Program to view 2 synchronized videos simultaneously for quality comparison

[miamicanes]

Is there a program that allows you to view two video clips simultaneously (say, in two vertically-stacked windows) in a way that makes it easy to compare the relative quality of the two?

Ideally, such a program would be capable of automatically keeping the two videos in sync as long as you manually indicate a starting point in each that's within a few seconds of the other's.

It would attempt to faithfully replicate the gamma & color balance of a video monitor fed by s-video (possibly with the ability to simulate composite and modulator-broadcast-to-channel-3 as well).

It would allow you to watch the two playback in realtime, use the mousewheel as a jog dial to speed up or slow down playback, or (in frame-by-frame mode) use the mouse wheel to step through field/frame by field/frame.

It would provide multiple ways of dealing with the interlace problem, including ways to easily view only odd fields, only even fields, simulated interlace (slightly fading alternate scanlines and weakly blending the values of adjacent scanlines being "retraced" at that moment to simulate the effect of lines from the last field fading while lines from the current field slightly bleed over their fading phosphors), and adaptive deinterlacing.

It would also provide realtime statistics showing the objective quality of each (s/n ratio, etc), and provide an option to overlay each view with an alpha-blended mask showing areas where one file is significantly worse than the other.

So... does anything remotely like this exist?

[Bjs]

Every time I looked I kept getting "two triple cheese , side order of fries" ... idiot google .

http://forum.doom9.org/archive/index.php/t-121000.html

The problem is overlay , which was not covered in the discussion ... it would need to be a single player with both clips showing ... the script may help , but depending on the streams involved , you may need a powerful system to keep the playback frame accurate .

However , none of the relevant info about either clip would be available ... the individual details .

Alpha masks are simple to create with the gimp ... positioning them accurately would take time .

Two clips + script + vdub gets close ... but going backwards can cause problems .

[manono]

Yeah, AviSynth can do almost all of what you want, except for maybe overlaying the statistics you want (although it does have a number of statistics commands). You can play the script in a player, such as Media Player Classic, which can pause and advance a frame at a time. There will be a bit of a learning curve, though:

http://avisynth.org/mediawiki/Main_Page

[jagabo]

An AVS script which also shows the differences between the two and amplified differences:

# If Videos start at different frames 
frameadjust=0 

# Videos to compare: (v1 is original, v2 is encoded or whatever) 

v1 = AviSource("_v1.avi").trim(frameadjust,0)
v2 = AviSource("_v2.avi")
sub = v1.subtract(v2) 
substrong = sub.levels(112,1,144,0,255) 

return StackVertical(StackHorizontal(v1.subtitle("original"),v2.subtitle("encoded")),StackHorizontal(sub.subtitle("Difference"),substrong.subtitle("Difference amplified")))