Loop AVMutableCompositionTrack

Question

I have got two audio tracks on me that I combine with one another like this:

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

AVMutableC         


        

Answer 1

In swift with repeat whiel Loop.

fix video length 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 Output:

[(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))]

Use:

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

Answer 2

I think it should work:

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;
           }
     }
}

Answer 3

On the Gaurav response you should change this line:
audioDuration = CMTimeSubtract(totalDuration,videoDuration);

to:
audioDuration = CMTimeSubtract(videoDuration,currentTime);

Otherwise the audiotrack will be longer than the video ( that will be just black )