AVURLAsset不能使用iphone

Question

即时通讯同步的音频和视频文件使用AVURLAsset.Im得到导出的文件，但只有音频导出，而不是video.How来解决这个issue.please帮助me.Thanks提前。

我正在使用下面的代码：

moviePlayer = [[VideoPlay alloc]initWithNibName:@"VideoPlay" bundle:nil];


    if(sp==1){
           NSURL *VUrl = [NSURL URLWithString:elements.videoUrl];
        NSURL *AUrl = [NSURL URLWithString:elements.audioUrl1 ];
        NSLog(@"%@--%@",AUrl,VUrl);




        AVURLAsset* audioAsset = [[AVURLAsset alloc]initWithURL:AUrl options:nil];
        AVURLAsset* videoAsset = [[AVURLAsset alloc]initWithURL:VUrl options:nil];

        AVMutableComposition* mixComposition = [AVMutableComposition composition];

        AVMutableCompositionTrack *compositionCommentaryTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio                                                                                                     preferredTrackID:kCMPersistentTrackID_Invalid];
        [compositionCommentaryTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, audioAsset.duration) 
                                            ofTrack:[[audioAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0] 
                                             atTime:kCMTimeZero error:nil];

        AVMutableCompositionTrack *compositionVideoTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo                                                                                                preferredTrackID:kCMPersistentTrackID_Invalid];
        [compositionVideoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, videoAsset.duration) 
                                       ofTrack:[[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] 
                                        atTime:kCMTimeZero error:nil];

        AVAssetExportSession* _assetExport = [[AVAssetExportSession alloc] initWithAsset:mixComposition 
                                                                              presetName:AVAssetExportPresetPassthrough];   

        NSString *videoName = @"export.m4v";

        NSString *exportPath = [NSTemporaryDirectory() stringByAppendingPathComponent:videoName];
        NSURL    *exportUrl = [NSURL fileURLWithPath:exportPath];

        if ([[NSFileManager defaultManager] fileExistsAtPath:exportPath]) 
        {
            [[NSFileManager defaultManager] removeItemAtPath:exportPath error:nil];
        }
         NSLog(@"Export Status %d-- ", _assetExport.status);
        _assetExport.outputFileType = @"com.apple.quicktime-movie";
        NSLog(@"file type %@",_assetExport.outputFileType);
        _assetExport.outputURL = exportUrl;
        _assetExport.shouldOptimizeForNetworkUse = YES;

        [_assetExport exportAsynchronouslyWithCompletionHandler:
         ^(void ) { 

             NSLog(@"hello");
             switch (_assetExport.status) 
             {
                 case AVAssetExportSessionStatusFailed:
                 {
                     NSLog (@"FAIL %@",_assetExport.error);
                     if ([[NSFileManager defaultManager] fileExistsAtPath:[_assetExport.outputURL path]]) 
                     {
                         [[NSFileManager defaultManager] removeItemAtPath:[_assetExport.outputURL path] error:nil];
                     }

                     //                            // [self performSelectorOnMainThread:@selector (ritenta)
                     //                                                    withObject:nil
                     //                                                 waitUntilDone:NO];
                     break;
                 }
                 case AVAssetExportSessionStatusCompleted: 
                 {

                     //                            // [self performSelectorOnMainThread:@selector (saveVideoToAlbum:)
                     //                                                    withObject:exportPath
                     //                                                 waitUntilDone:NO];
                     break;
                 }
                 case AVAssetExportSessionStatusCancelled: 
                 {
                     NSLog (@"CANCELED");

                     break;
                 }
             }
             NSLog(@"Export Status %d-- %@", _assetExport.status, _assetExport.outputURL);
             if(_assetExport.status==3){
                moviePlayer.videolink = _assetExport.outputURL;
                 [self presentModalViewController:moviePlayer animated:YES];    
                 [moviePlayer readyPlayer];
             }

            }


         ];                
           }

Answer 1

1. 将您的代码简化为显示问题的smallest working sample。
2. 检查返回的错误。
3. 尝试使用不同的导出预设代替AVAssetExportPresetPassthrough.

Answer 2

尝试不同的导出预设，而不是AVAssetExportPresetPassthrough和NSString *videoName = @"export.mp4“，而不是NSString *videoName = @"export.m4v"；