INTRODUCTION
-This is wimlib version 1.6.0 (January 2014). wimlib is a C library for
+This is wimlib version 1.6.2 (March 2014). wimlib is a C library for
creating, modifying, extracting, and mounting files in the Windows Imaging
Format (WIM files). These files are normally created using the ImageX
(imagex.exe) or Dism (Dism.exe) utilities on Windows, but wimlib is distributed
A WIM file may be either stand-alone or split into multiple parts. Split WIMs
are read-only and cannot be modified.
+Since version 1.6.0, wimlib also supports ESD (.esd) files, except when
+encrypted. These are still WIM files but they use a newer version of the file
+format.
+
IMAGEX IMPLEMENTATION
wimlib itself is a C library, and it provides a documented public API (See:
COMPRESSION RATIO
-wimlib (and wimlib-imagex) can create XPRESS, LZX, or LZMS compressed WIM archives.
-The following tables compare the compression ratio and performance for creating
-a compressed x86_64 Windows PE image. Note: these timings were done on Windows
-so that the times would be fully comparable; however, wimlib may have even
-better performance on other operating systems such as Linux. Timings were done
-with 2 CPUs available, both of which automatically are used by wimlib for both
-XPRESS and LZX, and also by imagex.exe but apparently only for LZX. Results for
-LZMS compression are excluded because the creation of LZMS compressed WIM
-archives is not yet recommended.
-
- Table 1. WIM size
-
- XPRESS Compression LZX Compression
- wimlib-imagex (v1.5.3): 207,444,390 bytes 188,106,091 bytes
- Microsoft imagex.exe (Windows 7): 209,960,209 bytes 188,224,481 bytes
-
- Table 2. Time to create WIM
-
- XPRESS Compression LZX Compression
- wimlib-imagex (v1.5.3): 73 sec 202 sec
- Microsoft imagex.exe (Windows 7): 90 sec 149 sec
-
-The above LZX data are using explicitly specified maximum compression
-('--compress=maximum') as of wimlib v1.5.3. If `wimlib-imagex capture' or
-`wimlib-imagex capture' is instead run with no '--compress' argument, then a
-faster LZX compressor is used; it will produce results in between those given
-for XPRESS and LZX above.
-
-Note: if the absolute maximum but still compatible (i.e. not changing the
-compression chunk size) LZX compression ratio is desired, `wimlib-imagex
-optimize WIMFILE --recompress --compress-slow' on one of the above
-LZX-compressed WIMs produces a WIM of 187,089,943 bytes in about 400 seconds.
+wimlib (and wimlib-imagex) can create XPRESS, LZX, or LZMS compressed WIM
+archives. wimlib includes its own compression codecs and does not use the
+compression API available on some versions of Windows. The below table provides
+the results (file size, in bytes, and time to create, in seconds) of capturing a
+WIM containing an x86 Windows PE image, using various compression types and
+options. When applicable, the results with the equivalent Microsoft
+implementation in WIMGAPI, which is the library used by ImageX and Dism, are
+included.
+
+ ===========================================================================
+ | Compression type || wimlib (v1.6.1) | WIMGAPI (Windows 8) |
+ ===========================================================================
+ | None [1] || 531,979,435 in 18s | 531,980,333 in 24s |
+ | XPRESS [2] || 207,369,912 in 22s | 209,886,010 in 39s |
+ | LZX (quick) [3] || 194,876,901 in 29s | N/A |
+ | LZX (normal) [4] || 187,962,713 in 158s | 188,163,523 in 125s |
+ | LZX (slow) [5] || 186,913,423 in 358s | N/A |
+ | LZMS (non-solid) [6] || 176,880,594 in 182s | N/A |
+ | LZMS (solid) [7] || 136,507,304 in 494s | 126,735,608 in 623s |
+ ===========================================================================
+
+Notes:
+ [1] '--compress=none' for wimlib-imagex;
+ '/compress none' or no option for ImageX.
+
+ [2] '--compress=fast' or '--compress=XPRESS' for wimlib-imagex;
+ '/compress fast' or no option for ImageX.
+ Compression chunk size is 32768 (the default for XPRESS).
+
+ [3] No compression option specified to wimlib-imagex; no known equivalent for
+ WIMGAPI (ImageX uses XPRESS compression if no option specified).
+ Compression chunk size is 32768 (the default for LZX).
+
+ [4] '--compress=maximum' or '--compress=LZX' for wimlib-imagex;
+ '/compress maximum' for ImageX.
+ Compression chunk size is 32768 (the default for LZX).
+
+ [5] '--compress=maximum --compress-slow' for wimlib-imagex;
+ no known equivalent for WIMGAPI.
+ Compression chunk size is 32768 (the default for LZX).
+
+ [6] '--compress=recovery' or '--compress=LZMS' for wimlib-imagex;
+ no known way to create the equivalent with WIMGAPI.
+ Compression chunk size is 131072 (the default for LZMS). Note: this
+ compression type is not generally recommended due to its limited
+ compatibility with the MS implementations.
+
+ [7] '--compress=recovery --solid' or '--compress=LZMS --solid' for
+ wimlib-imagex; WIMCreateFile with WIM_COMPRESSION_LZMS and flag
+ 0x20000000 for WIMGAPI. Compression chunk size in packed resources is
+ 33554432 for wimlib, 67108864 for WIMGAPI. Note: this compression type
+ is not generally recommended due to its limited compatibility with the MS
+ implementations. Also, due to the large chunk size, wimlib uses about
+ 500MB of memory per thread when compressing in this format.
+
+The above timings were done on Windows 8 (x86) so that side-by-side comparisons
+with the Microsoft implementation would be possible; however, wimlib may have
+even better performance on other operating systems such as Linux. The system
+had 2 CPUs and 2 GiB of memory available. All times were done with the page
+cache warmed, so the times primarily measure the performance of the compression
+algorithms and not the time to read data from disk, which presumably is similar
+in each implementation.
+
+Below are results for compressing the Canterbury corpus using wimlib (v1.6.1),
+WIMGAPI (Windows 8), and some other formats/programs, including the archive size
+only. Note that the Canterbury corpus includes no duplicate files or hard
+links, which WIM handles better than most other formats by storing only distinct
+data streams.
+
+ =================================================
+ | Format | Size (bytes) |
+ =================================================
+ | tar | 2,826,240 |
+ | WIM (WIMGAPI, None) | 2,814,278 |
+ | WIM (wimlib, None) | 2,813,856 |
+ | WIM (WIMGAPI, XPRESS) | 825,410 |
+ | WIM (wimlib, XPRESS) | 792,024 |
+ | tar.gz (gzip, default) | 738,796 |
+ | ZIP (Info-ZIP, default) | 735,334 |
+ | tar.gz (gzip, -9) | 733,971 |
+ | ZIP (Info-ZIP, -9) | 732,297 |
+ | WIM (wimlib, LZX quick) | 722,196 |
+ | WIM (WIMGAPI, LZX) | 651,766 |
+ | WIM (wimlib, LZX normal) | 639,464 |
+ | WIM (wimlib, LZX slow) | 633,144 |
+ | WIM (wimlib, LZMS non-solid) | 590,252 |
+ | tar.bz2 (bzip, default) | 565,008 |
+ | tar.bz2 (bzip, -9) | 565,008 |
+ | WIM (wimlib, LZMS solid) | 534,218 |
+ | WIM (wimlib, LZMS solid, slow) | 529,904 |
+ | WIM (WIMGAPI, LZMS solid) | 521,232 |
+ | tar.xz (xz, default) | 486,916 |
+ | tar.xz (xz, -9) | 486,904 |
+ | 7z (7-zip, default) | 484,700 |
+ | 7z (7-zip, -9) | 483,239 |
+ =================================================
NTFS SUPPORT
(https://code.google.com/p/libdivsufsort/) and algorithms from 7-Zip as well as
several published papers.
-lz77.c contains a hash-table-based LZ77 matchfinder that is based on code from
-zlib but has been rewritten. This code is applicable to XPRESS, LZX, and LZMS,
-all of which are partly based on LZ77 compression.
+lz_hash.c contains a hash-table-based LZ77 matchfinder that is based on code
+from zlib but has been rewritten. This code is applicable to XPRESS, LZX, and
+LZMS, all of which are partly based on LZ77 compression.
A limited number of other free programs can handle some parts of the WIM
file format:
git://wimlib.net / wimlib / blobdiff