http://www.avisynth.org/Deinterlacing & Pulldown Removal:
All PAL, NTSC, and SECAM video is interlaced, which means that only every other line is broadcast at each refresh interval. Deinterlacing filters let you take care of any problems caused by this. IVTC (inverse telecine, aka pulldown removal) filters undo the telecine process, which comes from differences between the timing of your video and its original source.
[Decomb Filter package (by Donald Graft)]: This package of plugin functions for AviSynth provides the means to remove combing artifacts from telecined progressive streams, interlaced streams, and mixtures thereof. Functions can be combined to implement inverse telecine for both NTSC and PAL streams. [YV12, YUY2]
[Motion compensated deinterlace filter "TomsMoComp" (by Tom Barry)]: This filter uses motion compensation and adaptive processing to deinterlace video source (not for NTSC film). [YV12]
Also see Auto24FPS and AutoDeint in the Misc Plugins section, below.
Spatio-Temporal Smoothers:
These filters use color similarities and differences both within and between frames to reduce noise and improve compressed size. They can greatly improve noisy video, but some care should be taken with them to avoid blurred movement and loss of detail.
[Tiya3d (by Marc FD)]: spatio-temporal smoother, [discussion]. [YV12]
[FluxSmooth (by SansGrip)]: spatio-temporal smoother, [discussion]. [YV12]
[NoMoSmooth (by SansGrip)]: A motion adaptive spatio-temporal smoother: [documentation]; [discussion]. [YV12]
[Convolution3D (by Vlad59)]: Convolution3D is a spatio-temporal smoother. It applies a 3D convolution to similar pixels in consecutive frames. [dicussion] [YV12]
Spatial Smoothers:
These use color similarities and differences within a frame to improve the picture and reduce compressed size. They can smooth out noise very well, but overly aggressive settings for them can cause a loss of detail.
[Chroma Noise Reducer (by Marc FD)]: Reduces the noise on the chroma (UV) and preserves the luma (Y), [discussion]. [YV12, YUY2]
[Deen (by Marc FD)]: Several denoisers. [YV12]
[Dynamical Noise Reduction 2 filter "DNR2"] [YV12]
Also see KenKunNR in the Misc Plugins section, below.
Temporal Smoothers:
These filters use color similarities and differences between frames to improve the picture and reduce compressed size. They can get rid of most noise in stationary areas without losing detail, but overly strong settings can cause moving areas to be blurred.
[TemporalCleaner (by Jim Casaburi; ported to AviSynth by Vlad59)]: A simple but very fast temporal denoiser, aimed to improve compressibility. [YV12]
Also see KenKunNRT in the Misc Plugins section, below.
Sharpen/Soften Plugins:
These are closely related to the Spatial Smoothers, above. They attempt to improve image quality by sharpening or softening edges.
[asharp (by MarcFD)]: adaptive sharpening filter, [discussion]. [YV12]
[WarpSharp YV12 (by xxx, ported to AviSynth by Sh0dan)]: (use it before any cropping) [YV12]
[Unfilter plugin (by Tom Barry)]: This filter softens/sharpens a clip. It implements horizontal and vertical filters designed to (slightly) reverse previous efforts at softening or edge enhancment that are common (but ugly) in DVD mastering. [discussion] [YV12]
Also see WarpSharp, Xsharpen, and UnsharpMask in the Misc Plugins section, below.
Resizers:
not yet :(
Subtitles:
[Vobsub/Textsub (by Gabest)]: For the subtitle fans!
MPEG Decoder (source) Plugins:
["MPEG2DEC3" (by Marc FD)]: A MPEG2DEC.DLL modification with deblocking and deringing, [dicussion]. Note that the colorspace information of dvd2avi is disregarded when using mpeg2dec.
AC3 Decoder (source) Plugins:
[AC3Source (by Marc FD)]: Let's you import AC3 audio and downmixes it to stereo.
MPA Decoder (source) Plugins:
[MPASource (by Warpenterprises)]: A mp1/mp2/mp3 audio decoder plugin.
Misc Plugins:
[Imagesequence plugin (by Bzzz, modified by Warpenterprises and Sh0dan)]: Let's you import image sequences like .TIF, .TGA and .JPG files (images need to be 24 or 32 bits per pixel).
[Deflicker filter (by Donald Graft, port of the VirtualDub filter): This filter corrects video that has frame luminance variations over time, what we might generically call flickering. ''[YUY2]''
[Dup (by Donald Graft)]: This is intended for use in clips that have a significant number of duplicate content frames, but which differ due to noise. Typically anime has many such duplicates. By replacing noisy duplicates with exact duplicates, a bitrate reduction can be achieved. [YV12, YUY2]
[AviSynth monitor "avsmon" (by johann.Langhofer)]: This plugin enables you to preview the video during the conversion and to determine the exact audio delay. [YV12, YUY2?, RGB?]
[YUV-bitmap import filter "raw422" (by Marc FD)]: YUV-bitmap import filter, it supports YUY2/YVUV/UYVY/VYUY.
[Blockbuster (by SansGrip)]: reduces or eliminates DCT blocks ("dark blocks") from an encode, [discussion], YV12 support in version 0.5 or higher. [YV12]
[DctFilter (by Tom Barry)]: Reduces high frequency noise components using Discrete Cosine Transform and its inverse. Results in a high compressibility gain, when it is used at the end of your script. Height/width must be a multiple of 16. [YV12]
[Undot (by Tom Barry)]: UnDot is a simple median filter for removing dots, that is stray orphan pixels and mosquito noise. It basicly just clips each pixel value to stay within min and max of its eight surrounding neigbors. [YV12]