened, a Threshold of 255 sharpens nothing in the frame. In order for you to see how much of a frame is sharpened enable “only mask” and press “Preview”, play with the slider “Threshold” and set it to your liking. All that “white” in your Preview will be sharpened.
Once you’ve set your Threshold to your liking don’t forget to turn off “only mask”! Now play with the slider Strength and set to your liking. Each video needs a different setting I’ve concluded so far. This is how the different msharp settings look like: Sharpen filter off, Sharpen Strength 127/Threshold 255, Sharpen Strength 127/Threshold 0, Sharpen Strength 35/Threshold 20, Sharpen Strength 30/Threshold 3. Sharpen filter with “only mask” activated: Threshold 255, Threshold 0, Threshold 30, Threshold 15, Threshold 7, Threshold 3, Threshold 1.
ffdshow filter: Bitmap overlay (Watermark) First thing fist: The watermark image needs to be a bitmap (.bmp). Everything else is pretty straightforward. Position your watermark with the sliders “Horizontal/Vertical position”. Choose the mode of watermark inclusion and its Opacity. Preview your settings.