XDVDFS (Also known as XISO) is the image format used for [[Xbox Game Disc|Xbox Game Discs]].
It is stored in the data area.

== Format ==

Each sector is 2048 bytes.

=== Filesystem ===

{{FIXME|reason=More info}}

=== Volume descriptor ===

32 sectors which are zero-filled.
The Volume descriptor is 4096 bytes, but split into 2x 2048 sections.

* '''Section 1:''' The first data is the magic at sector 32. It is always "MICROSOFT*XBOX*MEDIA". {{FIXME|reason=How does this work?}}
* '''Section 2:''' The first data is the magic at sector 32. It is always "MICROSOFT*XBOX*MEDIA". {{FIXME|reason=Describe version information}}

==== Examples ====


{{FIXME|reason=The tool names appearing in this section are guessed by me, we should confirm each of these - JayFoxRox}}
{{FIXME|reason=This lacks a couple of XDK versions}}
{{FIXME|reason=The byte offsets of each version field are missing}}

===== Wave 1 =====

Developers used xblayout to create DVD layout.
Then generated the final image using xbpremaster.
The final image was submitted to Microsoft.

* [[Azurik: Rise of Perathia]] (NTSC)
** xblayout version: 1.0.3926.1
** xbpremaster version: 1.0.3926.1
* [[Genma Onimusha]] (PAL)
** xblayout version: 1.0.4039.1
** xbpremaster version: 1.0.4039.2
* [[Max Payne]] (PAL)
** xblayout version: 1.0.4134.1
** xbpremaster version: 1.0.4242.1
* [[Petit Copter]] (Japanese)
** xblayout version: 1.0.4361.1
** xbpremaster version: 1.0.4361.2
* [[007 - Agent Under Fire]] (PAL)
** xblayout version: 1.0.4432.1
** xbpremaster version: 1.0.4432.1

===== Wave 2 =====

{{FIXME|reason=This is a theory. Confirm please}}.
Developers used a new version of xblayout and submitted the layout + content to Microsoft
All games with xblayout > 4808 use a new random padding algorithm.
Microsoft generated the final image.

* [[Metal Gear Solid 2 - Substance]] (NTSC)
** xblayout version: 1.0.4721.1
* [[Blade II]] (NTSC)
** xblayout version: 1.0.4808.1
* [[Battle Engine Aquila]] (PAL)
** xblayout version: 1.0.4831.1

===== Wave 3 =====

{{FIXME|reason=This is a theory. Confirm please}}.
Same as wave 2, but Microsoft upgraded their tool to use new random padding.

* [[Metal Gear Solid 2 - Substance]] (PAL)
** xblayout version: 1.0.5120.1
* [[Shenmue II]] (PAL)
** xblayout version: 1.0.5120.1

===== Wave 4 =====

{{FIXME|reason=This is a theory. Confirm please}}.
Same as wave 3, but developers now had to use the xbgamedisc tool instead of xblayout.
The mastering tool used by microsoft also leaves a version identifier now.

* [[Star Wars - Knights of the Old Republic]] (PAL)
** xbgamedisc version: 2.1.0.5233.1
** mastering tool version: 2.1.0.5233.1
* [[Indiana Jones and the Emperor's Tomb]] (PAL)
** xbgamedisc version: 2.1.0.5233.1
** mastering tool version: 2.1.0.5233.1
* [[Dynasty Warriors 4]] (PAL)
** xbgamedisc version: 2.1.0.5344.1
** mastering tool version: 2.1.0.5344.1
* [[The Matrix - Path of Neo]] (PAL)
** xbgamedisc version: 2.1.0.5849.1
** mastering tool version: 2.1.0.5849.1
* [[The Suffering - Ties That Bind]]
** xbgamedisc version: 2.1.0.5849.1
** mastering tool version: 2.1.0.5849.1
* [[Reservoir Dogs]] (PAL)
** xbgamedisc version: 2.1.0.5849.1
** mastering tool version: 2.1.0.5849.1

=== Directory Entry ===

==== Version 4361  ====

File entry flags:
* READONLY = 0x01
* HIDDEN = 0x02
* SYSTEM = 0x04
* DIRECTORY = 0x10
* ARCHIVE = 0x20
* NORMAL = 0x80

=== File data blocks ===

==== Version 4361  ====

Incomplete sectors are padded with 0x00 bytes.

=== Random blocks ===

==== Version 3926 - 4721 ====

Seeded and then starting to emit bytes in data area.
Filled with the following algorithm:

<pre>
// State
uint32_t a;
uint32_t b;
uint32_t c;

// Helper
static uint32_t Value(void) {
uint64_t result;
result = c;
result += 1;
result *= b;
result %= 0xFFFFFFFB;
c = result & 0xFFFFFFFF;
return c ^ a;
}

// buffer must be at even address, length must be multiple of 2
void Fill(uint16_t* buffer, size_t length) {
while(length >= 2) {
*buffer++ = Value() >> 8;
length -= 2;
}
}

void Seed() {
const uint32_t b_seeds[8] = {
0x52F690D5,
0x534D7DDE,
0x5B71A70F,
0x66793320,
0x9B7E5ED5,
0xA465265E,
0xA53F1D11,
0xB154430F
};

FILETIME ft;
GetSystemTimeAsFileTime(&ft);
uint32_t seed = ft.dwLowDateTime ^ ft.dwHighDateTime;
a = 0;
b = b_seeds[seed & 7];
c = seed;
a = Value();
}
</pre>

The RNG is seeded when the mastering tool / wizard is started.
The first portion of the code to use this random number generator is the code which generates layer 0 and layer 1.

==== Version 4831 - 5849 ====

The algorithm was switched to RC4-256-drop-2048.

<pre>

#include <openssl/rc4.h>

RC4_KEY rc4key;

void Fill(uint8_t* buffer, size_t length) {
// We need a zero buffer as OpenSSL will want to XOR the keystream with data.
// The XDVDFS random data is the keystream without changes, so we let XOR OpenSSL XOR with 0x00 bytes.
uint8_t zero_buffer[length];
memset(zero_buffer, 0x00, length);
RC4(&rc4key, length, zero_buffer, buffer);
}

void Seed() {
union {
uint8_t raw[16];
struct {
struct _FILETIME SystemTimeAsFileTime; // first 8 bytes, little-endian
uint64_t tsc; // later 8 bytes, little-endian
};
} key;

// Initialize seed
key.tsc = rdtsc();
GetSystemTimeAsFileTime(&key.SystemTimeAsFileTime);
RC4_set_key(&rc4key, 16, &key);

// Drop the first 2048 bytes of the RC4 keystream
uint8_t discard_buffer[2048];
Fill(discard_buffer, 2048);
}
</pre>

The RNG is seeded when the mastering tool / wizard is started.
The first portion of the code to use this random number generator is the code which generates layer 0 and layer 1.

=== Security blocks ===

==== Version 4361  ====

Treated like random block.

== Tools ==

* [https://github.com/OpenXDK/xbiso XBISO]
* [https://github.com/mborgerson/extract-xiso extract-xiso]