Export for color correction questions...

DavidBeier

DavidBeier

Veteran
Ok, I'm currently working on a project in Avid Xpress Pro HD 5.23. I shot it on the DVX100A in 24p. As this is the my last SD project before I move up to HD and there is such little resolution to work with, I'm trying to go ahead and get as much quality as I can.

There are several shots that will require some compositing. Stuff like drawing matts, keying out things, compositing two images, and making some sections of the image in color and other in black and white. For these I've decided to go ahead and use discreet combustion 4.0.

I captured the footage in standard DV25 since the DVX100A is mini-DV anyway so I wouldn't lose quality. I've found most of the clips that need outside work and am trying to export them.

However, I'm wondering how I should export. I've been doing a number of tests with weird results (all using quicktime formats).

If I export them "same as source" or "quicktime refernce" the file looks pretty good when I play it on quicktime but seems to be missing the nice crushed blacks I worked so hard to get. If find this odd as it still looks crushed in the Avid monitor. Also, when I try to import these files into Combustion they look REALLY blurry, far lower resolution than they did in Avid or in Quicktime. Why?

I've tried the DV/DVPro setting with the quality at "best" but that also produced odd results. The blacks still were hazy when I looked at it in quicktime but where perfectly crushed in Combustion and very sharp.

The Avid DV100 codec looked great in quicktime but ran very slowly and didn't show up in Combustion (looked like pure black).

Finally, I tried uncompressed quicktime which, of course, looked fantastic in both Quicktime and Combustion but took almost 1 gig of space for a 30 second clip!

What's the best setting to keep the highest quality? Is there anything I can do in Avid or Combustion to retain quality? How can I ensure the highest quality not only when I send it back from Combustion to Avid but also when I go ahead and want to print my Avid project to tape or export to a DVD?
 
DavidBeier said:
Also, when I try to import these files into Combustion they look REALLY blurry, far lower resolution than they did in Avid or in Quicktime. Why?
Click to expand...

What's your quality setting in Combustion? Preview or Best will give you a pretty crisp picture. The other options are low res options for working with your composites.

On your other questions I don't have specific answers, but here's my Combustion workflow that I've been using for several years now:

Export the clip in Avid as QT Reference (using the Avid DV codec). Import that clip into a Combustion Workspace. Do my compositing, export from Combustion as a Quicktime Movie with the Animation codec (yeah, it's a lot of disc space, but hard drives are cheap). Import back into Avid.

Hope that helps.
 
A QuickTime Reference file is just a QuickTime wrapper into your original video data, so it's as good as you're going to get, i.e. your best export option from Avid to Combustion. Also, it is a handy way to make .mxf files available to Combustion if you're using the HVX200.

When you bring the footage into Combustion, don't forget to make sure the footage is set to "lower field first" if you are doing NTSC. Mine defaults to "no fields".

Also, your best bet for going from Combustion back to Avid is to render out a .png sequence or .tga sequence.

geo.
 
GeoMar said:
don't forget to make sure the footage is set to "lower field first" if you are doing NTSC. Mine defaults to "no fields".
Click to expand...

But if you're using progressive footage then you would want "no fields" selected.
 
krestofre said:
here's my Combustion workflow that I've been using for several years now:

Export the clip in Avid as QT Reference (using the Avid DV codec). Import that clip into a Combustion Workspace. Do my compositing, export from Combustion as a Quicktime Movie with the Animation codec (yeah, it's a lot of disc space, but hard drives are cheap). Import back into Avid.
Click to expand...

Thanks for sharing your workflow,

I'd like to ask a couple of questions though as I think I'm going wrong somewhere, because this is exactly the workflow I wish would work for me but doesn't.

I want a lossless workflow from Avid through Combustion4.

When I import a QT ref file into combustion the image loses a lot of resolution. It isn't a preview problem though. I know it's something C4 is doing because the QTref plays perfect and really sharp in Quicktime's player.

Is there something I'm overlooking?

