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Old November 17th, 2010, 03:58 PM   #1
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NeoHD changes clip length?

I converted an hour of 1440 x 1920 HDV - and when the original clip and the cineform converted clip are laid in the timeline on top of each other, the cineform clip is about 8 frames longer after 57 minutes. they are lined up at the start - so cineform is somehow adding 8 frames? at about 30 minutes in, the cineform clip is about 4 frames ahead.

This is for a multi camera shoot - with HDV being mixed with DV - so we noticed the audio echo at the end.

Just want to make sure I didn't do anything wrong when converting.
all clips are drop-frame.

any ideas? If this is the way it is, I can deal with it.

thanks
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Old November 17th, 2010, 04:31 PM   #2
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You should be able to work that out. Use 50% opacity to see it there is frame duplications or skips, then report you findings to support.
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Old November 18th, 2010, 07:42 AM   #3
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In comparing the audio track waveforms - the cineform clip seems to just be getting more spaced out.
at the start of the timeline, the waveforms match up. but if I scan forward a 5 minutes, the cineform waveform has expanded to the right, but not a whole frame's worth. so if I were to extract a frame, the cineform waveform would be a little to the left of the original.

and the actual length of the two clips is exactly the same. it's just the video and audio content that seems to be expanded (?)
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Old November 18th, 2010, 08:54 AM   #4
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Please look again at the video. Video can't expand without duplicating frames, that would be weird. Find the missing or duplicated frames. Check the frame rate and make sure frame blend is off.
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Old November 20th, 2010, 06:14 AM   #5
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This reads rather like the problem Cliff Etzel raised
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Old November 20th, 2010, 10:45 AM   #6
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Not a good example, that customer just did not investigate the issue when we pointed out the video can't just get out of sync without a physical duplication or frame dropping -- he never told us which it was. We can fix the issue once we know what it is. Just layout the video on the original with opacity set at 50%, then you can see if there are error. Other helpful trick, colorize the CineForm green and the source red, then you can easily see if one slips compared to the other. If this can't be done, send both files to support.
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Old November 21st, 2010, 08:27 AM   #7
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"the video can't just get out of sync without a physical duplication or frame dropping. Video can't expand without duplicating frames, that would be weird. Find the missing or duplicated frames."

With the clips sync'd up at the heads, after 5 mintutes the cineform video and audio have "slid" to the right by less than a frame. So I don't think it's caused by dropped frames.

I'd be happy to transfer the avi's of both the original clip and the cineform dub to a dvd and send to you. Just let me know where and to who's attention. thanks.
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Old November 21st, 2010, 12:21 PM   #8
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video sliding by less than one frame, is technically not possible if the clips have the same frame rate. What is half a frame of video? Add don't say a field. :)

Now audio can slip, as half a frame of audio is like 1000 samples. If it is audio only, we need to at the audio decoders on you system. We don't do any audio processing (unless you request a frame rate change) so the source audio decoder would needs to be faulty (unlikely.)

Please recheck what you where see for a video slip, as a frame drop or duplication, is the only reason that can cause a sync slip -- if the frame rates are the same. Again make sure frame blend is off, as if the frame rates are not identical, you are wasting compute power and blurring your video. If you have blend on and the one clip has frame rate 23.98 (wrong) and the other 23.976 (right) the error is less than a frame after 5 minutes. Accurate frame rate is most likely your issue, please check that.

As I don't know which NLE you are using, I can't help you on with the blending and frame rate controls.
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