self-updating metadata?

Forgive me if this question has been answered before, I’m not familiar enough with the correct jargon to be able to search on it.

I sometimes listen to music streams through, which as far as I know is not responsible for providing the metadata about individual tracks-- that comes from the source, right? Is there a way in Audacity to encode ‘timed metadata,’ or inline changes, into mp3 or ogg files, so that it displays in the player (such as Vox)? For example, updating a multi-movement classical work with the tempo indications for each movement?

If you downloaded the stream as a file there may be metatadata in the file or (for OGG) for the separate streams in one file. If you recorded it, there won’t be metadata. Of course, we assume you already have copyright holders’ permission to download or record.

Audacity has Metadata Tags editor. You can look there to see what metadata there is, but it only shows metadata for the last file or stream. Audacity does not export multi-stream files, so if you want separate metadata per movement you have to export one file per movement or put the tempo for each movement into one metadata tag, or into separate metadata tags.

Unless you put the tempo indications for all movements in the Comments field, they may not be treated as standard metadata by the player, even if you use MP3 and enter “BPM” as the tag name. So whether the player shows tempo outside the Comments field depends on the player.