我正在尝试使用UI
ImagePickerController(不是现有的视频,而是一个在线)上的用户相机拍摄的视频,以上传到我的服务器,花费少量的时间来做到这一点,所以更小的尺寸是理想的,而不是30- 45Mb的新品质相机.
以下是针对iOS 8的Swift进行压缩的代码,它可以令人惊奇地压缩,从35 mb下降到2.1 mb.
func convertVideo(inputUrl: NSURL,outputURL: NSURL)
{
//setup video writer
var videoAsset = AVURLAsset(URL: inputUrl,options: nil) as AVAsset
var videoTrack = videoAsset.tracksWithMediaType(AVMediaTypeVideo)[0] as AVAssetTrack
var videoSize = videoTrack.naturalSize
var videoWriterCompressionSettings = Dictionary(dictionaryLiteral:(AVVideoAverageBitRateKey,NSNumber(integer:960000)))
var videoWriterSettings = Dictionary(dictionaryLiteral:(AVVideoCodecKey,AVVideoCodecH264),(AVVideoCompressionPropertiesKey,videoWriterCompressionSettings),(AVVideoWidthKey,videoSize.width),(AVVideoHeightKey,videoSize.height))
var videoWriterInput = AVAssetWriterInput(mediaType: AVMediaTypeVideo,outputSettings: videoWriterSettings)
videoWriterInput.expectsMediaDataInRealTime = true
videoWriterInput.transform = videoTrack.preferredTransform
var videoWriter = AVAssetWriter(URL: outputURL,fileType: AVFileTypeQuickTimeMovie,error: nil)
videoWriter.addInput(videoWriterInput)
var videoReaderSettings: [String:AnyObject] = [kCVPixelBufferPixelFormatTypeKey:kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange]
var videoReaderOutput = AVAssetReaderTrackOutput(track: videoTrack,outputSettings: videoReaderSettings)
var videoReader = AVAssetReader(asset: videoAsset,error: nil)
videoReader.addOutput(videoReaderOutput)
//setup audio writer
var audioWriterInput = AVAssetWriterInput(mediaType: AVMediaTypeAudio,outputSettings: nil)
audioWriterInput.expectsMediaDataInRealTime = false
videoWriter.addInput(audioWriterInput)
//setup audio reader
var audioTrack = videoAsset.tracksWithMediaType(AVMediaTypeAudio)[0] as AVAssetTrack
var audioReaderOutput = AVAssetReaderTrackOutput(track: audioTrack,outputSettings: nil) as AVAssetReaderOutput
var audioReader = AVAssetReader(asset: videoAsset,error: nil)
audioReader.addOutput(audioReaderOutput)
videoWriter.startWriting()
//start writing from video reader
videoReader.startReading()
videoWriter.startSessionAtSourceTime(kCMTimeZero)
//dispatch_queue_t processingQueue = dispatch_queue_create("processingQueue",nil)
var queue = dispatch_queue_create("processingQueue",nil)
videoWriterInput.requestMediaDataWhenReadyOnQueue(queue,usingBlock: { () -> Void in
println("Export starting")
while videoWriterInput.readyForMoreMediaData
{
var sampleBuffer:CMSampleBufferRef!
sampleBuffer = videoReaderOutput.copyNextSampleBuffer()
if (videoReader.status == AVAssetReaderStatus.Reading && sampleBuffer != nil)
{
videoWriterInput.appendSampleBuffer(sampleBuffer)
}
else
{
videoWriterInput.markAsFinished()
if videoReader.status == AVAssetReaderStatus.Completed
{
if audioReader.status == AVAssetReaderStatus.Reading || audioReader.status == AVAssetReaderStatus.Completed
{
}
else {
audioReader.startReading()
videoWriter.startSessionAtSourceTime(kCMTimeZero)
var queue2 = dispatch_queue_create("processingQueue2",nil)
audioWriterInput.requestMediaDataWhenReadyOnQueue(queue2,usingBlock: { () -> Void in
while audioWriterInput.readyForMoreMediaData
{
var sampleBuffer:CMSampleBufferRef!
sampleBuffer = audioReaderOutput.copyNextSampleBuffer()
println(sampleBuffer == nil)
if (audioReader.status == AVAssetReaderStatus.Reading && sampleBuffer != nil)
{
audioWriterInput.appendSampleBuffer(sampleBuffer)
}
else
{
audioWriterInput.markAsFinished()
if (audioReader.status == AVAssetReaderStatus.Completed)
{
videoWriter.finishWritingWithCompletionHandler({ () -> Void in
println("Finished writing video asset.")
self.videoUrl = outputURL
var data = NSData(contentsOfURL: outputURL)!
println("Byte Size After Compression: \(data.length / 1048576) mb")
println(videoAsset.playable)
//Networking().uploadVideo(data,fileName: "Test2")
self.dismissViewControllerAnimated(true,completion: nil)
})
break
}
}
}
})
break
}
}
}// Second if
}//first while
})// first block
// return
}
这是我的UIImagePickerController调用compress方法的代码
func imagePickerController(picker: UIImagePickerController,didFinishPickingMediaWithInfo info: [NSObject : AnyObject])
{
// Extract the media type from selection
let type = info[UIImagePickerControllerMediaType] as String
if (type == kUTTypeMovie)
{
self.videoUrl = info[UIImagePickerControllerMediaURL] as? NSURL
var uploadUrl = NSURL.fileURLWithPath(NSTemporaryDirectory().stringByAppendingPathComponent("captured").stringByAppendingString(".mov"))
var data = NSData(contentsOfURL: self.videoUrl!)!
println("Size Before Compression: \(data.length / 1048576) mb")
self.convertVideo(self.videoUrl!,outputURL: uploadUrl!)
