1 | <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
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2 | <HTML>
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3 | <HEAD>
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4 | <META http-equiv="Content-Type" content="text/html; charset=Windows-1252">
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5 | <TITLE>-m (Set compression Method) switch</TITLE>
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6 | <LINK href="style.css" rel="stylesheet" type="text/css">
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7 | </HEAD>
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8 |
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9 | <BODY>
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10 |
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11 | <H1>-m (Set compression Method) switch</H1>
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12 |
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13 | <P>Specifies the compression method.</P>
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14 |
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15 | <H4>Syntax</H4>
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16 |
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17 | <PRE class="syntax">
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18 | -m<method_parameters>
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19 |
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20 | </PRE>
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21 |
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22 | <P>The format for this switch depends on the archive type.</P>
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23 |
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24 | <UL>
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25 | <LI><TD><A class="parameter" href="#Zip">Zip</A></TD>
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26 | <LI><TD><A class="parameter" href="#GZ">GZip</A></TD>
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27 | <LI><TD><A class="parameter" href="#BZ2">BZip2</A></TD>
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28 | <LI><TD><A class="parameter" href="#7Z">7z</A></TD>
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29 | <LI><TD><A class="parameter" href="#XZ">XZ</A></TD>
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30 | </UL>
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31 |
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32 | <H2><A name="Zip"></A>Zip</H2>
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33 | <TABLE>
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34 | <TR>
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35 | <TH width="160">Parameter</TH>
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36 | <TH align="center">Default</TH>
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37 | <TH>Description</TH> </TR>
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38 | <TR>
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39 | <TD><A class="parameter" href="#ZipX">x=[0 | 1 | 3 | 5 | 7 | 9 ]</A></TD>
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40 | <TD align="center">5</TD>
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41 | <TD>Sets level of compression.</TD> </TR>
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42 | <TR>
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43 | <TD>m={MethodID}</TD>
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44 | <TD align="center">Deflate</TD>
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45 | <TD>Sets a method: Copy, Deflate, Deflate64, BZip2, LZMA, PPMd.</TD> </TR>
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46 | <TR>
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47 | <TD><A class="parameter" href="#Deflate_FastBytes">fb={NumFastBytes}</A></TD>
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48 | <TD align="center">32</TD>
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49 | <TD>Sets number of Fast Bytes for Deflate encoder.</TD> </TR>
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50 | <TR>
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51 | <TD><A class="parameter" href="#Zip_Pass">pass={NumPasses}</A></TD>
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52 | <TD align="center">1</TD>
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53 | <TD>Sets number of Passes for Deflate encoder.</TD></TR>
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54 | <TR>
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55 | <TD><A class="parameter" href="#ZipDictionarySize">d={Size}[b|k|m]</A></TD>
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56 | <TD align="center">900000</TD>
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57 | <TD>Sets Dictionary size for BZip2</TD></TR>
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58 | <TR>
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59 | <TD><A class="parameter" href="#ZipMemorySize">mem={Size}[b|k|m]</A></TD>
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60 | <TD align="center">24</TD> <TD>Sets size of used memory for PPMd.</TD></TR>
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61 | <TR>
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62 | <TD><A class="parameter" href="#ZipOrder">o={Size}</A></TD>
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63 | <TD align="center">8</TD> <TD>Sets model order for PPMd.</TD></TR>
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64 | <TR>
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65 | <TD><A class="parameter" href="#ZipMultiThread">mt=[off | on | {N}]</A></TD>
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66 | <TD align="center">on</TD>
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67 | <TD>Sets multithreading mode.</TD></TR>
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68 | <TR>
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69 | <TD>em={EncryptionMethodID}</TD>
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70 | <TD align="center">ZipCrypto</TD>
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71 | <TD>Sets a encryption method: ZipCrypto, AES128, AES192, AES256</TD> </TR>
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72 | <TR> <TD><A class="parameter">tc=[off | on]</A></TD>
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73 | <TD align="center">off</TD> <TD>Stores NTFS timestamps for files: Modification time, Creation time, Last access time.</TD> </TR>
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74 | <TR> <TD><A class="parameter">cl=[off | on]</A></TD>
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75 | <TD align="center">off</TD> <TD>7-Zip always uses local code page for file names.</TD> </TR>
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76 | <TR> <TD><A class="parameter">cu=[off | on]</A></TD>
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77 | <TD align="center">off</TD> <TD>7-Zip uses UTF-8 for file names that contain non-ASCII symbols.</TD> </TR>
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78 | </TABLE>
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79 |
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80 | <P>By default (if <B>cl</B> and <B>cu</B> switches are not specified), 7-Zip uses UTF-8 encoding
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81 | only for file names that contain symbols unsupported by local code page.</P>
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82 |
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83 | <DL>
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84 | <DT><A name="ZipX"></A>x=[0 | 1 | 3 | 5 | 7 | 9 ]</DT>
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85 | <DD>
