This adds a metadata test case for extracting data from an opus test
file. The added file is just converted from test.ogg and the same
metadata fields are used.
Signed-off-by: Toke Høiland-Jørgensen <toke@toke.dk>
If you ever need an empty flac file with metadata again:
1. Get a flac file (like https://archive.org/download/NineInchNailsTheSlip24bit96khz/01999999.flac)
2. Tag it with Musicbrainz Picard
3. Truncate it, keeping only tags with `ffmpeg -i in.flac -ss 0 -to 0.001 out.flac`
Thanks @HgO for the trick!
Eliot Berriot