AVAssetExportSession 导出需要很多时间
AVAssetExportSession export takes a lot of time
我的目标是让用户 select 从照片中提取视频，然后让他在上面添加标签。
这是我得到的：
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函数的实现：
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 的最后一个函数：
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
}
代码运行良好，输出视频有标签，但如果我 select 1 分钟的视频，导出需要 28 秒。
我搜索过它并尝试删除 layerInsctuction 转换，但没有效果。
尝试添加：
assetExport.shouldOptimizeForNetworkUse = false
也没效果。
此外，尝试为 AVAssetExportSession 设置 AVAssetExportPresetPassthrough，在这种情况下，视频导出时间为 1 秒，但标签已消失。
任何帮助将不胜感激，因为我陷入困境。感谢您的宝贵时间。
这与您的问题没有直接关系，但您的代码是倒退的：
assetExport.exportAsynchronously {
let library = ALAssetsLibrary()
library.writeVideoAtPath(toSavedPhotosAlbum: url, completionBlock: {
switch assetExport.status {
不不不。首先完成资产导出。然后，如果您想这样做，您可以再次复制到其他地方。所以这需要像这样：
assetExport.exportAsynchronously {
switch assetExport.status {
case .completed:
let library = ALAssetsLibrary()
library.writeVideoAtPath...
其他评论：
ALAssetsLibrary 已死。这不是复制到用户照片库的方式。使用照片框架。
您的原始代码很奇怪，因为还有很多其他情况您没有测试。您只是 假设 default 意味着 .completed。太危险了。
我能想到的唯一方法是通过比特率和分辨率降低质量。
这是通过应用于 AssetExporter 的 videoSettings 的字典完成的，为此我必须使用名为 SDAVAssetExportSession
的框架
然后通过更改 videoSettings 我可以播放质量以获得最佳质量/速度。
let compression = [AVVideoAverageBitRateKey : 2097152(DESIRED_BITRATE),AVVideoProfileLevelKey : AVVideoProfileLevelH264BaselineAutoLevel]
let videoSettings = [AVVideoCodecKey : AVVideoCodecH264, AVVideoWidthKey : maxWidth, AVVideoHeightKey : maxHeight, AVVideoCompressionPropertiesKey:compression]
这是我加快速度的唯一方法。
我的目标是让用户 select 从照片中提取视频，然后让他在上面添加标签。
这是我得到的：
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函数的实现：
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 的最后一个函数：
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
}
代码运行良好，输出视频有标签，但如果我 select 1 分钟的视频，导出需要 28 秒。
我搜索过它并尝试删除 layerInsctuction 转换，但没有效果。
尝试添加：
assetExport.shouldOptimizeForNetworkUse = false
也没效果。
此外，尝试为 AVAssetExportSession 设置 AVAssetExportPresetPassthrough，在这种情况下，视频导出时间为 1 秒，但标签已消失。
任何帮助将不胜感激，因为我陷入困境。感谢您的宝贵时间。
这与您的问题没有直接关系，但您的代码是倒退的：
assetExport.exportAsynchronously {
let library = ALAssetsLibrary()
library.writeVideoAtPath(toSavedPhotosAlbum: url, completionBlock: {
switch assetExport.status {
不不不。首先完成资产导出。然后，如果您想这样做，您可以再次复制到其他地方。所以这需要像这样：
assetExport.exportAsynchronously {
switch assetExport.status {
case .completed:
let library = ALAssetsLibrary()
library.writeVideoAtPath...
其他评论：
ALAssetsLibrary 已死。这不是复制到用户照片库的方式。使用照片框架。
您的原始代码很奇怪，因为还有很多其他情况您没有测试。您只是 假设
default意味着.completed。太危险了。
我能想到的唯一方法是通过比特率和分辨率降低质量。
这是通过应用于 AssetExporter 的 videoSettings 的字典完成的，为此我必须使用名为 SDAVAssetExportSession
然后通过更改 videoSettings 我可以播放质量以获得最佳质量/速度。
let compression = [AVVideoAverageBitRateKey : 2097152(DESIRED_BITRATE),AVVideoProfileLevelKey : AVVideoProfileLevelH264BaselineAutoLevel]
let videoSettings = [AVVideoCodecKey : AVVideoCodecH264, AVVideoWidthKey : maxWidth, AVVideoHeightKey : maxHeight, AVVideoCompressionPropertiesKey:compression]
这是我加快速度的唯一方法。