Monday, April 11, 2011

Scene Change Detection

Simple Scene Detection Using YDifference

Code:
#Script to find scene changes

filename = "e:\scenes.txt"
global blankthreshold=2.0
source = AVISource("e:\fs.avi").convertTOYV12().killaudio()

#Comment out the following lines after blankthreshold has been determined
script = """Subtitle("\nNext/Prev = " + String( YDifferenceToNext(last) \
                    / YDifferenceFromPrevious(last) ), lsp=0)"""
final = ScriptClip(source,script)
return final

#Uncomment the following two lines when doing the actual scene detection
#WriteFileIf(source, filename, "(YDifferenceToNext(last) / \
#           YDifferenceFromPrevious(last)>blankthreshold)", "current_frame+1", append = false)
Scene Detection Using MVTools2
Code:
#Script to find scene changes

Loadplugin("C:\Program Files\AviSynth 2.5\plugins\MVTools\mvtools2.dll")

filename = "e:\scenes.txt"
BlockChangeThresh  = 350 # Default: 350. Increase to reduce number of scenes detected;
                         # Determines whether a block has changed from prev frame.
Num_blocks_changed =  90 # Default: 90. Increase to reduce number of scenes detected;
                         # How many changed blocks (given threshhold) must change to trigger scene change

source=AVISource("e:\fs.avi").killaudio().colorYUV(autogain=true) #add this to increase contrast
source_fields=source.separatefields().selecteven().convertTOYV12(interlaced=false)
source_super = source_fields.MSuper(pel=2, sharp=0)

backward_vec = MAnalyse(source_super,isb = true, delta = 1, blksize=16,search=0)

SceneChange = MSCDetection (source_fields, backward_vec,thSCD1=BlockChangeThresh,thSCD2=Num_blocks_changed)

#Uncomment following line for troubleshooting. It puts the scene change threshold numbers on the screen.
ScriptClip(source_fields,"Subtitle(String(AverageLuma(SceneChange ) ),align=5)")

#This line writes frame numbers to file. These can be imported into Vegas or other editor
#WriteFileIf(source_fields,filename, "(AverageLuma(SceneChange)>30)" , "current_frame+1", flush=false)
Scene Detection Using Depanestimate
Code:
#Script to find scene changes
loadPlugin("c:\Program Files\AviSynth 2.5\plugins\depanestimate.dll")
loadPlugin("c:\Program Files\AviSynth 2.5\plugins\depan.dll")

filename = "e:\scenes.txt"

AVISource("e:\fs.avi").convertTOYV12(interlaced=true).killaudio()
separatefields().selecteven().convertTOYV12(interlaced=false)

#The "trust" parameter is what determines the scene change threshold.
#Lower number results in fewer scenes.
data=DepanScenes( DepanEstimate(trust=2) )

#Uncomment following line to help determine "trust" value.
ScriptClip("Subtitle(String(AverageLuma(data ) ),align=5)")

#WriteFileIf(filename, "(AverageLuma(data)>30)" , "current_frame", flush=false)
Scene Detection Using Remove Dirt
Code:
#Script to find scene changes
filename = "e:\scenes.txt"
Scene_Thresh = 2.0  #Higher number = more scenes

AVISource("e:\fs.avi").ConvertToYV12()

Begin = Blackness(last)
End=Subtitle("END OF SCENE", align=1,size=30)
Motion=Subtitle("GLOBAL MOTION",align=5,size=30)

#ScriptClip("Subtitle(String(SCSelect(Last,BlackFrame) ),align=5)")
scene_change = SCSelect(Last,Begin,End,Motion,Dfactor=Scene_Thresh )

#Remove comment to see scene change numbers
ScriptClip("Subtitle(String(AverageLuma(scene_change ) ),align=5)")

#Uncomment next line to actually create scene change numbers
#WriteFileIf(filename, "AverageLuma(scene_change )<17" , "current_frame", flush=false)

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