nostr:npub19v7lz5n67uygmsr24rsw9arejnfxhwa3npkk00qpe8tx5ujdtpgs95al4a ah, didn't realize there was a difference with audio only mp4s

"Although M4A and MP4 files are similar, they are not the same. M4A files are compressed using the 'AAC' lossy, which gives them a smaller file size than MP4."