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86 | <P>Sets level of compression. x=0 means Copy mode (no compression).</P>
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87 | <P>Deflate / Deflate64 settings:</P>
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88 | <TABLE>
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89 | <TR> <TH>Level</TH> <TH>NumFastBytes</TH> <TH>NumPasses</TH> <TH>Description</TH> </TR>
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90 | <TR> <TD class="cc">1</TD> <TD class="cc" rowspan=3>32</TD> <TD class="cc" rowspan=3>1</TD> <TD>Fastest</TD> </TR>
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91 | <TR> <TD class="cc">3</TD> <TD>Fast</TR>
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92 | <TR> <TD class="cc">5</TD> <TD>Normal</TR>
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93 | <TR> <TD class="cc">7</TD> <TD class="cc">64</TD> <TD class="cc">3</TD> <TD>Maximum</TD> </TR>
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94 | <TR> <TD class="cc">9</TD> <TD class="cc">128</TD> <TD class="cc">10</TD> <TD>Ultra</TD> </TR>
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95 | </TABLE>
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96 |
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97 | <P>x=1 and x=3 with Deflate method set fast mode for compression.</P>
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98 |
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99 | <P>BZip2 settings:</P>
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100 | <TABLE>
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101 | <TR> <TH>Level</TH> <TH>Dictionary</TH> <TH>NumPasses</TH> <TH>Description</TH> </TR>
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102 | <TR> <TD class="cc">1</TD> <TD class="cc">100000</TD> <TD class="cc" rowspan=3>1</TD> <TD>Fastest</TD> </TR>
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103 | <TR> <TD class="cc">3</TD> <TD class="cc">500000</TD> <TD>Fast</TD> </TR>
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104 | <TR> <TD class="cc">5</TD> <TD class="cc" rowspan=3>900000</TD> <TD>Normal</TD> </TR>
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105 | <TR> <TD class="cc">7</TD> <TD align="center">2</TD> <TD>Maximum</TD> </TR>
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106 | <TR> <TD class="cc">9</TD> <TD align="center">7</TD> <TD>Ultra</TD> </TR>
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107 | </TABLE>
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108 | </DD>
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109 |
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110 | <DT><A name="Deflate_FastBytes"></A>fb={NumFastBytes}</DT>
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111 | <DD>
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112 | <P>Sets the number of fast bytes for the Deflate/Deflate64 encoder.
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113 | It can be in the range from 3 to 258 (257 for Deflate64).
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114 | Usually, a big number gives a little bit better
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115 | compression ratio and a slower compression process.
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116 | A large fast bytes parameter can significantly increase the compression ratio
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117 | for files which contain long identical sequences of bytes.</P>
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118 | </DD>
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119 | <DT><A name="Zip_Pass"></A>pass={NumPasses}</DT>
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120 | <DD>
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121 | <P>Sets number of passes for Deflate encoder. It can be in the range from 1 to 15 for Deflate and
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122 | from 1 to 10 for BZip2. Usually, a big number gives a little bit better
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123 | compression ratio and a slower compression process.
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124 | </P>
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125 | </DD>
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126 | <DT><A name="ZipDictionarySize"></A>d={Size}[b|k|m]</DT>
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127 | <DD>
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128 | <P> Sets the Dictionary size for BZip2. You must specify the size in bytes, kilobytes, or megabytes.
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129 | The maximum value for the Dictionary size is 900000b. If you do not specify any symbol
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130 | from set [b|k|m], dictionary size will be calculated as DictionarySize = 2^Size bytes.</P>
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131 | </DD>
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132 |
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133 | <DT><A name="ZipMemorySize"></A>mem={Size}[b|k|m]</DT>
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134 | <DD>
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135 | <P> Sets the size of memory used for PPMd. You must specify the size in bytes, kilobytes, or megabytes.
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136 | The maximum value is 256 MB = 2^28 bytes. The default value
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137 | is 24 (16MB). If you do not specify any symbol from the set [b|k|m], the
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138 | memory size will be calculated as (2^Size) bytes. PPMd uses the same
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139 | amount of memory for compression and decompression.</P>
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140 | </DD>
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141 |
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142 | <DT><A name="ZipOrder"></A>o={Size}</DT>
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143 | <DD>
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144 | <P>Sets the model order for PPMd. The size must be in the range [2,16]. The default value is 8.</P>
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145 | </DD>
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146 |
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147 | <DT><A name="ZipMultiThread"></A>mt=[off | on | {N}]</DT>
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148 | <DD>
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149 | <P>Sets multithread mode. If you have a multiprocessor or multicore system,
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150 | you can get a speed increase with
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151 | this switch. This option affects only compression (with any method) and
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152 | decompression of BZip2 streams.
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153 | Each thread in the multithread mode uses 32 MB of RAM for buffering.
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154 | If you specify {N}, 7-Zip tries to use N threads.</P>
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155 | </DD>
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156 | </DL>
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157 |
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158 | <H2><A name="GZ"></A>GZip</H2>
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159 | GZip uses the same parameters as Zip, but GZip compresses only with Deflate method.
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160 | So GZip supports only the following parameters: x, fb, pass.
