Apple II Monochrome Real Hardware Capture
0My previous captures from my Apple IIe all shared the same flaw, the consumer-oriented composite video capture devices I own just do not have the bandwidth to capture all the video information of the Apple II video signal. The result is unevenly sized pixels and shimmering columns. Here are captures showing that it is possible to capture every pixel output by an Apple IIe regardless of mode.
By use of a professional capture card, namely the Datapath VisionRGB E1s, you can capture every pixel the Apple II can display and in all modes. While the Datapath seemingly has no support for Composite Video or S-Video it only lacks support for NTSC or PAL color video. A monochrome analog video signal is just luma and sync and makes up the Y component of a Component video YPbPr signal. The Datapath supports YPbPr Component.
If you connect the Apple //e's composite video output to the Y-input of of a component to a VGA connector and then a VGA to DVI adapter, you can see monochrome video on the Datapath, but only with pure text modes. The Apple II video signal combines monochrome video (luma), sync and a color burst signal. The color burst is a short signal that occurs on every line before the active picture signal and it tells the TV to display color on that line. The color burst is necessary for NTSC to display color but does not provide color information in and of itself. Unfortunately the Datapath will not display a luma signal if it detects a color burst signal. The Apple II does not provide a color burst signal in pure text modes but does in all graphics modes and all mixed text and graphics modes.
Choplifter and Karateka both use high resolution graphics and Prince of Persia uses a mixture of high resolution and double high resolution graphics. In order for the Datapath to understand the video signal, these video modes cannot output a color burst. There is a way to keep the color burst from being added to the video signal with an Apple //e (and most other Apple II models), but it does require a reversible modification to the mainboard.
The Apple II's video signal does not have any inherent color. Color is produced by the NTSC decoding process, which can mistake high bandwidth luma as chroma. When the luma bandwidth is a multiple (7.159MHz, 14.318MHz) of the color carrier frequency (3.579MHz), then artifact color can be produced with NTSC color decoding methods. This method can be simulated in video post-processing and hopefully a method will be available in the future to turn native Apple II monochrome video into color video with a high degree of faithfulness to NTSC decoding principles. The IBM CGA adapter is more complex because it produces direct or modulated color as well as artifact color. In other words, the IBM adapter has color information in its video signal in several of its graphics modes, so getting pixel-perfect composite video capture from it is more difficult than the Apple //e when it produces direct color. Many IBM PC games use a high resolution graphics mode with composite artifact colors and use white pixels as the base, so they could also be colorized by the same method.
I did not have anything connected to the Apple speaker, so this video is silent. You can use my prior videos on these games if you need to hear what these games should sound like. I did give some proper color variations to breakup the monotony of a single monochrome color!
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