如何解决如何在视频或 CAtextlayer 上添加测试我想在录制的视频上显示文字当我这样做时，音频很好，视频变为空白提前致谢
我正在录制 3 个视频并将它们合并为一个。我需要所有视频的文字。正在做，但没有成功。视频变黑，音频正常。当我没有 CALayer 时，一切都很好需要帮助。 我的代码有问题，或者我做错了，请指导我。
private func doMerge(arrayVideos:[AVAsset],animation:Bool,completion:@escaping Completion) -> Void {
var insertTime = CMTime.zero
var arrayLayerInstructions:[AVMutableVideoCompositionLayerInstruction] = []
var outputSize = CGSize.init(width: 0,height: 0)
// Determine video output size
for videoAsset in arrayVideos {
let videoTrack = videoAsset.tracks(withMediaType: AVMediaType.video)[0]
let assetInfo = orientationFromTransform(transform: videoTrack.preferredTransform)
var videoSize = videoTrack.naturalSize
if assetInfo.isPortrait == true {
videoSize.width = videoTrack.naturalSize.height
videoSize.height = videoTrack.naturalSize.width
}
if videoSize.height > outputSize.height {
outputSize = videoSize
}
}
if outputSize.width == 0 || outputSize.height == 0 {
outputSize = defaultSize
}
// Silence sound (in case of video has no sound track)
// let silenceURL = Bundle.main.url(forResource: "silence",withExtension: "mp3")
// let silenceAsset = AVAsset(url:silenceURL!)
// let silenceSoundTrack = silenceAsset.tracks(withMediaType: AVMediaType.audio).first
// Init composition
let mixComposition = AVMutableComposition.init()
for videoAsset in arrayVideos {
// Get video track
guard let videoTrack = videoAsset.tracks(withMediaType: AVMediaType.video).first else { continue }
// Get audio track
var audioTrack:AVAssetTrack?
if videoAsset.tracks(withMediaType: AVMediaType.audio).count > 0 {
audioTrack = videoAsset.tracks(withMediaType: AVMediaType.audio).first
}
else {
// audioTrack = silenceSoundTrack
}
// Init video & audio composition track
let videoCompositionTrack = mixComposition.addMutableTrack(withMediaType: AVMediaType.video,preferredTrackID: Int32(kCMPersistentTrackID_Invalid))
let audioCompositionTrack = mixComposition.addMutableTrack(withMediaType: AVMediaType.audio,preferredTrackID: Int32(kCMPersistentTrackID_Invalid))
do {
let startTime = CMTime.zero
let duration = videoAsset.duration
// Add video track to video composition at specific time
try videoCompositionTrack?.insertTimeRange(CMTimeRangeMake(start: startTime,duration: duration),of: videoTrack,at: insertTime)
// Add audio track to audio composition at specific time
if let audioTrack = audioTrack {
try audioCompositionTrack?.insertTimeRange(CMTimeRangeMake(start: startTime,of: audioTrack,at: insertTime)
}
// Add instruction for video track
let layerInstruction = videoCompositionInstructionForTrack(track: videoCompositionTrack!,asset: videoAsset,standardSize: outputSize,atTime: insertTime)
// Hide video track before changing to new track
let endTime = CMTimeAdd(insertTime,duration)
if animation {
let timeScale = videoAsset.duration.timescale
let durationAnimation = CMTime.init(seconds: 1,preferredTimescale: timeScale)
layerInstruction.setopacityRamp(fromStartOpacity: 1.0,toEndOpacity: 0.0,timeRange: CMTimeRange.init(start: endTime,duration: durationAnimation))
}
else {
layerInstruction.setopacity(0,at: endTime)
}
arrayLayerInstructions.append(layerInstruction)
// Increase the insert time
insertTime = CMTimeAdd(insertTime,duration)
}
catch {
print("Load track error")
}
// Watermark Effect
let size = videoTrack.naturalSize
// create text Layer
let titleLayer = CATextLayer()
titleLayer.backgroundColor = UIColor.clear.cgColor
