通过 AVAssetExportSession 导出 mp4 失败

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【中文标题】通过 AVAssetExportSession 导出 mp4 失败【英文标题】:Exporting mp4 through AVAssetExportSession fails 【发布时间】:2017-01-09 09:04:37 【问题描述】:

我开始说我花了很多时间搜索文档、这里和其他地方的帖子,但我无法找到解决这个问题的方法。

我使用AVAssetExportSession 导出存储在AVAsset 实例中的.mp4 文件。 我要做的是:

我检查了AVAssetisExportable 属性 然后我得到一个与AVAsset 实例兼容的exportPresets 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% 的时间,我需要的预设总是包含在列表中,但我也尝试了直通选项,但它无论如何都不起作用)

outputFileTypeAVFileTypeMPEG4,我也尝试通过将.mp4 扩展名分配给文件,但没有任何效果。 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=此操作不支持 media., 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)
    

【问题讨论】:

【参考方案1】:

似乎将AVAsset 实例转换为AVMutableComposition 就可以了。如果有人知道这行得通的原因,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)
    

【讨论】:

嗨@Dincer,对不起,到目前为止我还没有在ios11上尝试过,我停止了那个项目 是的,这很奇怪,但是使用合成可以解决问题。【参考方案2】:

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。

【讨论】:

***.com/questions/56729461/…【参考方案3】:

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)
    

【讨论】:

【参考方案4】:

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。 这就是你需要做的。

【讨论】:

AVURLAsset.resourceLoader 应该与AVAssetExportSession 无关(适用于任何 AVAsset,而不仅仅是 AVURLAsset) 虽然这是零意义,但实际上这就是您所要做的。将资产资源加载器上的委托设置为 self 并符合协议。您甚至不必实现任何方法或任何东西。【参考方案5】:

我遇到了这个问题,因为Microphone 权限被关闭/拒绝。一旦我设置打开它,这个错误就消失了。

【讨论】:

【参考方案6】:

我通过从AVMutableComposition 中删除媒体类型为.audio 和空segmentsCompositionTrack 解决了这个问题

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

【讨论】:

【参考方案7】:

我遇到了同样的错误,当我尝试 ExportSessionAVAssetExportPresetPassthrough 时总是失败,在我的情况下,我不能使用另一个预设,因为我必须具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"

叉子对我来说很棒,它保存的分辨率与之前的视频相同

【讨论】:

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