[英]AVAssetExportSession export takes a lot of time
我的目標是讓用戶從照片中選擇視頻,然后讓他在其上添加標簽。
這是我所擁有的:
let audioAsset = AVURLAsset(url: selectedVideoURL)
let videoAsset = AVURLAsset(url: selectedVideoURL)
let mixComposition = AVMutableComposition()
let compositionVideoTrack = mixComposition.addMutableTrack(withMediaType: AVMediaTypeVideo, preferredTrackID: Int32(kCMPersistentTrackID_Invalid))
let compositionAudioTrack = mixComposition.addMutableTrack(withMediaType: AVMediaTypeAudio, preferredTrackID: Int32(kCMPersistentTrackID_Invalid))
let clipVideoTrack = videoAsset.tracks(withMediaType: AVMediaTypeVideo)[0]
let clipAudioTrack = audioAsset.tracks(withMediaType: AVMediaTypeAudio)[0]
do {
try compositionVideoTrack.insertTimeRange(CMTimeRangeMake(kCMTimeZero, videoAsset.duration), of: clipVideoTrack, at: kCMTimeZero)
try compositionAudioTrack.insertTimeRange(CMTimeRangeMake(kCMTimeZero, audioAsset.duration), of: clipAudioTrack, at: kCMTimeZero)
compositionVideoTrack.preferredTransform = clipVideoTrack.preferredTransform
} catch {
print(error)
}
var videoSize = clipVideoTrack.naturalSize
if isVideoPortrait(asset: videoAsset) {
videoSize = CGSize(width: videoSize.height, height: videoSize.width)
}
let parentLayer = CALayer()
let videoLayer = CALayer()
parentLayer.frame = CGRect(x: 0, y: 0, width: videoSize.width, height: videoSize.height)
videoLayer.frame = CGRect(x: 0, y: 0, width: videoSize.width, height: videoSize.height)
parentLayer.addSublayer(videoLayer)
// adding label
let helloLabelLayer = CATextLayer()
helloLabelLayer.string = "Hello"
helloLabelLayer.font = "Signika-Semibold" as CFTypeRef?
helloLabelLayer.fontSize = 30.0
helloLabelLayer.contentsScale = mainScreen.scale
helloLabelLayer.alignmentMode = kCAAlignmentNatural
helloLabelLayer.frame = CGRect(x: 0.0, y: 0.0, width: 100.0, height: 50.0)
parentLayer.addSublayer(helloLabelLayer)
// creating composition
let videoComp = AVMutableVideoComposition()
videoComp.renderSize = videoSize
videoComp.frameDuration = CMTimeMake(1, 30)
videoComp.animationTool = AVVideoCompositionCoreAnimationTool(postProcessingAsVideoLayer: videoLayer, in: parentLayer)
let instruction = AVMutableVideoCompositionInstruction()
instruction.timeRange = CMTimeRangeMake(kCMTimeZero, mixComposition.duration)
let layerInstruction = videoCompositionInstructionForTrack(track: compositionVideoTrack, asset: videoAsset)
instruction.layerInstructions = [layerInstruction]
videoComp.instructions = [instruction]
if let assetExport = AVAssetExportSession(asset: mixComposition, presetName: AVAssetExportPreset640x480) {
let filename = NSTemporaryDirectory().appending("video.mov")
if FileManager.default.fileExists(atPath: filename) {
do {
try FileManager.default.removeItem(atPath: filename)
} catch {
print(error)
}
}
let url = URL(fileURLWithPath: filename)
assetExport.outputURL = url
assetExport.outputFileType = AVFileTypeMPEG4
assetExport.videoComposition = videoComp
