https://wiki.openzim.org/w/index.php?title=LZMA2_compression&feed=atom&action=historyLZMA2 compression - Revision history2024-03-29T14:00:58ZRevision history for this page on the wikiMediaWiki 1.36.1https://wiki.openzim.org/w/index.php?title=LZMA2_compression&diff=1118&oldid=prevKelson at 16:08, 17 October 20102010-10-17T16:08:15Z<p></p>
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td>
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 16:08, 17 October 2010</td>
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<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>'''LZMA2 (de)compression''' is the standard and only one compression algorithm supported in ZIM. In the <del style="font-weight: bold; text-decoration: none;">zimlib, </del>this done with the xz-utils library.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>'''LZMA2 (de)compression''' is the standard and only one compression algorithm supported in ZIM. In the <ins style="font-weight: bold; text-decoration: none;">standart implementation </ins>this done with the xz-utils library.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>A problem with LZMA2 is, that with higher compression rates the memory needed for decompression increases. Using the highest rate 9, 65 MB RAM is needed. On the Nanonote, which we want to support we have only 32 MB installed. Tests showed, that level 4 is too much, but 3 is ok. xz-utils has a additional extreme-flag, which justifies the lzma2 parameters so that the compression ratio of lzma2 level 3 is almost identical with bzip2 (deprecated). The big advantage is, that decompression of lzma2 is much faster (factor 3-4) than bzip2. The downside is, that creating zim files with lzma2 is much slower than bzip2 and the support for xz-utils is not yet that widespread.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>A problem with LZMA2 is, that with higher compression rates the memory needed for decompression increases. Using the highest rate 9, 65 MB RAM is needed. On the Nanonote, which we want to support we have only 32 MB installed. Tests showed, that level 4 is too much, but 3 is ok. xz-utils has a additional extreme-flag, which justifies the lzma2 parameters so that the compression ratio of lzma2 level 3 is almost identical with bzip2 (deprecated). The big advantage is, that decompression of lzma2 is much faster (factor 3-4) than bzip2. The downside is, that creating zim files with lzma2 is much slower than bzip2 and the support for xz-utils is not yet that widespread.</div></td></tr>
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</table>Kelsonhttps://wiki.openzim.org/w/index.php?title=LZMA2_compression&diff=1117&oldid=prevKelson at 16:06, 17 October 20102010-10-17T16:06:28Z<p></p>
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 16:06, 17 October 2010</td>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>'''LZMA2 (de)compression''' is the standard and only one compression algorithm supported in ZIM. In the zimlib, this done with the xz-utils library.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>'''LZMA2 (de)compression''' is the standard and only one compression algorithm supported in ZIM. In the zimlib, this done with the xz-utils library.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>A problem with LZMA2 is, that with higher compression rates the memory needed for decompression increases. Using the highest rate 9, 65 MB RAM is needed. On the Nanonote, which we want to support we have only 32 MB installed. Tests showed, that level 4 is too much, but 3 is ok. xz-utils has a additional extreme-flag, which justifies the <del style="font-weight: bold; text-decoration: none;">lzma </del>parameters so that the compression ratio of <del style="font-weight: bold; text-decoration: none;">lzma </del>level 3 is almost identical with bzip2 (deprecated). The big advantage is, that decompression of <del style="font-weight: bold; text-decoration: none;">lzma </del>is much faster (factor 3-4) than bzip2. The downside is, that creating zim files with <del style="font-weight: bold; text-decoration: none;">lzma </del>is much slower than bzip2 and the support for xz-utils is not yet that widespread.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>A problem with LZMA2 is, that with higher compression rates the memory needed for decompression increases. Using the highest rate 9, 65 MB RAM is needed. On the Nanonote, which we want to support we have only 32 MB installed. Tests showed, that level 4 is too much, but 3 is ok. xz-utils has a additional extreme-flag, which justifies the <ins style="font-weight: bold; text-decoration: none;">lzma2 </ins>parameters so that the compression ratio of <ins style="font-weight: bold; text-decoration: none;">lzma2 </ins>level 3 is almost identical with bzip2 (deprecated). The big advantage is, that decompression of <ins style="font-weight: bold; text-decoration: none;">lzma2 </ins>is much faster (factor 3-4) than bzip2. The downside is, that creating zim files with <ins style="font-weight: bold; text-decoration: none;">lzma2 </ins>is much slower than bzip2 and the support for xz-utils is not yet that widespread.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Here are some test results:</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Here are some test results:</div></td></tr>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Creating a file with 55498 index entries with 28936 articles.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Creating a file with 55498 index entries with 28936 articles.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>bzip2 (deprecated):</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">;</ins>bzip2 (deprecated):</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div> size: 90207329</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div> size: 90207329</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div> creating: 0:02:18</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div> creating: 0:02:18</div></td></tr>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div> reading random access on Nanonote: 0.7 #/s</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div> reading random access on Nanonote: 0.7 #/s</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><del style="font-weight: bold; text-decoration: none;">lzma</del>:</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">;lzma2</ins>:</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div> size: 90286916</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div> size: 90286916</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div> creating: 0:12:01</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div> creating: 0:12:01</div></td></tr>
