Using the entire CD space...

[Guntz]

Just a random thought on how a traditional game could benefit from utilizing the full, non-exploited 650MB read limit on the Sega CD. Not an FMV game of course, I mean stuff like Sonic CD, Lunar or Final Fight CD. Games like that.

The first thing that comes to me when I think of this idea is not necessarily a bigger game in terms of level size for instance (since that depends on RAM), but a longer game in general. In Sonic CD for instance, you could probably have 20 - 25 zones well before nearing the 650MB limit. The thought it just intriguing...

[kool kitty89]

You mean games using more than the 550 MB (63 minute) "low density" CDs that most (if not all) Sega CD games used?

Using larger discs would mostly facilitate more CD-DA or streaming video as game data usually didn't go past ~10% of the capacity. (often far less)
So it's unlikely you'd have larger levels or more game content as CD capacity wouldn't have been the limiting factor there anyway.

Streaming media is the big part of games from that time (and the following generation too -even the case with some 6th gen or some current gen stuff, though far less often).

As it was, other than going up to a 650 (72 minute) disc, you could just bump it up to 2 discs, though only FMV games did that iirc.
As far as audio goes, the 2 other ways to get more content onto 1 CD would be using synthesized music for some portions (YM2612+PSG+PCM, like Silpheed, Sonic CD's past stages, NovaStorm, Popful Mail, etc), or you could stream lower quality or perhaps even compressed audio.
In the latter case, that would mean having a suitable amount of buffered audio data in RAM and lots of stopping and seeking on the CD-ROM drive. (CD-DA just streams at 1x, for lower bitrate audio, it would be stop and go -the smaller the buffer in RAM, the more stop and go)
So that could put more wear on the drive and make more noise.

If you did do that, the best you'd get from converting CD-DA (44.1 KHz 16-bit stereo) would be 32 kHz 8-bit stereo, which would allow roughly 2.75 times the audio (ie if you had an hour of CD-DA, you could have about 2 hours and 45 minutes of lower quality PCM). You could have lower sample rates than that too, but quality drops accordingly (probably wouldn't want to go below 22 kHz if you wanted decent music) or you could drop to mono. Then, you might manage compression too, but that probably wouldn't be necessary. (you've got the CD 68000 though, even with overhead from managing the CD-ROM data -one disadvantage vs using CD-DA is CPU overhead for managing the data I think, with red book audio being the only exception to CPU overhead for CD-ROM access -other than setting loop points)

For dropping down to to the different PCM format (especially the specific sign-magnitude format used by the ricoh chip), processing to optimize sound in the different format would likely be desirable. (to minimize aliasing)

What might be interesting is is you streamed audio, but then added realtime instruments on top of that (FM, PSG, and PCM -though PCM would have to fit in wave RAM without disrupting the streaming/buffered PCM)



The one other thing is if you didn't mean physically more disc space, but just more data on-disc, and while CD-DA is already as dense as you can get (176.4 MB/s), other data is not: the problem is that for such formating, you lose error correction, hence why the standard 150 MB/s PC mode 1 data is used. The usual exception to this is streaming video and other non-critical data, or data that's critical to have a higher bitrate, but as it is, it seems a lot of FMV still used mode 1 as well (and was thus also more reliable). I suspect Silpheed might have used "mode 2, form 2" data which uses little or no error correction and is close to the CD-DA bitrate. (that would explain the finicky nature of that game)
Mode 2, form 2 is the standard format used for VCDs (Philips' White Book video), and from what I understand is the format used for most FMV on the 3DO, PSX, Jaguar and Saturn, probably also used for streaming PCM/compressed audio other than CD-DA. (probably including WAV files: which could include compressed and uncompressed PCM)

For FMV, using mode 2 form 2 wouldn't mean more content (same for any continuous streaming content -ie no stops opposed to the lower bitrate PCM I mentioned above), but it would mean a higher bitrate and thus better quality FMV. (larger screen size, higher framerate, or lower compression ratio)

[villahed94]

At least i´ve tried it ant recorded aprox. 700 mb

[Lastcallhall]

Final Fight, Lunar 1&2, and various others were close to the 550 limit back then. Final Fight's data track took up 350MB or so, with music taking up another 200MB. I don't think Lunar was that bad, but then you had TONS of audio data that would either have to have been compressed, shortened, or omitted altogether if you wanted more space.

[tomaitheous]

Just a random thought on how a traditional game could benefit from utilizing the full, non-exploited 650MB read limit on the Sega CD. Not an FMV game of course, I mean stuff like Sonic CD, Lunar or Final Fight CD. Games like that.

The first thing that comes to me when I think of this idea is not necessarily a bigger game in terms of level size for instance (since that depends on RAM), but a longer game in general. In Sonic CD for instance, you could probably have 20 - 25 zones well before nearing the 650MB limit. The thought it just intriguing...

