Are CD-Rs bad for the DC?

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Post by |darc| » Wed Feb 12, 2003 3:17 pm

Captain Skyhawk wrote:If you selfboot your stuff and you use a dummyfile, how can you be sure it will be burned at the beginning of the disc? Sure you must name the file 00000.dum or something, but when I use Nero for example I can set the priority of the files making sure it comes at the beginning of the disc. Is there a mkisof switch for it?
I forgot what is is, but you can have a switch for mkisofs to make it read the priority of certain files from a txt file.

EDIT:
You need to copy all of the data files and follow the instructions in the Echelon selfboot kit, with a couple of modifications.

1) You need to create a sort file (let's call it "sort_file.txt" in this example) in your self-boot work directory that contains a single line:

data/dummyfile

"data" is the path of the subdir that contains the data files, *relative* to the dir that you are running mkisofs from. It's important to get the relative dirspec right, otherwise the sort won't work properly. "1000" can be replaced by any number greater than 0.

2) When you create the ISO file, add the -sort parameter to
the command line:

mkisofs -C x,y -V NEW -l -o data.iso -sort sort_file.txt data

In this command line, x and y are the numbers you obtained using the "cdrecord -msinfo" command, "data.iso" is the path to your iso file, and "data" is the path to the data files.
Last edited by |darc| on Wed Feb 12, 2003 3:35 pm, edited 2 times in total.
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Post by Nyarlathotep » Wed Feb 12, 2003 3:19 pm

The 'benefit' to dummying for the DC (and is not particularly neccessary for the majority of DC Homebrew... Smash DC does love that laser use though :P ) is that as a property of the GDROM format the data is read from the 'outside' of the disk inwards...


5---------------------4-----------3------2---1[hole in middle of CD]

So the laser starts at the outside(5) of the disk and works inwards(4,3,2,1) (the opposite of how most CD drives work, which would go 1,2,3,4,5) so if all your game data is stored at 1, and your music is stored at 2 (a la Smash DC) the laser has to go from 5 to 1 everytime the music changes / loops.

If you have a 600MB dummy file, then the music and game data will be pushed outwards on the disk so theyll be at or around the 5 on the pic above, so the DCs laser has very little movement to do.

Just making a large Dream Inducer disk seems to have the same dummying effect too of course, and is a lot more fun to make :wink:
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Post by BlackAura » Wed Feb 12, 2003 4:27 pm

What I did for the last disc I burned was 'dummied' it using about 400MB of source code that I was using to build a Linux system - I just don't want to have to download all that again, because it took me about two weeks.

What you basically have to do is fill up as much of the disc as possible (leaving room for the programs, of course), and then put the programs on the end.
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Post by Warmachine » Wed Feb 12, 2003 4:32 pm

I still dont know how to "dummy" a file. Also does "dummying" a file make it start quicker??
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Post by WaCk0 » Wed Feb 12, 2003 4:38 pm

We can also use this cool dummy file creator software. Its a freeware and create files of any size. :wink:

here: http://mynikko.com/dummy/
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Post by Warmachine » Wed Feb 12, 2003 5:04 pm

Is there another way that one only gos up to mbs
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Post by rmila75 » Wed Feb 12, 2003 5:59 pm

Is it safe to assume that a dummied CD-R will look visually different than an undummied disc? In other words, will the undummied disc look like it has an unused or "unburned" section on the disc surface?
Does the software some of you mention include a way to gauge how much dummy space you need to use for each specific disc you create?
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Post by Cless » Wed Feb 12, 2003 7:06 pm

rmila75 wrote:Is it safe to assume that a dummied CD-R will look visually different than an undummied disc? In other words, will the undummied disc look like it has an unused or "unburned" section on the disc surface?
Does the software some of you mention include a way to gauge how much dummy space you need to use for each specific disc you create?
Its pretty simple to figure out how much space you need. You count how big the files are on the cdr.
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Post by Warmachine » Wed Feb 12, 2003 7:27 pm

soo is there a nother way???
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Post by |darc| » Wed Feb 12, 2003 7:32 pm

rmila75 wrote:Is it safe to assume that a dummied CD-R will look visually different than an undummied disc? In other words, will the undummied disc look like it has an unused or "unburned" section on the disc surface?
Does the software some of you mention include a way to gauge how much dummy space you need to use for each specific disc you create?
Yes, it will have more data on the disk, it will have more stuff on it that is burned, it will NOT look like it has unused area, because it doesn't.

You will need to calculate how much space you need. And MAKE SURE you name it 000DUMMY.DAT, because if not, you could send the dummy to the end of the disk and the stuff in the beginning, or even worse, have the dummy between the files on the disk, the motor will have to seek over the dummy and go back and forth every time it needs different data!
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Post by Warmachine » Wed Feb 12, 2003 7:37 pm

so thats how u make it darc.... :wink:
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Post by khendar » Wed Feb 12, 2003 8:53 pm

I'm wondering why none of this can be done with the Sega Saturn. It has always seemed more reliable than the DC to me. Is it just not capable of doing any of the things needed for emulation? Surely, most of the games being emulated don't require the power of the DC.
I think its probably got something to do with the fact that the Saturn was a lot harder to program than the DreamCast is. The dual-chip of the Saturn gave a lot of developers a headache, which may explain why so many developers dropped out of the Saturn so early and started developing for PSX.

