Compression Artifacts in DVCPRO HD graphics

[Sean Oneil]

Those look like typical compression artifacts. Unfortunately that graphic doesn’t pass through the compressor very well.

DVCProHD is a pretty lossy codec. It’s great to shoot on, and it’s a great that you can capture the format natively. But you should render your final output as uncompressed for the best results..

Sean

[Walter Biscardi]

I haven’t seen any artifacting like this with the DVCPro HD codec here. It’s incredibly pristine, but I don’t create anything in the Animation codec and then change it over to DVCPro HD. I create and render everything in DVCPro HD.

What I do see is that the background element has a lot of texture in it and it’s blue which is a noisy color anyway. I’m figuring the combination of that fine texture and the color are contributing to the compression you’re seeing.

We’ve created dozens of animations via After Effects rendered in DVCPro HD and thousands of graphics in Photoshop all brought into FCP and I have not seen any compression artifacts like what you’re seeing anywhere yet, other than in regular video.

Walter Biscardi, Jr.
https://www.biscardicreative.com

“I reject your reality and substitute my own!” – Adam Savage, Mythbusters

[Brent Altomare]

Thanks for the responses!

Sean – That’s exactly what I was thinking (that the noise looks like a compression artifact), but the noise I’m seeing in this particular case is as bad as anything I’ve ever seen come out of DV.

Walter – I didn’t think about rendering the graphic out in the DVCPRO HD CODEC. I guess that would make a lot of sense…

One question (that I’m sure I can answer myself once I’m in the office), does DVCPRO HD allow you to render out an alpha channel? That’s why we’ve always done all our our motion graphics renders in the Animation CODEC, for clean renders plus a alpha channel. That’s not a problem with this particular graphic, but it will be for other graphics work we do.

Maybe I’ll make a couple copies of the timeline and change the CODEC on each one… That might give me a clue as to where the problem lies. I’ll also modify the graphic and try a couple different colors.

Any other suggestions or ideas are always welcome!

—
Brent Altomare
Groovy Like a Movie
(877) 3-GROOVY

[Uli Plank]

DVCPro HD will not carry an alpha channel. But what about rendering a separate alpha if needed?

Regards,

Uli

Author of “DVDs gestalten und produzieren”, a book on professional DVD-authoring in German.

[Graeme Nattress]

You’re seeing the pretty typical failings of the DVCproHD codec, which, you must remember, is more compressed and more viscious on your video and graphics than plain old DV. If you’re mastering back out to a DVCproHD deck, nothing is going to save you from the codec, so all you can do is very slightly blur your graphics to take the absolute fine edge off them, and then they’ll compress a lot better.

If you’re mastering out to a less compressed tape format like D5 or HDCAM SR, then by all means, move to an uncompressed timeline and that will fix your graphics until they go to air and get the hell compressed out of them by the digital broadcast, at which point they’ll look bad again.

Graeme

– http://www.nattress.com – Film Effects and Standards Conversion for FCP

[David Fox]

One more example of DVCpro HD compression strangeness. The still is from a 1200a tape output; one frame with artifacts in an otherwise normal output. The problem frames only occurred where there were subtitles (digital heaven plugin). The video in the “dropouts” is from 6 frames earlier in the video, I assume that the error correction circuit was overwhelmed. Any other observations? I don’t have the details from the FCP system that the show was edited on, but it was native DVCpro HD.

David

[Blub06]

To me it looks for all the world like a generational thing. As in, changing something on top or below and rendering using the previous render. I don

[Brent Altomare]

[Blub06] “As in, changing something on top or below and rendering using the previous render.”

We are sure that we’re looking at new renders (turned layers on and off to be sure).

The general concensus seems to be that this is expected behavior from DVCPRO HD. That really surprises (and disappoints) me.

Oh well… just something we’ll have to work around, I guess.

Thanks again to all the COWites for the help! If anyone else has any additional input, it certainly is appreciated.

—
Brent Altomare
Groovy Like a Movie
(877) 3-GROOVY

[Blub06]

I hope this is not too pedantic, but, for me the first rule of filters is, place them on a clip, double click the clip so it loads into the source window, go tot he filters/control tab in the source window and mess around with the filter.

In truth I only use the 8 point garbage matte, its twice the fun!

Conceptually speaking, the filter allows you to see video that is behind the clip you have the filter on. In other words if you have a shot of people in a car on V2 and a shot of the sky on V1 when you use the filter on the car shot it will reveal the sky behind depending on how you shape the matte. Each of the 8 points can be animated over time so you can mess with it if the subjects should move.

If you want to do an ND grad, you can have your clip on V1, put the 8 point garbage matte on it and as you move the 8 points around you will only see the black that is the default color behind all the video. You can adjust the feathering of the edge as well as other things. If you want there to be color in the grad you can lift the video on V1 and put it on V2 and then put some kind of color on V1 by using any of a number of tools and when you do the grad you can get a color feathered to your shot.

Here is a short form instruction to this filter. When you go to the filter tab you will see that there are 8 points in the record monitor (if your play head is on the shot you just put the matte on) and these correspond to the 8 controls in the filter pallet. You click on the plus sights next to any of the 8 control points in the filter pallet and then click on the record monitor (hold down the mouse) and drag it around to some point you like. Go to the filter pallet and manipulate the feather and choke.

Its not fun to do but it gives nice results for many different jobs.

Chris