5 Replies Latest reply on Apr 14, 2010 8:59 AM by motonutty

    Minimizing color banding and digital noise in compressed footage

    cowboymustache Level 1

      I am working on an project for a client where the ultimate delivery format is 1080p footage that is compressed enough that it can be played back on a laptop. It also needs to be delivered as a windows media file and a .mov. The source footage and comps I made in AE look great, no banding over color gradients, no noise in the footage,etc. I used H.264 and the Windows Media Encoder at very high data rates, pretty much as far as I could push it and still get the file to play back smoothly. The majority of the footage looks great (Windows Media codecs look amazingly sharp for all you Apple nerds, including myself, out there) but any shot that has a gradiation in color or a bloom from a light (some AE lights, some real life footage) have slight but noticable banding in the color and also digital noise over these same areas. To make matters worse, the clips are being shown on large LED monitors (1/2 inch to 2 inch spaceing between the LED's, the type of screen used in a stadium) which seems to make the banding more noticeable (makes sense, there are a lot less pixels there to display the image). Does anyone have any tips for minimzing this? I was not working in 32 bit color for this project because there were lots of layers and large plates I was working with, but like I said, the banding seems to be introduced when I compress the footage. The client is using Windows Media Player and Quicktime to playback these files. I optimized the settings of their video card, which helped, but the issue is still there. Any tips would awesome. Thanks folks.

        • 1. Re: Minimizing color banding and digital noise in compressed footage
          Mylenium Most Valuable Participant

          Normal behavior and not much you can do about it. This happens due to color space conversion and quantisation during compression. You may try to add some subtle noise to enforce more finer compression blocks being produced at the cost of compression efficiency, but that's pretty much it. For your LED screen, simply add a Gamma correction to compensate for the perceived increase in contrast.

           

          Mylenium

          • 2. Re: Minimizing color banding and digital noise in compressed footage
            345712473471 Level 1

            Tell your client that if he wants his video engineered correctly then he needs to hire a video engineer. Or you can be a jack of all trades, whatever.

            • 3. Re: Minimizing color banding and digital noise in compressed footage
              cowboymustache Level 1

              How do Blue Ray compressions codecs compare in this type of case? I realize that they are pretty compressed too, haven't tried them out yet myself. The client actually manufactures the LED screens, most of their customers use the HDMI input on the screens conversion box to play back live footage of concerts, events, etc. They had me make a montage of text/images/etc. to show off the screens but they are trying to play back my HD files on an outdated windows machine....Fun, Fun, Fun. Maybe I'll advise them to pick up a RAID drive or buy a better computer.....I at least have to wear as many hats as I can to be able to pass the buck and explain to them why it's not my fault. ha ha..

              • 4. Re: Minimizing color banding and digital noise in compressed footage
                Mylenium Most Valuable Participant

                In strict technical terms, they are more or less equal. Even BD H.264 uses the same methods as plain H.264, it just uses otehr matrices/ profiles for optimization. Generally, this will be hard to compare. Unless you can run the same clip via BD and natively played back from a computer, this may go nowhere. The thing here is, that BD players do Gamma correction and all that and also can negotiate color settings via HDMI, so what you see via the player must not necessarily look the same when extracting the files and viewing them on a PC. The biggest difference probably is, that a lot of BD movies use 24p and quite high data rates, which of course by itself reduces chances for artifacts. anyway, you could probably spend hours reseraching this including quite detailed tests from video magazines, but that may not get you any closer to a solution. what instead might be a better strategy is to work on the coloring and "texture" of your piece. You may be able to considerably improve the results by adding slight adjustments here and there, especially reducing the contrast of neighboring colors where it is too harsh. this is similar to the old broadcast safe thing, it just doesn't need to be as excessive. Slightly reduce the luminance of bright elements and perhaps take down the saturation a notch and it may already be a lot better.

                 

                Mylenium

                • 5. Re: Minimizing color banding and digital noise in compressed footage
                  motonutty

                  I run into this issue all the time - what helps (but not eliminates the issue completely) is this workaround: 1) using a very high-end compression engine (like "Compressor"), and B) adding an adjustment layer over background elements that will create banding (gradients, blurs, feathered edges, etc) that adds a small amount of noise. Just be sure to have your type-layers and anything that is crisp and clear reside on top of that. It'll not do away with the banding completely, but helps a good deal to hide it.