我的目標是讓用戶從照片中選擇視頻,然後讓他在其上添加標籤。AVAssetExportSession導出需要很長時間
以下是我有:
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")
}
})
}
實施isVideoPortrait
功能:
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
}
而對於video composition layer instruction
的最後一個函數:
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
}
代碼工作得很好,輸出視頻有標籤,但如果我選擇1分鐘視頻,請輸出ta凱斯28秒。
我已經搜索了它,並試圖刪除layerInsctuction
變換,但沒有效果。
試圖添加: assetExport.shouldOptimizeForNetworkUse = false
也沒有效果。
此外,試圖設置AVAssetExportPresetPassthrough
爲AVAssetExportSession
,在這種情況下視頻出口1秒但標籤已經消失。
任何幫助將不勝感激,因爲我陷入困境。謝謝你的時間。
您正在做兩件耗時的事情:導出和複製到相冊中。哪一個花了很長時間? – matt
另外:當某些事情需要很長時間並且您想知道爲什麼時,請使用儀器。你嘗試過嗎?它告訴你什麼? – matt
@matt基本上,出口需要很多時間。複製到照片專輯需要1秒。我還沒有使用過儀器,當我運行儀器時,是否應該使用「活動監視器」? – mikle94