Enable tests with ffmpeg8 on Windows

[traversaro]

Fix #951 . The problem was the mixing of defaults and conda-forge that is explicitly not supported by conda-forge https://conda-forge.org/docs/user/transitioning_from_defaults/, see also #974 (comment) .

[traversaro]

There is still a failure:

=========================== short test summary info ===========================
FAILED test/test_encoders.py::TestAudioEncoder::test_bad_input_parametrized[to_file] - AssertionError: Regex pattern did not match.
 Regex: 'avcodec_open2 failed: Invalid argument'
 Input: 'invalid sample rate=10. Supported sample rate values are: 44100, 48000, 32000, 22050, 24000, 16000, 11025, 12000, 8000'
FAILED test/test_encoders.py::TestAudioEncoder::test_bad_input_parametrized[to_tensor] - AssertionError: Regex pattern did not match.
 Regex: 'avcodec_open2 failed: Invalid argument'
 Input: 'invalid sample rate=10. Supported sample rate values are: 44100, 48000, 32000, 22050, 24000, 16000, 11025, 12000, 8000'
FAILED test/test_encoders.py::TestAudioEncoder::test_bad_input_parametrized[to_file_like] - AssertionError: Regex pattern did not match.
 Regex: 'avcodec_open2 failed: Invalid argument'
 Input: 'invalid sample rate=10. Supported sample rate values are: 44100, 48000, 32000, 22050, 24000, 16000, 11025, 12000, 8000'
FAILED test/test_encoders.py::TestAudioEncoder::test_against_cli[to_file-flac-8000-2-None-asset0] - json.decoder.JSONDecodeError: Expecting ',' delimiter: line 3460 column 10 (char 111086)
==== 4 failed, 959 passed, 364 skipped, 3 deselected in 321.68s (0:05:21) =====

I actually encountered the same problem in conda-forge/torchcodec-feedstock#33 . Basically, the workaround added in 1dd1bc7 are not required for ffmpeg >= 7.1 .

[Dan-Flores]

Thank you for this great fix @traversaro!