I was yelling at the screen wondering why he didn't run an 1/8" audio cable from his Audacity direct to the Commodore. The tape was fun maybe but more sources of error.
Yes, but only in the sense that it will threshold any input into a 1-bit signal. If you feed it audio you can use it as a primitive 1-bit sampler. You can even get something that you can play back as recognizable music that way. I haven't tried feeding audio straight in the read pin of the cassette port, but the C64 is so resilient that I'd be surprised if you wouldn't get reasonable results with some minor adjustments.
Still, you would need to cut it up or make an adapter of some sort, then connect that to the 3.5mm audio jack of some smartphone or modern computer. I can see how just copying to a tape may be less fuss.
Edit:
this adapter suggests it is a bit of hassle actually:
That adapter includes pointless leds and attempts to clean up the signal in various ways to make it more reliable. You can likely do without for a one off transfer, at the cost of some hassle getting your audio output right.
The 'simple stupid' approach is to cut off a 3.5mm cable, de-isolate one of the wires and tape it to the read pin. I've done that (just connected random analog signals straight to an io pin with tape) to interface to other ports on the c64. It's incredible what it will tolerate.
But sure, if you have both a cassette player and a datasette to hand, it will definitively be easier.
If the C64 playback head is stereo (or reads one of the L/R tracks and ignores the other), that would likely work. But in this video he mentioned how he suspected that his audio tape deck failed him (it definitely records in stereo) while the data recorder that ultimately worked might be mono (in which case it might record a single track, twice as wide). Magnetic tape doesn't inherently have tracks until you lay some down with a record head.
When transferring from the jack output of my PC to a CPC-464,
I use a "cassette jack adapter" that I bought second-hand for 1€.
Faster and more reliable that going through a cassette.
Even when transferring to a machine fitted with a disk drive (e.g. a CPC-6128) the audio cable option has the benefit of no moving part (no swapping disks, etc) and is thus faster than using a PC to write to a floppy disk to be read by the CPC. I use this cable: https://coolnovelties.co.uk/coolnovelties/amstrad-cpc-pcw/27... .
SD card readers exist for the CPC, and other ways to inject data from the PC, but nothing beats a 1-10€ adapter/cable, simplicity and cost-wise.
