如何合并视频和音频文件？

Question

我的问题是：如何合并时长几乎相同的视频和音频文件？

我搜索并得到了这个问题的一些答案。然而，当我尝试他们提供的代码时，它只是不会生成“非零字节”电影。

你能看一下它哪里出了问题吗？

-(void)putTogether
{
NSLog(@"Starting to put together all the files!");

AVMutableComposition *mixComposition = [AVMutableComposition composition];

NSString *audioPath = @"/Users/admin/Documents/Sound.caf";
NSURL *audioUrl = [NSURL fileURLWithPath:audioPath];
//AVURLAsset *audioasset = [AVURLAsset URLAssetWithURL:audioUrl options:nil];
AVURLAsset *audioasset = [[AVURLAsset alloc]initWithURL:audioUrl options:nil];

NSString *videoPath = @"/Users/admin/Documents/video.mp4";
NSURL *videoUrl = [NSURL fileURLWithPath:videoPath];
//AVURLAsset *videoasset = [AVURLAsset URLAssetWithURL:videoUrl options:nil];
AVURLAsset *videoasset = [[AVURLAsset alloc]initWithURL:videoUrl options:nil];

NSString *moviepath = @"/Users/admin/Documents/fmovie.mov";
NSURL *movieUrl = [NSURL fileURLWithPath:moviepath];

if([[NSFileManager defaultManager] fileExistsAtPath:moviepath])
{
    [[NSFileManager defaultManager] removeItemAtPath:moviepath error:nil];
}

AVMutableCompositionTrack *compositionTrackB = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
AVAssetTrack *clipVideoTrackB = [[videoasset tracksWithMediaType:AVMediaTypeVideo] lastObject];
[compositionTrackB insertTimeRange:CMTimeRangeMake(      kCMTimeZero, videoasset.duration)  ofTrack:clipVideoTrackB atTime:kCMTimeZero error:nil];

AVMutableCompositionTrack *compositionTrackA = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
AVAssetTrack *clipAudioTrackA = [[audioasset tracksWithMediaType:AVMediaTypeAudio] lastObject];
[compositionTrackA insertTimeRange:CMTimeRangeMake(kCMTimeZero, audioasset.duration)  ofTrack:clipAudioTrackA atTime:kCMTimeZero error:nil];

AVAssetExportSession *exporter =[[AVAssetExportSession alloc] initWithAsset:mixComposition presetName:AVAssetExportPresetHighestQuality];
//AVAssetExportSession *exporter =[AVAssetExportSession exportSessionWithAsset:mixComposition presetName:AVAssetExportPresetLowQuality];
NSParameterAssert(exporter!=nil);
exporter.outputFileType=AVFileTypeQuickTimeMovie;
exporter.outputURL=movieUrl;
CMTime start=CMTimeMake(0, 600);
CMTime duration=CMTimeMake(600, 600);
CMTimeRange range=CMTimeRangeMake(start, duration);
exporter.timeRange=range;
[exporter exportAsynchronouslyWithCompletionHandler:nil];
}

Answer 1

（OP通过问题中的编辑回答。转换为社区维基答案。请参阅问题没有答案，但问题在评论中得到解决（或在聊天中扩展））

OP 写道：

我解决了我的问题。

对于那些和我有同样问题的人，这里有一个简单的解决方案：

a.删除以下代码：

CMTime start=CMTimeMake(0, 600);
CMTime duration=CMTimeMake(600, 600);
CMTimeRange range=CMTimeRangeMake(start, duration);
exporter.timeRange=range;

b.（可选）重写完成处理程序：

[exporter exportAsynchronouslyWithCompletionHandler:^{ 
    switch ([exporter status]) {
        case AVAssetExportSessionStatusFailed:
            NSLog(@"Export failed: %@", [[exporter error] localizedDescription]);
            break;
        case AVAssetExportSessionStatusCancelled:
            NSLog(@"Export canceled");
            break;
        default:
            break;
    } 
}];

c.然后等待足够长的时间让程序完成写入。