ios 循环AVMutableCompositionTrack

goqiplq2 于 2023-05-30 发布在 iOS

关注(0)|答案(4)|浏览(123)

我有两个音轨，我把它们像这样合并在一起：

AVMutableComposition *composition = [[AVMutableComposition alloc] init];

AVMutableCompositionTrack *compositionAudioTrack = [composition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
[compositionAudioTrack setPreferredVolume:1.0];
AVAsset *avAsset = [AVURLAsset URLAssetWithURL:originalContentURL options:nil];
AVAssetTrack *clipAudioTrack = [[avAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];
[compositionAudioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, avAsset.duration) ofTrack:clipAudioTrack atTime:kCMTimeZero error:nil];

AVMutableCompositionTrack *compositionAudioTrack1 = [composition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
[compositionAudioTrack1 setPreferredVolume:0.01];
NSString *soundOne1  =[[NSBundle mainBundle]pathForResource:@"jingle1" ofType:@"m4a"];
NSURL *url1 = [NSURL fileURLWithPath:soundOne1];
AVAsset *avAsset1 = [AVURLAsset URLAssetWithURL:url1 options:nil];
AVAssetTrack *clipAudioTrack1 = [[avAsset1 tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];
[compositionAudioTrack1 insertTimeRange:CMTimeRangeMake(kCMTimeZero, avAsset.duration) ofTrack:clipAudioTrack1 atTime:kCMTimeZero error:nil];

正如你所看到的，第一个AVAsset是第二个轨道的基本长度，这意味着如果我有一个很长的第二个轨道，它将被削减，这正是我想要的方式。
然而，我需要能够循环第二个轨道，以便如果第一个轨道太长，第二个轨道继续下去。我后来必须保存产生的轨道上光盘，这是一个重要的因素以及。
在我做了一项研究之后，我发现在iOS中没有方便的方法来循环播放曲目。其中一种方法是在AVMutableComposition处多次插入第二首曲目，但这对我来说听起来很奇怪。任何基于这个主题的想法都是非常有用的。

ios

来源：https://stackoverflow.com/questions/20211694/loop-avmutablecompositiontrack

4条答案

按热度按时间

b0zn9rqh1#

我认为它应该工作：

CMTime videoDuration = avAsset.duration;
if(CMTimeCompare(videoDuration, audioAsset.duration) == -1){
    [compositionAudioTrack1 insertTimeRange:CMTimeRangeMake(kCMTimeZero, avAsset.duration) ofTrack:clipAudioTrack1 atTime:kCMTimeZero error:nil];
}else if(CMTimeCompare(videoDuration, audioAsset.duration) == 1){
     CMTime currentTime = kCMTimeZero;
     while(YES){
           CMTime audioDuration = audioAsset.duration;
           CMTime totalDuration = CMTimeAdd(currentTime,audioDuration);
           if(CMTimeCompare(totalDuration, videoDuration)==1){
              audioDuration = CMTimeSubtract(totalDuration,videoDuration);

           }
           [compositionAudioTrack1 insertTimeRange:CMTimeRangeMake(kCMTimeZero, audioDuration) ofTrack:clipAudioTrack1 atTime:currentTime error:nil];
           currentTime = CMTimeAdd(currentTime, audioDuration);
           if(CMTimeCompare(currentTime, videoDuration) == 1 || CMTimeCompare(currentTime, videoDuration) == 0){
               break;
           }
     }
}

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zaq34kh62#

在Gaurav响应中，您应该更改这一行：
audioDuration = CMTimeSubtract(totalDuration,videoDuration);
致：
audioDuration = CMTimeSubtract(videoDuration,currentTime);
否则音轨将长于视频（这将只是黑色）

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rkttyhzu3#

在Swift中使用repeat whiel循环。

修复视频长度isuue*

let audioLength = CMTime(value: 100, timescale: 1)
let videoLength = CMTime(value: 220, timescale: 1)

func getAudioRepeatInfo(audioLength:CMTime, videoLength:CMTime) -> [(at:CMTime, duration:CMTime)] {
    var at = [(at:CMTime, duration:CMTime)](), start = CMTime.zero
    repeat {
        let info = (at:start, duration: min(CMTimeSubtract(videoLength, start), audioLength) )
        at.append(info)
        start = CMTimeAdd(start, info.duration)
    } while start < videoLength
    return at
}

var ranges =  getAudioRepeatInfo(audioLength: audioLength, videoLength: videoLength)

Playground输出：

[(at: __C.CMTime(value: 0, timescale: 1, flags: __C.CMTimeFlags(rawValue: 1), epoch: 0), duration: __C.CMTime(value: 100, timescale: 1, flags: __C.CMTimeFlags(rawValue: 1), epoch: 0)),
 (at: __C.CMTime(value: 100, timescale: 1, flags: __C.CMTimeFlags(rawValue: 1), epoch: 0), duration: __C.CMTime(value: 100, timescale: 1, flags: __C.CMTimeFlags(rawValue: 1), epoch: 0)),
 (at: __C.CMTime(value: 200, timescale: 1, flags: __C.CMTimeFlags(rawValue: 1), epoch: 0), duration: __C.CMTime(value: 20, timescale: 1, flags: __C.CMTimeFlags(rawValue: 1), epoch: 0))]

用途：

for info in repeatInfo {
    try compositionAudioTrack1?.insertTimeRange(.init(start: .zero, duration: info.duration), of: assetTrack, at: info.at)
}

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4szc88ey4#

Gaurav在Swift 5.5中回答（他的解决方案是正确的，并且运行得很好）。

let videoDuration = avAsset.duration

  if (CMTimeCompare(videoDuration, audioAsset.duration) == -1) {
    // Handle insertTimeRange
  } else if (CMTimeCompare(videoDuration, audioAsset.duration) == 1) {

    var currentTime = CMTime.zero

    while(true) {
      let audioDuration = audioAsset.duration
      let totalDuration = CMTimeAdd(currentTime, audioDuration)

      if (CMTimeCompare(totalDuration, videoDuration) == 1) {
        audioDuration = CMTimeSubtract(videoDuration, currentTime)
      }
  
      // Handle insertTimeRange
  
      currentTime = CMTimeAdd(currentTime, audioDuration)
      if(CMTimeCompare(currentTime, videoDuration) == 1 || CMTimeCompare(currentTime, videoDuration) == 0){
        break
      }
    }
  }

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ios 循环AVMutableCompositionTrack

4条答案

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