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适用于 iOS 的 Xcode

我遇到的问题是播放 AVMutableComposition。我正在创建组合，然后在 for 循环中将 AVURLAssets 添加到它。我正在添加所有内容，就像我将类似地将对象添加到可变数组中一样，然后尝试在之后播放它，但没有播放。这是我的代码：

AVMutableComposition *composition = [AVMutableComposition composition];

int count;

count = array.count;

for (int y=0;y<count;y++){    

        NSURL *url;

            url = [NSURL fileURLWithPath:[NSString stringWithFormat:@"%@/%@.mp3", [[NSBundle mainBundle] resourcePath],[array objectAtIndex:y]]];





        NSDictionary *options = [NSDictionary dictionaryWithObject:[NSNumber numberWithBool:YES] forKey:AVURLAssetPreferPreciseDurationAndTimingKey];

        AVURLAsset *sourceAsset = [[AVURLAsset alloc] initWithURL:url options:options];

        //calculate times
        NSNumber *time = [soundArray1 objectAtIndex:1];

        double timenow = [time doubleValue];
        double insertTime = (240*y);

        CMTime douTime = CMTimeMake(240, timenow);
        CMTime staTime = CMTimeMake(0, 1);
        CMTimeRange editRange = CMTimeRangeMake(staTime,douTime);

        CMTime insTime = CMTimeMake(insertTime, timenow);


        NSError *editError;


        [composition insertTimeRange:editRange ofAsset:sourceAsset atTime:insTime error:&editError];

    }


AVPlayer* mp = [AVPlayer playerWithPlayerItem:[AVPlayerItem playerItemWithAsset:composition]];


[mp play];

我假设我完全错了，但是我在循环中而不是之后添加了这个，在 if 中并打开一个 NSRunLoop 来检查（有点糟糕，但这只是为了测试！）：

    AVMutableComposition *composition = [AVMutableComposition composition];

int count;

count = array.count;

for (int y=0;y<count;y++){    

        NSURL *url;

            url = [NSURL fileURLWithPath:[NSString stringWithFormat:@"%@/%@.mp3", [[NSBundle mainBundle] resourcePath],[array objectAtIndex:y]]];





        NSDictionary *options = [NSDictionary dictionaryWithObject:[NSNumber numberWithBool:YES] forKey:AVURLAssetPreferPreciseDurationAndTimingKey];

        AVURLAsset *sourceAsset = [[AVURLAsset alloc] initWithURL:url options:options];

        //calculate times
        NSNumber *time = [soundArray1 objectAtIndex:1];

        double timenow = [time doubleValue];
        double insertTime = (240*y);

        CMTime douTime = CMTimeMake(240, timenow);
        CMTime staTime = CMTimeMake(0, 1);
        CMTimeRange editRange = CMTimeRangeMake(staTime,douTime);

        CMTime insTime = CMTimeMake(insertTime, timenow);


        NSError *editError;


        [composition insertTimeRange:editRange ofAsset:sourceAsset atTime:insTime error:&editError];



    if(y==3){

    AVPlayer* mp = [AVPlayer playerWithPlayerItem:[AVPlayerItem playerItemWithAsset:composition]];


    [mp play];


    [[NSRunLoop currentRunLoop] runUntilDate:[NSDate dateWithTimeIntervalSinceNow:20]];

        }
    }

在这里，我只是给了我的数组 4 个元素，并让它在第 4 次运行时播放合成。它工作并以完美的顺序播放了我的 4 个音频文件。

我需要做什么才能使我的作曲在这个循环之后而不是在循环中播放？我是否误用了系统？

编辑：通过将我打开的 RunLoop 代码粘贴到最后，它会播放。我应该这样做，还是有更好的方法来做到这一点？

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1 回答 1

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所以我以错误的方式解决了这个问题。我需要为每个元素创建一个 AVMutableCompositionTrack 并将其添加到我的合成中

       NSDictionary *options = [NSDictionary dictionaryWithObject:[NSNumber numberWithBool:YES]
                                                            forKey:AVURLAssetPreferPreciseDurationAndTimingKey];

        AVURLAsset *sourceAsset = [[AVURLAsset alloc] initWithURL:url options:options];

        //calculate times
        NSNumber *time = [soundArray1 objectAtIndex:1];

        double timenow = [time doubleValue];

        double insertTime = (240*y);

                    AVMutableCompositionTrack *track =
        [composition addMutableTrackWithMediaType:AVMediaTypeAudio
                                 preferredTrackID:kCMPersistentTrackID_Invalid];

        //insert the audio track from the asset into the track added to the mutable composition
        AVAssetTrack *myTrack = [[sourceAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];
        CMTimeRange myTrackRange = myTrack.timeRange;
        NSError *error = nil;
        [track insertTimeRange:myTrackRange
                                      ofTrack:myTrack
                                       atTime:CMTimeMake(insertTime, timenow) 
                                        error:&error];

        [sourceAsset release];

其次是

AVPlayerItem *playerItem = [AVPlayerItem playerItemWithAsset:composition];
self.player = [[AVPlayer alloc] initWithPlayerItem:playerItem];


        [self.player play];

在接口部分中将播放器声明为属性

@interface SecondViewController ()



@property (nonatomic, assign) AVPlayer *player;



@end
于 2012-05-30T17:45:21.103 回答