CSW -r -s45454 -k tape
(.csw is automatically appended)
Set volume so that the green VU meter is half way across the screen and make sure there is no clipping, which is displayed on the second red VU meter.
Now that you've established your volume settings, you need to rewind the tape to the beginning. Press a key so that sampling begins. Wait until the end of the tape and press a key to stop sampling. A CSW & WAV file will have been created.
Decompress the CSW to a VOC file and try to decode it, using the command:
CSW -d filename
(file extension is not required as CSW assumes .csw) ,P.Try and decode the VOC with the following command line syntax:
VOC2TZX /cpc /pilot 1024 /maxp 20 filename.voc
See if you get all the blocks to decode; on standard tapes you will get a header followed by a data block, so you should get pairs displayed. This is not always the case with tapes that use non-standard loading schemes.
If you don't get this and there are a number of blocks but no pattern try altering the values for /pilot (1024 - 2048) and /maxp (20 - 35). With luck this proceedure should yeild better results and you will become a master of decoding.
Once you get the tape to decode and the blocks look good, you can omit the /cpc switch to get a TZX. Rename this .TZX to .CDT. I'm not sure why it's bad to use /cpc, but I think it's something to do with assumptions which are untrue (timings etc).
If you have no luck than you can try the proceedure again using the WAV file. As VOC2TZX currently doesn't handle CSW or WAV you have to convert it, but this could be to our advantage. I've found that many of my troublesome tapes convert if you apply a filter to the WAV->CSW->VOC. To do this just use the following: "CSW -fr1 filename.wav", you could also use other filter like -fl600. There are other filters available but I've not used them so far.
If all else fails then send the tape to me and I'll have a go at them :-)