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xhunter
June 22nd, 2004, 00:18
Does anyone know how I can get information on the .gcm file extension of which Dolphin Emu opens. I have tried Google for about 4 or 5 days straight and there is nothing on the net. I have also tried MSN and a few P2P Apps. I know how to open them up and view there data, but I would like to know some specifications on the encoding data structure of the .gcm. I have realized it is almost like an .iso image, but there are no special programs that make these that I can find. I am working on a "Tool" right now for these files, and do not want to go through all the trouble of doing it myself, when someone else may have already done this. Please get back with me on this. :happy:

PsyMan
June 22nd, 2004, 00:35
GCM files are ISO files renamed to GCM. You can open them with a program that opens ISO files if you just rename them.

xhunter
June 22nd, 2004, 01:19
And the famous words from Psyman -

GCM files are ISO files renamed to GCM. You can open them with a program that opens ISO files if you just rename them.

LMAO:happy:
that right there is called a bad rip. If you are doing that, then you probably never get any result with Dolphin emu. Go ahead and rip that GC game of yours into .iso file. It is'nt going to work. You will have so many sectors missing from it, and I would be surprised if you actually obtain any of the files through your DVD Drive, unless you can afford a company GC game writer which can perform reading tasks as well,that is if you can find one, you aren't going to get **** off that disc. .GCM is in fact a file extension/file type that is not recognized by Win32 or any other OS besides what Dolphin can read, Just like .z64, .v64, .gba, .smd, .smc, .32x. The only thing different about it is its a DVD image instead of a (Random-Accessed Memory) RAM Cart. It is still a ROM (Read-Only Memory) image just like the other extensions I listed above. Like the extensions above, it has its own encoding for the structure. I want to know this so that I can better help the GC Emu community. :baaa:

Acorn
June 22nd, 2004, 01:27
Like psyman said... .gcm is a renamed .iso. You can stream data from a gamecube with the pso hack and a broadband adapter. I think the authors made the extention .gcm so you don't see/confuse non gamecube images with gamecube images. Really. Try opening a gcm in daemon, or isobuster, it works.

Edit: here, ector himself says it: http://www.emutalk.net/showthread.php?t=18450&highlight=gcm

knowitman
June 22nd, 2004, 01:29
They are right. It is an ISO. I have ran homebrew GC software in Dolphin that when I d/led it was in ISO format. I just renamed it .gcm and it worked.

PsyMan
June 22nd, 2004, 01:33
So the structure is the same for both of them gcm=iso, got it Mr know-everything?

Knuckles
June 22nd, 2004, 01:35
And the famous words from Psyman -

GCM files are ISO files renamed to GCM. You can open them with a program that opens ISO files if you just rename them.

LMAO:happy:
that right there is called a bad rip. If you are doing that, then you probably never get any result with Dolphin emu. Go ahead and rip that GC game of yours into .iso file. It is'nt going to work. You will have so many sectors missing from it, and I would be surprised if you actually obtain any of the files through your DVD Drive, unless you can afford a company GC game writer which can perform reading tasks as well,that is if you can find one, you aren't going to get **** off that disc. .GCM is in fact a file extension/file type that is not recognized by Win32 or any other OS besides what Dolphin can read, Just like .z64, .v64, .gba, .smd, .smc, .32x. The only thing different about it is its a DVD image instead of a (Random-Accessed Memory) RAM Cart. It is still a ROM (Read-Only Memory) image just like the other extensions I listed above. Like the extensions above, it has its own encoding for the structure. I want to know this so that I can better help the GC Emu community. :baaa:

by your reaction, you reallly know nothing about it, he tells you what is it and you laught at it and tell it's not that but you dunno as **** about it. You says you want info about, we tell you what it is and you say no, it's a bad rip, ect, blah blah blah.... all those guys are right, GCM ARE iso.All my games here are ISOs renamed to GCM and every single of them are running great. So I can only call you a n00b that try to get info on something he THINKS he know better than everyone but doesn't know anything.

I said what I wanted

xhunter
June 22nd, 2004, 02:04
Knuckles, do you think I would have not tried to have opened it with as many programs as possible before looking for all the information? I've tried it all and the only thing that opens these files is GC-Tool which paradox and Icarus specifically designed to open these files. I don't know what kind of .gcm
file(s) you have, but isobuster, winiso, daemon tools, alcohol 120%, NeroImage Drive, and UltraISO only show that they can pick it up as an image file, but they cannot open it to view any. The .gcm file, works like an .iso as it stores all types of files, just like an .iso, but can only be opened to view the files by using GC-Tool. Opening the file does absolute **** for me but just lets me view what the game is made up of like the .szp, .bti, and .h4m files it mainly consists of throughout the whole image. Please do not call me a no0b, as I am very familiar with emulation, and have worked on a few N64 wrappers and Tools.

Knuckles
June 22nd, 2004, 02:16
then why you didn't simply asked informations about the GC DISC FORMAT instead??? Since the PC can't read them, so can't see files in it (due to special format), the iso utils are only seeing that there is 104GB of data. GCM are ISO, that's all.

xhunter
June 22nd, 2004, 02:23
The reason Windows :down: cannot see the files is'nt because it is a "special" format. Well it kind of is, if you think of it, but the DVD is meant to be read in an opposite direction, and clusters of data are spread throughout the disc. This is Nintendos solution to the burning issue they seem to have. :bounce:

PsyMan
June 22nd, 2004, 04:02
Well, it's like trying to access an NTFS formated HD under windows 9x. Windows 9x cannot read NTFS formated disks.
You should not misunderstand the phrases "image format" and "CD format", they do not mean the same thing. Image format indicates the format of a virtual CD (each burning program has its own format but it may be compatible with formats from other programs). CD format on the other hand is the way a real CD is created in order to be compatible with specific systems.
The weird thing about the Gamecube disks is that they are not readable by any CD-DVD drive (like the Dreamcast and XBOX disks), but even if they were readable (the ISOs of these disks are readable) they use a format that the operating system cannot read (this is possible only by applications made for this purpose like the GC-Tool).

