Compare

Compares two clips (the "filtered" clip and the "original" clip) and returns the following data for each frame:

Mean Absolute Deviation [1]

(minimum, average, maximum)

Mean Deviation

(minimum, average, maximum)

Max. Positive Deviation

Max. Negative Deviation

Peak Signal-to-Noise Ratio (PSNR) [2]

(minimum, average, maximum)

PSNR

(minimum, average, maximum)

Overall PSNR

This data is displayed on screen by default (see Examples), or can optionally be written to a logfile.

By default a PSNR graph is displayed; this graph shows overall PSNR visually as a timeline that grows left-to-right along the bottom of the screen as the clip plays.

Syntax and Parameters

Compare (clip filtered, clip original, string "channels", string "logfile", bool "show_graph")

filtered, original

Source clips; the "filtered" clip and the "original" clip. Size and color formats must match.

All color formats supported except 32-bit float.

The "filtered" clip is returned.

channels

Define which color channels to be compared by their initial letters, e.g. "R" (=red).

Valid channel letters are:

• R, G, B, A for RGB(A) clips.

• Y, U, V, A for YUV(A) clips.

• Y for single channel greyscale clips.

Letters are not case sensitive and may be given in any order.

By default, all channels are compared (except for the alpha (A) channel).

Default: ""

logfile

If specified, the results will be written to a file, and not drawn on the clip.

Using a logfile is much faster if you need to compare a lot of frames.

Default: ""

show_graph

If true, the PSNR graph is drawn on the clip.

Default: true

Examples

• Basic usage – display differences on screen:

  LSMASHVideoSource("sintel-2048-surround.mp4")
  A = BicubicResize(640, 272).Crop(80, 0, -80, 0)
  B = A.Sharpen(1.0) ## Sharpen is our filter under test
  return Compare(B, A)
  

• Create a log file:

  Compare(clip1, clip2, log="compare.log")
  

• Compare chroma channels only:

  Compare(clip1, clip2, channels="UV")
  

• See also the Doom9 discussion.

Changelog

Version	Changes
AviSynth+ 3.7.2	Fix: channels now defaults to "Y" instead of "YUV" for greyscale input. Compare: fix 10-14 bit support (graph, PSNR).
AviSynth+ r2150	Compare: port to 16 bits (RGB48/64, Planar YUV(A)/RGB(A)). Fix: Negative SAD in 8 bit SSE branches.
AviSynth 2.5.8	YV12 support.

$Date: 2022/02/18 19:42:53 $