Best And worst Quality FMV (Streaming video) on the Sega CD?

[kool kitty89]

For time gal, (75*0x800-32552)/(20*24*32) would mean you could get a max of 7.8 fps just for the uncompressed tile data and 32KHz audio data. But if you start adding in palettes and palette maps, this optimal frame rate gets smaller, so ~6.3 seems appropriate.

Yes, but it's all just 16 colors per frame (so no color map and only 24 bytes per frame for CRAM updates) and the audio doesn't sound anywhere near 32 kHz (it doesn't even sound very good for 16 kHz, but that would seem likely -few if any games used 11 kHz iirc).
Very few examples of Japanese developed games used more than 1 palette for FMV. (Game Arts was one of the exceptions and, interestingly, did so with the very first example of FMV on the system -Tenka Fubu- which seems to be fairly similar to Sewer Shark and Night Trap)

It seems to be the exact same framerate and audio quality as Tenbu MCD Special, but with the frame cropped horizontally from 240 down to 192 pixels. (the intro portion also seems to use the same dithering scheme as Tenbu -different from Road Avenger, which has a lower color threshold and looks much more like typical floyd steinberg dithering)
Albeit, at that quality (240x160 16 colors 6.3 FPS), Tenbu would still have the bandwidth for 32 kHz PCM, but it definitely doesn't sound even close to that. (and that's assuming the data rate is actually maintained close to the 153600 bytes/s peak for mode 1 data)

So, given it's 16 colors per frame andassuming 16 kHz PCM, that would allow the same screen size and framerate as Road Avenger (7.5 FPS, or one update every 8 NTSC video frames), or a higher framerate at the 192x160 frame size. (doing 1/7th of 60 Hz would give ~8.6 FPS and should fit the bandwidth)

For Sonic CD FMV audio, I think the original FMV 32KHz 8 bit mono would suffice since 8 bit mono is the easiest to use for SCD FMV.

We were talking about trying to use paired channels for higher res (perhaps 13 or 14-bit) output via the ricoh chip here:
http://www.sega-16.com/forum/showthr...on-the-RF5C164

If that did work, you could do 8-bit ulaw, ADPCM decompressed to high res, or uncompressed high res PCM (though that would waste bandwidth). Of course, any such use of the ricoh chip would require double the buffer space in wave RAM (or more frequent updates of smaller buffers), so doing it Sonic CD style (32k double buffered and updated only once per second) would limit that to 16 kHz mono, but obviously you could do much more with smaller buffers updated more often. (albeit, at the expense of more overhead)


But yes, the existing 32 kHz PCM renditions are pretty good in any case.

[kool kitty89]

I had another look at the Sonic CD intro, and paid specific attention to what scenes were cut and what the duration of the cut sequences totaled to. It turns out to be approximately 18 seconds (that's seconds at the speed of the PC/etc versions) that are missing from the 90 second total, so the Sega CD version would be only ~72 seconds if those cuts were made directly. However, the video was slowed down to match the original duration, which would mean 80% of the original speed, or slowing a 30 FPS animation to 24 FPS and then cutting that down to 8 FPS by only using 1 of every 3 frames. (or from another perspective, they cut the source animation to 10 FPS by throwing out 2 of every 3 frames, slowed it to 8 FPS and cut out another 20% of the scenes used)