// Get the video from the info and set it appropriately.
/*self.dismissViewControllerAnimated(true,completion: { () -> Void in
//self.next.enabled = true
})*/
}
}
正如我上面提到的,这个文件大小减少了,但是当我得到文件(它仍然是.mov类型)时,quicktime无法播放. Quicktime最初尝试转换它,但中途失败(打开文件后1-2秒)我甚至测试了AVPlayerController中的视频文件,但它没有提供有关电影的任何信息,它只是一个播放按钮没有蚂蚁加载,没有任何长度只是“ – ”的时间通常在播放器. IE是一个不会播放的损坏的文件.
我确定它与写入资产的设置有关,因为它是视频写作或音频写作我根本不知道.甚至可能是读取导致其破坏的资产.我已经尝试更改变量,并设置不同的键读取和写入,但我没有找到正确的组合,这可以吸收,我可以压缩,但得到一个损坏的文件.我不确定,任何帮助将不胜感激. Pleeeeeeeeease.
解决方法
安德鲁的答案是好的,并作为我在Swift 2.2中实施它的基础.但是,自从他发布以来,有一些事情发生了变化,所以我现在正在使用它,这样可以产生很好的效果.
您可以使用视频文件的现有URL和压缩副本的目标URL来调用此方法.
这是Swift 3.0的答案.
请参阅下面的2.2,虽然它没有更新,以反映改进的风格,因为3.0一个.
extension ViewController: AVCaptureFileOutputRecordingDelegate {
func capture(_ captureOutput: AVCaptureFileOutput!,didFinishRecordingToOutputFileAt outputFileURL: URL!,fromConnections connections: [Any]!,error: Error!) {
guard let data = NSData(contentsOf: outputFileURL as URL) else {
return
}
print("File size before compression: \(Double(data.length / 1048576)) mb")
let compressedURL = NSURL.fileURL(withPath: NSTemporaryDirectory() + NSUUID().uuidString + ".m4v")
compressVideo(inputURL: outputFileURL as URL,outputURL: compressedURL) { (exportSession) in
guard let session = exportSession else {
return
}
switch session.status {
case .unknown:
break
case .waiting:
break
case .exporting:
break
case .completed:
guard let compressedData = NSData(contentsOf: compressedURL) else {
return
}
print("File size after compression: \(Double(compressedData.length / 1048576)) mb")
case .failed:
break
case .cancelled:
break
}
}
}
func compressVideo(inputURL: URL,outputURL: URL,handler:@escaping (_ exportSession: AVAssetExportSession?)-> Void) {
let urlAsset = AVURLAsset(url: inputURL,options: nil)
guard let exportSession = AVAssetExportSession(asset: urlAsset,presetName: AVAssetExportPresetMediumQuality) else {
handler(nil)
return
}
exportSession.outputURL = outputURL
exportSession.outputFileType = AVFileTypeQuickTimeMovie
exportSession.shouldOptimizeForNetworkUse = true
exportSession.exportAsynchronously { () -> Void in
handler(exportSession)
}
}
}
Swift 2.2的答案
let compressedURL = NSURL.fileURLWithPath(NSTemporaryDirectory() + NSUUID().UUIDString + ".m4v")
compressVideo(outputFileURL,outputURL: compressedURL) { (session) in
switch session.status {
case .Unknown:
break
case .Waiting:
break
case .Exporting:
break
case .Completed:
let data = NSData(contentsOfURL: compressedURL)
print("File size after compression: \(Double(data!.length / 1048576)) mb")
case .Failed:
break
case .Cancelled:
break
}
}
这可以使用switch语句处理所有可能的结果.我把大部分都留空,因为内容会根据应用程序而有所不同.
对于实际的压缩方法,我实现了一个展开,并改变了var.
func compressVideo(inputURL: NSURL,outputURL: NSURL,handler:(session: AVAssetExportSession)-> Void) {
let urlAsset = AVURLAsset(URL: inputURL,options: nil)
if let exportSession = AVAssetExportSession(asset: urlAsset,presetName: AVAssetExportPresetMediumQuality) {
exportSession.outputURL = outputURL
exportSession.outputFileType = AVFileTypeQuickTimeMovie
exportSession.shouldOptimizeForNetworkUse = true
exportSession.exportAsynchronouslyWithCompletionHandler { () -> Void in
handler(session: exportSession)
}
}
}
我测试了几个视频,并看到一些非常显着的减少(例如：20 MB变成500k).
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