Auto Decimate

Original topic: http://speeddemosarchive.com/forum/index.php/topic,10578.0.html

So I revisited an AviSynth filter called Dup by Neuron2. It analyzes the video, looks for duplicate frames and has the ability to create a log file which can be parsed to determine if a video is likely F1, 2, or 3. The filter is not 100% accurate - such was my expectation the last time I visited this and subsequently became discouraged and gave up - but I don't think it needs to be.

• Download Dup (2.30) and extract to AviSynth plugins directory
• Created two text files: dupcount.bat and RunNullVideoPass.vcf. Modify path to vdub.exe cli as needed.

RunNullVideoPass.vcf

VirtualDub.Open(VirtualDub.params[0]);
VirtualDub.RunNullVideoPass();

dupcount.bat

@echo off
SETLOCAL ENABLEDELAYEDEXPANSION

SET vdubdir=C:\Program Files\VirtualDub-1.9.5
SET duplog=%~dp1dup.txt
SET unique=0
SET duplicate=0

"%vdubdir%\vdub.exe" /i RunNullVideoPass.vcf %1

FOR /F "skip=2 tokens=3,6 delims=: " %%G IN ('type "%duplog%"') DO (
	IF "%%G"=="%%H" (
		IF !dupseq! LEQ 2 (
			SET /A unique= !unique! + 1
			SET /A duplicate= !duplicate! + !dupseq!
		)
		SET dupseq=0
	) ELSE (
		SET /A dupseq=!dupseq! + 1
	)
)

SET /A total = %unique% + %duplicate%
SET /A uniquepercent = (%unique% * 100) / %total%
ECHO.
ECHO Frames counted: %total%
ECHO Unique: %unique%
ECHO Percentage: %uniquepercent%
ECHO.
PAUSE

• Add following AviSynth code after separatefields

Dup(threshold=20, blksize=16, debug=true, log="dup.txt")

• Open a command prompt: dupcount.bat avisynthscript.avs

• Result of F1 video, short sample:

http://img5.imageshack.us/img5/866/dup.png

Obviously not 100%, but if it's above 50%.... Can play with the thresholds after doing more testing... (nate? :) )

Any thoughts?

Extra links: [1]

edit- Menus will affect results from the dup filter... The above screenshot was a sample of sonic 2 which had a little bit of intro. Take out the intro and the percentage rises to 97 percent. May be possible to add a bit more logic to the batch file, detecting when there's a string of duplicates higher than say.. 3-5 and ignoring them.

edit- Updated batch code with above idea, getting surprisingly accurate results: 95/49/33% on F1/F2/F3. Basically the code ignores sequences of DDDU or DDDDDDDDDU, etc. It will count only sequences of UU, DU, DDU.

http://img188.imageshack.us/img188/5900/50520378.png http://img188.imageshack.us/img188/4189/40394732.png http://img181.imageshack.us/img181/2788/60997384.png