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161 |
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162 | <H2><A name="BZ2"></A>BZip2</H2>
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163 | <TABLE>
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164 | <TR>
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165 | <TH width="160">Parameter</TH>
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166 | <TH align="center">Default</TH>
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167 | <TH>Description</TH> </TR>
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168 | <TR>
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169 | <TD><A class="parameter" href="#BZip2X">x=[1 | 3 | 5 | 7 | 9 ]</A></TD>
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170 | <TD align="center">5</TD>
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171 | <TD>Sets level of compression.</TD> </TR>
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172 | <TR>
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173 | <TD><A class="parameter" href="#BZip2Pass">pass={NumPasses}</A></TD>
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174 | <TD align="center">1</TD>
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175 | <TD>Sets number of Passes for Bzip2 encoder.</TD></TR>
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176 | <TR>
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177 | <TD><A class="parameter" href="#BZip2DictionarySize">d={Size}[b|k|m]</A></TD>
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178 | <TD align="center">900000</TD>
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179 | <TD>Sets Dictionary size for BZip2</TD></TR>
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180 | <TR>
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181 | <TD><A class="parameter" href="#BZip2MultiThread">mt=[off | on | {N}]</A></TD>
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182 | <TD align="center">on</TD>
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183 | <TD>Sets multithreading mode.</TD></TR>
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184 | </TABLE>
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185 |
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186 | <DL>
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187 | <DT><A name="BZip2"></A>x=[1 | 3 | 5 | 7 | 9 ]</DT>
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188 | <DD>
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189 | <P>Sets level of compression</P>
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190 | <TABLE>
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191 | <TR> <TH>Level</TH> <TH>Dictionary</TH> <TH>NumPasses</TH> <TH>Description</TH> </TR>
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192 | <TR> <TD class="cc">1</TD> <TD class="cc">100000</TD> <TD class="cc" rowspan=3>1</TD> <TD>Fastest</TD> </TR>
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193 | <TR> <TD class="cc">3</TD> <TD class="cc">500000</TD> <TD>Fast</TD> </TR>
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194 | <TR> <TD class="cc">5</TD> <TD class="cc" rowspan=3>900000</TD> <TD>Normal</TD> </TR>
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195 | <TR> <TD class="cc">7</TD> <TD align="center">2</TD> <TD>Maximum</TD> </TR>
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196 | <TR> <TD class="cc">9</TD> <TD align="center">7</TD> <TD>Ultra</TD> </TR>
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197 | </TABLE>
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198 | </DD>
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199 |
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200 | <DT><A name="BZip2DictionarySize"></A>d={Size}[b|k|m]</DT>
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201 | <DD>
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202 | <P> Sets the Dictionary size for BZip2. You must specify the size in bytes, kilobytes, or megabytes.
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203 | The maximum value for the Dictionary size is 900000b. If you do not specify any symbol
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204 | from set [b|k|m], dictionary size will be calculated as DictionarySize = 2^Size bytes.</P>
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205 | </DD>
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206 |
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207 | <DT><A name="#BZip2Pass"></A>pass={NumPasses}</DT>
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208 | <DD>
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209 | <P>Sets the number of passes. It can be in the range from 1 to 10.
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210 | The default value is 1 for normal mode, 2 for maximum mode and 7 for ultra mode.
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211 | A bigger number can give a little bit better compression ratio and a slower compression process.
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212 | </P>
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213 | </DD>
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214 | <DT><A name="BZip2MultiThread"></A>mt=[off | on | {N}]</DT>
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215 | <DD>
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216 | <P>Sets multithread mode. If you have a multiprocessor or multicore system,
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217 | you can get a speed increase with
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218 | this switch. If you specify {N}, for example mt=4, 7-Zip tries to use 4 threads.</P>
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219 | </DD>
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220 | </DL>
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221 |
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222 | <H2><A name="7Z"></A>7z</H2>
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223 | <TABLE>
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224 | <TR> <TH width="80">Parameter</TH> <TH align="center">Default</TH> <TH>Description</TH> </TR>
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225 | <TR> <TD><A class="parameter" href="#SevenZipX">x=[0 | 1 | 3 | 5 | 7 | 9 ]</A></TD>
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226 | <TD align="center">5</TD><TD>Sets level of compression.</TD> </TR>
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227 | <TR> <TD><A class="parameter" href="#Solid">s=[off | on | [e] [{N}f] [{N}b | {N}k | {N}m | {N}g]</A></TD>
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228 | <TD align="center">on</TD> <TD>Sets solid mode.</TD> </TR>
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229 | <TR> <TD><A class="parameter" href="#Filter">f=[off | on]</A></TD>
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230 | <TD align="center">on</TD> <TD>Enables or disables compression filters for executable files.</TD> </TR>
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231 | <TR> <TD><A class="parameter" href="#HeaderCompress">hc=[off | on]</A></TD>
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232 | <TD align="center">on</TD> <TD>Enables or disables archive header compressing.</TD> </TR>
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233 | <TR> <TD><A class="parameter" href="#HeaderEncrypt">he=[off | on]</A></TD>
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234 | <TD align="center">off</TD> <TD>Enables or disables archive header encryption.</TD> </TR>
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235 | <TR> <TD><A class="parameter" href="#Bind">b{C1}[s{S1}]:{C2}[s{S2}]</A></TD>
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236 | <TD align="center"> </TD> <TD>Sets binding beetwen coders.</TD> </TR>
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237 | <TR> <TD><A class="parameter" href="#MethodID">{N}={MethodID}[:param1][:param2][..]</A></TD>
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238 | <TD align="center">LZMA</TD> <TD>Sets a method: LZMA, LZMA2, PPMd, BZip2, Deflate, Delta, BCJ, BCJ2, Copy.</TD> </TR>
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239 | <TR> <TD><A class="parameter" href="#MultiThread">mt=[off | on | {N}]</A></TD>