print(NSDate().timeIntervalSince1970)
assetExport.exportAsynchronously {
print(NSDate().timeIntervalSince1970)
let library = ALAssetsLibrary()
library.writeVideoAtPath(toSavedPhotosAlbum: url, completionBlock: {
(url, error) in
switch assetExport.status {
case AVAssetExportSessionStatus.failed:
p("failed \(assetExport.error)")
case AVAssetExportSessionStatus.cancelled:
p("cancelled \(assetExport.error)")
default:
p("complete")
p(NSDate().timeIntervalSince1970)
if FileManager.default.fileExists(atPath: filename) {
do {
try FileManager.default.removeItem(atPath: filename)
} catch {
p(error)
}
}
print("Exported")
}
})
}
isVideoPortrait
函數的實現:
func isVideoPortrait(asset: AVAsset) -> Bool {
var isPortrait = false
let tracks = asset.tracks(withMediaType: AVMediaTypeVideo)
if tracks.count > 0 {
let videoTrack = tracks[0]
let t = videoTrack.preferredTransform
if t.a == 0 && t.b == 1.0 && t.c == -1.0 && t.d == 0 {
isPortrait = true
}
if t.a == 0 && t.b == -1.0 && t.c == 1.0 && t.d == 0 {
isPortrait = true
}
if t.a == 1.0 && t.b == 0 && t.c == 0 && t.d == 1.0 {
isPortrait = false
}
if t.a == -1.0 && t.b == 0 && t.c == 0 && t.d == -1.0 {
isPortrait = false
}
}
return isPortrait
}
video composition layer instruction
的最后一個功能是:
func videoCompositionInstructionForTrack(track: AVCompositionTrack, asset: AVAsset) -> AVMutableVideoCompositionLayerInstruction {
let instruction = AVMutableVideoCompositionLayerInstruction(assetTrack: track)
let assetTrack = asset.tracks(withMediaType: AVMediaTypeVideo)[0]
let transform = assetTrack.preferredTransform
instruction.setTransform(transform, at: kCMTimeZero)
return instruction
}
代碼運行良好,輸出視頻帶有標簽,但是如果我選擇1分鍾的視頻,則導出需要28秒。
我已經搜索了它,並試圖刪除layerInsctuction
轉換,但是沒有效果。
試圖添加: assetExport.shouldOptimizeForNetworkUse = false
也無效。
另外,嘗試為AVAssetExportSession
設置AVAssetExportPresetPassthrough
,在這種情況下,視頻導出時間為1秒,但標簽消失了。
任何幫助將不勝感激,因為我陷入困境。 謝謝你的時間。
這與您的問題沒有直接關系,但是您的代碼在這里是向后的:
assetExport.exportAsynchronously {
let library = ALAssetsLibrary()
library.writeVideoAtPath(toSavedPhotosAlbum: url, completionBlock: {
switch assetExport.status {
不不不。 首先,您完成資產導出。 然后,如果您要這樣做,則可以再次復制到其他地方。 所以這需要像這樣:
assetExport.exportAsynchronously {
switch assetExport.status {
case .completed:
let library = ALAssetsLibrary()
library.writeVideoAtPath...
其他的建議:
ALAssetsLibrary已死。 這不是復制到用戶照片庫中的方法。 使用照片框架。
您的原始代碼很奇怪,因為您還沒有測試很多其他情況。 您只是假設 default
表示.completed
。 太危險了
我能想到的唯一方法是通過比特率和分辨率降低質量。
這是通過應用到AssetExporter的videoSettings的字典來完成的,為此,我不得不使用一個名為SDAVAssetExportSession
的框架
然后,通過更改videoSettings,我可以播放質量以獲得最佳質量/速度。
let compression = [AVVideoAverageBitRateKey : 2097152(DESIRED_BITRATE),AVVideoProfileLevelKey : AVVideoProfileLevelH264BaselineAutoLevel]
let videoSettings = [AVVideoCodecKey : AVVideoCodecH264, AVVideoWidthKey : maxWidth, AVVideoHeightKey : maxHeight, AVVideoCompressionPropertiesKey:compression]
這是我加快速度的唯一方法。
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