我正在使用 m3u8 视频格式来流式传输视频，现在我需要显示相同的字幕。
我在Apple文档中搜索，发现可以通过使用
closedCaptionDisplayEnabledAVPlayer我有兴趣知道字幕的格式应该是什么？ .srt 格式可以吗？
我也可以使用
MPMoviePlayerController如有任何帮助，我们将不胜感激。
更新 03/06/2020： 在 GitHub 上，jbweimar 创建了一个示例项目，该项目使用看起来非常有前途的
AVAssetResourceLoaderDelegate2018 年 10 月 30 日更新： 值得检查 Apple 工程师的回答（感谢 @allenlini 指出）。他提出了一个涉及
AVAssetResourceLoaderDelegate原答案：
似乎在 m3u8 流描述中引用 WebVTT 文件是官方支持的方式。 “事后”添加它们似乎不受官方支持（请参阅Apple 工程师的声明（页面底部））。
但是，这并不意味着您无法让它工作;-)。 在 Chris Adamson 的 这个精彩的演示文稿 和 示例项目 (ZIP)、Apple 开发者论坛上的这篇文章 和 Abdul Azeem 的 Ray Wenderlich 教程 的帮助下，我能够让它工作。这是 Abdul Azeem 示例代码和 Chris 示例项目的修改版本。
注意如何使用AVMediaTypeText
而不是
AVMediaTypeSubtitle。这似乎是 iOS 中的一个错误。
// 1 - Load video asset
AVAsset *videoAsset = [AVURLAsset assetWithURL:[[NSBundle mainBundle] URLForResource:@"video" withExtension:@"mp4"]];
// 2 - Create AVMutableComposition object. This object will hold your AVMutableCompositionTrack instances.
AVMutableComposition *mixComposition = [[AVMutableComposition alloc] init];
// 3 - Video track
AVMutableCompositionTrack *videoTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo
preferredTrackID:kCMPersistentTrackID_Invalid];
[videoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, videoAsset.duration)
ofTrack:[[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0]
atTime:kCMTimeZero error:nil];
// 4 - Subtitle track
AVURLAsset *subtitleAsset = [AVURLAsset assetWithURL:[[NSBundle mainBundle] URLForResource:@"subtitles" withExtension:@"vtt"]];
AVMutableCompositionTrack *subtitleTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeText
preferredTrackID:kCMPersistentTrackID_Invalid];
[subtitleTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, videoAsset.duration)
ofTrack:[[subtitleAsset tracksWithMediaType:AVMediaTypeText] objectAtIndex:0]
atTime:kCMTimeZero error:nil];
// 5 - Set up player
AVPlayer *player = [AVPlayer playerWithPlayerItem: [AVPlayerItem playerItemWithAsset:mixComposition]];
@JohannesFahrenkrug 答案 的 Swift 版本。希望这对某人有用：
let localVideoAsset = Bundle.main.url(forResource: "L1C1P1C3", withExtension: "mp4")
//Create AVMutableComposition
let videoPlusSubtitles = AVMutableComposition()
//Adds video track
let videoTrack = videoPlusSubtitles.addMutableTrack(withMediaType: .video, preferredTrackID: kCMPersistentTrackID_Invalid)
try? videoTrack?.insertTimeRange(CMTimeRangeMake(kCMTimeZero, localVideoAsset.duration),
of: localVideoAsset.tracks(withMediaType: .video)[0],
at: kCMTimeZero)
//Adds subtitle track
let subtitleAsset = AVURLAsset(url: Bundle.main.url(forResource: "L1C1P1C3", withExtension: ".mp4.vtt")!)
let subtitleTrack = videoPlusSubtitles.addMutableTrack(withMediaType: .text, preferredTrackID: kCMPersistentTrackID_Invalid)
try? subtitleTrack?.insertTimeRange(CMTimeRangeMake(kCMTimeZero, localVideoAsset.duration),
of: subtitleAsset.tracks(withMediaType: .text)[0],
at: kCMTimeZero)
区别似乎在于，对于 AVPlayer，您可以使用 closeCaptionDisplayEnabled 属性控制是否显示字幕。
使用 MPMoviePlayerController，用户可以使用设置应用程序中的开关来控制是否显示字幕。您在应用程序中无法对此进行编程控制。
注意： 只能将本地项目（资产）插入到 AVMutableComposition 中，远程项目（如 HTTP 视频流）在 iOS 15 之前将无法工作。
将 HTTP 流插入 AVMutableComposition
斯威夫特5
func play() {
guard let videoUrl = Bundle.main.url(forResource: "ElephantsDream", withExtension: "mp4")?.absoluteURL,
let subtitleUrl = Bundle.main.url(forResource: "subtitles-en", withExtension: "vtt")?.absoluteURL else {
return
}
let videoAsset = AVURLAsset(url: videoUrl)
let subtitleAsset = AVURLAsset(url: subtitleUrl)
// Create AVMutableComposition object. This object will hold your AVMutableCompositionTrack instances.