I'm also not sure I understand resolution. I assumed this: the higher the number of pixels the sharper the image... ie miniDV at 720x576 is as sharp as it will get with miniDV. But if I export a tga sequence from Avid at that res then it isnt as sharp as the QT reference. Surely 720x576 should look exactly the same with any format of export.

and bafflingly, if i manually double up the pixel width and height then the image is sharper... how is this possible??? surely it should just be bigger and but pixelated (ie. every pixel becomes 4 pixels, 2x2)

I'm lost.

If anyone understands this it'd save my mind from imploding.

Alex
 
Try putting a checkmark in the "Use Avid DV codec" box when exporting the QT Ref and then import that one into C4. I seem to remember this being an issue once.

Let me know if that doesn't work.

Regarding resolution, you have the concept down, I think that the results you're seeing in C4 are the result of it not liking the regular QT Ref out of Avid and I think that using the Avid DV codec will help.
 
DV 25 is a compressed 5:1 with 4:1:1 color space format. Every time you render something, the frames get decompressed, effect applied, then compressed back to DV25. Remember that the word"codec" comes from CO-mpression and DEC-ompression.

As far as color space, Avid works internally in SMPTE digital television space -meaning RGB is from 16|16|16 to 235|235|235 (black to white). Film, graphics and computers work from 0-255. When exporting, the QT options have 601 (SMPTE digital 16-235) or RGB (0-255) If you are roundtripping and are planning on broadcast output, you want to keep 601 on export and then import. Does Combustion render in RGB space that is different?

If you export as TGA to TIFF, the DV25 4:1:1 files gets decompressed to a full uncompressed 4:2:2 RGB format (preserving 601 color space if selected as such).

QT reference is the Avid media as is wrapped in a QT container so that other QT aware apps can use the material. There has got to be something within Combustion that is causing you to see this differently. Try the TGA/TIFF route again and see if the quality remains the same after the render.


Michael
 
MichaelP said:
If you export as TGA to TIFF, the DV25 4:1:1 files gets decompressed to a full uncompressed 4:2:2 RGB format (preserving 601 color space if selected as such).
Click to expand...

Wow! I did not know that. *Chris begins rethinking his workflow.*

Thanks Michael.
 
QT ref problems

QT ref problems

Hello,

I am attempting to adopt a similar workflow for use with the HVX200 but am having problems with my QuickTime reference file. The video plays fine in Avid but after exporting- my video is very “choppy” on playback. If I bring up the “Show Movie info” Window in QuickTime, it does show the Avid DV100 codec as being used and the proper frame rate under “Movie FPS” which in this case is 23.97. The “Playing FPS” however reveals that it is only playing back at around an average of 3 frames per second. Audio appears to playback normally. This problem also exists when the footage is imported into Combustion 4.

I also seem to have this problem with just about everything I try and export from Avid. This same issue exists if I export a QuickTime movie using the Avid DNxHD codec REGARDLESS of quality setting or a Windows Media version 9 file. I was however able to export a SD QT movie that played back normally.

I have downloaded the latest (updated June 10) “Avid QuickTime Codec’s” from the Avid website and installed them and am running the latest drivers for my video card. While I am currently playing back from a single IDE hard drive, export to and playback from a 15,000 RPM SCSI disk, with the original media on it, did not resolve the problem.

My system:
Dual P4 2.8 GHz
1GB RAM
ATI video card
Avid Xpress Pro 5.2.4
QuickTime 7.0.4

If anyone has any suggestions as to what might be wrong, I would greatly appreciate them! Thanks.

-trane
 
Sounds like your system isn't powerful enough to play HD footage back in real time. If the FPS reading in QT is accurate, then the export is correct.
 
I tend to doubt it. I was able to export my material as an uncompressed QT movie which plays back fine. Its a huge 14GB file too.

Thanks though :)
 
Playing back uncompressed is quite different (processor wise) than decoding and playing back DVCPro HD. The size of the file doesn't matter either.

