如何从视频文件中提取音频不使用 FFmpeg?
我想用AVMutableComposition
and AVURLAsset
用于解决它,例如从 .mov 到 .m4a 文件的转换。
以下 Swift 5 / iOS 12.3 代码展示了如何从电影文件中提取音频(.mov)并将其转换为音频文件(.m4a) 通过使用AVURLAsset
, AVMutableComposition
and AVAssetExportSession
:
import UIKit
import AVFoundation
class ViewController: UIViewController {
@IBAction func extractAudioAndExport(_ sender: UIButton) {
// Create a composition
let composition = AVMutableComposition()
do {
let sourceUrl = Bundle.main.url(forResource: "Movie", withExtension: "mov")!
let asset = AVURLAsset(url: sourceUrl)
guard let audioAssetTrack = asset.tracks(withMediaType: AVMediaType.audio).first else { return }
guard let audioCompositionTrack = composition.addMutableTrack(withMediaType: AVMediaType.audio, preferredTrackID: kCMPersistentTrackID_Invalid) else { return }
try audioCompositionTrack.insertTimeRange(audioAssetTrack.timeRange, of: audioAssetTrack, at: CMTime.zero)
} catch {
print(error)
}
// Get url for output
let outputUrl = URL(fileURLWithPath: NSTemporaryDirectory() + "out.m4a")
if FileManager.default.fileExists(atPath: outputUrl.path) {
try? FileManager.default.removeItem(atPath: outputUrl.path)
}
// Create an export session
let exportSession = AVAssetExportSession(asset: composition, presetName: AVAssetExportPresetPassthrough)!
exportSession.outputFileType = AVFileType.m4a
exportSession.outputURL = outputUrl
// Export file
exportSession.exportAsynchronously {
guard case exportSession.status = AVAssetExportSession.Status.completed else { return }
DispatchQueue.main.async {
// Present a UIActivityViewController to share audio file
guard let outputURL = exportSession.outputURL else { return }
let activityViewController = UIActivityViewController(activityItems: [outputURL], applicationActivities: [])
self.present(activityViewController, animated: true, completion: nil)
}
}
}
}
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