ios - AVMutableVideoComposition 无法播放

Question

我的设置如下:在我的应用程序的这一部分中，用户可以将视频排成一行。这些视频之间可能有间隙，或者稍后从 0 开始。

为了实现这一目标，我添加了一个功能，该功能添加全黑视频并在每个间隙期间循环播放:

func getBlackVideoSegments(timerange: CMTimeRange) -> [AVCompositionTrackSegment] {
    var compositionTrackSegments = [AVCompositionTrackSegment]()
    if CMTimeCompare(timerange.duration, RTGlobals.blackVideo.duration) == -1 {
        let compositionTrackSegment = AVCompositionTrackSegment(URL: RTGlobals.blackVideoURL, trackID: RTGlobals.blackVideoAssetTrack.trackID, sourceTimeRange: CMTimeRangeMake(kCMTimeZero, timerange.duration), targetTimeRange: timerange)
        compositionTrackSegments.append(compositionTrackSegment)
        addVideoCompositionInstruction(RTGlobals.blackVideoAssetTrack, timeRange: timerange, assetTrack: videoCompositionTrack)
    } else {
        var currentStart = timerange.start
        var filledDuration = kCMTimeZero
        while CMTimeCompare(filledDuration, timerange.duration) == -1 {
            let durationToFill = CMTimeSubtract(timerange.duration, filledDuration)
            var durationAdded = RTGlobals.blackVideo.duration
            if CMTimeCompare(durationAdded, durationToFill) == 1 {
                durationAdded = durationToFill
            }

            let compositionTrackSegment = AVCompositionTrackSegment(URL: RTGlobals.blackVideoURL, trackID: RTGlobals.blackVideoAssetTrack.trackID, sourceTimeRange: CMTimeRangeMake(kCMTimeZero, durationAdded), targetTimeRange: CMTimeRangeMake(currentStart, durationAdded))
            compositionTrackSegments.append(compositionTrackSegment)
            addVideoCompositionInstruction(RTGlobals.blackVideoAssetTrack, timeRange: CMTimeRangeMake(currentStart, durationAdded), assetTrack: videoCompositionTrack)

            currentStart = CMTimeAdd(currentStart, durationAdded)
            filledDuration = CMTimeAdd(filledDuration, durationAdded)
        }
    }
    return compositionTrackSegments
}

这是我设置指令的方法:

func addVideoCompositionInstruction(videoAssetTrack: AVAssetTrack, timeRange: CMTimeRange, assetTrack: AVAssetTrack) {
    let instruction = AVMutableVideoCompositionInstruction()
    instruction.timeRange = timeRange
    let layerInstruction = AVMutableVideoCompositionLayerInstruction(assetTrack: assetTrack)

    let videoSize = CGSizeMake(1920.0, 1080.0)

    var transform = videoAssetTrack.preferredTransform
    var scale:CGFloat = 1.0
    var offset:CGFloat = 0.0

    if fabs(videoAssetTrack.preferredTransform.b) == 1.0 && fabs(videoAssetTrack.preferredTransform.c) == 1.0 {
        scale = videoSize.height / videoAssetTrack.naturalSize.width
        offset = (videoSize.width - (videoAssetTrack.naturalSize.height * scale)) / 2.0
    } else {
        scale = videoSize.height / videoAssetTrack.naturalSize.height
    }
    transform = CGAffineTransformConcat(CGAffineTransformConcat(transform, CGAffineTransformMakeScale(scale, scale)), CGAffineTransformMakeTranslation(offset, 0))

    layerInstruction.setTransform(transform, atTime: timeRange.start)

    instruction.layerInstructions = [layerInstruction]

    instructions.append(instruction)
}

说明和片段都是无缝的，并在最后填充整个构图。

但是，每次我添加这些黑色视频片段时，播放都会失败。播放器只是在出现黑色视频时停止。

有人看出问题了吗？我就是无法理解它。

非常感谢!

安德烈亚斯

Answer 1

我的问题的答案很简单:只需更新到 iOS 9.3苹果目前的框架显然已经被打破。仍然存在一些情况，它不能完美地工作，但没关系。我猜它会在 9.4 中修复

再见!安德烈亚斯