titleLayer.contentsScale = UIScreen.main.scale
titleLayer.string = "Dummy text"
titleLayer.foregroundColor = UIColor.white.cgColor
titleLayer.font = UIFont(name: "Helvetica",size: 28)
titleLayer.shadowOpacity = 0.5
titleLayer.alignmentMode = CATextLayerAlignmentMode.center
titleLayer.frame = CGRect(x: 0,y: 50,width: size.width,height: size.height)
let videolayer = CALayer()
videolayer.backgroundColor = UIColor.clear.cgColor
// videolayer.frame = CGRect(x: 0,y: 0,height: size.height)
// let layercomposition = AVMutableVideoComposition()
// layercomposition.frameDuration = CMTimeMake(value: 1,timescale: 30)
// layercomposition.renderSize = size
mainComposition.animationTool = AVVideoCompositionCoreAnimationTool(postProcessingAsVideoLayer: videolayer,in: titleLayer)
}
// Main video composition instruction
let mainInstruction = AVMutableVideoCompositionInstruction()
mainInstruction.timeRange = CMTimeRangeMake(start: CMTime.zero,duration: insertTime)
mainInstruction.layerInstructions = arrayLayerInstructions
// Main video composition
// mainComposition = AVMutableVideoComposition()
mainComposition.instructions = [mainInstruction]
mainComposition.frameDuration = CMTimeMake(value: 1,timescale: 30)
mainComposition.renderSize = outputSize
// Export to file
let path = NstemporaryDirectory().appending("mergedVideo.mp4")
let exportURL = URL.init(fileURLWithPath: path)
// Remove file if existed
FileManager.default.removeItemIfExisted(exportURL)
// Init exporter
let exporter = AVAssetExportSession.init(asset: mixComposition,presetName: AVAssetExportPresetHighestQuality)
exporter?.outputURL = exportURL
exporter?.outputFileType = AVFileType.mp4
exporter?.shouldOptimizeforNetworkUse = true
exporter?.videoComposition = mainComposition
// Do export
exporter?.exportAsynchronously(completionHandler: {
dispatchQueue.main.async {
self.exportDidFinish(exporter: exporter,videoURL: exportURL,completion: completion)
}
})
}
解决方法
只需更改此部分
let assetInfo = orientationFromTransform(transform: videoTrack.preferredTransform)
var videoSize = videoTrack.naturalSize
if assetInfo.isPortrait == true {
videoSize.width = videoTrack.naturalSize.height
videoSize.height = videoTrack.naturalSize.width
}
// let size = videoTrack.naturalSize
// create text Layer
let titleLayer = CATextLayer()
titleLayer.backgroundColor = UIColor.clear.cgColor
titleLayer.contentsScale = UIScreen.main.scale
titleLayer.string = questions[counter]
counter = counter + 1
titleLayer.foregroundColor = UIColor.black.cgColor
titleLayer.font = UIFont(name: "Helvetica",size: 28)
titleLayer.shadowOpacity = 0.5
titleLayer.alignmentMode = CATextLayerAlignmentMode.center
titleLayer.frame = CGRect(x: 0,y: 0,width: videoSize.width,height: videoSize.height)
let videolayer = CALayer()
videolayer.backgroundColor = UIColor.clear.cgColor
videolayer.backgroundColor = UIColor.red.cgColor
videolayer.frame = CGRect(x: 0,height: videoSize.height)
let parentlayer = CALayer()
parentlayer.frame = CGRect(x: 0,height: videoSize.height)
parentlayer.addSublayer(videolayer)
parentlayer.addSublayer(titleLayer)
// let layercomposition = AVMutableVideoComposition()
// layercomposition.frameDuration = CMTimeMake(value: 1,timescale: 30)
// layercomposition.renderSize = size
mainComposition.animationTool = AVVideoCompositionCoreAnimationTool(postProcessingAsVideoLayer: videolayer,in: parentlayer)
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