This is a set of tools which can read sampled MSX tapes and convert them to the standard .cas format and back to .wav samples. This package consist of three tools: wav2cas, cas2wav and casdir.
The most important tool is wav2cas, this tool does the actual conversion of audio samples to the .cas format. The cas2wav is the reverse process and converts .cas files back to audio samples, which can be read on a real MSX. The casdir tool gives a detailed list of the contents of the .cas file. The last two tools are pretty straight forward and will not be described any further in this document.
The wav2cas tool requires a .wav file as input. It will analyse the signal and create a .cas file. It will work on 'copy-protected' tapes which use their own custom loader using the bios routines for the actual retrieval of data. Unfortunately tapes exist which don't use the bios routines (e.g. a lot of Gremlin games used a entirely different format). These will not work. Fortunately, a lot of publishers did use the bios calls, and they should work fine.
However, keep in mind that the tape medium was not the most reliable medium to store data on; remember cleaning your heads, tuning your heads and playing with the phase and volume settings on your datarecorder? This tool can have good results, but if the signal is too much deteriorated it will probably fail.
You get the best results by sampling the tapes at the highest sample frequency as possible. It does not matter if the sample is 16 or 8 bits; if it is 16 bits it will be converted to 8 bits. Sample the signal as loud as possible, but make sure the signal does not clip!.
The wav2cas tool has 4 arguments to play with, but the default settings should work fine if it is a clean clear signal. The -t argument requires an integer which defines a threshold; if the signal is noisy you could try a higher value to get better results. The -e argument also requires an integer and defines the amount of 'envelope' correction, you could try increasing and decreasing this to get better results. The -n argument will maximize the signal and the final -p argument will phase shift the signal.
This should be enough info to get you started in converting your old cassette tapes to .cas files. Good luck!
- all: added support for 64 bit systems (thanks to Peter Koellner)
- cas2wav: allow custom gaptime between blocks.
- cas2wav: added multi cpu support
- wav2cas: added multi cpu support
- casdir: compile warnings fixed Credits go to Ramones for the applied changes, thanks!
- cas2wav: increased gap between data and headers
- wav2cas: fixed bug in wav reading
- wav2cas: changed default phase
- first public release