View Single Post
Old 29th May 2006, 01:50   #1  |  Link
Fudoh
Registered User
 
Join Date: Sep 2003
Posts: 15
Search for dropouts - how to mark or output ?

Hi fellows,

I've started digitizing old VHS tapes recently. As some of them are in very bad condition, there are bad fields (completely green) in the captured videos from time time.

Since I don't have the time to watch the captures in realtime, I've done this script to find the bad fields

clip = AviSource("d:\temp\source.avi").ConvertToYV12
white = AviSource("d:\temp\dropouts\white.avi").ConvertToYV12
black = AviSource("d:\temp\dropouts\black.avi").ConvertToYV12

ConditionalFilter(clip, white, black, "UDifferenceFromPrevious()", ">", "25", true)

white.avi is 2 hours solid white, black.avi is solid black.

The output is completely black with a white frame every time a bad (green) field appears in the source video. With the video output I can use the "find next transition" button in Virtual Dub to find the exact locations of the bad fields easily.

Problem is that it's only approx. 1/2 realtime and I have to note down the frame position and push the scan button again after every bad field. (BUT I can do while doing more important things on the PC anyway...)

So - I wonder - can the ImageWriter or ScriptClip function be combined with this one in any way ?? It would be great if the bad frames from the source.avi could be saved via ImageWriter in some way. Since only a field is bad when a dropout occurs I could still identify the position with a framegrab from this position...

I've seen that ScriptClip can even output the frame's' number, but I cannot figure out how to combine it with the conditionalfilter....

Any ideas or hints would be highly appreciated !!

Thanks,
Fudoh

Last edited by Fudoh; 29th May 2006 at 01:58.
Fudoh is offline   Reply With Quote