allow more than one candidate backends

[lifeiteng]

No description provided.

[pzelasko]

Can you elaborate why is this change needed?

[lifeiteng]

I want to try use different backends for opus: export LHOTSE_LEGACY_OPUS_LOADING=1 will have two backends (ffmpeg + soundfile).

[pzelasko]

Could you instead remove the condition in lines 514-515 in lhotse/audio/backend.py?

lhotse/lhotse/audio/backend.py

Lines 514 to 515 in 509f4a9

	if isinstance(path_or_fd, (Path, str)) and str(path_or_fd).endswith(".opus"):
	return True # use libnsdfile for OPUS

[lifeiteng]

Could you instead remove the condition in lines 514-515 in lhotse/audio/backend.py?

lhotse/lhotse/audio/backend.py

Lines 514 to 515 in 509f4a9

	if isinstance(path_or_fd, (Path, str)) and str(path_or_fd).endswith(".opus"):
	return True # use libnsdfile for OPUS

done

[pzelasko]

Thanks, I meant to also revert the change removing the check for unique backends - I think it is useful.