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240 | <TD align="center">on</TD> <TD>Sets multithreading mode.</TD> </TR>
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241 | <TR> <TD><A class="parameter">tc=[off | on]</A></TD>
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242 | <TD align="center">off</TD> <TD>Stores file creation timestamps.</TD> </TR>
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243 | </TABLE>
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244 |
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245 | <DL>
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246 | <DT><A name="SevenZipX"></A>x=[0 | 1 | 3 | 5 | 7 | 9 ]</DT>
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247 | <DD>
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248 | <P>Sets level of compression</P>
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249 | <TABLE>
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250 | <TR> <TH>Level</TH> <TH>Method</TH> <TH>Dictionary</TH> <TH>FastBytes</TH> <TH>MatchFinder</TH> <TH>Filter</TH> <TH>Description</TH> </TR>
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251 | <TR> <TD align="center">0</TD> <TD align="center">Copy</TD> <TD align="center"></TD> <TD align="center"></TD> <TD align="center"></TD> <TD align="center"></TD> <TD>No compression.</TD> </TR>
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252 | <TR> <TD align="center">1</TD> <TD align="center">LZMA</TD> <TD align="center">64 KB</TD> <TD align="center">32</TD> <TD align="center">HC4</TD> <TD align="center">BCJ</TD> <TD>Fastest compressing</TD> </TR>
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253 | <TR> <TD align="center">3</TD> <TD align="center">LZMA</TD> <TD align="center">1 MB</TD> <TD align="center">32</TD> <TD align="center">HC4</TD> <TD align="center">BCJ</TD> <TD>Fast compressing</TD> </TR>
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254 | <TR> <TD align="center">5</TD> <TD align="center">LZMA</TD> <TD align="center">16 MB</TD> <TD align="center">32</TD> <TD align="center">BT4</TD> <TD align="center">BCJ</TD> <TD>Normal compressing</TD> </TR>
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255 | <TR> <TD align="center">7</TD> <TD align="center">LZMA</TD> <TD align="center">32 MB</TD> <TD align="center">64</TD> <TD align="center">BT4</TD> <TD align="center">BCJ</TD> <TD>Maximum compressing</TD> </TR>
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256 | <TR> <TD align="center">9</TD> <TD align="center">LZMA</TD> <TD align="center">64 MB</TD> <TD align="center">64</TD> <TD align="center">BT4</TD> <TD align="center">BCJ2</TD><TD>Ultra compressing</TD> </TR>
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257 | </TABLE>
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258 | <P>Note: "x" works as "x=9".</P>
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259 | </DD>
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260 |
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261 | <DT><A name="Solid"></A>s=[off | on | [e] [{N}f] [{N}b | {N}k | {N}m | {N}g)]</DT>
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262 | <DD>
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263 | <P> Enables or disables solid mode. The default mode is s=on.
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264 | In solid mode, files are grouped together. Usually, compressing in
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265 | solid mode improves the compression ratio.</P>
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266 |
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267 | <TABLE>
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268 | <TR> <TD>e</TD> <TD>Use a separate solid block for each new file extension</TD> </TR>
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269 | <TR> <TD>{N}f</TD> <TD>Set the limit for number of files in one solid block</TD> </TR>
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270 | <TR> <TD>{N}b | {N}k | {N}m | {N}g</TD> <TD>Set a limit for the total size of a solid block in bytes</TD> </TR>
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271 | </TABLE>
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272 |
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273 | <P>These are the default limits for the solid block size:</P>
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274 |
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275 | <TABLE>
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276 | <TR> <TH width="150">Compression Level</TH> <TH>Solid block size</TH> </TR>
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277 | <TR> <TD>Store</TD> <TD>0 B</TD> </TR>
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278 | <TR> <TD>Fastest</TD> <TD>16 MB</TD> </TR>
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279 | <TR> <TD>Fast</TD> <TD>128 MB</TD> </TR>
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280 | <TR> <TD>Normal</TD> <TD>2 GB</TD> </TR>
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281 | <TR> <TD>Maximum</TD> <TD>4 GB</TD> </TR>
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282 | <TR> <TD>Ultra</TD> <TD>4 GB</TD> </TR>
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283 | </TABLE>
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284 |
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285 |
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286 | <P>Limitation of the solid block size usually decreases compression ratio but gives the following advantages:</P>
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287 | <UL>
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288 | <LI>Decreases losses in case of future archive damage.
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289 | <LI>Decreases extraction time of a group of files (or just one
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290 | file), so long as the group doesn't contain the entire archive.</LI></LI>
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291 | </UL>
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292 | <P>The updating of solid .7z archives can be slow, since it
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293 | can require some recompression.</P>
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294 |
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295 | <P>Example:</P>
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296 | <PRE class="example">
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297 | s=100f10m
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298 | </PRE>
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299 | <P>set solid mode with 100 files & 10 MB limits per one solid block.</P>
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300 |
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301 | <DT><A name="Filter"></A>f=[off | on]</DT>
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302 | <DD>
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303 | <P>Enables or disables compression filters for executable files:
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304 | dll, exe, ocx, sfx, sys. It uses BCJ2 filter in Ultra mode and BCJ
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305 | filter in other modes. The default mode is f=on.
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306 | </P>
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307 | <DT><A name="HeaderCompress"></A>hc=[off | on]</DT>
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308 | <DD>
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309 | <P> Enables or disables archive header compressing. The default mode is hc=on.
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310 | If archive header compressing is enabled, some parts of archive header will
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311 | be compressed with LZMA method.
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312 | </P>
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313 | <DT><A name="HeaderEncrypt"></A>he=[off | on]</DT>
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314 | <DD>
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315 | <P> Enables or disables archive header encryption. The default mode is he=off.
