通过 AVAssetExportSession 导出 mp4 失败

Question

我开始说我花了很多时间搜索文档、此处和其他地方的帖子，但我无法找到解决此问题的方法。

我正在使用 AVAssetExportSession 导出存储在 AVAsset 实例中的 .mp4 文件。我做的是：

我检查了AVAsset

isExportable

然后我得到一个 exportPresets 与 AVAsset 实例兼容的数组
我使用 AVAssetExportPreset1920x1080，或者，如果不存在，我尝试使用 AVAssetExportPresetPassthrough 导出媒体（仅供参考，100% 的情况下，我需要的预设总是包含在列表中，但我也尝试了 passthrough 选项，但它不管用）

outputFileType 是 AVFileTypeMPEG4 我也尝试过为文件分配 .mp4 扩展名，但没有任何效果。我总是收到这个错误

Error Domain=AVFoundationErrorDomain Code=-11838 "Operation Stopped" UserInfo={NSUnderlyingError=0x600000658c30 {Error Domain=NSOSStatusErrorDomain Code=-12109 "(null)"}, NSLocalizedFailureReason=The operation is not supported for this media., NSLocalizedDescription=Operation Stopped}

下面是我使用的代码

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

似乎将 AVAsset 实例转换为 AVMutableComposition 就成功了。如果有人知道这有效的原因，请告诉我。

这是新的_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

检查您是否正确设置了 AVURLAsset 的委托属性。

[self.playerAsset.resourceLoader setDelegate:self queue:dispatch_get_main_queue()];

并且符合AVAssetResourceLoaderDelegate协议。这就是您需要做的。

Answer 3

我运行遇到这个问题是因为 Microphone 权限是 off/denied。一旦我设置打开它，这个错误就消失了。

Answer 4

我遇到了同样的问题，因为我在没有音频的视频中添加了音轨。删除音轨修复了它。

Answer 5

Swift 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)
    }
}

Answer 6

我通过从 AVMutableComposition

中删除媒体类型 .audio 和空 segments 的 CompositionTrack 解决了这个问题

if let audioTrack = exportComposition.tracks(withMediaType: .audio).first,
    audioTrack.segments.isEmpty {
        exportComposition.removeTrack(audioTrack)
}

Answer 7

我有同样的错误，当我尝试 ExportSession 和 AVAssetExportPresetPassthrough 总是失败，在我的情况下我不能使用另一个预设，因为我必须有与原始视频相同的分辨率

我修好了

let asset = AVAsset(url: originUrl)
let videoTrack = asset.tracks( withMediaType: .video ).first! as AVAssetTrack

let videoComposition = AVMutableVideoComposition()
videoComposition.renderSize = CGSize(
       width: videoTrack.naturalSize.width, 
       height: videoTrack.naturalSize.height
)
videoComposition.frameDuration = CMTime(
       value: 1, 
       timescale: videoTrack.naturalTimeScale
)
        
let transformer = AVMutableVideoCompositionLayerInstruction(
       assetTrack: videoTrack 
)
transformer.setOpacity(1.0, at: CMTime.zero)
        
let instruction = AVMutableVideoCompositionInstruction()
instruction.timeRange = timeRange
instruction.layerInstructions = [transformer]
videoComposition.instructions = [instruction]

guard let exportSession = AVAssetExportSession(
       asset: asset, 
       presetName: AVAssetExportPresetMediumQuality
) else {
       return handleFailure(error: .mediaSavingError, completion: completion)
}
        
exportSession.videoComposition = videoComposition
exportSession.outputURL = outputUrl
exportSession.outputFileType = .mp4
exportSession.timeRange = timeRange

exportSession.exportAsynchronously { [weak self] in 
    "your code"
}

Forks 非常适合我，它保存的分辨率与之前的视频相同

通过 AVAssetExportSession 导出 mp4 失败

Exporting mp4 through AVAssetExportSession fails

avfoundation

avassetexportsession

swift