Yet another bloody Bad Apple!! demo for the Mega CD

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Ralakimus
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Yet another bloody Bad Apple!! demo for the Mega CD

Post by Ralakimus » Fri Sep 24, 2021 9:32 pm

As mentioned in this thread, I have made my own Mega CD version of everyone's favorite 2hu video, Bad Apple!! May as well share it here, because why not.

Unlike the Cinepak version that was released some time ago, this uses a custom made codec. It packs 4 256x224 1BPP frames into 1 4BPP frame, played back at 30 FPS (the same method used for the SEGA logo in Sonic 3D blast, making it so that it only loads 1 image every 8 frames. Useful for getting more data prepared. Each frame is compressed with a basic LZ compression (vladikcomper's Comper, it was just what I had easily accessible at the time), and I play the audio at 15360 Hz. With this, I am able to separate the video into 2 second packets and be able to seamlessly stream the data from the CD and play it.

The process of playback involves setting Word RAM into 1M/1M mode, and then loading a packet of video data every 2 seconds into a Word RAM bank. While the Mega Drive receives the data, decompresses it, and displays it, the Mega CD prepares the audio data for the PCM chip, and loads the next packet into the other Word RAM bank. Swap banks and repeat.

I've only ever tested this on NTSC, and I can confirm it at least works on a US Model 2. Obviously, it's badly desynced on PAL. The easiest way to get it working on PAL would be to use a 25 FPS version of the video, and stream the audio at a lower quality so it can fit in the larger packet time, but I haven't been arsed to do that, so bleh lol.

Yes, the Genesis demo still looks better since that has a larger bit depth ;P Damn CD loading times and Word RAM size.

Video
Download
The Garbage Source Code

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