demucs: RuntimeError: Couldn't find appropriate backend to handle uri

🐛 Bug Report

Running demucs on my M1 Max Macbook Pro i get an error:

❯ python3 -m demucs -d mps --two-stems=vocals ~/Desktop/03\ -\ 3OH\!3\ -\ Dont\ Trust\ Me.mp3
Important: the default model was recently changed to `htdemucs` the latest Hybrid Transformer Demucs model. In some cases, this model can actually perform worse than previous models. To get back the old default model use `-n mdx_extra_q`.
Selected model is a bag of 1 models. You will see that many progress bars per track.
Separated tracks will be stored in /Users/silman/repo/karaoke-gen/separated/htdemucs
Separating track /Users/silman/Desktop/03 - 3OH!3 - Dont Trust Me.mp3
100%|██████████████████████████████████████████████| 193.04999999999998/193.04999999999998 [00:09<00:00, 19.45seconds/s]
Traceback (most recent call last):
  File "<frozen runpy>", line 198, in _run_module_as_main
  File "<frozen runpy>", line 88, in _run_code
  File "/Users/silman/.local/lib/python3.11/site-packages/demucs/__main__.py", line 10, in <module>
    main()
  File "/Users/silman/.local/lib/python3.11/site-packages/demucs/separate.py", line 206, in main
    save_audio(sources.pop(model.sources.index(args.stem)), str(stem), **kwargs)
  File "/Users/silman/.local/lib/python3.11/site-packages/demucs/audio.py", line 260, in save_audio
    ta.save(str(path), wav, sample_rate=samplerate,
  File "/Users/silman/.local/lib/python3.11/site-packages/torchaudio/_backend/utils.py", line 287, in save
    backend = dispatcher(uri, format, backend)
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/silman/.local/lib/python3.11/site-packages/torchaudio/_backend/utils.py", line 220, in dispatcher
    raise RuntimeError(f"Couldn't find appropriate backend to handle uri {uri} and format {format}.")
RuntimeError: Couldn't find appropriate backend to handle uri separated/htdemucs/03 - 3OH!3 - Dont Trust Me/vocals.wav and format None.

this happens even if i use -d cpu or change the stems choice, the same error happens with .flac files as well

Your Environment

M1 Max Macbook Pro with 64 GB RAM, 24 Core GPU on MacOS Ventura 13.6

❯ python -V
Python 3.11.5

torch                         2.1.0
torchaudio                    2.1.0


❯ which ffmpeg
/opt/homebrew/bin/ffmpeg

❯ ffmpeg -version
ffmpeg version 6.0 Copyright (c) 2000-2023 the FFmpeg developers
built with Apple clang version 14.0.3 (clang-1403.0.22.14.1)
configuration: --prefix=/opt/homebrew/Cellar/ffmpeg/6.0_1 --enable-shared --enable-pthreads --enable-version3 --cc=clang --host-cflags= --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libaribb24 --enable-libbluray --enable-libdav1d --enable-libjxl --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librist --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libsvtav1 --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libspeex --enable-libsoxr --enable-libzmq --enable-libzimg --disable-libjack --disable-indev=jack --enable-videotoolbox --enable-audiotoolbox --enable-neon

❯ which sox
/opt/homebrew/bin/sox

❯ sox --version
sox:      SoX v