[_qbjt]

As a Sega fanboy, this makes me happy. That copy protection scheme (outer ring spiral) is quite something. I find it amusing that Sega went with yet another proprietary disc format for the Dreamcast (GD-ROM) and that system is able to load homebrew code from any CD-R / CD-RW without any modifications to the hardware.

[uxp100]

Yeah, that is something. They thought better hardware protection was unnecessary because they believed in the strength of their software solution (which was quickly cracked)? The games could be larger, so that CDs could not fit them without changes. IIRC early Soul Calibur burns had their music down-sampled to fit 650 MB. And was it Skies of Arcadia that really did have too much content to fit on a CD, without serious changes?

Also, you mention CD-RW, but IIRC you could not boot off CD-RW, only CD-R. Or maybe that was the softmodded xbox?

[christoph]

Dreamcast games varied in size massively. Crazy Taxi was only around 100mb. So small in fact that when initially burnt to a CD the drive couldn't load files fast enough (as files were closer to the inner ring of the disc). Tools were then released to 'pad' the game files out to be closer to the outer edge with a dummy file. Files close to the outer edge can be read faster as the drive laser can cover more distance per revolution.

Skies of Arcadia was I believe the biggest ever 'released' - 2x1GB. A group called Echelon did manage to release it after many months/1 year+(?) without anything ripped, sized to fit on 2x700mb CD-R's. They pre-compressed the whole game and wrote a custom on-the-fly decompresser. Apparently this did slow the game down in places, but the technical achievement certainly needs to be appreciated.

[uxp100]

Oh yes, I remember padding the image, and Echelon, of course. I still have the tools somewhere in my backups.

You mention the read speed issues, meaning the dreamcast drive was CAV. Were all data drives of the time CAV? Are audio CD players CAV? Not some 40 second skip protection discman, but like a hifi unit from the 80s (since my naive 80s implementation would not like the data rate changing across the disc)? Does CAV vs CLV have any meaning here, or is pretty much laserdisc only terms?

All things I vaguely feel like I should know (like if all optical media has pits that are the same length across the disc. I think not, again laserdisc.) I love my dreamcast. Left one in an apartment 6 years ago when I moved out. It could be still there. Still have one.

[__david__]

CDs are CLV, data-wise. But many CD-ROM drives can also read at faster-than-realtime-audio speeds, and in those cases reading at the outer edge of the disc can net faster rates. IE, a 2x CD-ROM might not be 2x throughout the whole disc.

[Grazester]

I believe they did no such thing(proof would be greatly appreciated). What they did was downsample the audio files and the pvr game textures.

To achieve what you claim would more than likely mean game engine modification and without the source code I dont see that happening.

[christoph]

If you search google for their Skies of Arcadia nfo file, you will see this is clearly what they claim. I won't link to it here due to other material hosted on those sites. The trainer injected into the executable also makes this claim (you can view this on pouet.net).

I have little reason to doubt their claims given their clear technical skill spanning multiple console generations (Echelon might have only been associated with the Dreamcast/PS2, but it's obvious that their 'group' were behind multiple other, very highly technically accomplished scene groups).

Access to the source code is even a possibility - at one point they routinely released games weeks or even months before street dates.

http://dcemulation.org/phpBB/viewtopic.php?f=34&t=97250 is worth a read for an indication of some of the shenanigans that were afoot back in those days.

[voltagex_]

Wonderful. I love things like this. In these days of Steam DB and people scrutinising every byte, it seems like the easter egg / message from the developer has gone by the wayside.

https://tcrf.net/The_Cutting_Room_Floor has a lot of examples of left over / hidden content but nothing as cool as a message left for a particular group.

[uxp100]

Honestly, inserting compression doesn't sound impossible. Difficult, but a few months and a team of people and it sounds achievable. Warez folks do some crazy stuff.

However, I read some forums from the time, it sounds like the results weren't great. Mainly folks notice sound triggering noticably late. So uh, Maybe instead of downsampling they built a MP3 decoder, but to use the existing system, it couldn't stream the audio, so they had to decompress the clip completely into a buffer before playback?

[ZenoArrow]

> "Skies of Arcadia was I believe the biggest ever 'released' - 2x1GB"

Bigger than Shenmue / Shenmue 2? IIRC both Shenmue games spanned 3 GD-ROMs.

[christoph]

Sorry, I wasn't very clear. In my head I was thinking in terms of games that weren't ripped/downsampled to 'fit' on an 80min CD-R. I think the largest release was probably D2, which from memory needed 5x99min CDR's and even then numerous elements were downsampled/ripped/etc.

[lucb1e]

> That copy protection scheme (outer ring spiral) is quite something.

Yeah about that, I don't get it. Is there data hidden in that spiral that acts as a checksum for the CD or something? Or is it of special material that lights up differently under certain light (like money)?

To me it doesn't look that hard to duplicate a simple spiral, but then I know nothing about it.

[christoph]

Consumer CD writers and CD-R's don't have the ability to write anything similar to the disc.

Gamecube discs utilised a similar technology which you can easily see on the disc surface - http://www.gamesx.com/grafx/ngcdisc2.jpg & https://en.wikipedia.org/wiki/Nintendo_optical_discs#Burst_c...

Years before, companies actually did a similar thing with floppy discs, albeit in a slightly different way.

https://en.wikipedia.org/wiki/Bad_sector

[rasz_pl]

original Playstation used similar copy protection trick - ASCII string SCE(I/E/A) was stored in pregap pre-groove wobble between the leadin and the first track. PSX used Three-beam pickup and was able to track this wobble and extract code from radial tracking error signals. Modchips simply injected same error signal for couple of seconds after closing CD lid, enough for the CD controller to recognize it as "original".

[voltagex_]

Any idea why PS modchips used to kill the drive laser pretty quickly?

[rasz_pl]

they didnt. lasers were poor to begin with, plus weaker media(cdr) probably caused extra mechanism movements (focusing)

edit: hmm, now that I think about it, its possible someone incompetent made modchip that would keep sending wooble constantly, that could cause tracking problems and tire mechanism pretty fast.