But, good luck fixing your problem. :)
 
That’s interesting. Makes sense that decompressing would hit the processors harder. I checked my system resources during playback using Windows Task Manager to see if this was the issue. My processors are not above 25% usage during playback of the affected clips, and my memory usage is even lower.

Krestofre- May I ask what you’re setup looks like? Hardware setup, versions of Avid and QuickTime? This might help me pinpoint my problem.

After updating to QuickTime 7.1 today, playback ceased to be choppy as all I got was black on screen for video. Disabling Direct Draw in QuickTime got rid of the black but brought back the frame rate issue. Then, having read that Avid 5.2.4 added support for QuickTime 7.0.3, I rolled back to that version to no avail. I have also made my media drive a pair of raided 10,000 RPM SCSI drives. This still has not resolved the problem.

Any other suggestions?

Thanks again for the info.

-trane
 
I'm Mac based. I primarily use a G4 Powerbook with 1.5 GB of RAM and my system choaks on 1080 footage. I can barely do 720 in Quicktime.

What kind of video card do you have? You weren't too specific about that in your original post, but everything else on your systems looks like it should be capable.
 
Sorry you've had to wait for a reply for so long. I've been out of town and stuff.

Anyway, Quicktime issue ... I guess anything is possible, but I don't really see how. Maybe you could take your QT file to another computer and see if it plays alright and compare specs. That might helps us troubleshoot.
 
I just ran into this problem as well. I had some footage in which an actor stands up only to reveal the corner of a light outside of the action safe, but still in the frame.

I had applied a color correction to the clip, set my in-out points and sent to After Effects as a quicktime ref.

After I did my After Effects work I brought it back into Avid only to find that the footage I brought it had a different look then the rest of the clip. After talking with a co-worker who has much more experience in Avid he told me to try changing the color space to RGB instead of 601.

Give that a try when exporting.
 
Quicktime+Quicktime Reference = Serious Problems

Quicktime+Quicktime Reference = Serious Problems

Hello all you Quicktimers,
First off, I've diligently searched this forum and the web re the problems described below. No joy.
Second off, this is a Windows system running AMD dual core, 1Gig memory, all SCSI disk.

Now to cases.
First off, I was experiencing the exact same problem as reported by Mr. E. Trane in his 6-10 post. In addition though, I also saw choppy video with playback in Avid. I was using Quicktime 7.0.4.80. I'm sure you all saw the message regarding get the latest Quicktime, fixes a lotta stuff. So I downloaded Quicktime 7.1.0.210. The choppy video in the Avid playback went away - smooth as silk. The choppy video playback of the QT Ref gen'd .mov went from choppy to...pure, solid, forever BLACK. Did the usual things: re-validated download, install, etc. re-installed latest codecs from Avid, yes, use AVID dv codec checked, tried both colorspaces, even went so far as to check/uncheck other settings - no joy.

Has anyone else experienced this problem? (The closest I could find was a white screen which seemed to be fixed with a P2 driver download; this was a laptop situation however.) If so, please let me know what I need to do to fix it. Aplologies if this is a well known problem (sure didn't turn up anything on searches as noted.) I'd like it to be because, with this variey of experience, it seems a little innocuous that AVID would be so dependent on the functioning of a product they don' t make or maintain and yet is a crucial component of the workflow. Much thanks for any and all input/help. /s/ Lost in Black:badputer:
 
I don't think that QT 7.1 is qualified to use with Avid until the next 5.5 release of Xpress Pro. You're probably going to have to roll back your QT install or wait for that 5.5 release (which should come out tomorrow or Friday).
 
Thank you for all the help and suggestions.

As for playback on another computer: the problem seems to follow with the material. My other computer is not nearly as fast or new as the one I edit on, but playback of the files on that computer results in the same problem.

I tried the RGB, vs. 701 thing, but it didn’t resolve the problem. My issue seems to be related to frame rate not color space.
 
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