Question

更新了代码示例，控制台输出和信息

我试图获取视频合成的总持续时间，将其除以10，向上舍入，然后循环并以这些间隔拼接视频合成。

它有效，但在“当前时间”之后＃39;变为60+，它会抛出一个＆＃34;在此服务器上找不到请求的URL。＆＃34;

基本上如果它确定它需要产生9个剪辑，它会在前6个成功后失败而另外3个也失败。另外我的numLoop并没有按预期工作，它几乎看起来while循环在9个剪辑中的任何一个之前完成正在尝试。

非常喜欢帮助/洞察所有9个片段的导出。

我注意到如果视频长度少于60秒，则成功率为100％。我选择的超过60秒的任何视频都会在第7个剪辑中失败。

这是我的方法：

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


}

这是exportDidFinish方法：

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))")
})
}
}

这是控制台输出：

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

Answer 1

好的，有些新闻。

自iOS 8以来，ALAssetsLibrary已被弃用，Apple将所有人移至Photos Framework进行此操作。好消息是AVAssetExportSession不被弃用。虽然您可以继续使用已弃用的API，但重写exportDidFinish函数以使用新API可能是个好主意。
splitVideo函数中的while循环抛出十个并发导出操作。说实话，这是一个猜测，但我怀疑，一旦你进入剪辑6，就会出现一些资源争用。

所以需要重新设计才能更友好一点。最好的办法是使用NSOperationQueue maxConcurrentOperationsCount设置为1（即串行队列）。

类似的东西：

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导出操作一次运行一个而不是一次尝试。如果成功，您可以尝试增加maxConcurrentOperationsCount以获得一些多线程。

AVAssetExportSession仅适用于前6次

1 个答案: