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README.md
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@ -4,7 +4,7 @@ lrzip - Long Range ZIP or LZMA RZIP
A compression utility that excels at compressing large files (usually > 10-50 MB). A compression utility that excels at compressing large files (usually > 10-50 MB).
Larger files and/or more free RAM means that the utility will be able to more Larger files and/or more free RAM means that the utility will be able to more
effectively compress your files (ie: faster / smaller size), especially if the effectively compress your files (ie: faster / smaller size), especially if the
filesize(s) exceed 100 MB. You can either choose to optimize for speed (fast filesize(s) exceed 100 MB. You can either choose to optimise for speed (fast
compression / decompression) or size, but not both. compression / decompression) or size, but not both.
@ -89,6 +89,8 @@ Simple 'n Easy™: `sudo make install`
|`lrzip -z filename`|An archive "filename.lrz" compressed with **ZPAQ** that can give extreme compression, but takes a bit longer than forever to compress and decompress.| |`lrzip -z filename`|An archive "filename.lrz" compressed with **ZPAQ** that can give extreme compression, but takes a bit longer than forever to compress and decompress.|
|`lrzip -l filename`|An archive lightly compressed with **LZO**, meaning really, really fast compression and decompression.| |`lrzip -l filename`|An archive lightly compressed with **LZO**, meaning really, really fast compression and decompression.|
|`lrunzip filename.lrz`|Decompress filename.lrz to filename.| |`lrunzip filename.lrz`|Decompress filename.lrz to filename.|
|`lrz filename`|As per lrzip above but with gzip compatible semantics (i.e. will be quiet and delete original file)
|`lrz -d filename.lrz`|As per lrunzip above but with gzip compatible semantics (i.e. will be quiet and delete original file)
### lrzip internals ### lrzip internals
@ -281,13 +283,13 @@ its very nature has very little redundancy. This means that there is not
much that can actually be compressed. If your video/audio/picture is in a much that can actually be compressed. If your video/audio/picture is in a
high bitrate, there will be more redundancy than a low bitrate one making it high bitrate, there will be more redundancy than a low bitrate one making it
more suitable to compression. None of the compression techniques in lrzip are more suitable to compression. None of the compression techniques in lrzip are
optimised for this sort of dat optimised for this sort of data.
> A: However, the nature of rzip preparation > A: However, the nature of rzip preparation
means that you'll still get better compression than most normal compression means that you'll still get better compression than most normal compression
algorithms give you if you have very large files. ISO images of dvds for algorithms give you if you have very large files. ISO images of dvds for
example are best compressed directly instead of individual .VOB files. ZPAQ is example are best compressed directly instead of individual .VOB files. ZPAQ is
the only compression format that can do any significant compression of the only compression format that can do any significant compression of
multimedi multimedia.
> A: > A:
> Q: Is this multithreaded? > Q: Is this multithreaded?
@ -397,9 +399,14 @@ compression backend (lzma) needs to compress.
> Q: This version is much slower than the old version? > Q: This version is much slower than the old version?
> A: Make sure you have set CFLAGS and CXXFLAGS. An unoptimized build will be > A: Make sure you have set CFLAGS and CXXFLAGS. An unoptimised build will be
almost 3 times slower. almost 3 times slower.
> Q: Why not update to the latest version of libzpaq?
> A: For reasons that are unclear the later versions of libzpaq create
corrupt archives when included with lrzip
#### LIMITATIONS #### LIMITATIONS
Due to mmap limitations the maximum size a window can be set to is currently Due to mmap limitations the maximum size a window can be set to is currently
2GB on 32bit unless the -U option is specified. Files generated on 64 bit 2GB on 32bit unless the -U option is specified. Files generated on 64 bit
@ -465,7 +472,7 @@ Persons above are listed in chronological order of first contribution to **lrzip
#### README Authors #### README Authors
Con Kolivas (`ckolivas` on GitHub) <kernel@kolivas.org> Con Kolivas (`ckolivas` on GitHub) <kernel@kolivas.org>
Sat, 11 March 2011: README Fri, 10 June 2016: README
Also documented by Also documented by
Peter Hyman <pete@peterhyman.com> Peter Hyman <pete@peterhyman.com>