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What is going on with the "blip"
  • 31 Replies sorted by
  • bdegaziobdegazio
    The blip at the beginning doesn't bother me at all, you just cut it off in post. Others may have different priorities and working methods though.

    When I worked in 35mm features the beginning second or so and about the same length at the END of most takes were unusable due to flash frames or poor sound sync as the camera got up to speed. And with IMAX it takes about 7-10 seconds for the film speed to stabilize when the camera starts rolling, so the first part of every shot has terrible varying frame rate and exposure. The film stock and processing that gets wasted because of that costs a fortune when added up over a complete film shoot!

    I agree with Chris - fixing the blip seems to me to be a low priority detail. I'd much rather see 1080p60 (or even 1080p120 !)

  • cbrandincbrandin
    Vitaliy,

    That seems like such a good and simple idea. AVC codecs that do 2 passes do 2 full passes (i.e. they take twice as long). One could pre-process every frame, come to think of it, doing the bare minimum processing to determine detail, dunamic range, etc... roughly and probably improve encoding considerably. For example, just doing FFTs in several small sampled regions in a frame could be very useful before actually encoding a frame. You wouldn't even have to go so far as MJPEG encoding.

    Chris
  • cbrandincbrandin
    @bdegazio

    Yeah, I posted in an earlier thread that when it comes to start-up, the GH2 actually outperforms an IMAX camera. Actually, I left out the part about "when it comes to" (saying instead "in some ways") and just posted that the GH2 outperforms the IMAX - but nobody fell for it:)

    Chris
  • LPowellLPowell
    On the GH1, the AVCHD encoder had a tendency to over-estimate the bitrate needed for the second I-frame. This was the culprit that caused patches to fail immediately after the start of recording. To guard against this hazard, I attempted to suppress the initial bitrate in order to keep the second I-frame under control. While it wasn't as noticeable on the GH1 as in the GH2, the image quality of the first GOP in the AVCHD stream has always been suboptimal.
  • cbrandincbrandin
    @LPowell

    Have you looked at StreamEye Slim? It's only $50. I've been using it to investigate the quantization stuff. It's cheap enough and it can tell you all kinds of things about the coding process - quantizations, motion vectors, macroblocks - everything. Aside from having pop-ups that will tell you everything about a particular macroblock, it also has an info box that will tell you what the min and max Q values are for a frame, etc... It has a couple of quirks, though. It doesn't recognize Panasonic file extensions (you have to select "All"), and the tool-tips (pop-ups) for each macroblock don't show up unless the video display window is selected (when you advance a frame, for example, it deselects the video window and the tool tips don't work until you click on the video window).

    Chris
  • LPowellLPowell
    @cbrandin Thanks for the tip on Streameye Slim's price. I'll download it tonight.
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