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316 | </P>
|
---|
317 | <DT>{N}</DT>
|
---|
318 | <DD>
|
---|
319 | <P>Sets order of methods. It is used also to associate parameters with
|
---|
320 | methods. Numbers must begin from 0. Methods that have smaller numbers will be used
|
---|
321 | before others.</P>
|
---|
322 | </DD>
|
---|
323 |
|
---|
324 | <DT><A name="Bind"></A>b{C1}[s{S1}]:{C2}[s{S2}]</DT>
|
---|
325 | <DD>
|
---|
326 | <P> Binds output stream S1 in coder C1 with input stream S2 in coder C2.
|
---|
327 | If stream number is not specified, stream with number 0 will be used.
|
---|
328 | </P>
|
---|
329 | <P> Usally coder has one input stream and
|
---|
330 | one output stream. In 7z some coders can have multiple input and output streams.</P>
|
---|
331 |
|
---|
332 | <P>For example, <A class="parameter" href="#BCJ2">BCJ2</A> encoder has one
|
---|
333 | input stream and four output streams.</P>
|
---|
334 | </DD>
|
---|
335 |
|
---|
336 | <DT><A name="MultiThread"></A>mt=[off | on | {N}]</DT>
|
---|
337 | <DD>
|
---|
338 | <P>Sets multithread mode. If you have a multiprocessor or multicore system,
|
---|
339 | you can get a increase with this switch.
|
---|
340 | 7-Zip supports multithread mode only for LZMA / LZMA2 compression and
|
---|
341 | BZip2 compression / decompression. If you specify {N}, for example mt=4,
|
---|
342 | 7-Zip tries to use 4 threads. LZMA compression uses only 2 threads.
|
---|
343 | </P>
|
---|
344 | </DD>
|
---|
345 |
|
---|
346 | <DT><A name="MethodID"></A>{N}={MethodID}[:param1][:param2] ... [:paramN]</DT>
|
---|
347 | <DD>
|
---|
348 | <P>Sets compression method. You can use any number of methods.
|
---|
349 | The default method is LZMA. </P>
|
---|
350 | <P>Parameters must be in one of the following forms:</P>
|
---|
351 | <UL>
|
---|
352 | <LI>{ParamName}={ParamValue}.
|
---|
353 | <LI>{ParamName}{ParamValue}, if {ParamValue}
|
---|
354 | is number and {ParamName} doesn't contain numbers.
|
---|
355 | </UL>
|
---|
356 |
|
---|
357 | <P>Supported methods:</P>
|
---|
358 | <TABLE>
|
---|
359 | <TR> <TH width="60">MethodID</TH> <TH>Description</TH> </TR>
|
---|
360 | <TR> <TD><A class="parameter" href="#LZMA">LZMA</A></TD> <TD>LZ-based algorithm</TD> </TR>
|
---|
361 | <TR> <TD><A class="parameter" href="#LZMA2">LZMA2</A></TD> <TD>LZMA-based algorithm</TD> </TR>
|
---|
362 | <TR> <TD><A class="parameter" href="#PPMd">PPMd</A></TD> <TD>Dmitry Shkarin's PPMdH with small changes</TD> </TR>
|
---|
363 | <TR> <TD>BZip2</TD> <TD>BWT algorithm</TD> </TR>
|
---|
364 | <TR> <TD>Deflate</TD> <TD>LZ+Huffman</TD> </TR>
|
---|
365 | <TR> <TD>Copy</TD> <TD>No compression</TD> </TR>
|
---|
366 | </TABLE>
|
---|
367 |
|
---|
368 | <P>Supported filters:</P>
|
---|
369 | <TABLE>
|
---|
370 | <TR> <TH width="60">MethodID</TH> <TH>Description</TH> </TR>
|
---|
371 | <TR> <TD><A class="parameter" href="#Delta">Delta</A></TD> <TD>Delta filter</TD> </TR>
|
---|
372 | <TR> <TD>BCJ</TD> <TD>converter for x86 executables</TD> </TR>
|
---|
373 | <TR> <TD><A class="parameter" href="#BCJ2">BCJ2</A></TD> <TD>converter for x86 executables (version 2)</TD> </TR>
|
---|
374 | <TR> <TD>ARM</TD> <TD>converter for ARM (little endian) executables</TD> </TR>
|
---|
375 | <TR> <TD>ARMT</TD> <TD>converter for ARM Thumb (little endian) executables</TD> </TR>
|
---|
376 | <TR> <TD>IA64</TD> <TD>converter for IA-64 executables</TD> </TR>
|
---|
377 | <TR> <TD>PPC</TD> <TD>converter for PowerPC (big endian) executables</TD> </TR>
|
---|
378 | <TR> <TD>SPARC</TD> <TD>converter for SPARC executables</TD> </TR>
|
---|
379 | </TABLE>
|
---|
380 | <P>Filters increase the compression ratio for some types of files. Filters
|
---|
381 | must be used with one of the compression method (for example, BCJ + LZMA).</P>
|
---|
382 | </DD>
|
---|
383 |
|
---|
384 | <H4><A name="LZMA"></A>LZMA</H4>
|
---|
385 | <P> LZMA is an algorithm based on Lempel-Ziv algorithm.
|
---|
386 | It provides very fast decompression (about 10-20 times faster than compression).
