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Diffstat (limited to 'programs/zstd.1.md')
| -rw-r--r-- | programs/zstd.1.md | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/programs/zstd.1.md b/programs/zstd.1.md index 93c6fa40010e..3ab2667a0483 100644 --- a/programs/zstd.1.md +++ b/programs/zstd.1.md @@ -244,13 +244,15 @@ Compression of small files similar to the sample set will be greatly improved. This compares favorably to 4 bytes default. However, it's up to the dictionary manager to not assign twice the same ID to 2 different dictionaries. -* `--train-cover[=k#,d=#,steps=#,split=#]`: +* `--train-cover[=k#,d=#,steps=#,split=#,shrink[=#]]`: Select parameters for the default dictionary builder algorithm named cover. If _d_ is not specified, then it tries _d_ = 6 and _d_ = 8. If _k_ is not specified, then it tries _steps_ values in the range [50, 2000]. If _steps_ is not specified, then the default value of 40 is used. If _split_ is not specified or split <= 0, then the default value of 100 is used. Requires that _d_ <= _k_. + If _shrink_ flag is not used, then the default value for _shrinkDict_ of 0 is used. + If _shrink_ is not specified, then the default value for _shrinkDictMaxRegression_ of 1 is used. Selects segments of size _k_ with highest score to put in the dictionary. The score of a segment is computed by the sum of the frequencies of all the @@ -262,6 +264,9 @@ Compression of small files similar to the sample set will be greatly improved. If _split_ is 100, all input samples are used for both training and testing to find optimal _d_ and _k_ to build dictionary. Supports multithreading if `zstd` is compiled with threading support. + Having _shrink_ enabled takes a truncated dictionary of minimum size and doubles + in size until compression ratio of the truncated dictionary is at most + _shrinkDictMaxRegression%_ worse than the compression ratio of the largest dictionary. Examples: @@ -275,6 +280,10 @@ Compression of small files similar to the sample set will be greatly improved. `zstd --train-cover=k=50,split=60 FILEs` + `zstd --train-cover=shrink FILEs` + + `zstd --train-cover=shrink=2 FILEs` + * `--train-fastcover[=k#,d=#,f=#,steps=#,split=#,accel=#]`: Same as cover but with extra parameters _f_ and _accel_ and different default value of split If _split_ is not specified, then it tries _split_ = 75. |