3 Replies Latest reply on May 3, 2008 11:11 AM by Mylenium

    Black Levels in MPEG-2 files

      This is a problem I've been trying to solve for months. Whenever I encode an MPEG-2 file, regardless of what program I'm using (After Effects CS3, Sorensen Squeeze, among others), the black levels are milky grey, not black. This is a short film originally shot on 35mm; it is now a 10-bit DPX log sequence. The footage looks great in After Effects - black levels are all correct. When I export a QuickTime file from it, it looks good. But if I encode an MPEG-2 file, either directly from After Effects or using a different encoder, the blacks turn milky grey and the contrast/gamma in general just look a little off.

      Any insight anyone has into this problem would be greatly appreciated.

      Win XP/Intel Quad Core/4GB Ram
        • 1. Re: Black Levels in MPEG-2 files
          Mylenium Most Valuable Participant
          MPEG-II (DVD) uses a chroma subsampling like several other broadcast formats and, surprise, surprise, it also use the limited luma range. So the behavior is perfectly normal (as it's intedned to be viewed on TVs, obviously). Unless you pre-adjust your stuff to fall within the specs while retaining the contrast, it will always look washed out. Only the MPEG-II variations for HD output allow full ranges.

          Mylenium
          • 2. Re: Black Levels in MPEG-2 files
            Level 1
            Thanks for the response. A friend of mine encoded an MPEG-2 file from a very similar set-up as mine and the blacks are very rich, and all the colors are more vibrant. Any ideas of what settings I should be adjusting (and at what part of this process) in order to arrive at richer colors? Is it the actual encoding that's causing it or is the color space I'm working in in After Effects?
            • 3. Re: Black Levels in MPEG-2 files
              Mylenium Most Valuable Participant
              It's a combination of the two, most likely. In general you will want to work in vanilla sRGB or 601/ Rec 709 when preparing content for DVD to be able to predict the colors as they will go on DVD. Other color profiles will use a different Gamma, which ultimately will result in a completely different effective output upon render than the one you may be seeing in your composition based on the workspace profile and log/lin conversion. This is especially critical with outputs via Adobe Media Encoder, image sequences or certain Quicktme flavors, all of which are aware of color profiles and in part allow embedding that info. A short way to bypass some of your issues may be the "preserve RGB" option on the output module color management tab, though it may cause your video to look over-saturated. Ultimately you will probably have to derive a dedicated DVD version of your project or base the actual MPEG-II transcode on a pre-rendered, color managed file. As an last item, make sure to check your monitor's Gamma and review the final output on a real TV and DVD player.

              Mylenium