Conversion Methods

Conversion Methods

Getting Started	Using the App	Technical Reference	Project
Home	Usage Guide	Architecture	Repository
Installation	Conversion Methods	XDVDFS Technical Docs	Building from Source
	XISO Explorer	Troubleshooting & FAQ	Release Notes

---

All conversion is performed in-process by the XISOSharp library, with CHDSharp handling CHD output. No external conversion binaries are required or bundled. The Convert tab can produce optimized XISO, compressed ZAR, compressed CSO, compressed CCI, or compressed CHD output from the same packing pipeline, and the Decompress tab turns any of those containers back into a plain ISO.

How It Works

XISOSharp repacks the game partition into an optimized XISO:

1. The XDVDFS volume descriptor is located (auto-detecting Redump/XGD partition offsets).
2. The directory tree is read and the file data is copied into a new, tightly packed XISO.
3. Gaps between files are removed, and the optimized tag is written so later runs can skip already-converted files.

What Gets Removed

• Video Partition (DVD movie/demonstration content) — ~7–387 MB removed
• End Padding (empty sectors after the last file) — variable
• System Update (optional, when Skip $SystemUpdate is enabled) — ~100–300 MB removed

Visual Comparison

Redump ISO (Original):
[Video Partition][XDVDFS: Header][Dir][File A][gap][File B][gap][File C][Padding]

XISOSharp Output:
[XDVDFS: Header][Dir][File A][File B][File C]   (gaps removed, tightly packed)
                      ^    ^    ^
                 Files repositioned for maximum compression

Features

• Smallest output size — files are packed tightly, with video partition and padding removed.
• No external tools — the conversion engines (XISOSharp and CHDSharp) ship inside the application.
• Redump-aware — automatically detects XGD1/XGD2/XGD3 and hybrid partition offsets.
• Already-optimized files are skipped — images carrying the optimized tag are not converted again.
• Optional $SystemUpdate skipping for extra space savings — also honored for already-optimized inputs written as CSO/CHD (they are rewritten through the filter before packing).
• Optional output integrity check — the new XISO is structurally audited, then every non-CHD output is compared with its source (file paths, sizes and per-file SHA-256 hashes). A deliberate $SystemUpdate removal is not counted as a mismatch.
• Integrated with the application's progress reporting, cancellation, and disk monitoring.

Output Formats

The Convert tab can produce five output formats from the same optimized packing pipeline:

Format	Extension	Description
XISO (default)	.iso	Optimized, tightly packed XISO image. Already-optimized inputs are skipped.
ZAR	.zar	ZArchive: the game-partition file tree packed with pure-C# zstd (level 6, 64 KiB blocks, raw fallback for incompressible blocks). Byte-compatible with zarchive.exe/xboxkit, and Xenia canary loads it directly.
CSO	.cso	CISO v2 (LZ4, byte-identical to xdvdfs compress), written as a single file. Redump/non-optimized inputs are first repacked to a temporary optimized XISO, then compressed.
CCI	.cci	CCI/CCIM (LZ4 levels 1–9, level 9 by default), written as a single file. Redump/non-optimized inputs are first repacked to a temporary optimized XISO, then compressed.
CHD	.chd	CHD v5 (Compressed Hunks of Data) written by CHDSharp with the chdman createdvd preset: 4096-byte hunks, 2048-byte units, and the lzma,zlib,huff,flac codec list. Redump/non-optimized inputs are first repacked to a temporary optimized XISO, then encoded with the DVD metadata tag; the output is deep-verified against every hunk checksum.

Skip $SystemUpdate applies to all five formats: XISO, CSO, CCI, and CHD omit the folder during the rewrite, and ZAR excludes it from the archive tree. Check Output Integrity deep-verifies the newly created CHD (all hunks and hashes); for XISO, CSO, CCI and ZAR it audits the output and then compares the output file tree with the source (paths, sizes and optional SHA-256 checksums) through XisoValidator. A deliberately removed $SystemUpdate folder is ignored during that comparison.

Decompression

The Decompress tab turns container images back into a plain sector image:

Input	Method
.cso / split .1.cso	CisoReader.DecompressToIso
.cci / split .1.cci	XisoCci.DecompressToIso
.zar	XisoZarchive.ConvertZarToIso (the tree is repacked, so the tree hash is preserved while the sector layout may differ)
.chd	the decompressed ChdImageStream is copied to an ISO
GOD/SVOD header (its .data folder is resolved automatically)	the mapped logical image is copied to an ISO

Plain .iso/.xiso/.img inputs are listed but skipped as already uncompressed. Each result can be structurally audited before it is reported as successful, and Delete Originals removes the source image (including every part of a split set) only after a successful decompression.

---

Archive Support

.zip, .7z, and .rar archives are processed transparently:

1. The archive is extracted to a temporary folder (SharpCompress is used first; the bundled 7-Zip CLI handles complex .7z archives).
2. The first ISO/XISO/IMG inside is converted to the selected output format with XISOSharp/CHDSharp; additional images, non-image entries, and unsafe entries are reported as skipped.
3. Temporary files are cleaned up.

Encrypted or password-protected archives are detected up front and skipped with a clear message. With Delete Originals enabled, an archive is deleted only when every entry was extracted and every extracted image was converted — skipped entries keep the archive.