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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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|
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291 </UL>
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|
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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
|
|
|
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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|
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305 filter in other modes. The default mode is f=on.
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|
|
306 </P>
|
|
|
307 <DT><A name="HeaderCompress"></A>hc=[off | on]</DT>
|
|
|
308 <DD>
|
|
|
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
|
|
|
311 be compressed with LZMA method.
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|
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312 </P>
|
|
|
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.
|
|
|
316 </P>
|
|
|
317 <DT>{N}</DT>
|
|
|
318 <DD>
|
|
|
319 <P>Sets order of methods. It is used also to associate parameters with
|
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320 methods. Numbers must begin from 0. Methods that have smaller numbers will be used
|
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321 before others.</P>
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|
|
322 </DD>
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323
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|
324 <DT><A name="Bind"></A>b{C1}[s{S1}]:{C2}[s{S2}]</DT>
|
|
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325 <DD>
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|
|
326 <P> Binds output stream S1 in coder C1 with input stream S2 in coder C2.
|
|
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327 If stream number is not specified, stream with number 0 will be used.
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|
328 </P>
|
|
|
329 <P> Usally coder has one input stream and
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330 one output stream. In 7z some coders can have multiple input and output streams.</P>
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331
|
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332 <P>For example, <A class="parameter" href="#BCJ2">BCJ2</A> encoder has one
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333 input stream and four output streams.</P>
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|
334 </DD>
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335
|
|
|
336 <DT><A name="MultiThread"></A>mt=[off | on | {N}]</DT>
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|
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337 <DD>
|
|
|
338 <P>Sets multithread mode. If you have a multiprocessor or multicore system,
|
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|
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,
|
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|
342 7-Zip tries to use 4 threads. LZMA compression uses only 2 threads.
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|
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343 </P>
|
|
|
344 </DD>
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|
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345
|
|
|
346 <DT><A name="MethodID"></A>{N}={MethodID}[:param1][:param2] ... [:paramN]</DT>
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|
|
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>
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|
351 <UL>
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|
|
352 <LI>{ParamName}={ParamValue}.
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353 <LI>{ParamName}{ParamValue}, if {ParamValue}
|
|
|
354 is number and {ParamName} doesn't contain numbers.
|
|
|
355 </UL>
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|
|
356
|
|
|
357 <P>Supported methods:</P>
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|
358 <TABLE>
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359 <TR> <TH width="60">MethodID</TH> <TH>Description</TH> </TR>
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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
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593 <P>adds <SPAN class="filename">*.exe</SPAN> and <SPAN class="filename">*.dll</SPAN>
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594 files to archive <SPAN class="filename">archive.7z</SPAN> using BCJ2 converter,
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595 LZMA with 8 MB dictionary for main output stream (s0),
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596 and LZMA with 512 KB dictionary for s1 and s2 output streams of BCJ2.</P>
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597
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598
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599 <PRE class="example">
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600 7z a -t7z archive.7z *.txt -m0=PPMd
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601 </PRE>
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602
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603 <P>adds <SPAN class="filename">*.txt</SPAN> files to archive
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604 <SPAN class="filename">archive.7z</SPAN> using PPMd method.</P>
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605
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606
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607
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608
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609 <H4>Commands that can be used with this switch</H4>
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610
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611 <P>
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612 <A href="../commands/add.htm">a (Add)</A>,
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613 <A href="../commands/delete.htm">d (Delete)</A>,
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614 <A href="../commands/update.htm">u (Update)</A>,
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615 </P>
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616
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617 <H4>See also</H4>
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618
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619 <P>
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620 <B>Switches:</B>
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621 <A href="type.htm">-t (set Type of archive)</A>,
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622 </P>
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623
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624 </BODY>
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625 </HTML>
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