wp_read_audio_metadata() keeps no tags from FLAC, Ogg or M4A files

[JoeFusco]

wp_add_id3_tag_data() reads tags only from ID3. FLAC and Ogg files store tags as Vorbis comments, and M4A files as QuickTime atoms, so these files keep no title, artist, album, year or track number.

Steps to reproduce

ffmpeg -f lavfi -i anullsrc -t 1 -metadata title=Test -metadata artist=Band t.flac
ffmpeg -f lavfi -i anullsrc -t 1 -metadata title=Test -metadata artist=Band t.mp3

Upload both and compare wp_get_attachment_metadata(). The MP3 has title and artist; the FLAC has neither. Reproduces on trunk with no plugins active.

Proposed fix

When a file has no ID3 tags, read the first tag set in $data['tags'], renaming keys to their ID3 names:

Vorbis / QuickTime	ID3
albumartist, album_artist	band
date, creation_date	year
tracknumber	track_number
discnumber, disc_number	part_of_a_set
lyrics	unsynchronised_lyric

ID3 takes precedence when both exist, and tags never replace what was read from the stream, such as its encoder.

wp_add_id3_tag_data() reads tags only from ID3, so FLAC, Ogg and M4A files keep no title, artist, album, year or track number. When a file has no ID3, this reads the first other tag set getID3 found, renaming the keys whose ID3 name differs, and never replaces what was read from the stream. For files core already handles, the only change is that videos also keep their container tags (such as encoding_tool on MP4); no existing value changes.

<details>
<summary>Use of AI Tools</summary>

AI assistance: Yes
Tool(s): Claude Code
Model(s): claude-opus-5-5
Used for: Finding the bug, writing the patch and its tests; reviewed by me.

</details>

Thanks @josephfusco - the code looks good! It would be good to have some more users testing it with real files or some data or documentation to back up the fields you chose.

[adamsilverstein]

@JoeFusco can you give some steps to reproduce / testing instructions - where to upload the files and where to look for the missing data. Does this apply to all files in the specified formats?