|
---|
387 | Memory requirements for compression and decompression also are different (see
|
---|
388 | <A class="parameter" href="#DictionarySize">d={Size}[b|k|m]</A> switch for details).</P>
|
---|
389 |
|
---|
390 | <TABLE>
|
---|
391 | <TR> <TH width="80">Parameter</TH> <TH align="center">Default</TH> <TH>Description</TH> </TR>
|
---|
392 |
|
---|
393 | <TR> <TD><A class="parameter" href="#LZMAMode">a=[0|1]</A></TD>
|
---|
394 | <TD align="center">1</TD> <TD>Sets compressing mode</TD> </TR>
|
---|
395 | <TR> <TD><A class="parameter" href="#DictionarySize">d={Size}[b|k|m]</A></TD>
|
---|
396 | <TD align="center">24</TD> <TD>Sets Dictionary size</TD> </TR>
|
---|
397 | <TR> <TD><A class="parameter" href="#MatchFinder">mf={MF_ID}</A></TD>
|
---|
398 | <TD align="center">bt4</TD> <TD>Sets Match Finder</TD> </TR>
|
---|
399 | <TR> <TD><A class="parameter" href="#FastBytes">fb={N}</A></TD>
|
---|
400 | <TD align="center">32</TD> <TD>Sets number of Fast Bytes</TD></TR>
|
---|
401 | <TR> <TD><A class="parameter" href="#MatchFinderCycles">mc={N}</A></TD>
|
---|
402 | <TD align="center">32</TD><TD>Sets Number of Cycles for Match Finder</TD> </TR>
|
---|
403 | <TR> <TD><A class="parameter" href="#LitContext">lc={N}</A></TD>
|
---|
404 | <TD align="center">3</TD> <TD>Sets number of Literal Context bits - [0, 8]</TD></TR>
|
---|
405 | <TR> <TD><A class="parameter" href="#LitPos">lp={N}</A></TD>
|
---|
406 | <TD align="center">0</TD> <TD>Sets number of Literal Pos bits - [0, 4]</TD></TR>
|
---|
407 | <TR> <TD><A class="parameter" href="#PosBits">pb={N}</A></TD>
|
---|
408 | <TD align="center">2</TD> <TD>Set number of Pos Bits - [0, 4]</TD></TR>
|
---|
409 | </TABLE>
|
---|
410 |
|
---|
411 |
|
---|
412 | <DL>
|
---|
413 | <DT><A name="#LZMAMode"></A>a=[0|1]</DT>
|
---|
414 | <DD>
|
---|
415 | <P> Sets compression mode: 0 = fast, 1 = normal.
|
---|
416 | Default value is 1.</P>
|
---|
417 | </DD>
|
---|
418 | <DT><A name="DictionarySize"></A>d={Size}[b|k|m]</DT>
|
---|
419 | <DD>
|
---|
420 | <P> Sets Dictionary size for LZMA. You must specify the size in bytes, kilobytes, or megabytes.
|
---|
421 | The maximum value for dictionary size is 1 GB = 2^30 bytes. Default values for LZMA
|
---|
422 | are 24 (16 MB) in normal mode, 25 (32 MB) in maximum mode (-mx=7)
|
---|
423 | and 26 (64 MB) in ultra mode (-mx=9).
|
---|
424 | If you do not specify any symbol from the set [b|k|m], the
|
---|
425 | dictionary size will be calculated as DictionarySize = 2^Size bytes.
|
---|
426 | For decompressing a file compressed by LZMA method with dictionary size N, you need
|
---|
427 | about N bytes of memory (RAM) available.
|
---|
428 | </P>
|
---|
429 | </DD>
|
---|
430 | <DT><A name="MatchFinder"></A>mf={MF_ID}</DT>
|
---|
431 | <DD>
|
---|
432 | <P> Sets Match Finder for LZMA. Default method is bt4.
|
---|
433 | Algorithms from hc* group don't provide a good compression ratio,
|
---|
434 | but they often work pretty fast in combination with fast mode (a=0).
|
---|
435 | Memory requirements depend on dictionary size (parameter "d" in table below).
|
---|
436 | </P>
|
---|
437 | <TABLE>
|
---|
438 | <TR> <TH>MF_ID</TH> <TH class="cc">Dictionary</TH> <TH class="cc" colspan = 2>Memory Usage</TH> <TH class="cc" colspan = 2>Description</TH> </TR>
|
---|
439 | <TR> <TD class="cc">bt2</TD> <TD></TD> <TD align="right"> 9.5 * d</TD> <TD class="cc" rowspan=6> + 4 MB</TD> <TD class="cc" rowspan=4>Binary Tree</TD> <TD>2 bytes hashing</TD> </TR>
|
---|
440 | <TR> <TD class="cc">bt3</TD> <TD></TD> <TD align="right">11.5 * d</TD> <TD>3 bytes hashing</TD> </TR>
|
---|
441 | <TR> <TD class="cc" rowspan=2>bt4</TD> <TD class="cc">64 KB ... 48 MB</TD> <TD align="right">11.5 * d</TD> <TD class="cc" rowspan=6>4 bytes hashing</TD> </TR>
|
---|
442 | <TR> <TD class="cc">64 MB ... 1024 MB</TD> <TD align="right">10.5 * d</TD> </TR>
|
---|
443 | <TR> <TD class="cc" rowspan=2>hc4</TD> <TD class="cc">64 KB ... 48 MB</TD> <TD align="right"> 7.5 * d</TD> <TD class="cc" rowspan=2>Hash Chain </TD></TR>
|
---|
444 | <TR> <TD class="cc">64 MB ... 1024 MB</TD> <TD align="right"> 6.5 * d</TD> </TR>
|
---|
445 | </TABLE>
|
---|
446 | <P>Note: Your operation system also needs some amount of physical memory for internal purposes.
|
---|
447 | So keep at least 32MB of physical memory unused.</P>
|
---|
448 | </DD>
|
---|
449 |
|
---|
450 | <DT><A name="FastBytes"></A>fb={N}</DT>
|
---|
451 | <DD>
|
---|
452 | <P>Sets number of fast bytes for LZMA. It can be in the range from 5 to 273.
|
---|
453 | The default value is 32 for normal mode and 64 for maximum and ultra modes.
|
---|
454 | Usually, a big number gives a little bit better
|
---|
455 | compression ratio and slower compression process.
