Slightly OT: Compression Artifacts in DVCPRO HD Footage

GroovyBrent

GroovyBrent

Member
Hey All -

I asked this question over at Creative COW and want to try and verify/refute the answers I got over there (in other words, I didn't like the answer I got from Mom, so I'm running to Dad to try and get a different answer).

On one of our projects, we're noticing some pretty bad artifacts in the lower thirds once the graphic is rendered. These artifacts don't show up in exported still frames, and they do not show up when the graphic is unrendered.

The graphic is built by bringing in a blue abstract QuickTime movie encoded in the Animation CODEC with Final Cut Pro text on top of that.

It's a little hard to see what is going on because the only way I was able to show the problem was to actually take a photo with my digital camera of the monitor.

We're using FCP 5.0.4, QT7, AJA Kona II and a Panasonic 50" monitor.

Am I looking at expected artifacts from DVCPRO HD (I hope not!), or is there something else going on here?

it is a little hard to see in these thumbnails, but the problem is most noticeable in the space between the "E" and "R" in the first image. The second image shows the "clean" image as it looks before rendering (with no artifacts).

artifacts_thm.jpg


no_artifacts_thm.jpg


Full resolution images are available at:

Full size image with artifacts
Full size image without artifacts

Is this expected DVCPROHD behavior? Or is there something else going on here?
 
Did you shoot with a P2 camera?

Did you shoot with a P2 camera?

If you shot with an P2 camera, see Apple's comment...

Final Cut Pro 5.1.1 resolves an issue in using the Import Panasonic P2 feature with
720p/24PN footage resulting in duplicate frames in rendered sequences.
Click to expand...

So you may really need to upgrade to 5.1.1.

If you shot with the Varicam, then it is definitely odd to be getting that result. However, it could have something to do with the Animation codec. Have you tried another codec to test that? Perhaps there's some issue with the render engine and the Animation codec...

cheers.
 
We have 5.1.1 on order... expecting it to arrive this week. So we'll test that as a possibility when it arrives (we shot with the HVX200).

We haven't had an opportunity to import the graphic in another CODEC (we need the alpha channel as the graphic has some partial transparancy).

I also wondered if it might have something to do with using FCP's built-in text generator, which has long history of being yucky (that's the technical term), but text from photoshop showed the same artifacts.
 
Will have to wait on 5.1.1...

Will have to wait on 5.1.1...

Your best and truest test I guess will be when you get 5.1.1 and can re-import some footage with that and test with that. Because there's been a lot of "5.0.4 + P2 = unhappy" documented around the net.

Also, is there no way for you to perhaps do the rendering in a different software package? Something dealing with transparency sounds like something for After Effects or perhaps even Motion, but not natively in FCP. That might at least be something to try while you have to wait on the arrival of 5.1.1.

cheers.
 
Hi, Brent,
It looks suspiciuosly like a DVCproHD codec artifact... Try going to Sequence -> Settings -> Video Processing and check "Render all in high precision YUV" . Second, try setting Motion Filtering Quality to Best...
I'm also in San Diego and would love to come out and check out your setup ;-)

best,
-Greg
 
Looks like normal DCT compression artifacts to me.
Remember that DVCPRO HD is 6.7:1 compression, which is more than DV....
 
Barry_Green said:
Looks like every rendered title in DV I've ever done...
Click to expand...

You are absolutely right. It looks like DV. That's why I'm a little confused and concerned. I know DVCPRO HD is "more compressed" than DV, but... well... I'm just really surprised if this is normal.
 
gregpen said:
Hi, Brent,
It looks suspiciuosly like a DVCproHD codec artifact... Try going to Sequence -> Settings -> Video Processing and check "Render all in high precision YUV" . Second, try setting Motion Filtering Quality to Best...
Click to expand...

I'll check my settings and see if that helps. Thanks for the suggestion.

I'll PM you to set up a time for you to swing by!
 
VaricamLife said:
Also, is there no way for you to perhaps do the rendering in a different software package? Something dealing with transparency sounds like something for After Effects or perhaps even Motion, but not natively in FCP. That might at least be something to try while you have to wait on the arrival of 5.1.1.
Click to expand...

These are lower thirds, and I hate to have to switch programs just to change someone's name or title. But maybe I'll try that with all the same files. If I get BETTER results in After Effects than I do in FCP using identical media, then I have a clue that the problem lies (at least partially) in FCP and not inherently in the DVCPRO CODEC.
 
Anders Holck said:
Looks like normal DCT compression artifacts to me.
Remember that DVCPRO HD is 6.7:1 compression, which is more than DV....
Click to expand...
Yea... I know... but... [whine] Isn't this supposed to be BETTER than DV25?[/whine]
 
No, in DVCPRO HD the frame is larger and color resolution is 2 x better (4:2:2), but the compression algorithm is the same as DV, so you will experience the same mosquito noise artifacts, which is visible in all DCT codecs.

DVCPRO 50 is much better as the compression is lower but it is also the same algorithm.
 
what did you build the graphic in? Motion, AE etc.
Avoid FCP text. That could be your problem.
I usually do uncompressed CG, then import into FCP, then render in whatever codec.
Usually artifacts are minimal.
 
The graphic was built in After Effects and rendered out using the Animation CODEC (because I need the alpha channel).

I kind of hoped that FCP text would be the problem, but I saw similiar results with Photoshop text.

I'm going to play with some other files and see what I need to do to achieve better results.

Thanks so much for the reply!
 
I edit my DVCProHD programs in a DVCProHD Timeline, then, once picture is locked, drop that timeline into an uncompressed timeline and THEN do the graphics...it turns out MUCH better that way.
 
This is 100% a DVCproHD codec issue. For broadcast stuff, I usually do an uncompressed online. A compromise could be copying over to an uncompressed sequence before adding your titles/graphics. As much as people like to diss HDV and talk 4:2:2, etc. DVCproHD is not a great codec to edit in (HDV is worse to edit in), especially if you have lots of CC, effects or graphics. I always say it is acceptable, but not optimal....


ash =o)
 
AshG said:
This is 100% a DVCproHD codec issue. For broadcast stuff, I usually do an uncompressed online. A compromise could be copying over to an uncompressed sequence before adding your titles/graphics. As much as people like to diss HDV and talk 4:2:2, etc. DVCproHD is not a great codec to edit in (HDV is worse to edit in), especially if you have lots of CC, effects or graphics. I always say it is acceptable, but not optimal....


ash =o)
Click to expand...


Absolutely. if you are working with a BlackMagic Design or AJA card, you can alter your sequence settings to use the Apple Uncompressed 10 bit codec and then render from there. It is a much cleaner way to do it, and your board will support realtime output to a video monitor.
 
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