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我正在合并多个视频并在 AVPlayer 中播放。视频开始正​​常，但一段时间后视频冻结并且只播放音频。我有一个UISlider有助于在视频中前进或后退的seekToTime:.

所以奇怪的是，在视频冻结后，如果我使用滑块前进或后退，视频开始播放得非常好。我已经在多个设备上尝试了我的应用程序。

所以基本上我必须使用seekToTime:方法在每次冻结时给视频一个轻推。

我用于合并视频和播放的代码如下：

AVAsset *asset0 = [self currentAsset:0];
AVAsset *asset1 = [self currentAsset:1];
AVAsset *asset2 = [self currentAsset:2];
AVAsset *asset3 = [self currentAsset:3];
AVAsset *asset4 = [self currentAsset:4];

NSArray *assets = @[asset0, asset1, asset2, asset3, asset4];

AVMutableComposition *mutableComposition = [AVMutableComposition composition];
AVMutableCompositionTrack *videoCompositionTrack = [mutableComposition addMutableTrackWithMediaType:AVMediaTypeVideo
                                                                                   preferredTrackID:kCMPersistentTrackID_Invalid];
AVMutableCompositionTrack *audioCompositionTrack = [mutableComposition addMutableTrackWithMediaType:AVMediaTypeAudio
                                                                                   preferredTrackID:kCMPersistentTrackID_Invalid];

NSMutableArray *instructions = [NSMutableArray new];
CGSize size = CGSizeZero;

CMTime time = kCMTimeZero;
for (AVAsset *asset in assets)
{
    AVAssetTrack *assetTrack = [asset tracksWithMediaType:AVMediaTypeVideo].firstObject;
    AVAssetTrack *audioAssetTrack = [asset tracksWithMediaType:AVMediaTypeAudio].firstObject;

    NSError *error;
    [videoCompositionTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, assetTrack.timeRange.duration)
                                   ofTrack:assetTrack
                                    atTime:time
                                     error:&error];
    if (error) {
        NSLog(@"Error - %@", error.debugDescription);
    }

    [audioCompositionTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, assetTrack.timeRange.duration)
                                   ofTrack:audioAssetTrack
                                    atTime:time
                                     error:&error];
    if (error) {
        NSLog(@"Error - %@", error.debugDescription);
    }

    AVMutableVideoCompositionInstruction *videoCompositionInstruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
    videoCompositionInstruction.timeRange = CMTimeRangeMake(time, assetTrack.timeRange.duration);
    videoCompositionInstruction.layerInstructions = @[[AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:videoCompositionTrack]];
    [instructions addObject:videoCompositionInstruction];

    time = CMTimeAdd(time, assetTrack.timeRange.duration);

    if (CGSizeEqualToSize(size, CGSizeZero)) {
        size = assetTrack.naturalSize;;
    }
}

AVMutableVideoComposition *mutableVideoComposition = [AVMutableVideoComposition videoComposition];
mutableVideoComposition.instructions = instructions;

mutableVideoComposition.frameDuration = CMTimeMake(1, 30);
mutableVideoComposition.renderSize = size;

pi = [AVPlayerItem playerItemWithAsset:mutableComposition];
pi.videoComposition = mutableVideoComposition;

player = [AVPlayer playerWithPlayerItem:[[CameraEngine engine] pi]];

player.volume = 0.75;
playerLayer = [AVPlayerLayer playerLayerWithPlayer: player];

playerLayer.frame = self.bounds;
[self.layer addSublayer: playerLayer];
[playerLayer setNeedsDisplay];
[player play];

更新：找到描述类似问题的链接。但他的解决方案并没有得到很好的理解。

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1 回答 1

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你为什么打电话[AVPlayer playerWithPlayerItem:[[CameraEngine engine] pi]]而不是[AVPlayer playerWithPlayerItem:pi]？您构建您的作品并将其分配给它pi在任何地方都没有使用。尝试[AVPlayer playerWithPlayerItem:pi]改用。

如果这无助于尝试改变你的videoComposition一代。尝试执行以下操作：

AVMutableVideoCompositionInstruction *videoCompositionInstruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
videoCompositionInstruction.timeRange = CMTimeRangeMake(kCMTimeZero, mutableComposition.timeRange.duration);
videoCompositionInstruction.layerInstructions = @[[AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:[mutableComposition tracksWithMediaType:AVMediaTypeVideo].firstObject]];

AVMutableVideoComposition *mutableVideoComposition = [AVMutableVideoComposition videoComposition];
mutableVideoComposition.instructions = @[videoCompositionInstruction];

mutableVideoComposition.frameDuration = CMTimeMake(1, 30);
mutableVideoComposition.renderSize = size;

在你的for循环之后。希望这可以帮助！

于 2015-04-03T18:35:54.033 回答