CD+G... FMV playback?

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MrTamk1s
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CD+G... FMV playback?

Post by MrTamk1s » Mon Mar 02, 2015 9:07 pm

Crazy idea time! I have always wondered, could CD+G graphics be encoded in the R through W CD subchannels of a Sega CD game disc and then allow the Sega CD to use the subchannels as an FMV source in-game? Could the Sega CD's game disc style be combined with the CD+G format in the subchannels, and can the Sega CD utilize the appropriate CD+G related BIOS calls while in-game to play the FMV? Would CD+G FMVs have enough bandwidth to compete with real FMV, or would such FMVs be of low-quality and slow (like Rock Paintings)?

For Sega CD homebrew development, I would imagine that, if this technique would be possible and feasible, it would be an easier way to do FMV playback instead of programming an FMV codec and decoding the compressed graphics on-the-fly. Hypothetically, all one would have to do is to create a Sega CD game, create CD+G tracks for the audio, and then send the appropriate BIOS calls to play the audio CD+G track, which will play both the music and display the video simultaneously in-sync, although I would reckon the uncompressed video would eat up CD storage space fast and would have to be used sparingly. Also, finding good software to make custom CD+G audio tracks would be difficult. Such a technique would be a codeless solution for cutscenes or for games with video backgrounds (think Silpheed, but much more scaled back.)

Unfortunately, I do not have the programming skills to experiment with such an idea, but am just wondering if the Sega CD hardware, Sega CD game and CD+G disc formats, and BIOS would allow such a possibility.
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Mask of Destiny
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Post by Mask of Destiny » Wed Mar 04, 2015 3:41 am

I'm not really familiar with the BIOS calls for CD+G so I can't say how easy they would be to use from a game, but CD+G has really limited bandwidth for the graphics (I believe 3600 bytes per second, compared to 176400 bytes per second for the audio). This is enough for karaoke CDs, but not really enough for anything you might accurately call FMV.

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Post by Stef » Wed Mar 04, 2015 9:30 am

Yeah the +G stuff was done to display text during music, for Karaoke... far from what you require to display video :-/

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