Compares two clips (the "filtered" clip and the "original" clip) and returns the following data for each frame:
These data are displayed on screen by default (see example image), 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 clip_filtered, clip clip_original
[, string channels, string logfile, bool show_graph ] )
clip clip_filtered, clip_original =
- The "filtered" clip and the "original" clip. Size and color formats must match.
- Color format may be RGB24, RGB32, YUY2 or YV12.
- The "filtered" clip is returned.
string channels = ""
- Set the color channels to be compared with a combination of R,G,B [,A] or Y,U,V, depending on the source color format.
- By default, all channels are compared.
bool show_graph = true
- If true, (the default) the PSNR graph is drawn on the screen.
string 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.
- Basic usage – display differences on screen:
- Create a log file:
- Compare chroma channels only:
 External Links
|v2.58||Added YV12 support.|