This utility generates a wave file from a tape file. It uses libspectrum to handle TZX tapes, and code derived from p2raw to handle T81 tapes. It seems that libspectrum doesn't handle ZX81 data inside TZX tapes very well, but let me know otherwise (even better: submit a pull request).
$ ./tape2wav -h
Usage: tape2wav options...
-i filename Input file name
-o filename Output file name (default is tape2wav.wav)
-r sample_rate Output sample rate (default is 44100)
-s Stereo output (default is mono)
-8 Unsigned 8-bits per sample (default signed 16-bits)
-h This page
This utility uses SDL2 to play tapes directly to an audio device.
$ ./playtape -h
Usage: playtape options...
-i filename Input file name
-h This page
TZX is a tape format created to allow the faithful reproduction of ZX Spectrum tapes, even those that use custom loading routines. The format is documented here.
T81 is a tape format used by the EightyOne ZX81 emulator. There's a small utility in the etc folder which can create T81 files from a list of P files.
The utilities were tested only on the Fuse and EightyOne emulators. I've tested files from 8-bit, mono, 11,025 Hz to 16-bit, stereo, 192,000 Hz.
Please let me know your experiences loading the audio into the actual machines, including which device was used to play the wave files.
To generate wave data in chunks, which would be somewhat difficult specially in the T81 case, I decided to use soft coroutines to make my life easier, and ended up with the macros in src/coro.h.
The end result is something that resembles BASIC (with GOTOs and GOSUBs), see usage examples in tzx_play and t81_play.
src/coro.h is released under the CC0.