let mixComposition = AVMutableComposition()
let videoTrack = mixComposition.addMutableTrack(withMediaType: .video, preferredTrackID: kCMPersistentTrackID_Invalid)
let audioTrack = mixComposition.addMutableTrack(withMediaType: .audio, preferredTrackID: kCMPersistentTrackID_Invalid)
let subtitleTrack = mixComposition.addMutableTrack(withMediaType: .text, preferredTrackID: kCMPersistentTrackID_Invalid)
do {
try videoTrack?.insertTimeRange(CMTimeRangeMake(start: .zero, duration: videoAsset.duration),
of: videoAsset.tracks(withMediaType: .video).first!,
at: .zero)
try audioTrack?.insertTimeRange(CMTimeRangeMake(start: .zero, duration: videoAsset.duration),
of: videoAsset.tracks(withMediaType: .audio).first!,
at: .zero)
try subtitleTrack?.insertTimeRange(CMTimeRangeMake(start: .zero, duration: subtitleAsset.duration),
of: subtitleAsset.tracks(withMediaType: .text).first!, at: .zero)
} catch let err {
print(err.localizedDescription)
}
let player = AVPlayer(playerItem: AVPlayerItem(asset: mixComposition))
let vc = AVPlayerViewController()
vc.player = player
present(vc, animated: true) {
vc.player?.play()
}
}
如果您想使用服务器端视频和字幕，您需要像这样使用。
iOS 15
func play() {
if #available(iOS 15.0.0, *) {
let videoUrl = URL(string: "https://wwww.acme.com/video/elephantsdream.mov")!
let subtitleUrl = URL(string: "https://wwww.acme.com/subtitle/subtitles-en.vtt")!
let videoAsset = AVURLAsset(url: videoUrl)
let subtitleAsset = AVURLAsset(url: subtitleUrl)
let mixComposition = AVMutableComposition()
let videoTrack = mixComposition.addMutableTrack(withMediaType: .video, preferredTrackID: kCMPersistentTrackID_Invalid)
let audioTrack = mixComposition.addMutableTrack(withMediaType: .audio, preferredTrackID: kCMPersistentTrackID_Invalid)
let subtitleTrack = mixComposition.addMutableTrack(withMediaType: .text, preferredTrackID: kCMPersistentTrackID_Invalid)
Task {
if let videoTrackItem = try await videoAsset.loadTracks(withMediaType: .video).first {
try videoTrack?.insertTimeRange(CMTimeRangeMake(start: .zero, duration: videoAsset.duration),
of: videoTrackItem,
at: .zero)
}
if let audioTrackItem = try await videoAsset.loadTracks(withMediaType: .audio).first {
try audioTrack?.insertTimeRange(CMTimeRangeMake(start: .zero, duration: videoAsset.duration),
of: audioTrackItem,
at: .zero)
}
if let subtitleTrackItem = try await subtitleAsset.loadTracks(withMediaType: .text).first {
try subtitleTrack?.insertTimeRange(CMTimeRangeMake(start: .zero, duration: videoAsset.duration),
of: subtitleTrackItem,
at: .zero)
}
DispatchQueue.main.async {
let player = AVPlayer(playerItem: AVPlayerItem(asset: mixComposition))
let vc = AVPlayerViewController()
vc.player = player
self.present(vc, animated: true) {
vc.player?.play()
}
}
}
}
}
归功于 Nicholas Riley 发现了这一点）。无论出于何种原因，每次会话大约有 50 个（具体数字各不相同）。
我不知道 AVFoundation 或 MPMoviePlayer 级别是否支持 WebVTT，或者应用程序是否自行下载和解析字幕文件。快速搜索“webvtt m3u8”会发现对
此 HTTP Live Streaming Draft 的引用，这表明您可能能够通过简单地引用 m3u8 播放列表中的 WebVTT 文件来完成这项工作。不过，我没有给您提供示例，因为我无法轻松猜测 WWDC 会话的 m3u8 URL。
let videoAsset = AVURLAsset(url: videoUrl)
let subtitleAsset = AVURLAsset(url: subtitleUrl)
let mixComposition = AVMutableComposition()
let videoTrack = mixComposition.addMutableTrack(withMediaType: .video, preferredTrackID: kCMPersistentTrackID_Invalid)
let audioTrack = mixComposition.addMutableTrack(withMediaType: .audio, preferredTrackID: kCMPersistentTrackID_Invalid)
let subtitleTrack = mixComposition.addMutableTrack(withMediaType: .text, preferredTrackID: kCMPersistentTrackID_Invalid)
Task {
if let videoTrackItem = try await videoAsset.loadTracks(withMediaType: .video).first {
try await videoTrack?.insertTimeRange(CMTimeRangeMake(start: .zero, duration: videoAsset.load(.duration)),
of: videoTrackItem,
at: .zero)
}
if let audioTrackItem = try await videoAsset.loadTracks(withMediaType: .audio).first {
try await audioTrack?.insertTimeRange(CMTimeRangeMake(start: .zero, duration: videoAsset.load(.duration)),
of: audioTrackItem,
at: .zero)
}
if let subtitleTrackItem = try await subtitleAsset.loadTracks(withMediaType: .text).first {
try await subtitleTrack?.insertTimeRange(CMTimeRangeMake(start: .zero, duration: videoAsset.load(.duration)),
of: subtitleTrackItem,
at: .zero)
}
DispatchQueue.main.async {
let player = AVPlayer(playerItem: AVPlayerItem(asset: mixComposition))
let vc = AVPlayerViewController()
vc.player = player
self.present(vc, animated: true) {
vc.player?.play()
}
}
}
尝试使用本地和远程网址，它可以工作，主要是你的字幕必须带有 .vtt 扩展名