how_to_no_header.md



How to use the tool without header
A simple example to show how the compression tool works without the compression entity header.


Download the cmp_tool or build the tool


Create a configuration file


Create a cfg directory

mkdir cfg

To create a default 1d-differencing mode configuration:

./cmp_tool --diff_cfg > cfg/default_config_1d.cfg

To create a default model mode configuration:

./cmp_tool --model_cfg > cfg/default_config_model.cfg

Change the the samples and buffer_length parameters from 0 to 50
in the default_config_1d.cfg and default_config_model.cfg files


Compress data with the default configurations:


Create a directory for the compressed data

mkdir compressed


1d-differencing mode compression

./cmp_tool -c cfg/default_config_1d.cfg -d test_data/test_data1.dat --no_header -o compressed/data1

This creates these two files in the compressed directory:

data1.cmp        -> compressed test_data1.dat file

data1.info       -> decompression information for data1.cmp


Model mode compression

./cmp_tool -c cfg/default_config_model.cfg -d test_data/test_data2.dat -m test_data/test_data1.dat --no_header -o compressed/data2

We use test_data1.dat as the first model for test_data2.dat.
Creates these three files in the compressed directory:

data2.cmp         -> compressed test_data3.dat file

data2.info        -> decompression information for data2.cmp

data2_upmodel.dat -> updated model used to compress the next data in model mode


Decompress the data


Create a directory for the decompressed data

mkdir decompressed


Decompress data1.cmp

./cmp_tool -i compressed/data1.info -d compressed/data1.cmp -o decompressed/test_data1

Creates this file in the decompressed directory:

test_data1.dat   -> decompressed data1.cmp file


Decompress data2.cmp

./cmp_tool -i compressed/data2.info -d compressed/data2.cmp -m decompressed/test_data1.dat -o decompressed/test_data2

As for the compression we use test_data1.dat as our model for decompression.
Creates these two files in the decompressed directory:

test_data2.dat    -> decompressed data2.cmp file

data2_upmodel.dat -> updated model used to decompress the next data in model mode


Bonus: Check if the decompressed data are equal to the original data

The moment of truth!

diff test_data/test_data1.dat decompressed/test_data1.dat

diff test_data/test_data2.dat decompressed/test_data2.dat
And also check if the updated model is the same

diff compressed/data2_upmodel.dat decompressed/test_data2_upmodel.dat