Extracting assets from Sega CD games

[goldenband]

I think this may be a fairly naive question (for which I apologize in advance), but I've been wondering for a while about extracting and re-encoding assets from Sega CD games. Specifically, there are two projects I've wondered about:

1) Extracting non-Redbook audio from a game (e.g. the "GAME OVER" tune from Cobra Command, which seems truncated on my copy and which I'd like to hear in its entirety);

2) Adding subtitles to FMV content (e.g. the cutscenes in Earnest Evans and Anet Futatabi).

Can anyone offer an approximate rundown of what would be involved in extracting these, and what tools are available? Is there a good wiki (or equivalent) for Sega CD content hacking? Or is the answer basically "it depends on how the disc was authored and how the files were encoded, and you'll have to roll your own tools for almost every project"?

[ASSEMbler]

I think this may be a fairly naive question (for which I apologize in advance), but I've been wondering for a while about extracting and re-encoding assets from Sega CD games. Specifically, there are two projects I've wondered about:

1) Extracting non-Redbook audio from a game (e.g. the "GAME OVER" tune from Cobra Command, which seems truncated on my copy and which I'd like to hear in its entirety);

2) Adding subtitles to FMV content (e.g. the cutscenes in Earnest Evans and Anet Futatabi).

Can anyone offer an approximate rundown of what would be involved in extracting these, and what tools are available? Is there a good wiki (or equivalent) for Sega CD content hacking? Or is the answer basically "it depends on how the disc was authored and how the files were encoded, and you'll have to roll your own tools for almost every project"?

Are you talking about disassembling the executable or just the file types.

[l_oliveira]

Are you talking about disassembling the executable or just the file types.

Since "assets" is the term used to refer to data files such as graphics or sound samples, I think he mean the files other than program code...

As far as I can remember, the only thing I ever seen for MEGA-CD was a tool to extract/play the background movies for the Game Arts title "Silpheed".:nod:

[goldenband]

Yes, just the audio/visual files are what I'm after. I know some work has been done with Cinepak, but from what I can tell the resources out there are very piecemeal.

Well, here's a more concrete question to get things rolling: can anyone tell me something about how the cutscenes in Earnest Evans and Anet Futatabi are encoded? Are they static movie files that could theoretically be decoded, modified and re-encoded, or are they being rendered procedurally?

[segaloco]

Well from what I can tell of what I've been playing with with Sega CD, for FMV sequences there is that Cinepak stuff then STM format. STM format is basically the entire FMV video sequence stored as uncompressed VDP data. You would just need to disassemble the game's STM viewer to get the data which determines the resolution and framerate and stuff. As for non-RedBook audio, that's usually PCM that routes through the SMPS-PCM driver. You can read up on the SegaCD PCM format in one of the leaked Rex Sabio Sega CD manuals, although I forget which....(well this is all assuming your games used stuff like SMPS-PCM and the STM format, I'm not sure what else there is, as Sega CD had a much smaller library so you wouldn't have the diversity that Mega Drive had what with GEMS and SMPS Z80 and SMPS 68k and Cube etc...)

Edit: Oh, look for PCM000.bin in the iso, that's a good indicator of SMPS-PCM presence. If that's not it then the audio isn't Sega CD PCM but rather DAC audio and that's just a standard Mega Drive format that you can look around for converters for. I'm not sure if there is a SMPS-PCM converter though...

[goldenband]

Thanks for that, segaloco. Much of it goes over my head, but I'll try using what you wrote, plus what I found here, as a starting point to track down the Cobra Command music I'm looking to extract.