Infer audio file extension
Infer audio file extension for audio filenames without extension (audio files downloaded from the Hub).

This will avoid unnecessary conversions of audio files without extension.

Follow-up of:
- #2180

Fix #2181.
Infer audio file extension: Infer audio file extension for audio filenames without extension (audio files downloaded from the Hub).

This will avoid unnecessary conversions of audio files without extension.

Follow-up of:
- #2180

Fix #2181.