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社区首页 >问答首页 >AVAssetExportSession只工作前6次

问AVAssetExportSession只工作前6次
EN

Stack Overflow用户
提问于 2016-08-20 17:50:22
回答 1查看 711关注 0票数 0

更新的代码示例、控制台输出和信息

我试图得到一个视频构图的总持续时间，除以10，集合，然后按这些间隔循环并拼接视频构图。

它可以工作，但是在'currentDuration‘变成60+之后，它会抛出一个“在此服务器上找不到所请求的URL”。

基本上，如果它确定它需要生成9个剪辑，那么它成功了前6个，而失败了另外3个。而且，我的numLoop没有像预期的那样工作，在尝试这9个剪辑之前，while循环几乎完成了。

希望得到一些帮助/洞察力，使所有9个剪辑导出.

我注意到，如果视频长度小于60秒，它的成功率是100%。任何我选择超过60秒的视频都会在第7段失败。

以下是我的方法：

代码语言：javascript
复制
func splitVideo(videoComposition: AVMutableVideoComposition) {


let fileManager = NSFileManager.defaultManager()
let documentsPath : String = NSSearchPathForDirectoriesInDomains(.DocumentDirectory,.UserDomainMask,true)[0]

//grab total duration/number of splits
let exporter: AVAssetExportSession = AVAssetExportSession(asset: asset!, presetName:AVAssetExportPresetHighestQuality)!
let totalDuration = Float64(CMTimeGetSeconds(exporter.asset.duration))
let totalDurationPieces = (totalDuration/10)
var numberOfSplits=Int(ceil(Double(totalDurationPieces)))

//prepare for loop
var loopNum : Int = 0
var currentDuration : Float64 = 0
var sessionNumber = (arc4random()%1000)

let opQueue = NSOperationQueue()
    opQueue.maxConcurrentOperationCount = 1

    while loopNum < numberOfSplits {

        //new exporter
        var destinationPath: String = documentsPath + "/splitVideo-"+String(sessionNumber)
        destinationPath+="-"+String(Int(loopNum))+".mp4"

        let new_exporter = AVAssetExportSession(asset: asset!, presetName:AVAssetExportPresetHighestQuality)!

        new_exporter.outputURL = NSURL(fileURLWithPath: destinationPath as String)
        new_exporter.videoComposition = videoComposition
        new_exporter.outputFileType = AVFileTypeMPEG4
        new_exporter.shouldOptimizeForNetworkUse = false

        new_exporter.timeRange = CMTimeRangeMake(
            CMTimeMakeWithSeconds(currentDuration, framesPerSecond!),CMTimeMakeWithSeconds(Float64(10),framesPerSecond!))

        // Set up the exporter, then:
        opQueue.addOperationWithBlock { () -> Void in
            new_exporter.exportAsynchronouslyWithCompletionHandler({
                dispatch_async(dispatch_get_main_queue(),{
                    print("Exporting... \(loopNum)")
                    self.exportDidFinish(new_exporter, loopNum: loopNum)
                })
            }) // end completion handler
        } // end block



        //prepare for next loop
        loopNum = loopNum+1
        currentDuration = currentDuration+10

    if(loopNum>=numberOfSplits){
        self.allExportsDone(Int(numberOfSplits))
        }
} // end while


}

下面是exportDidFinish方法：

代码语言：javascript
复制
func exportDidFinish(session: AVAssetExportSession, loopNum: Int) {
let outputURL: NSURL = session.outputURL!
let library: ALAssetsLibrary = ALAssetsLibrary()
if(library.videoAtPathIsCompatibleWithSavedPhotosAlbum(outputURL)) {
    library.writeVideoAtPathToSavedPhotosAlbum(outputURL, completionBlock: {(url, error) in
//done
print("Success on \(Int(loopNum))")
})
}
}

