How to Read Id3 Tags/Other Metadata from an Hls Stream in Swift/Avkit

how to read id3 tags / other metadata from an HLS stream in swift / AVKIT

This is how I achieved it:

import UIKit
import AVKit
import AVFoundation
import MediaPlayer

class ViewController: UIViewController{

    let player = AVPlayer()
    var playerItem: AVPlayerItem!
    let asset = AVAsset(url: URL(string: "https://db2.indexcom.com/bucket/ram/00/05/05.m3u8")!)

    override func viewDidLoad() {
        prepareToPlay()
        player.play()
    }

    func prepareToPlay() {
        playerItem = AVPlayerItem(asset: asset)
        playerItem.addObserver(self, forKeyPath: "timedMetadata", options: [], context: nil)
        player.replaceCurrentItem(with: playerItem)
        printTimeStamp()
    }

    func printTimeStamp() {
        print("▼⎺▼⎺▼⎺▼⎺▼⎺▼⎺▼⎺▼")
        print("PROGRAM-DATE-TIME: ")
        print(playerItem.currentDate() ?? "No timeStamp")
        print("▲_▲_▲_▲_▲_▲_▲_▲\n\n")
    }

    override func observeValue(forKeyPath: String?, of: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
        if forKeyPath != "timedMetadata" { return }

        printTimeStamp()

        let data: AVPlayerItem = of as! AVPlayerItem

        guard let timedMetadata = data.timedMetadata else { return }

        for item in timedMetadata {
            switch item.commonKey {

            case .commonKeyAlbumName?:
                print("AlbumName: \(item.value!)")
            case .commonKeyArtist?:
                print("Artist: \(item.value!)")
            case .commonKeyArtwork?:
                print("Artwork: \(item.value!)")
            case .commonKeyAuthor?:
                print("Author: \(item.value!)")
            case .commonKeyContributor?:
                print("Contributor: \(item.value!)")
            case .commonKeyCopyrights?:
                print("Copyrights: \(item.value!)")
            case .commonKeyCreationDate?:
                print("CreationDate: \(item.value!)")
            case .commonKeyCreator?:
                print("creator: \(item.value!)")
            case .commonKeyDescription?:
                print("Description: \(item.value!)")
            case .commonKeyFormat?:
                print("Format: \(item.value!)")
            case .commonKeyIdentifier?:
                print("Identifier: \(item.value!)")
            case .commonKeyLanguage?:
                print("Language: \(item.value!)")
            case .commonKeyMake?:
                print("Make: \(item.value!)")
            case .commonKeyModel?:
                print("Model: \(item.value!)")
            case .commonKeyPublisher?:
                print("Publisher: \(item.value!)")
            case .commonKeyRelation?:
                print("Relation: \(item.value!)")
            case .commonKeySoftware?:
                print("Software: \(item.value!)")
            case .commonKeySubject?:
                print("Subject: \(item.value!)")
            case .commonKeyTitle?:
                print("Title: \(item.value!)")
            case .commonKeyType?:
                print("Type: \(item.value!)")

            case .id3MetadataKeyAlbumTitle?:
                print("id3MetadataKeyAlbumTitle: \(item.value!)")

            default:
                print("other data: \(item.value!)")
            }
        }
    }
}

AVKit and ID3 metadata keys

There are two versions of tags: ID3 2.2's 3 byte tags, and 2.3+'s 4 byte tags. The constants declared in AVMetadataKey are the 4 byte tags.

If you're seeing the 3 byte tags as the key, then it must be a file tagged with the 21-year-old v2.2 tags and AVAsset is giving them to you as-is, so you'll just need to do the conversion yourself. There aren't that many tags, so you can easily make a conversion list yourself.

Using AAC with ID3 tags with AVPlayer

Every frame in an aac file starts with an ADTS header that contains its sample rate. And every frame is exactly 1024 samples. Hence every frame is sample_rate/1024 seconds long with the first frames starting at zero. From this, you can walk the file, and calculate every frames timestamp.

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