2 Replies Latest reply on Sep 25, 2008 1:08 PM by (Marco_Grubert)

    Staying broadcast legal across Adobe products

      I am trying to finish a training video that's meant to go on NTSC DVD. As far as I understand the output voltage levels should be between 7.5 and 100 IRE. Not having any diagnostics hardware I am not sure how to verify this.

      Googling tells me that RGB values ought to be between 16 and 235 in order to avoid these extreme signal levels later on. Now here's my question: does the Adobe Media Encoder in AE and/or the one in Premiere do any scaling/clamping ? If I pass in a range of 0-255 will it be clamped? If I pass in 16-235 will that value be used as-is or scaled?

      After importing my DV video in Premiere Pro I noticed that it's mostly legal with very few excursions into superblack. However, after exporting the same clip to a lossless AVI from Premiere the levels were stretched to 0-255. When color correcting this in After Effects should I then scale it down to 16-235 before rendering it to mp2 ?
        • 1. Re: Staying broadcast legal across Adobe products
          Level 1
          The output levels depend on the codec. Now that I've confused you let me try and explain. Some codecs automatically expand the levels then compress them on render so that if you render to the same codec that was used when the footage was captured you have no problem. Other codecs do not.

          A quick test of a short render is in order. Drop your captured footage in a comp, set up some sampling target areas using guidelines to check the rgb levels using the info palette and your mouse cursor. Check the lightest area in your footage and the darkest.

          Now render this footage ( you'll only really need a frame or two) to the same codec you captured with and to a different codec like QT's Animation, drop the renders in the timeline and compare. If the rgb levels changed then you've got to make adjustments, if they didn't you're fine.

          Another thing you can check is an area in your footage where the whites are completely blown out or the blacks are completely black. If either of these check out with values around 235 and 16 then you will need to adjust the values of other elements added to the comp to stay in compliance.

          Having said all that, I usually do my color grading with Color Finesse (which is included in AE and has scopes) or with Magic Bullet (which also has scopes) and I'm not bashful at all about crushing blacks or clipping whites if that's the look I want.
          • 2. Re: Staying broadcast legal across Adobe products
            Level 1
            Thank you Rick. What application do you use for DVD mastering? As far as I can tell the Adobe Media Encoder in Encore/Premiere always scales 0-255 to 16-235, no matter what..

            Also when importing full range YUV footage into AE and exporting it unchanged, Premiere Pro tells me that the extremes got compressed, e.g. my DV footage has 110 IRE luma (according to Premiere) - import that footage in AE, export as DV-AVI and looking at it in Premiere shows a max. 100 IRE with highlights compressed to 90-100.