以下是控制台输出：

代码语言：javascript
复制
Exporting... 9
2016-08-20 13:39:27.980 TrimVideo[4776:1576022] Video /var/mobile/Containers/Data/Application/BE125EB7-AFC4-48B5-95C3-941B420BB71F/Documents/splitVideo-972-6.mp4 cannot be saved to the saved photos album: Error Domain=NSURLErrorDomain Code=-1100 "The requested URL was not found on this server." UserInfo={NSUnderlyingError=0x1457f43f0 {Error Domain=NSPOSIXErrorDomain Code=2 "No such file or directory"}, NSErrorFailingURLStringKey=file:///var/mobile/Containers/Data/Application/BE125EB7-AFC4-48B5-95C3-941B420BB71F/Documents/splitVideo-972-6.mp4, NSErrorFailingURLKey=file:///var/mobile/Containers/Data/Application/BE125EB7-AFC4-48B5-95C3-941B420BB71F/Documents/splitVideo-972-6.mp4, NSURL=file:///var/mobile/Containers/Data/Application/BE125EB7-AFC4-48B5-95C3-941B420BB71F/Documents/splitVideo-972-6.mp4, NSLocalizedDescription=The requested URL was not found on this server.}
Exporting... 9
2016-08-20 13:39:27.984 TrimVideo[4776:1576022] Video /var/mobile/Containers/Data/Application/BE125EB7-AFC4-48B5-95C3-941B420BB71F/Documents/splitVideo-972-7.mp4 cannot be saved to the saved photos album: Error Domain=NSURLErrorDomain Code=-1100 "The requested URL was not found on this server." UserInfo={NSUnderlyingError=0x1457f88c0 {Error Domain=NSPOSIXErrorDomain Code=2 "No such file or directory"}, NSErrorFailingURLStringKey=file:///var/mobile/Containers/Data/Application/BE125EB7-AFC4-48B5-95C3-941B420BB71F/Documents/splitVideo-972-7.mp4, NSErrorFailingURLKey=file:///var/mobile/Containers/Data/Application/BE125EB7-AFC4-48B5-95C3-941B420BB71F/Documents/splitVideo-972-7.mp4, NSURL=file:///var/mobile/Containers/Data/Application/BE125EB7-AFC4-48B5-95C3-941B420BB71F/Documents/splitVideo-972-7.mp4, NSLocalizedDescription=The requested URL was not found on this server.}
Exporting... 9
2016-08-20 13:39:27.988 TrimVideo[4776:1576022] Video /var/mobile/Containers/Data/Application/BE125EB7-AFC4-48B5-95C3-941B420BB71F/Documents/splitVideo-972-8.mp4 cannot be saved to the saved photos album: Error Domain=NSURLErrorDomain Code=-1100 "The requested URL was not found on this server." UserInfo={NSUnderlyingError=0x14687cb30 {Error Domain=NSPOSIXErrorDomain Code=2 "No such file or directory"}, NSErrorFailingURLStringKey=file:///var/mobile/Containers/Data/Application/BE125EB7-AFC4-48B5-95C3-941B420BB71F/Documents/splitVideo-972-8.mp4, NSErrorFailingURLKey=file:///var/mobile/Containers/Data/Application/BE125EB7-AFC4-48B5-95C3-941B420BB71F/Documents/splitVideo-972-8.mp4, NSURL=file:///var/mobile/Containers/Data/Application/BE125EB7-AFC4-48B5-95C3-941B420BB71F/Documents/splitVideo-972-8.mp4, NSLocalizedDescription=The requested URL was not found on this server.}
Exporting... 9
Success on 9
Exporting... 9
Success on 9
Exporting... 9
Success on 9
Exporting... 9
Success on 9
Exporting... 9
avmutablecomposition
cmtime
ios
swift
avassetexportsession
EN

回答 1

Stack Overflow用户

回答已采纳

发布于 2016-08-20 18:51:42

好吧，一些消息。

  1. ALAssetsLibrary从iOS 8开始就不再受欢迎了，苹果把每个人都转移到Photos来做这件事。好消息是，AVAssetExportSession没有受到反对。虽然您可以继续使用不推荐的API，但重写该exportDidFinish函数以使用新API可能是个好主意。
  2. splitVideo函数中的while循环抛出十个并发导出操作。老实说，这只是一个猜测，但我怀疑，一旦到了第6段，就会出现一些资源争用。

因此，这需要重新设计，使之更加友好。最好的选择是使用NSOperationQueue，将maxConcurrentOperationsCount设置为1(即串行队列)。

类似于：

代码语言：javascript
复制
let opQueue = NSOperationQueue()
opQueue.maxConcurrentOperationsCount = 1

for loopNum in 0..<numberOfSplits {

   // Set up the exporter, then:

    opQueue.addOperationWithBlock { () -> Void in
        new_exporter.exportAsynchronouslyWithCompletionHandler({
            dispatch_async(dispatch_get_main_queue(),{
                print("Exporting... \(loopNum)")
                self.exportDidFinish(new_exporter, loopNum: loopNum)
            })
        } // end completion handler
    } // end block

} // end while

这样做的目的是确保每次只运行一个导出操作，而不是一次尝试。如果成功的话，您可以尝试提高maxConcurrentOperationsCount来进行多线程处理。

票数 1
EN
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：

https://stackoverflow.com/questions/39057099

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