Dreamcast runs a version of Windows, which is a shite-load easier to program for.
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Post by |darc| » Wed Feb 12, 2003 8:58 pm

khendar wrote:Dreamcast runs a version of Windows, which is a poop-load easier to program for.
No... There is a library version of Windows for Dreamcast, WinCE, but only a few apps use this (Sintendo, Old Boob!boy, DCMP3, and GypPlay). The DC does NOT run Windows CE. The WinCE is on the disc of the WinCE applications, and obviously we don't burn that on every disk. In fact, most commercial games don't use WinCE anyway, they use Katana, Sega's dev kit.
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Post by lux92886 » Wed Feb 12, 2003 9:40 pm

First, the DC is much more powerful than the Saturn. Secondly, Saturn just doesn't have the RAM to load roms, and the emulator.

As far as cd-r's ruining the Dreamcast, well I guess it could. Seems if you use the wrong type of cd-r, it would (my dc hates fuji discs, but memorex seem to work good)
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Post by doragasu » Thu Feb 13, 2003 5:08 pm

Captain Skyhawk wrote:If you selfboot your stuff and you use a dummyfile, how can you be sure it will be burned at the beginning of the disc? Sure you must name the file 00000.dum or something, but when I use Nero for example I can set the priority of the files making sure it comes at the beginning of the disc. Is there a mkisof switch for it?
To reorder the files like you want using MKISOFS, first you must create a "sort file", for example, "example.srt". Consider for example that your homebrewn has the followinf files (including a dummy file called "dummy.bin") in the example folder:

dummy.bin
1st_read.bin
image00.jpg
image01.jpg
movie.avi

Now, in the sort file you must put the files and a number indicating their priority. The path must be relative to the mkisofs location, so if the "example" folder is in the same path than mkisofs, the sort file can be, for example:

example/dummy.bin 1000
example/1st_read.bin 999
example/movie.avi -1000

The bigger the priority number is, the nearer the file is to the center of the drive, so in this example, the first file would be "dummy.bin", then next to it "1st_read.bin" and the last file would be "movie.avi". The "image00.jpg" and "image01.jpg" are ommited, so their priority is the default (0), so "image00.jpg" is next to "1st_read.bin" and "image01.jpg" is next to "image00.jpg". You can put also directories in the sort file, and all the files in the specified directory will use the specified priority.

When the sort file is completed, you must call mkisofs with the -sort switch, like for example:

mkisofs -C 0,11700 -V Example_disc -l -sort example.srt -o example.iso example

And that's all. I hope I have expressed myself clearly, because my english isn't very good.
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Post by fishman » Fri Feb 14, 2003 7:49 pm

i think Tomb Raider Chronicles used WinCE (it shows the WinCE logo when the game boots up)

As for cd-rs wrecking your dreamcast, i wouldn't worry too much about it as long as you generally play only the great emulators from this site and no backups :D
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Post by EvilSporkMan » Sat Feb 15, 2003 11:51 am

The Saturn prolly needs a modchip.
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Post by Hobbes T Tiger » Sun Feb 16, 2003 4:12 pm

I've wondered about this myself. I too seem to have one of the indestructible original run Dreamcasts and hope it lasts a long time yet.

But, coincidentally, earlier today I was playing Crazy Taxi and it amazed me how much disc access there was. And that reminds me of Ecco as well. I take on board the point about grouping the data together, but these games still seem to have a heck of a lot of access in them.


I suppose the safest thing is to think of your discs as a bit like your PC hard drive and make sure they aren't "fragmented" as this must increase the laser and motor work, even if it's not actually that bad in the short term.
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Post by yodanut » Sun Feb 16, 2003 9:19 pm

doragasu wrote:
Captain Skyhawk wrote:If you selfboot your stuff and you use a dummyfile, how can you be sure it will be burned at the beginning of the disc? Sure you must name the file 00000.dum or something, but when I use Nero for example I can set the priority of the files making sure it comes at the beginning of the disc. Is there a mkisof switch for it?
To reorder the files like you want using MKISOFS, first you must create a "sort file", for example, "example.srt". Consider for example that your homebrewn has the followinf files (including a dummy file called "dummy.bin") in the example folder:

dummy.bin
1st_read.bin
image00.jpg
image01.jpg
movie.avi
Actually, if he's going to use the MKISOFS/CDRecord method, he might as well dummy the CD with a really long audio track. It serves the same purpose and is very easy to do. Just record whatever songs you want on the first session instead of using the audio.raw file. Just don't fill up the CD since you'll have to leave room for the ISO that follows. There's a tutorial that explains how on the main page of the site, so try it out.
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Post by doragasu » Mon Feb 17, 2003 4:01 pm

yodanut wrote:Actually, if he's going to use the MKISOFS/CDRecord method, he might as well dummy the CD with a really long audio track. It serves the same purpose and is very easy to do. Just record whatever songs you want on the first session instead of using the audio.raw file. Just don't fill up the CD since you'll have to leave room for the ISO that follows. There's a tutorial that explains how on the main page of the site, so try it out.
Yes, you are right, but that's only for dummying the CD. Using sort files, you can order all the files burned in the CD. Most times it's not needed, and with only adding a dummy is more than enough, but it's good to know all the posibilities...
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