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Old October 30th, 2007, 05:51 PM   #1
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High Qaulity Vs. Low in HD Link

My comp works much better with low quality setting in HD Link. My question is is there any quality difference in the end spitting out to HDV tape between high quality and low quality captures?
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Old October 30th, 2007, 06:15 PM   #2
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Yes. I have tried different levels, and it obviously gets better as you go up the line. I don't know extact tech details, but you're essentially talking bit rates, I am guessing.
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Old October 30th, 2007, 06:41 PM   #3
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thanks...Ill keep it in High mode
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Old October 30th, 2007, 06:56 PM   #4
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Lower bit rates decode easier (faster) so CPU performance is better. But we don't recommend Low for online post work. Low is included in case somebody has a special need for it - similar for FilmScan 2 at the Highest end. For most post work we recommend either High or FilmScan.
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Old October 31st, 2007, 12:32 PM   #5
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Another option for you if you don't mind working off the lower-quality while doing your effects and color corrections, etc:

Capture your m2t's.
Convert them to low quality cineform
Perform your edit.
Delete your Cineform files
Reconvert the m2ts to High or FS Cineform files, *replacing the original files with exactly the same names*
Open Premiere, and let it be 'tricked' into thinking these are the same files
Perform final render out.


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Old October 31st, 2007, 01:23 PM   #6
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I was thinking about doing this actually. Because my PC has trouble working with files at the High Quality setting, so I would prefer to use the Medium Quality setting.

In the end though, I do want the better quality files being rendered out to Blu-Ray. So I'm gonna try your suggestion in re-transcoding the files and using the same filenames to trick Premiere Pro. I assume the timecode and frames will be exactly the same.

Also, is this a good step to take even if you're not ascending to a higher quality setting. Say, if you'll be doing a lot of color correcting, or playing around a bunch in Magic Bullet Looks or something? I assume this kind of stuff gives quite the generation loss, even if you remove most of the effects. Not sure how noticeable the degradation would be though, probably not very (and probably not at all to my eye).
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Old October 31st, 2007, 01:33 PM   #7
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Once you remove effects, it reverts back to the source, no generation loss there.

Also, if you take my workflow suggestion, make sure to doublecheck your color corrections, etc, to make sure they look the same/how you want them once replaced.

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Old October 31st, 2007, 02:45 PM   #8
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I've actually taken this principle one step forwards and would urge caution.

I captured my footage as per normal, then used VirtualDub to create very low quality 640x360 XviD AVI files which I sent via FTP across a continent or two to my editor.

He then used VirtualDub to resize back to HD and encode into CFHD where he did the rough editing in Aspect HD, before emailing me the Premiere Pro 2.0 project. I then loaded it up and pointed it to the original captures with a view to exporting final vids.

In short it didn't work, the edit points were off - I suspect because DirectShow CineForm captures use a two-frame picture group whereas files generated by the CineForm VFW codec use one. I had to fix the problem by putting the original captures through VirtualDub, encoding them into the CFHD VFW codec to make the Premiere projects work.

Although not optimal this was fine because the target deliverable asset was a lossy WMV any way. Plus of course, CineForm is great at multigeneration video as we all know.

However, despite the problems I had, I think that if both of your sets of footage are derived via HDLink you should be OK. But I'd put together a very simple edit using a single clip first, then try replacing the footage to check that it works.
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Old October 31st, 2007, 04:12 PM   #9
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Ouch!

Thanks for the forewarning, that does sound like a painful situation. Appreciate the warning that it might not go as smoothly in some other workflows!


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Old October 31st, 2007, 04:25 PM   #10
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I suppose you could do this same thing, editing first in NTSC DV output using the Cineform capture conversion process, then substituting for a High definition file at the end. I will try that in Vegas in a day or to see what out come I get.
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Old November 1st, 2007, 02:06 AM   #11
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I think it would be best to stick with the same project settings - ie 1080p/24 CineForm or whatever.

As I said, chances are that if your 'real' files and proxy files were both derived from HDLink you should be fine. As is the norm with Digital Foundry, we just liked to make the whole process more complicated ;)

Certainly the whole notion of capturing on location overseas, FTPing low res proxies to the editor who then sent back the Premiere Pro projects worked fine for me... eventually :) It also opens up some pretty astonishing opportunities with regards distributed editing - one man on site capturing, several people anywhere in the world producing the Premiere Pro projects.

I think my advice would be just to do some simple tests firsts. One clip, a whole bunch of edits, and one export using the proxies and one export using the real footage. Drag and drop both into VirtualDub and check the edit points on a frame by frame, side by side basis.
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