Dispute: Jeremy Young - Arcade - Donkey Kong - Points [Hammer Allowed] - Player: Billy L Mitchell - Score: 1,062,800
Scoundrl provided. Many thanks to him for contributing here.
So far, we can not find any unexplainable inconsistencies with our current findings with Original Donkey Kong Arcade rasterization. The conclusion regarding the variance seen in the posted screenshot is the direct result of the source video capturing frame rate, which was set to 25 fps.
At 25 fps, there was literally no way for all of the displayed frames to be captured by the camera. And the camera snapping away at 25 fps while looking at a 30fps screen is invariably going to catch the screen drawing right in the middle of a frame transition resulting in a split screen (part of the old frame and part of the new frame) image being compressed and encoded.
The split screen can appear as a diagonal line since the monitor refresh rate is faster than the camera capture, so the refresh line will appear to "move" during the picture taking and therefore the line will not be straight up and down (it will look diagonal.)
Here is an example of the diagonal line in action (right screen - Ken House). Here you are actually looking at 2 different frames split across the diagonal line. The 25 fps camera took a picture at that transitional moment, since it was not in synch. Notice how just a tiny portion of the ladder is showing on the 3rd girder. It is being partially drawn (or erased) and the very single frame it is drawn in has not yet completed its rasterization (or erasure.)
This occurrence is how the below image became possible. As you can see from the image above, the upper left corner of the DK screen, the 25 fps digital capture rate catches the incoming lower 1/2 diagonally half mid-frame, while the outgoing upper half is still present on the CRT phosphors.
We we will continue to investigate this video. If @Scoundrl grants us permission to make it available for download we will do so (or he can make it available himself.)
I looked back on xelnia's page 19 post with the original frame still gifs and with the one of the direct camera footage of actual cab, you can see that with the mpeg encoding you see that items from consecutive frames (Kong& barrels, and oil) show the same behavior, only there the algorithm determined that the 'motion' (ie difference between the two frames) needed to be interpolated with Kong being displayed first and the oil second), and the ladder behavior is consistent with arcade and not mame.
The oil drum-vs-Donkey Kong signature was never going to be fully reliable because cameras, especially digital varieties, record things in sometimes unexpected ways.
The Hank Chien example posted earlier, for example ( https://www.youtube.com/watch?v=Tg5ct3nrRzA&t=28m13s ). Obviously we have oil drum before Donkey Kong here.
Fortunately, this video also serves as a perfect example of camera shenanigans. Scoot ahead to 3h5m24s ( https://www.youtube.com/watch?v=Tg5ct3nrRzA&t=3h5m24s ) and watch the Donkey Kong screen frame by frame from that moment, as Hank is maneuvering his camera. Because the camera is not stationary, you will be able to recognize that it is capturing the Donkey Kong screen at this moment in a weird fashion: Half of the newest frame is overwriting half of the previous frame, along a diagonal line from the upper-left to the lower right:
At this moment in the video, the screen is moving downwards (camera moving upwards). The lower-left half is the newer Donkey Kong frame, and is a little bit lower in the video's frame. The upper-right half is the previous frame.
Further complicating this specific phenomenon is the fact that this diagonal offset (as indicated by the yellow line) is not static but travels to the right before looping back to the left -- also easily recognizable through frame-by-frame scrutiny of Hank's video.
Now. If I were to cite a specific signature unique to both MAME and Billy's videos, but not reproducible through a happy video accident, let alone countless times across three separate high score runs, it would have to be Xelnia's original MAME 0.116-0.121 barrel transition:
MAME .. .. .. .. .. .. .. .. .. .. .. Billy
More specifically this thing here:
We have the top third of the board partially rendered, one bar conveniently complete from left to right with no breaks, and that uniquely cut-off bit on the bar below it. That's your smoking gun. To the best of my reckoning, you will never have a camera or a VCR spit that out if you start from a real Donkey Kong machine, and certainly not across multiple instances in the same run.
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