[StainlessS]

FBB,
Some Comments flagged by ssS:

Function VideoTek(clip clp) {
    clp
    nChannels=(HasAudio)?AudioChannels:0                        # HasAudio = audio_samples_per_second!=0

    #Errors checking
    Assert(IsPlanar && IsYUV,   "VideoTek: source must be planar YUV")       # ssS: IsPlanar simpler than IsYV12 etc
    Assert(nChannels<9,"VideoTek: sources with more than 8 audio channels are not supported")

    #Getting info
    #Resolution
    x=clp.Width()
    y=clp.Height()
    #Framerate
    fps=clp.FrameRate()                                         # ssS: Not FrameRateNumerator (check Src with eg Assumefps(30000,1001)
    #ColorSpace
    colorspace=clp.PixelType()

    #Taking care of High bit Depth
    Bpc = clp.BitsPerComponent
    clp.ConvertBits(bits=8)                                     # ssS: If already 8 bits then ConvertBits should do nothing anyway (return original)


# ...

See SendSpace below sig for Avs (not avsi, remove my comments and test code, and rename to avsi).

Appended testcode after your script, in the avs

AviSource("d:\Parade.avi")

Assumefps(30000,1001)           # Test FrameRate

# UnComment ONLY ONE of below

#ConvertToRGB32                                         # RGB32
#ConvertToRGB24                                         # RGB24
#ConvertToYUY2                                          # YUY2
#ConvertToYV12                                          # YV12
# v2.60 +
#ConvertToYV411                                         # YV411
#ConvertToYV16                                          # YV16
#ConvertToYV24                                          # YV24
#ConvertToY8                                            # Y8
# Avs+
#ConvertToRGB48                                         # RGB48     Intereleaved RGB  16 bit
#ConvertToRGB64                                         # RGB64     Intereleaved RGBA 16 bit

# ... + Loads more

# 32 Bit Float
#ConvertToRGB48.ConvertToPlanarRGB.ConvertBits(32)      # RGBPS
#ConvertToRGB64.ConvertToPlanarRGBA.ConvertBits(32)     # RGBAPS
#ConvertToY8.ConvertBits(32)                            # Y32
#ConvertToYV12.ConvertBits(32)                          # YUV420PS
#ConvertToYV16.ConvertBits(32)                          # YUV422PS
#ConvertToYV24.ConvertBits(32)                          # YUV444PS
#ConvertToYV12.ConvertBits(32).AddAlphaPlane            # YUVA420PS
#ConvertToYV16.ConvertBits(32).AddAlphaPlane            # YUVA422PS
ConvertToYV24.ConvertBits(32).AddAlphaPlane            # YUVA444PS
###################

Videotek

EDIT: Fix your avsi script and I'll remove this post.

EDIT:
More mods, posted on SendSpace. [also, removed references to clp after initializing Last].

Function VideoTek(clip clp) {
    clp
    nChannels=(HasAudio)?AudioChannels:0                        # HasAudio = audio_samples_per_second!=0

    #Errors checking                                            # ssS: Might as well do at beginning (after errchk, known Planar YUV & < 9 channels)
#    Assert(IsPlanar && IsYUV,   "VideoTek: source must be planar YUV")       # ssS: IsPlanar simpler than IsYV12 etc
    Assert(nChannels<9,"VideoTek: sources with more than 8 audio channels are not supported")

    #Getting info
    #Resolution
    x=Width()
    y=Height()
    #Framerate
    fps=FrameRate()                                             # ssS: Not FrameRateNumerator (check Src with eg Assumefps(30000,1001)
    #ColorSpace
    colorspace=PixelType()

    #Taking care of High bit Depth
    Bpc = BitsPerComponent


 #   ConvertBits(bits=8)                                     # ssS: If already 8 bits then ConvertBits should do nothing anyway (return original)
    ConvertToYUV444.ConvertBits(bits=8)                          # ssS: Convert To YV444, 8 bit, support all colorspace input

 # ...

Supports ALL input colorspace, not just Planar YUV. [Only tested with YUY2, RGB64, RGBPS + a few more, but all should work]

EDIT: Fixed Error in either Avs+ or VD2.
Bug report here in devs forum:- https://forum.doom9.org/showthread.p...58#post1927858

fix [Updated script on SendSpace]

Function VideoTek(clip clp) {
    clp
    nChannels=(HasAudio)?AudioChannels:0                        # HasAudio = audio_samples_per_second!=0

    #Errors checking
    Assert(nChannels<9,"VideoTek: sources with more than 8 audio channels are not supported")

    #Getting info
    #Resolution
    x=Width()
    y=Height()
    #Framerate
    fps=FrameRate()
    #ColorSpace
    colorspace=PixelType()

    #Taking care of High bit Depth
    Bpc = BitsPerComponent

    ConvertToYUV444
    (HasAlpha) ? RemoveAlphaPlane : NOP          # ssS: Avoid eg YUVA444 error in VirtualDub2 (OK in PotPlayer but grey screen in VD2 if YUVA)
    ConvertBits(bits=8)                          # ssS: Convert To YUV444, 8 bit, NO ALPHA, support all colorspace input

 # ...