[英]In Production Mode - I got "Operation Stopped" error when exporting video
[英]How to export arbitrary segment of video? “Operation Stopped” error when exporting last X seconds of video
目标是导出某些视频的任意片段(例如,中间三分之一,最后一半),但是AVAssetExportSession
仅在起点是视频的起点时成功。
如果cmStartTime
不为0,则AVAssetExportSession
失败,并显示以下错误:
失败:可选(错误域= AVFoundationErrorDomain代码= -11841“操作已停止” UserInfo = 0x175872d00 {NSLocalizedDescription =操作已停止,NSLocalizedFailureReason =无法合成视频。})。
// Create main composition & its tracks
let mainComposition = AVMutableComposition()
let compositionVideoTrack = mainComposition.addMutableTrackWithMediaType(AVMediaTypeVideo, preferredTrackID: CMPersistentTrackID(kCMPersistentTrackID_Invalid))
let compositionAudioTrack = mainComposition.addMutableTrackWithMediaType(AVMediaTypeAudio, preferredTrackID: CMPersistentTrackID(kCMPersistentTrackID_Invalid))
// Get source video & audio tracks
let videoURL = NSURL(fileURLWithPath: fileURL)
let videoAsset = AVURLAsset(URL: videoURL, options: nil)
let sourceVideoTrack = videoAsset.tracksWithMediaType(AVMediaTypeVideo)[0]
let sourceAudioTrack = videoAsset.tracksWithMediaType(AVMediaTypeAudio)[0]
// Define time values for video
let timescale = Int32(600)
let cmStartTime = CMTimeMake(Int64(CGFloat(0.5) * CGFloat(timescale)), timescale)
let cmEndTime = CMTimeMake(10, 1)
let timeRange = CMTimeRangeMake(cmStartTime, cmEndTime)
// Add source tracks to composition
do {
try compositionVideoTrack.insertTimeRange(timeRange, ofTrack: sourceVideoTrack, atTime: cmStartTime)
try compositionAudioTrack.insertTimeRange(timeRange, ofTrack: sourceAudioTrack, atTime: cmStartTime)
} catch {
printError("Error with insertTimeRange while exporting video: \(error)")
}
// Create video composition
let renderSize = compositionVideoTrack.naturalSize
let videoComposition = AVMutableVideoComposition()
videoComposition.renderSize = renderSize
videoComposition.frameDuration = CMTimeMake(Int64(1), Int32(frameRate))
// Add layer instruction to video composition
...
// Apply effects to video
...
// Define export URL
let exportPath = getUniqueTempPath(gMP4File)
let exportURL = NSURL(fileURLWithPath: exportPath)
// Create exporter
let exporter = AVAssetExportSession(asset: mainComposition, presetName: AVAssetExportPresetHighestQuality)!
exporter.videoComposition = videoComposition
exporter.outputFileType = AVFileTypeMPEG4
exporter.outputURL = exportURL
exporter.shouldOptimizeForNetworkUse = true
exporters.append(exporter)
// Export video
exporter.exportAsynchronouslyWithCompletionHandler() {
// Finish stuff
}
问题来自于不了解CMTimeRangeMake
和insertTimeRange
。
CMTimeRangeMake
的第二个值应该是剪辑的持续时间,而不是结束时间。 因此,如果您的开始时间是5秒标记,并且剪辑持续10秒,则第二个值应该是10,而不是15。
该atTime
的参数insertTimeRange
应kCMTimeZero
,因为我们的目标是创建一个新的剪辑。 换句话说,此值表示要在新轨道中从源轨道插入剪辑的位置。
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