[Coco] Cassete reading

[Robert Gault]

Two programs that can clean up and convert audio files to multiple formats are 
Cool Edit Pro and Audacity. The latter should be free. These programs will only 
create audio files not the .cas type that emulates a Coco tape.

I've tried to process some audio files made from tapes and have found a major 
problem is periodic mechanical noise introduced into the signal. The noise is 
what you might expect from a rubbing wheel that hits every revolution and 
glitches the audio signal. The next major problem is recording the tape signal 
at too low or too high levels so that the signal to noise ratio is too low or 
the signal clips adding distortion.
The is no good way to correct these problems while keeping the audio signal 
usable via the Coco tape input. The cleanup methods used with voice or music are 
not very good for the Frequency Shift Keying used on a Coco tape. You might 
think you could bandpass at the frequencies 1200 and 2400 but that hasn't worked 
for me.

However you record the tape, the final file should be mono and must be 11,025Hz 
8-bit WindowsPCM .wav to be read by an emulator. If you are feeding the audio to 
a Coco tape input, higher quality sound should also work. I've found that 
emulator programs do just as good a job of accepting .wav files as a real Coco.

Robert