Reference
What is media metadata?
Metadata is information that describes or controls a media file without being the main encoded picture or sound: title, artist, album, language, chapters, track names, artwork, dates, flags and more.
Different containers use different metadata systems
| Context | Examples |
|---|---|
| MP3 | ID3 tags, including text and embedded artwork |
| FLAC / Ogg-family workflows | Vorbis comments plus picture blocks/attachments depending on format |
| MP4 / M4A / MOV | Container atoms/boxes for names, artwork and other metadata |
| Matroska / MKV | Tags, chapters, track flags and attachments such as cover art or subtitle fonts |
Does editing metadata change audio or video quality?
Normally, no. Changing a title or artist tag does not re-encode the media stream. However, badly designed software can choose to rewrite or transcode a file, and adding large artwork increases total file size even though the audio/video payload is unchanged.
Embedded artwork is not always where the picture comes from
A player may display cover art stored inside the file, an external image such as folder.jpg, or artwork retrieved from an online database. Seeing artwork on screen therefore does not prove it is embedded in the media file.