从视频文件中提取音频 [英] Extract audio from video file

问题描述

如何在不使用FFmpeg 的情况下从视频文件中取消音频？

How can I extrace Audio from Video file without using FFmpeg?

我想用 AVMutableComposition 和 AVURLAsset 来解决it.eg从.mov转换为.m4a文件。

I want to use AVMutableComposition and AVURLAsset for solving it.e.g. conversion from .mov to .m4a file.

推荐答案

以下Swift 3代码显示了如何从电影文件中提取音频（ .mov ）并使用 AVURLAsset ， AVMutableComposition 将其转换为音频文件（ .m4a ） AVAssetExportSession ：

The following Swift 3 code shows how to extract audio from a movie file (.mov) and convert it to an audio file (.m4a) by using 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: AVMediaTypeAudio).first else { return }
            let audioCompositionTrack = composition.addMutableTrack(withMediaType: AVMediaTypeAudio, preferredTrackID: kCMPersistentTrackID_Invalid)
            try audioCompositionTrack.insertTimeRange(audioAssetTrack.timeRange, of: audioAssetTrack, at: kCMTimeZero)
        } catch {
            print(error)
        }

        // Get url for output
        let outputUrl = URL(fileURLWithPath: NSTemporaryDirectory() + "out.m4a")
        if FileManager.default.fileExists(atPath: exportUrl.path) {
            try? FileManager.default.removeItem(atPath: outputUrl.path)
        }

        // Create an export session
        let exportSession = AVAssetExportSession(asset: composition, presetName: AVAssetExportPresetPassthrough)!
        exportSession.outputFileType = AVFileTypeAppleM4A
        exportSession.outputURL = outputUrl

        // Export file
        exportSession.exportAsynchronously {
            guard case exportSession.status = AVAssetExportSessionStatus.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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