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</table>Kelsonhttps://wiki.openzim.org/w/index.php?title=LZMA2_compression&diff=1115&oldid=prevKelson at 16:05, 17 October 20102010-10-17T16:05:51Z<p></p>
<table style="background-color: #fff; color: #202122;" data-mw="interface">
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<col class="diff-marker" />
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td>
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 16:05, 17 October 2010</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l1">Line 1:</td>
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<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><del style="font-weight: bold; text-decoration: none;">LZMA </del>compression is done with the xz-utils library.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">'''LZMA2 (de)</ins>compression<ins style="font-weight: bold; text-decoration: none;">''' </ins>is <ins style="font-weight: bold; text-decoration: none;">the standard and only one compression algorithm supported in ZIM. In the zimlib, this </ins>done with the xz-utils library.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>A problem with <del style="font-weight: bold; text-decoration: none;">LZMA </del>is, that with higher compression rates the memory needed for decompression increases. Using the highest rate 9, 65 MB RAM is needed. On the Nanonote, which we want to support we have only 32 MB installed. Tests showed, that level 4 is too much, but 3 is ok. xz-utils has a additional extreme-flag, which justifies the lzma parameters so that the compression ratio of lzma level 3 is almost identical with bzip2. The big advantage is, that decompression of lzma is much faster (factor 3-4) than bzip2. The downside is, that creating zim files with lzma is much slower than bzip2 and the support for xz-utils is not yet that widespread.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>A problem with <ins style="font-weight: bold; text-decoration: none;">LZMA2 </ins>is, that with higher compression rates the memory needed for decompression increases. Using the highest rate 9, 65 MB RAM is needed. On the Nanonote, which we want to support we have only 32 MB installed. Tests showed, that level 4 is too much, but 3 is ok. xz-utils has a additional extreme-flag, which justifies the lzma parameters so that the compression ratio of lzma level 3 is almost identical with bzip2 <ins style="font-weight: bold; text-decoration: none;">(deprecated)</ins>. The big advantage is, that decompression of lzma is much faster (factor 3-4) than bzip2. The downside is, that creating zim files with lzma is much slower than bzip2 and the support for xz-utils is not yet that widespread.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Here are some test results:</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Here are some test results:</div></td></tr>
<tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l7">Line 7:</td>
<td colspan="2" class="diff-lineno">Line 7:</td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Creating a file with 55498 index entries with 28936 articles.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Creating a file with 55498 index entries with 28936 articles.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>bzip2:</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>bzip2 <ins style="font-weight: bold; text-decoration: none;">(deprecated)</ins>:</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div> size: 90207329</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div> size: 90207329</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div> creating: 0:02:18</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div> creating: 0:02:18</div></td></tr>
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</table>Kelsonhttps://wiki.openzim.org/w/index.php?title=LZMA2_compression&diff=1112&oldid=prevKelson: moved LZMA compression to LZMA2 compression2010-10-17T16:02:29Z<p>moved <a href="/wiki/LZMA_compression" class="mw-redirect" title="LZMA compression">LZMA compression</a> to <a href="/wiki/LZMA2_compression" title="LZMA2 compression">LZMA2 compression</a></p>
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 16:02, 17 October 2010</td>
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</table>Kelsonhttps://wiki.openzim.org/w/index.php?title=LZMA2_compression&diff=751&oldid=prevTntnet: Created page with 'LZMA compression is done with the xz-utils library. A problem with LZMA is, that with higher compression rates the memory needed for decompression increases. Using the highest r…'2010-01-01T23:31:08Z<p>Created page with 'LZMA compression is done with the xz-utils library. A problem with LZMA is, that with higher compression rates the memory needed for decompression increases. Using the highest r…'</p>
<p><b>New page</b></p><div>LZMA compression is done with the xz-utils library.<br />
<br />
A problem with LZMA is, that with higher compression rates the memory needed for decompression increases. Using the highest rate 9, 65 MB RAM is needed. On the Nanonote, which we want to support we have only 32 MB installed. Tests showed, that level 4 is too much, but 3 is ok. xz-utils has a additional extreme-flag, which justifies the lzma parameters so that the compression ratio of lzma level 3 is almost identical with bzip2. The big advantage is, that decompression of lzma is much faster (factor 3-4) than bzip2. The downside is, that creating zim files with lzma is much slower than bzip2 and the support for xz-utils is not yet that widespread.<br />
<br />
Here are some test results:<br />
<br />
Creating a file with 55498 index entries with 28936 articles.<br />
<br />
bzip2:<br />
size: 90207329<br />
creating: 0:02:18<br />
reading random access: 29 #/s<br />
creating full text index: 00:03:01<br />
size of full text index: 92184996<br />
reading random access on Nanonote: 0.7 #/s<br />
<br />
lzma:<br />
size: 90286916<br />
creating: 0:12:01<br />
reading random access: 120 #/s<br />
creating full text index: 00:03:03<br />
size of full text index: 87282408<br />
reading random access on Nanonote: 2.3 #/s<br />
<br />
The tests (except the benchmark on the Nanonote) are done on our test machine - a dual core AMD 2,6GHz.</div>Tntnet