The repository contains a file showing how to add AStim commands to a WAV file using the Python programming language.
Attention!
AStim works only with 16-bit WAV files with a sampling rate of 44100 Hz.
The script wavpatcher.py writes AStim commands to the right channel of the WAV file.
Two commands are written to the beginning of the file, enabling both the left and right channels. Commands to enable either only left or only right channel are also present in the script, but by default both channels are enabled.
Then trigger 6 is set to LOW. At the end of the file, trigger 6 is set to HIGH.
To run the script you need Python (3.4 or higher), numpy and scipy packages.
The script is run through the command line, as follows
$ python wavpatcher.py input_file_path -o output_file_path
If output_file_path is not specified (by the flag -o) input file will be rewritten.
For a description of the arguments, see the help message, which can be shown by running with the -h flag.
The commands are 3-bit, each bit is encoded with sequence of two 16-bit samples in the right channel:
0: -32768 and +32767;
1: +32767 and -32768.
There should be no gaps between the bits.
There must be at least one sample with zero value between commands.
If there are no commands, then there are only zero samples in the right channel.
If there are zero samples on the right channel, the A-Stim goes into mono (the right channel receives samples from the left channel).
If there are non-zero samples on the right channel, the A-Stim goes into standard stereo mode.
Commands:
- 000 - disable left channel, 001 - enable left channel (default);
- 010 - disable right channel, 011 - enable right channel (default);
- 100 - set trigger 6 LOW, 101 - set trigger 6 HIGH (default);
- 110 - set trigger 7 LOW, 111 - set trigger 7 HIGH (default).
The audio/examples folder contains examples of WAV files with added commands in the right channel.
The file audio/examples/output_example_1s.wav was obtained by processing the file audio/origin/input_example_1s.wav by the script wavpatcher.py.