DOGG
June 22nd, 2004, 05:34
the DVD is meant to be read in an opposite direction

That isn't true.

As for the original poster: There are programs which read the images and you are able to extract individual files from them. google it.

bohdy
June 22nd, 2004, 10:39
GCM files are ISO files renamed to GCM.

No, rather ISO files (of gamecube games) are .GCM files that have been renamed to ISO.

Gamecube disk images are not in any standardised format, and they are certainly not in ISO9660 format, which is what the .ISO extension in windows refers to. They will not be recognised by any image reading software that has not been written with gamecube in mind.

.GCM is the extension given to disk images used in development of GC software so it is a whole lot more accurate than .ISO, although I'm sure that no-one will care since .iso has become synonymous with "disk image" in most peoples minds.

PsyMan
June 22nd, 2004, 10:54
No comment... (tired of all this)

jareg
June 22nd, 2004, 11:23
I think he got the anwser guys :)

bLAdEbLA
June 22nd, 2004, 17:19
Am I just blind? Enough flaming, guys :)


Does anyone know how I can get information on the .gcm file extension of which Dolphin Emu opens.

If you're looking for information about the file-format, then it's been answered seemingly to the best of the members' abilities.

If you're looking for information on the content of the files, then do a search on the boards.

bohdy
June 22nd, 2004, 19:48
Actually, no-one has yet answered the topic creators question, so I will be nice and do so :)

You can find information about the gamecube disk structure (and hopefully GCM structure by extension since they are just raw reads) here: http://www.gc-linux.org/docs/yagcd/chap13.html

Oh and I wasn't flaming earlier, but merely educating ;)

bLAdEbLA
June 23rd, 2004, 09:22
Very useful information bohdy. Thanks! :)

On the topic of flame wars, I Was just trying to keep everyone friendly. :P

PsyMan
June 23rd, 2004, 09:31
I Was just trying to keep everyone friendly. :P
And you did great :)
We all lose it from time to time, so it's good to be someone cool around to keep the others friendly.

foogy
July 3rd, 2004, 20:51
GCM files are ISO files renamed to GCM. You can open them with a program that opens ISO files if you just rename them.

what program do you use to rename em'? ive used discjuggler and it just saves a small file 3mgs when i try ikaruga.

ps. is there anyway i can zip these files and still play em in dolphin? thanks

jareg
July 3rd, 2004, 21:09
what program do you use to rename em'?

How can you not get it you just right click on the imge the rename and then you but gcm instead of the iso

Gorxon
July 3rd, 2004, 21:40
Just some more info which I have no idea of it's accuracy (I would go for bohdy's link, but just in case you need the info written different):

===========================
3. DISK & FILE STRUCTURES
===========================

Disk header at offset 00000000

0000-0003 GameName
0004-0005 Comany
0006 Disk ID
0007 Version
0008 Streaming
0009 StreamBufSize

0420-0424 offset of main executable DOL
0424-0427 offset of the FST

Apploader at offset 00002440

0000-0009 Date (version) of the apploader in ASCII
000A-000F padding (0)
0010-0013 Apploader entrypoint
0014-0017 size of the apploader (32 bit)
0020-.... Apploader code (loaded at 81200000 in RAM)

Dol file format

Header Size = 100h bytes

0000-001B Text[0..7] sections File Positions
001C-0047 Data[0..10] sections File Positions
0048-0063 Text[0..7] sections Mem Address
0064-008F Data[0..10] sections Mem Address
0090-00AB Text[0..7] sections Sizes
00AC-00D7 Data[0..10] sections Sizes
00D8 BSS Mem address
00DC BSS Size
00E0 Entry Point

0100-.... Start of sections datas (body)

FST format

1st 32bits = nb of files, then we get a structure repeated for each file
structure looks like that :

NameOffset (32bits), diskAddr (32bits), fileSize (32bits)

if bit 31 of Nameoffset is set, it means we are entering in a directory,
that contains [fileSize] files

xhunter
July 3rd, 2004, 22:05
You need to have ISOBuster 1.6, when you go to open it, it will just say track 1. On the left panel it will say DVD. Right click DVD and then select convert to user data. When it asks you to save it, select the directory you would like it, and rename it to the proper name of the game, and at the end of it put .gcm. THESE ARE NOT ISO'S I DID MORE RESEARCH ON IT. They are made with a few programs all working together to use the GC as the reader and your computer as a server. Without the other users playing, you have a pure IMAGE of the game without any malicious files, so what I've read on about 30 sites. I will test this, and give feed back, to settle this matter.

Gorxon
July 3rd, 2004, 22:30
Eh, look, most of us know this already. The images dumped are 1:1 copies of the discs as the GC reads it (after it has gone through de-encryption if any). With garbage and all.
And it does not use a normal ISO format, so reading it using a program meant for the ISO format common for CD's etc is a waste of time (read earlier posts in this topic). I know its mentioned but somehow you don't get it? A file's last name has nothing to do with what the file really is. If I rename a .mp3 to zip it doesn't make it a zip file which winzip could understand, but it's still in mp3 format.

einstein123
July 10th, 2004, 02:31
There's one more thing... There ARE DVD readers that can read GC mini-dvds, but windows can't understand the information (It thinks that it is an protected Audio CD)
This happens with the programs that opens isos (they think that the image is an audio)