Changing Resolution

Even though it doesn't actually change the display size of video (the playback hardware and display does) the, changing resolution is still considered resizing. There are different methods that can be use for resizing that result in very different pictures. Which resizer will give you the best picture quality is completely subjective, but many people say that Bilinear resizing is the best for reducing resolution because it softens the picture, while Bicubic or Lanczos resizing is better for increasing resolution because it sharpens. You can try all of these lines and keep whichever one you want. Remember, sharper pictures contain more detail, and therefore may require more bitrate to look decent when encoded. Exceeding the amount of detail your MPEG-2 encoder can reproduce at a selected bitrate may result in encoder errors, also called artifacts.

AviSynth Commands

The AviSynth resize filters generally used, in order of increasing picture sharpness, are BilinearResize, BicubicResize, LanczosResize, and Lanczos4Resize. Like ColorMatrix, when resizing you'll want to tell the filter when your video is interlaced by adding interlaced=true to your command.

Bilinear Progressive


Bilinear Interlaced

BilinearResize(w,h, interlaced=true)

Bicubic Progressive


Bicubic Interlaced

BicubicResize(w,h, interlaced=true)

Lanczos Progressive


Lanczos Interlaced

LanczosResize(w,h, interlaced=true)

Lanczos4 Progressive


Lanczos4 Interlaced

Lanczos4Resize(w,h, interlaced=true)

Lanczos Progressive


Lanczos Interlaced

LanczosResize(w,h, interlaced=true)

Make sure to replace w with the width you're resizing to, and h with the height you're resizing to. In our case we should be using 720 for width and 576 for height so it should look something like this:


Placement In Your Script

Resizing should generally be done near the end of your script, although there are legitimate reasons to resize in the middle, sometimes multiple times. Resizing should always be done on progressive sources. Since the different fields in interlaced video aren't from the same moment in time (see our Frames and Framerates guide for more information), you must separate them before resizing. Fortunately we don't have any true video (just telecined film) so we won't need to cover that process.

Written by: Rich Fiscus