Switch -M<n> - set compression method
Choosing <n> from 0 to 5 you may select an appropriate compression method
|-m0||Store||Add files to archive without compression|
|-m1||Fastest||Fastest method (least compressive)|
|-m2||Fast||Fast compression method|
|-m3||Normal||Normal (default) compression method|
|-m4||Good||Good compression method (more compressive)|
|-m5||Best||Best compression method (most compressive but also most slow)|
If this switch is not specified, WinRAR uses "-m3" method (Normal compression).
By default, WinRAR uses only the general compression algorithm in -m1 and -m2 methods, advanced algorithms like audio and true color processing are enabled only in -m3..-m5 modes, the advanced text compression is activated only in -m4..-m5. This default can be overridden using -mc switch.
The compression method also can be selected through the "Compression method" list in the Archive name and parameters dialog.