|
---|
456 | </P>
|
---|
457 | </DD>
|
---|
458 | <DT><A name="MatchFinderCycles"></A>mc={N}</DT>
|
---|
459 | <DD>
|
---|
460 | <P>Sets number of cycles (passes) for match finder. It can be in range from 0 to 1000000000.
|
---|
461 | Default value is (16 + number_of_fast_bytes / 2) for BT* match finders and
|
---|
462 | (8 + number_of_fast_bytes / 4) for HC4 match finder.
|
---|
463 | If you specify mc=0, LZMA will use default value.
|
---|
464 | Usually, a big number gives a little bit better compression ratio and slower
|
---|
465 | compression process. For example, mf=HC4 and mc=10000 can provide almost the same
|
---|
466 | compression ratio as mf=BT4.</P>
|
---|
467 | </DD>
|
---|
468 | <DT><A name="LitContext"></A>lc={N}</DT>
|
---|
469 | <DD>
|
---|
470 | <P>Sets the number of literal context bits (high bits of previous literal).
|
---|
471 | It can be in range from 0 to 8.
|
---|
472 | Default value is 3. Sometimes lc=4 gives gain for big files.</P>
|
---|
473 | </DD>
|
---|
474 | <DT><A name="LitPos"></A>lp={N}</DT>
|
---|
475 | <DD>
|
---|
476 | <P>Sets the number of literal pos bits (low bits of current position for literals).
|
---|
477 | It can be in the range from 0 to 4.
|
---|
478 | The default value is 0. The lp switch is intended for periodical data when the
|
---|
479 | period is equal to 2^value (where lp=value). For example, for 32-bit (4 bytes)
|
---|
480 | periodical data you can use lp=2. Often it's better to set lc=0,
|
---|
481 | if you change lp switch.</P>
|
---|
482 | </DD>
|
---|
483 | <DT><A name="PosBits"></A>pb={N}</DT>
|
---|
484 | <DD>
|
---|
485 | <P>Sets the number of pos bits (low bits of current position).
|
---|
486 | It can be in the range from 0 to 4.
|
---|
487 | The default value is 2. The pb switch is intended for periodical data when the
|
---|
488 | period is equal 2^value (where lp=value). </P>
|
---|
489 | </DD>
|
---|
490 |
|
---|
491 | </DL>
|
---|
492 |
|
---|
493 | <H4><A name="LZMA2"></A>LZMA2</H4>
|
---|
494 | <P>LZMA2 is modified version of LZMA. it provides the following advantages over LZMA:</P>
|
---|
495 | <UL>
|
---|
496 | <LI>Better compression ratio for data than can't be compressed. LZMA2 can store such
|
---|
497 | blocks of data in uncompressed form. Also it decompresses such data faster.
|
---|
498 | <LI>Better multithreading support. If you compress big file, LZMA2 can split
|
---|
499 | that file to chunks and compress these chunks in multiple threads.
|
---|
500 | </UL>
|
---|
501 |
|
---|
502 | <TABLE>
|
---|
503 | <TR> <TH width="80">Parameter</TH> <TH align="center">Default</TH> <TH>Description</TH> </TR>
|
---|
504 |
|
---|
505 | <TR> <TD><A class="parameter" href="#ChunkSize">c={Size}[b|k|m]</A></TD>
|
---|
506 | <TD align="center">dictSize * 4</TD> <TD>Sets Chunk size</TD> </TR>
|
---|
507 | </TABLE>
|
---|
508 |
|
---|
509 | <P>If you don't specify ChunkSize, LZMA2 sets it to DictionarySize * 4.</P>
|
---|
510 |
|
---|
511 | <P>LZMA2 also supports all LZMA parameters, but lp+lc cannot be larger than 4.</P>
|
---|
512 |
|
---|
513 | <P>LZMA2 uses: 1 thread for each chunk in x1 and x3 modes; and
|
---|
514 | 2 threads for each chunk in x5, x7 and x9 modes.
|
---|
515 | If LZMA2 is set to use only such number of threads required for one chunk,
|
---|
516 | it doesn't split stream to chunks. So you can get different compression
|
---|
517 | ratio for different number of threads. You can get the best compression
|
---|
518 | ratio, when you use 1 or 2 threads.</P>
|
---|
519 |
|
---|
520 | <H4><A name="PPMd"></A>PPMd</H4>
|
---|
521 | <P> PPMd is a PPM-based algorithm. This algorithm is mostly based
|
---|
522 | on Dmitry Shkarin's PPMdH source code. PPMd provides very good compression ratio for
|
---|
523 | plain text files. There is no difference between compression speed and
|
---|
524 | decompression speed. Memory requirements for compression and decompression
|
---|
525 | also are the same.</P>
|
---|
526 | <TABLE>
|
---|
527 | <TR> <TH width="80">Parameter</TH> <TH align="center">Default</TH> <TH>Description</TH> </TR>
|
---|
528 | <TR> <TD><A class="parameter" href="#MemorySize">mem={Size}[b|k|m]</A></TD>
|
---|
529 | <TD align="center">24</TD> <TD>Sets size of used memory for PPMd.</TD> </TR>
|
---|
530 | <TR> <TD><A class="parameter" href="#Order">o={Size}</A></TD>
|
---|
531 | <TD align="center">6</TD> <TD>Sets model order for PPMd.</TD> </TR>
|
---|
532 | </TABLE>
|
---|
533 | <DL>
|
---|
534 | <DT><A name="MemorySize"></A>mem={Size}[b|k|m]</DT>
|
---|
535 | <DD>
|
---|
536 | <P> Sets the size of memory used for PPMd. You must specify the size in bytes, kilobytes, or megabytes.
