通过AVAssetExportSession导出mp4失败

Question

我开始说我花了很多时间在文档,帖子和其他地方搜索,但我无法找到解决这个问题的方法.

我AVAssetExportSession用于导出.mp4存储在AVAsset实例中的文件.我所做的是:

• 我检查了isExportable属性AVAsset
• 然后我得到一个exportPresets与AVAsset实例兼容的数组
• 我接受AVAssetExportPreset1920x1080,或者,如果不存在,我尝试导出媒体AVAssetExportPresetPassthrough(仅供参考,100%的时间,我需要的预设总是包含在列表中,但我也尝试了passthrough选项,但它无论如何都不起作用)

的outputFileType是AVFileTypeMPEG4,我也试图通过分配.mp4扩展到该文件,但没有什么使得它的工作.我总是收到这个错误

错误域= AVFoundationErrorDomain代码= -11838"操作已停止"UserInfo = {NSUnderlyingError = 0x600000658c30 {错误域= NSOSStatusErrorDomain代码= -12109"(null)"},NSLocalizedFailureReason =此媒体不支持该操作.,NSLocalizedDescription =操作已停止}

下面是我正在使用的代码

func _getDataFor(_ item: AVPlayerItem, completion: @escaping (Data?) -> ()) {
    guard item.asset.isExportable else {
        completion(nil)
        return
    }

    let compatiblePresets = AVAssetExportSession.exportPresets(compatibleWith: item.asset)
    var preset: String = AVAssetExportPresetPassthrough
    if compatiblePresets.contains(AVAssetExportPreset1920x1080) { preset = AVAssetExportPreset1920x1080 }

    guard
        let exportSession = AVAssetExportSession(asset: item.asset, presetName: preset),
        exportSession.supportedFileTypes.contains(AVFileTypeMPEG4) else {
        completion(nil)
        return
    }

    var tempFileUrl = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)[0].appendingPathComponent("temp_video_data.mp4", isDirectory: false)
    tempFileUrl = URL(fileURLWithPath: tempFileUrl.path)

    exportSession.outputURL = tempFileUrl
    exportSession.outputFileType = AVFileTypeMPEG4
    let startTime = CMTimeMake(0, 1)
    let timeRange = CMTimeRangeMake(startTime, item.duration)
    exportSession.timeRange = timeRange

    exportSession.exportAsynchronously {
        print("\(exportSession.error)")
        let data = try? Data(contentsOf: tempFileUrl)
        _ = try? FileManager.default.removeItem(at: tempFileUrl)
        completion(data)
    }
}

Answer 1

看起来像是AVAsset在一个AVMutableComposition诀窍中转换实例.如果,请,任何人都知道这个工作的原因让我知道.

这是新_getDataFor(_:completion:)方法实现

func _getDataFor(_ item: AVPlayerItem, completion: @escaping (Data?) -> ()) {
    guard item.asset.isExportable else {
        completion(nil)
        return
    }

    let composition = AVMutableComposition()
    let compositionVideoTrack = composition.addMutableTrack(withMediaType: AVMediaTypeVideo, preferredTrackID: CMPersistentTrackID(kCMPersistentTrackID_Invalid))
    let compositionAudioTrack = composition.addMutableTrack(withMediaType: AVMediaTypeAudio, preferredTrackID: CMPersistentTrackID(kCMPersistentTrackID_Invalid))

    let sourceVideoTrack = item.asset.tracks(withMediaType: AVMediaTypeVideo).first!
    let sourceAudioTrack = item.asset.tracks(withMediaType: AVMediaTypeAudio).first!
    do {
        try compositionVideoTrack.insertTimeRange(CMTimeRangeMake(kCMTimeZero, item.duration), of: sourceVideoTrack, at: kCMTimeZero)
        try compositionAudioTrack.insertTimeRange(CMTimeRangeMake(kCMTimeZero, item.duration), of: sourceAudioTrack, at: kCMTimeZero)
    } catch(_) {
        completion(nil)
        return
    }

    let compatiblePresets = AVAssetExportSession.exportPresets(compatibleWith: composition)
    var preset: String = AVAssetExportPresetPassthrough
    if compatiblePresets.contains(AVAssetExportPreset1920x1080) { preset = AVAssetExportPreset1920x1080 }

    guard
        let exportSession = AVAssetExportSession(asset: composition, presetName: preset),
        exportSession.supportedFileTypes.contains(AVFileTypeMPEG4) else {
        completion(nil)
        return
    }

    var tempFileUrl = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)[0].appendingPathComponent("temp_video_data.mp4", isDirectory: false)
    tempFileUrl = URL(fileURLWithPath: tempFileUrl.path)

    exportSession.outputURL = tempFileUrl
    exportSession.outputFileType = AVFileTypeMPEG4
    let startTime = CMTimeMake(0, 1)
    let timeRange = CMTimeRangeMake(startTime, item.duration)
    exportSession.timeRange = timeRange

    exportSession.exportAsynchronously {
        print("\(tempFileUrl)")
        print("\(exportSession.error)")
        let data = try? Data(contentsOf: tempFileUrl)
        _ = try? FileManager.default.removeItem(at: tempFileUrl)
        completion(data)
    }
}

Answer 2

斯威夫特5：

import Foundation
import AVKit

func getDataFor(_ asset: AVAsset, completion: @escaping (Data?) -> ()) {
    
    guard asset.isExportable,
          let sourceVideoTrack = asset.tracks(withMediaType: .video).first,
          let sourceAudioTrack = asset.tracks(withMediaType: .audio).first else {
              completion(nil)
              return
          }
    
    let composition = AVMutableComposition()
    let compositionVideoTrack = composition.addMutableTrack(withMediaType: .video, preferredTrackID: CMPersistentTrackID(kCMPersistentTrackID_Invalid))
    let compositionAudioTrack = composition.addMutableTrack(withMediaType: .audio, preferredTrackID: CMPersistentTrackID(kCMPersistentTrackID_Invalid))
            
    do {
        try compositionVideoTrack?.insertTimeRange(CMTimeRangeMake(start: .zero, duration: asset.duration), of: sourceVideoTrack, at: .zero)
        try compositionAudioTrack?.insertTimeRange(CMTimeRangeMake(start: .zero, duration: asset.duration), of: sourceAudioTrack, at: .zero)
    } catch {
        completion(nil)
        return
    }
    
    let compatiblePresets = AVAssetExportSession.exportPresets(compatibleWith: composition)
    var preset = AVAssetExportPresetPassthrough
    let preferredPreset = AVAssetExportPreset1920x1080
    if compatiblePresets.contains(preferredPreset) {
        preset = preferredPreset
    }
    
    let fileType: AVFileType = .mp4

    guard let exportSession = AVAssetExportSession(asset: composition, presetName: preset),
          exportSession.supportedFileTypes.contains(fileType) else {
              completion(nil)
              return
          }
    
    let tempFileUrl = URL(fileURLWithPath: NSTemporaryDirectory()).appendingPathComponent("temp_video_data")
    
    exportSession.outputURL = tempFileUrl
    exportSession.outputFileType = fileType
    let startTime = CMTimeMake(value: 0, timescale: 1)
    let timeRange = CMTimeRangeMake(start: startTime, duration: asset.duration)
    exportSession.timeRange = timeRange
    
    exportSession.exportAsynchronously {
        print(tempFileUrl)
        print(String(describing: exportSession.error))
        let data = try? Data(contentsOf: tempFileUrl)
        try? FileManager.default.removeItem(at: tempFileUrl)
        completion(data)
    }
}