Forum Replies Created

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  • Jeff Brown

    May 25, 2008 at 1:57 pm in reply to: can someone explain this, adjusting levels

    The problem is that when you convert video black (7.5 IRE) to computer black it actually translates as 16 RGB, not 0 RGB where it should be. Likewise, video white (100 IRE) translates to 235 RGB, not 255. So what you wind up with is less contrast, and blacks & whites that aren’t true.

    This is a very misleading statement, although not downright wrong. The 0 vs. 16 issue is hardware and system dependent. If you capture DV video via firewire, zero is zero and white is white; there is no “conversion.” If you capture via certain capture cards, 7.5 IRE is translated to zero. It depends on what is doing the conversion to digital. There are a multitude of combinations of translation to and from the digital domain, which can result in various combinations of analog and digital levels. Even certain software can introduce level changes (Avid QuickTime, e.g.). An erroneous statement like that mars an otherwise instructive page.
    And — this only applies to NTSC North American standard video. NTSC-J, PAL, and HD do not use setup (7.5 IRE black levels).

    -jeff

  • Jeff Brown

    May 23, 2008 at 3:02 pm in reply to: low audio levels when exporting

    Ah – that’s different.
    Can’t help much other than to suggest checking for unintended attenuation, like having the Master fader pulled down in the audio mixer panel in Premiere.
    You might also want to take a look at the exported WAV file in Premiere or Soundbooth to check the levels.

    -jeff

  • Jeff Brown

    May 20, 2008 at 3:01 pm in reply to: low audio levels when exporting

    Are you playing back DVD-video files in Windows Media Player? I think that is a known “issue” — I’d call it a bug — in Media Player. Compare a Hollywood DVD, you’ll find the same low output in Media Player.
    That’s been my experience, anyway.

    -jeff

  • Jeff Brown

    May 20, 2008 at 2:54 pm in reply to: AVI / QT Codex for Xena

    I have a couple clients using FCP; the real annoyance has been that FCP doesn’t directly support file sequences (stupid!)– has that changed recently? Many Mac users seem to thing QuickTime is the be-all and end-all for footage; they don’t grok the benefits of file sequences.

    -jeff

  • Jeff Brown

    May 19, 2008 at 3:38 pm in reply to: Vertical Black Bars on Capture

    If you were seeing thin black bars (about 10 pixels wide, maybe?), you are seeing what analog video looks like. It is not full-raster wide compared to DV. That’s just the way BetaCam is. (and VHS, for that matter). If you are outputting for the web, the best solution is to crop when you do the compression. If you are outputting for DVD or broadcast, don’t do anything– TVs are made to overscan the image slightly.
    In my biased opinion, it is better not to scale analog video for your edit. It’s low-res enough to begin with.

    -jeff

  • Jeff Brown

    May 19, 2008 at 3:27 pm in reply to: AVI / QT Codex for Xena

    Carl,
    The abbreviations I believe are:
    BE : Big Endian
    LE : Little Endian
    B2T: Bottom To Top
    T2B: Top To Bottom

    These are all variations in the way the frame data is written to the file; the order of the data within the file. It would all be the same data in the end. An analogy: each frame is a book; you can choose to order the pages front-to-back or back-to-front, or to read left-to-right or right-to-left. The story would be the same.
    In the end, it should not matter other than your external software (FCP, Premiere, After Effects, etc.) probably renders one “flavor” of DPX, one “flavor” of TGA, and so on, so that would be a good one to standardize on.

    -jeff

  • Jeff Brown

    May 14, 2008 at 12:39 pm in reply to: Batch Capture Digi Beta Problems

    Butch,
    Although I don’t have experience with digiBeta decks, I have used RS422 control with my BetaSP (PVW2900) successfully; WinXP, AJA 2K, Premiere CS3 (and CS2). I pass this along as it might point to some weirdness on the Sony side of things, as Ramona mentioned.
    I do need to double-check the TC captured, as recent projects haven’t required me to notice a 1-frame difference. I’ll try to confirm my results for you.

    -jeff

  • Jeff Brown

    May 13, 2008 at 2:54 pm in reply to: Zooming in on footage

    [David May] “the HD into SD and then back into HD,”

    That won’t get you anything. Jon was just suggesting HD into an SD-output project could help a bit.
    Zooming in on footage, even on film, is best avoided: hence the usefulness of storyboards! Chalk it up to a lesson learned…

    -jeff

  • [tyler smith] “i thought the green line on the right side of the waveform was represented peaks of blacks and whites”

    Hoo boy, do i feel stoopid. You’re right. I’m used to hardware ‘scopes; so I made a wrong assumption. But in the image of your overall waveform, I don’t really see anything below zero. Obviously, Premiere sees something there, and I’m not sure what.

    [tyler smith] “Should i also be stretching the blacks and whites as close to the 0 and 100 IRE level as closely as possible?”

    In my opinion –and take it for what it’s worth– see above ;>), you should not be stretching the levels “blindly”. Scopes are good to make sure the technical aspects of the video are correct, but for visual decisions, you really need a calibrated monitor to judge the image. Use ‘scopes to check your decisions, but trust your eyes too.

    -jeff

  • Jeff Brown

    May 9, 2008 at 2:27 pm in reply to: Zooming in on footage

    [David May] “my quality drops something shocking.”
    That’s video for ya’.
    Best case: standard def DV (NTSC) video is 720×480; you just don’t have many pixels to work with. And the image from all but very very expensive cameras is going to be pretty soft to start with. Rule of thumb is to not do more than about 120% enlargement. Beyond that it gets ugly fast, as you’ve discovered.

    -jeff

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