|
---|
537 | The maximum value is 2GB = 2^31 bytes. The default value
|
---|
538 | is 24 (16MB). If you do not specify any symbol from the set [b|k|m], the
|
---|
539 | memory size will be calculated as (2^Size) bytes. PPMd uses the same
|
---|
540 | amount of memory for compression and decompression.</P>
|
---|
541 | </DD>
|
---|
542 |
|
---|
543 | <DT><A name="Order"></A>o={Size}</DT>
|
---|
544 | <DD>
|
---|
545 | <P>Sets the model order for PPMd. The size must be in the range [2,32]. The default value is 6.</P>
|
---|
546 | </DD>
|
---|
547 | </DL>
|
---|
548 |
|
---|
549 | <H4><A name="BCJ2"></A>BCJ2</H4>
|
---|
550 | <P>BCJ2 is a Branch converter for 32-bit x86 executables (version 2).
|
---|
551 | It converts some branch instructions for increasing further compression.</P>
|
---|
552 | <P>A BCJ2 encoder has one input stream and four output streams:</P>
|
---|
553 | <UL>
|
---|
554 | <LI>s0: main stream. It requires further compression.</LI>
|
---|
555 | <LI>s1: stream for converted CALL values. It requires further compression.</LI>
|
---|
556 | <LI>s2: stream for converted JUMP values. It requires further compression.</LI>
|
---|
557 | <LI>s3: service stream. It is already compressed.</LI>
|
---|
558 | </UL>
|
---|
559 | <P>If LZMA is used, the size of the dictionary for streams
|
---|
560 | s1 and s2 can be much smaller (512 KB is enough for most cases)
|
---|
561 | than the dictionary size for stream s0.</P>
|
---|
562 |
|
---|
563 | <H4><A name="Delta"></A>Delta</H4>
|
---|
564 | <P>It's possible to set delta offset in bytes. For example, to compress 16-bit stereo
|
---|
565 | WAV files, you can set "0=Delta:4". Default delta offset is 1.</P>
|
---|
566 | </DL>
|
---|
567 |
|
---|
568 | <H2><A name="XZ"></A>XZ</H2>
|
---|
569 | XZ supports only LZMA2 codec now. The switches are similar to switches for 7z format.
|
---|
570 |
|
---|
571 | <H4>Examples</H4>
|
---|
572 |
|
---|
573 | <PRE class="example">
|
---|
574 | 7z a -tzip archive.zip *.jpg -mx0
|
---|
575 | </PRE>
|
---|
576 |
|
---|
577 | <P>adds <SPAN class="filename">*.jpg</SPAN> files to
|
---|
578 | <SPAN class="filename">archive.zip</SPAN> archive without compression.</P>
|
---|
579 |
|
---|
580 | <PRE class="example">
|
---|
581 | 7z a -t7z archive.7z *.exe *.dll -m0=BCJ -m1=LZMA:d=21 -ms -mmt
|
---|
582 | </PRE>
|
---|
583 |
|
---|
584 | <P>adds <SPAN class="filename">*.exe</SPAN> and <SPAN class="filename">*.dll</SPAN>
|
---|
585 | files to solid archive <SPAN class="filename">archive.7z</SPAN> using LZMA method with
|
---|
586 | 2 MB dictionary and BCJ converter. Compression will use multithreading optimization.</P>
|
---|
587 |
|
---|
588 | <PRE class="example">
|
---|
589 | 7z a -t7z archive.7z *.exe *.dll -m0=BCJ2 -m1=LZMA:d23 -m2=LZMA:d19 -m3=LZMA:d19
|
---|
590 | -mb0:1 -mb0s1:2 -mb0s2:3
|
---|
591 | </PRE>
|
---|
592 |
|
---|
593 | <P>adds <SPAN class="filename">*.exe</SPAN> and <SPAN class="filename">*.dll</SPAN>
|
---|
594 | files to archive <SPAN class="filename">archive.7z</SPAN> using BCJ2 converter,
|
---|
595 | LZMA with 8 MB dictionary for main output stream (s0),
|
---|
596 | and LZMA with 512 KB dictionary for s1 and s2 output streams of BCJ2.</P>
|
---|
597 |
|
---|
598 |
|
---|
599 | <PRE class="example">
|
---|
600 | 7z a -t7z archive.7z *.txt -m0=PPMd
|
---|
601 | </PRE>
|
---|
602 |
|
---|
603 | <P>adds <SPAN class="filename">*.txt</SPAN> files to archive
|
---|
604 | <SPAN class="filename">archive.7z</SPAN> using PPMd method.</P>
|
---|
605 |
|
---|
606 |
|
---|
607 |
|
---|
608 |
|
---|
609 | <H4>Commands that can be used with this switch</H4>
|
---|
610 |
|
---|
611 | <P>
|
---|
612 | <A href="../commands/add.htm">a (Add)</A>,
|
---|
613 | <A href="../commands/delete.htm">d (Delete)</A>,
|
---|
614 | <A href="../commands/update.htm">u (Update)</A>,
|
---|
615 | </P>
|
---|
616 |
|
---|
617 | <H4>See also</H4>
|
---|
618 |
|
---|
619 | <P>
|
---|
620 | <B>Switches:</B>
|
---|
621 | <A href="type.htm">-t (set Type of archive)</A>,
|
---|
622 | </P>
|
---|
623 |
|
---|
624 | </BODY>
|
---|
625 | </HTML>
|
---|