我一直在寻找解决方案,但到目前为止我找不到它 .
现在我正在使用AVMutableComposition创建一个音频文件并使用AVAssetExportSession将其写入磁盘,这样我就可以使用AVAudioPlayer加载它并在特定时间播放它 . 将它写入磁盘需要花费很多时间的事实会减慢速度,在某些情况下会使我的应用程序变得非常慢 .
音频的创建部分花费很少的时间,所以我想知道是否将文件导出到磁盘我可以像NSData一样导出它,所以我可以在AVAudioPlayer中使用它而无需从磁盘写入/读取
代码让soundPath =“temp”让filepath = NSURL(fileURLWithPath:NSBundle.mainBundle() . pathForResource(soundPath,ofType:“wav”)!)
var songAsset = AVURLAsset(URL: filepath, options: nil)
var track = composition.addMutableTrackWithMediaType(AVMediaTypeAudio, preferredTrackID: CMPersistentTrackID())
var source: AnyObject = songAsset.tracksWithMediaType(AVMediaTypeAudio)[0]
var startTime = CMTimeMakeWithSeconds(0, 44100)
var time_insert = CMTimeMakeWithSeconds(atTime, 44100)
var trackDuration = songAsset.duration
var longestTime = CMTimeMake(882000, 44100)
var timeRange = CMTimeRangeMake(startTime, longestTime)
var trackMix = AVMutableAudioMixInputParameters(track: track)
trackMix.setVolume(volume, atTime: startTime)
audioMixParams.insert(trackMix, atIndex: audioMixParams.count)
track.insertTimeRange(timeRange, ofTrack: source as AVAssetTrack, atTime: time_insert, error: nil)
这在发生整个轨道的循环中发生了几次
最后我用
var exporter = AVAssetExportSession(asset: composition, presetName: AVAssetExportPresetAppleM4A)
exporter.audioMix = audioMix
exporter.outputFileType = "com.apple.m4a-audio"
exporter.outputURL = NSURL(fileURLWithPath: fileName)
exporter.exportAsynchronouslyWithCompletionHandler({
switch exporter.status{
case AVAssetExportSessionStatus.Failed:
println("failed \(exporter.error)")
case AVAssetExportSessionStatus.Cancelled:
println("cancelled \(exporter.error)")
default:
println("complete")
callback()
}
})
导出文件 .
然后它调用一个回调加载声音并在一段时间内循环它 .
我没有使用普通循环属性循环的事实是每个文件可能与loopDuration的长度不同
callback: {
self.fillSoundArray()
self.fillSoundArray()
self.fillSoundArray()
}
private func fillSoundArray() {
var currentloop = self.current_loop++
let documentsPath = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)[0] as NSString
var fileName = documentsPath + "/temp.mp4"
var tempAudio = AVAudioPlayer(contentsOfURL: NSURL(fileURLWithPath: fileName), error: nil)
if (self.start_time == 0) {
self.start_time = tempAudio.deviceCurrentTime
}
queue.insert(tempAudio, atIndex: queue.count)
tempAudio.prepareToPlay()
tempAudio.delegate = self
tempAudio.playAtTime(start_time + currentloop*self.loopDuration)
}
1 回答
使用AVPlayerItem和AVPlayer快速预览您的音频构成