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ramiro
12-31-2003, 05:17 PM
hi,
Im working on a project shot in DV PAL, edited in AvidXpressDV. we have a lot of effect shots, either 3d or 2d. the composition and 2d will be done with fusion, so a lot of importing-exporting will take place between the two programs. since theyrunin different machines i cant use quick time reference and imtrying tofind the best(lossless?) way to do it. so far, exporting in dv sequence(.dv filles) from avid without using its codec and quick time uncompressed from fusion produced the best results. i need toknow if this is the best way or not.
thanks

ramiro
01-11-2004, 02:55 PM
anyone?

Jayk2k
01-12-2004, 04:04 PM
I don't have a lot of experience with DV formats other than to know they can be a pain to work with in VFX.

My suggestion to be certain would be to save everything as Targa files, and then move them between apps that way. Otherwise, you may end up with double compression, or worse.

ramiro
01-13-2004, 12:28 AM
By saving them to targa or any kind of frame format, means converting them from fields to frames, thus from the very beginning i loose resolution. it has to be a field based file. nany other ideas?

Jayk2k
01-13-2004, 04:18 AM
Any frame based format will still maintain any field information in the footage. If the field information is being lost, it's most likely due to the application you are using to generate the frames. It's up to the application to read the information in the full frame as fields.

If done in DFX+ or Digital Fusion, all you need to do is set the saver or loader to fields.

ramiro
01-13-2004, 11:01 PM
I dont quite understand what you mean. please correct me if im wrong, but any field-based footage when converted to frames looses information,plus its a non reversible operation. ive done some simple conversions in avid(exported frames), imported the footage to digital fusion, played a bit, saved it, rerimported it in avid(it automatically converts it to fields) and there was difference in the picture. since illnever be sure whether therell be any loss in this method, ill have to stick to the field based system,its a pain in the ass, i wish i could work with frames,especially roto work is extremely frustrating. Thats why imasking whether exporting to dv format without codec use is suitable. any avid users around?

Jayk2k
01-13-2004, 11:34 PM
When converting to PROGRESSIVE frames from fields you will be interpolating 1/2 of your height information, and losing 1/2 of your TEMPORAL resolution. Just plain bad.

Generally if it was shot on PROGRESSIVE first, you actually have more frame resolution than a fielded frame. A full 720x486 image.

How a fielded frame gets it's extra temporal resolution is by taking half of a vertical frame at time X, and then a second half vertical frame at time X.5. Thus you are really only ever working with an image that is 720x243. (in NTSC land)

I can't recall how an Avid exports things, but generally my luck with them has been dependant on the operator's knowledge.

There should be no conversion done as the Avid exports frames. No interpolation, no scaling, nothing. A frame is just 2 fields.

Then inside of Fusion, you specify that it is fielded footage, and Fusion will advance a half frame at a time alternating between odd and even fields. No resolution lost.

Then on the import of the footage back INTO the Avid, the same process should work, in that it will pull in single frames, each of which has two fields in it.

I know I have done this numerous times, and generally it comes down to figuring out the quirks of each system. One may have reversed field dominance, or some other bizarre quality.

All I can suggest is to test a number of output options, and name each one accurately until you find what works.

marchermann
01-23-2004, 01:45 AM
If you have a fast moving object in your dv footage you can already check the exported frames and easily see whether you still have the alternating lines of the two fields. If you don't then then you lost one field during the export already and the solution lies within XpressDV.

If the frames contain both fields, in DF you can check always check whether a tool treats the image sequence as fields or frames by going over it with the mouse and see whether the status line says "field 0" (or 1) or not.

When working with fields in DF don't worry about the display looking blocky. That's because it's ony one field at a time, stretched to full resolution. Your saver will finally combine the fields again.

As Jay2k also pointed out you have to be sure about the field dominance or order. Will the even lines be displayed first or the odd lines.

Just experiment a little with footage that has movement in it so you can clearly see the fields.

Marc

ramiro
02-03-2004, 10:49 PM
Ive been conducting numerous tests the last 2 weeks, also contacted the lab where well be doing the transfer to film. converting the field-based 720x568 footage to 1024x568 frames(not field based) there was a loss in sharpness(i was told from the lab that its normal, my only problem is that the loss was somewhat big, the picture is not exactly out of focus, but i wonder how sharp it would look in the big screen). doing a plain export of either native dv or quicktime reference file i got the best results possible, but as you suggested, working with fields is not the easiest thing in the world. if i export field based frame sequences, the problem remains, i still have to work with fields, which in DF produces a slight vertical displacement from field to field. since my work has to do with masks or painting away stuff mainly, its a real hassle.

ramiro
02-13-2004, 12:12 AM
please guys, i really need some feedback on this subject, i ve been trying really hard to find info, i have to get started with some shots, but if i dont know how to do the exporting/importing in the best possible way, im stuck.
does anyone at least know of a good 2d forum i can post this?
thanks

Jayk2k
02-13-2004, 02:02 AM
If you want my advice, here's what you do..

1) import the footage.
2) Add a fields tool, and set it to strip and interpolate filed 1.
3) Branch from the loader to a seconds field tool, and set to strip and interpolate field 2.
4) Blend the 2 frames back together at 50%.

This gives you a bit of motion blur, and will simulate a full frame pretty well. It's not great, but it's probably better than you're working with now.

this may cause issues if you are having to paint and do a lot of rig removal though, because the subject matter may not be as sharp because of the blending of fields.

Also, when resizing in fusion, i quite often find the Catmul Rom filter to give the best results.

Wizdoc
04-03-2004, 12:00 PM
I use uncompressed TIFFs when moving material back and forth in the pipeline (3D Max, DF, Premiere). I deal with progressive material, so fields haven't been a problem for me.

Have you tried a lossless video codec? Here's one, it's free:

http://www.alparysoft.com/prod/compression/index.php

ramiro
04-04-2004, 07:30 PM
my actual problem is not how to transfer my footage, but how to work with frigging fields, i hate this vertical displacement when i advance from field to field. if i apply a mask, i have to move it up and down all the time...
thanks for the codec though

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