Fdecimate: threshold for this video ?

[varunb]

Yahoo has just released a HD quicktime teaser of Harry Potter & the Order of the Phoenix at a frame rate of 29.97.

(LINK: http://playlist.yahoo.com/makeplaylist.dll?sid=30434860&sdm=web&pt=rd )

(Just add this link in ur download manager & add .mov extension before or after downloading)

After watching it, i was clearly able to make out that there are duplicate frames in it. My aim is to convert it into avi at a frame rate of 23.976. I used fdecimate & the output was smooth(motion) just as I expected but it jerked or missed a frame at a certain portion of the video. My problem is that i dont know which threshold value shud i use to prevent any frame dropping. I did read the manual of Fdecimate but i didn't understand how to calculate the correct threshold value by looking at the metrics. Can u guyz tell me as to which threshold value shud b used ? I believe its somewhere around 2.0 .

[Guest]

I don't want quicktime installed so I cannot look at your MOV file. If you can trancode it to HUFYUV then I can have a look at it.

What part of this do you not understand?

The process is as follows. Apply the FDecimate() filter with metrics enabled:

FDecimate(metrics=true)

This will display the difference metric for each frame (decimation is not performed when metrics=true). Inspect the metric for the duplicate frames. You need to find a number such that the metric for all the duplicates is below it, while the metric for the new pictures is above it. That number is the threshold that should be set for the 'threshold' parameter. It is usually about 1.0-2.5, but it may differ depending upon how noisy your clip is. It's important to get a good value for this threshold, so do it carefully, inspecting several sections of your clip.

If your clip is telecined, it will be better to use a normal IVTC process in preference to FDecimate().

[mitsubishi]

Wow quicktime is wierd, if I play as is (I have whatever QT bits KLcodec pack installs) it seems a little jerky and the audio seems to get overloaded and stops working after the first 'boom'. If I rename to mp4 it plays perfectly in MPC, disabling internal splitter mpc reports it playing a touch slower and the audio seems to start off out of sync but then is OK. Playing via avs the colour is offset to the right and the audio plays back about half speed...

[varunb]

Inspect the metric for the duplicate frames. You need to find a number such that the metric for all the duplicates is below it, while the metric for the new pictures is above it. That number is the threshold that should be set for the 'threshold' . Thats the thing that i am not able to understand, neuron 2. I have tried this ( i mean set metrics=true & inspect the video) a million times before but how am i suppose to figure out which frames are duplicate.
Can u b a bit more detailed please ?

[Guest]

You determine which frames are really duplicates by stepping through the video and looking at the frames with your eyes.

[varunb]

Ok i did as u said. I set metrics=true & watched the vidoe in vdub. All i noticed is dat initially the metric was somewhere around 2-6 & then it jumped to higher values like 10,20,30 & then came back to values around 2-4,5....so wat does this indicate ? how do i calculate threshold from here ?

[varunb]

hey wait i got it now. There were some frames where there was no motion. lets see if i am right.