I think it would be hard to try and utilize all that data. A lot of CD games have lots of redundant data, because it's faster to load like that and 600+ megs is huge (4800 megabits :P). But, imagine games where every new/different area has totally new drawn set of enemies or characters or such. No reusing any frames or such (with the exception of maybe your own character). I've seen many CD games that could have done this. They reload all new frames, but the artist was lazy/whatever and just re-used old frames. A real waste of potential.

[kool kitty89]

At least i´ve tried it ant recorded aprox. 700 mb

Of Audio?

Final Fight, Lunar 1&2, and various others were close to the 550 limit back then. Final Fight's data track took up 350MB or so, with music taking up another 200MB. I don't think Lunar was that bad, but then you had TONS of audio data that would either have to have been compressed, shortened, or omitted altogether if you wanted more space.

550 MB (or closer 553 MB rather) is only for mode 1 PC format data: full error correction standard 2048 bytes per sector 150 MB/s format.
For any red book CDDA, or mode 2 form 2 data (very close to bitrate as CDDA), it's more like 636 MB on a 550 MB data disc. (or 747 MB of CD-DA on a 650 MB data disc)

So a disc full of non-error corrected data (mode 2 form 2) or red book audio, could easily be well over 550 MB. , All games that are filled (or nearly filled) with red book audio tracks and/or FMV (or other data) in mode 2 form 2 would be above 550 MB. (but not games that aren't filled)
And games that do use tons of FMV, but use mode 1 data will be at or below 553 MB. (Night Trap disc 1 if 512 MB; most digital pictures stuff seems to use mode 1 data -a lot of FMV does -it would make it more reliable due to error correction, and I think Silpheed may demonstrate the cost of using mode 2 form 2 data) Any game with over ~53 minutes of red book audio would have to be above 550 MB.

If any went beyond 636 MB, you'd know for sure that a higher capacity disc was being used. (or anything more than 63 minutes of CD-DA)

[villahed94]

no game and data

[kool kitty89]

no game and data

What game uses that much data??? (or did you pad it so the game data was into the 700 MB region)

[Lastcallhall]

Of Audio?

Villahed94 is right - I've taken the Final Fight data track and mixed in my own audio to create my own soundtrack for the game and it came close to 700MB. loaded and played fine.

[tomaitheous]

550 MB (or closer 553 MB rather) is only for mode 1 PC format data: full error correction standard 2048 bytes per sector 150 MB/s format.
For any red book CDDA, or mode 2 form 2 data (very close to bitrate as CDDA), it's more like 636 MB on a 550 MB data disc. (or 747 MB of CD-DA on a 650 MB data disc)

The 550 meg limit (cooked, not raw) is probably just specification of the ISO-9660 format, and for the data track itself. Not the entire layout.

[kool kitty89]

Villahed94 is right - I've taken the Final Fight data track and mixed in my own audio to create my own soundtrack for the game and it came close to 700MB. loaded and played fine.

Yeah, but is it only CD-DA in the later data sections? (the question is whether non CD-DA can be held in regions beyond 650 MB)

[Team Andromeda]

If ones reads the translation notes to fit all the speech in Popful Mail the Speech was made mono and the sample rate cut to 22.05 Khz . Laughing Sales man also uses most of the Cd Rom storage

[villahed94]

It could be done if you segment the file as this:
the very first sectors for booting
then audio
Finally the data, which would be referred here by the boot sector
Theorically is possible.

[kool kitty89]

If ones reads the translation notes to fit all the speech in Popful Mail the Speech was made mono and the sample rate cut to 22.05 Khz . Laughing Sales man also uses most of the Cd Rom storage

That would be 8-bit 22.05 kHz mono then (using the PCM chip not CD-DA DAC), so cut to 1/8 the size of CD-DA data'a 44.1 kHz 16-bit stereo. (albeit it would take up more than 1/8 the disc space if mode 1 data was used -a bit over 1/7 the disc space; if mode 2 data was used, it would be very close to 1/8)

That would have to be buffered in RAM to play smoothly (vs the constant pauses seen in wing commander), which is what all FMV using such did as well (most digital pictures stuff used 22 kHz PCM too, some PCM used the max 32 kHz like Sonic CD and some may have used 2 PCM streams but I'm not sure), and of course, it's rather pointless to use stereo recording for voices. (you could still do hardware stereo panning with the PCM chip if that was ever desirable)

That would also have been done to allow audio data to stream along with graphics data for the cutscenes.
As it is there's a ton of unused space in popful mail (even for a 550 MB data disc), they could have used higher quality voice playback for some stuff at least: actually is seems like there's easily enough space for all the PCM to be 32 kHz, but maybe they had utilities that catered more to 22 kHz, or they had to use 22 kHz for the cutscenes and wanted to keep the same format across the board. (other than the 8:42 of red book audio included)

[Team Andromeda]

r they had to use 22 kHz for the cutscenes and wanted to keep the same format across the board. (other than the 8:42 of red book audio included)

They used a dynamic sampling algorithm ranging from 24 Khz to 38 Khz depending on how many voices or sounds were needed for the animation scene in question , Again all done in Mono to save on space.

In total Popful uses 349 MB