较慢 + 较快，有或没有音轨
我已经尝试并能够减慢资产。
compositionVideoTrack?.scaleTimeRange(timeRange, toDuration: scaledVideoDuration)成功了。
我做了一个课程，可以帮助您slower从AVAsset. + 点是你也可以制作它faster，另一个 + 点是它也会处理音频。
这是我的自定义类示例：
import UIKit
import AVFoundation
enum SpeedoMode {
case Slower
case Faster
}
class VSVideoSpeeder: NSObject {
/// Singleton instance of `VSVideoSpeeder`
static var shared: VSVideoSpeeder = {
return VSVideoSpeeder()
}()
/// Range is b/w 1x, 2x and 3x. Will not happen anything if scale is out of range. Exporter will be nil in case url is invalid or unable to make asset instance.
func scaleAsset(fromURL url: URL, by scale: Int64, withMode mode: SpeedoMode, completion: @escaping (_ exporter: AVAssetExportSession?) -> Void) {
/// Check the valid scale
if scale < 1 || scale > 3 {
/// Can not proceed, Invalid range
completion(nil)
return
}
/// Asset
let asset = AVAsset(url: url)
/// Video Tracks
let videoTracks = asset.tracks(withMediaType: AVMediaType.video)
if videoTracks.count == 0 {
/// Can not find any video track
completion(nil)
return
}
/// Get the scaled video duration
let scaledVideoDuration = (mode == .Faster) ? CMTimeMake(asset.duration.value / scale, asset.duration.timescale) : CMTimeMake(asset.duration.value * scale, asset.duration.timescale)
let timeRange = CMTimeRangeMake(kCMTimeZero, asset.duration)
/// Video track
let videoTrack = videoTracks.first!
let mixComposition = AVMutableComposition()
let compositionVideoTrack = mixComposition.addMutableTrack(withMediaType: AVMediaType.video, preferredTrackID: kCMPersistentTrackID_Invalid)
/// Audio Tracks
let audioTracks = asset.tracks(withMediaType: AVMediaType.audio)
if audioTracks.count > 0 {
/// Use audio if video contains the audio track
let compositionAudioTrack = mixComposition.addMutableTrack(withMediaType: AVMediaType.audio, preferredTrackID: kCMPersistentTrackID_Invalid)
/// Audio track
let audioTrack = audioTracks.first!
do {
try compositionAudioTrack?.insertTimeRange(timeRange, of: audioTrack, at: kCMTimeZero)
compositionAudioTrack?.scaleTimeRange(timeRange, toDuration: scaledVideoDuration)
} catch _ {
/// Ignore audio error
}
}
do {
try compositionVideoTrack?.insertTimeRange(timeRange, of: videoTrack, at: kCMTimeZero)
compositionVideoTrack?.scaleTimeRange(timeRange, toDuration: scaledVideoDuration)
/// Keep original transformation
compositionVideoTrack?.preferredTransform = videoTrack.preferredTransform
/// Initialize Exporter now
let outputFileURL = URL(fileURLWithPath: "/Users/thetiger/Desktop/scaledVideo.mov")
/// Note:- Please use directory path if you are testing with device.
if FileManager.default.fileExists(atPath: outputFileURL.absoluteString) {
try FileManager.default.removeItem(at: outputFileURL)
}
let exporter = AVAssetExportSession(asset: mixComposition, presetName: AVAssetExportPresetHighestQuality)
exporter?.outputURL = outputFileURL
exporter?.outputFileType = AVFileType.mov
exporter?.shouldOptimizeForNetworkUse = true
exporter?.exportAsynchronously(completionHandler: {
completion(exporter)
})
} catch let error {
print(error.localizedDescription)
completion(nil)
return
}
}
}
我将 1x、2x 和 3x 作为有效比例。类包含正确的验证和处理。以下是如何使用此功能的示例。
let url = Bundle.main.url(forResource: "1", withExtension: "mp4")!
VSVideoSpeeder.shared.scaleAsset(fromURL: url, by: 3, withMode: SpeedoMode.Slower) { (exporter) in
if let exporter = exporter {
switch exporter.status {
case .failed: do {
print(exporter.error?.localizedDescription ?? "Error in exporting..")
}
case .completed: do {
print("Scaled video has been generated successfully!")
}
case .unknown: break
case .waiting: break
case .exporting: break
case .cancelled: break
}
}
else {
/// Error
print("Exporter is not initialized.")
}
}
此行将处理音频缩放
compositionAudioTrack?.scaleTimeRange(timeRange, toDuration: scaledVideoDuration)