Jerky Footage

[Harry Clegg]

I recently had some 16mm film transferred to DVCPRO HD in Mexico City and brought back the clips in a hard disk drive. The transfer appeared to go well but when I reviewed the clips every second or so there's a slight jump which becomes very noticeable on movement. Playing back the deinterlaced footage frame by frame I discovered that ever 18-20 frames there were several double frames, ie two frames of video contained just one film frame. Interlaced, the footage runs somewhat more smoothly but with a loss of resolution.

 

The guy who did the transfer claims that the material was captured correctly and keeps sending me clips in different codecs to see if this solves the problem. So far nothing has worked.

 

I haven't had much prior experience with professional telecine. Is this kind of problem common? Does the material need to be transferred once more?

[Paul Bruening]

I'm no authority on the matter. Dominic Case is likely a good bet for this inquiry. It does kinda' smell like a computer, deinterlacing thing. It may be an algorithm or software setting that they are goofing up. Could you run the frames through a macro and automatically chop out the extra frames? That could be easier than go round and round with Mexico.

[Dominic Case]

THis stuff is a minefield. I'm no authority either . . . .who is?!

 

Was the transfer directly from film to DVCPRO-HD ? If so, what is your comment on "de-interlaced" about - there shouldn't be any interlacing involved. OR did it go through another tape format first, in which case what?

[Freya Black]

THis stuff is a minefield. I'm no authority either . . . .who is?!

 

Was the transfer directly from film to DVCPRO-HD ? If so, what is your comment on "de-interlaced" about - there shouldn't be any interlacing involved. OR did it go through another tape format first, in which case what?

 

When you say de-interlacing, do you actually mean pull down?

But you are in Pal world so there would be no pull down, unless in was tranfered at a weird frame rate I guess DVCPRO-HD can do all kinds.

 

*shrug*

 

love

 

Freya

Edited August 23, 2007 by Freya Black

[jan von krogh]

This stuff is a minefield.

indeed.

 

#1 have him send you a single frame sequence.

this opt out the

- codec

- decoding

- interpretation by player/nle

 

#2 if the problem still is there, things are more messy.

- what framerate did you shoot at. any overcrankings?

- what framerate shall the digital format have

[Harry Clegg]

Thanks for your replies. I would have come back to you before but for some reason I don't always receive notifications of postings.

 

The transfer went straight to disc and there was no tape involved.

 

I'm a bit confused about the whole interlaced aspect but I don't think it's crucial to the problem. Final Cut allows me to deinterlace the footage and there's a difference in the way it looks afterwards but the problem persists deinterlaced or not. There shouldn't be any pulldown because I shot at 25fps and since I'm in PAL territory this is the speed at which I want to play back.

 

I'm going to ask him to send me the footage as an image sequence, as suggested, though I assume this will mean uncompressed, ie very large file sizes.

 

Do you think it's worth asking him to put the footage onto a tape?

[jan von krogh]

Do you think it's worth asking him to put the footage onto a tape?

 

Not until you have identified the source of the problem.

dvcpro hd has several pitfalls regarding framerates of its own, so you would add another layer of possible sources for problems.

[Sam Wells]

But what format (codec) was it transferrred to ?

 

You could do a short image sequence to look for problems.

 

(If none, I'd opt for ProRes HQ over DVCProHD when it came to a codec to use for cutting in FCP)

 

There _are_ reasons to transfer from telecines to a tape format (HDCamSR; D5HD) before digitizing to disk although no one wants to hear about it..... I mean I'm in favor of going to disk when if possible, but if the system used can't handle it.....

 

-Sam

[jan von krogh]

You could do a short image sequence to look for problems.

i agree with sam.

 

(If none, I'd opt for ProRes HQ over DVCProHD when it came to a codec to use for cutting in FCP)

i would agree for a videocontainer, however i would recommend to start with a single frame sequence in order to rule out -any- influences of the codec.

dvcprohd can be dangerous - as it is able to contain different framerates, the application used for playback can misinterpret the internal metadata.

 

There _are_ reasons to transfer from telecines to a tape format (HDCamSR; D5HD) before digitizing to disk although no one wants to hear about it..... I mean I'm in favor of going to disk when if possible, but if the system used can't handle it.....

i agree with sam - however, it seems in this particular case, the telecine has been done to disk, if i understand correctly.

therefore, using a tapeexchange would add another layer of possible mistakes, and, indeed, cost.