ios - AVAssetExportSession-在IOS中加入2个mp4文件

Question

我正在尝试使用以下代码将2个预先存在的mpeg4视频加入到ipad2上。

-(void)mergeTestVideos
{

    //setup asset
    NSString *firstassetpath = [NSString stringWithFormat:@"%@mpeg4-1.mp4", NSTemporaryDirectory()];
    NSString *secondassetpath = [NSString stringWithFormat:@"%@mpeg4-2.mp4", NSTemporaryDirectory()];

    NSFileManager *fileManager = [NSFileManager defaultManager];

    AVAsset *firstAsset = [AVAsset assetWithURL:[NSURL fileURLWithPath:firstassetpath]];
    AVAsset *secondAsset = [AVAsset assetWithURL:[NSURL fileURLWithPath:secondassetpath]];

    NSLog(@"FirstAsset Is Readable = %d", firstAsset.isReadable);
    NSLog(@"FirstAsset Is playable = %d", firstAsset.isPlayable);
    NSLog(@"FirstAsset Is exportable = %d", firstAsset.exportable);
    NSLog(@"SecondAsset Is Readable = %d", secondAsset.isReadable);
    NSLog(@"SecondAsset Is playable = %d", secondAsset.isPlayable);
    NSLog(@"SecondAsset Is exportable = %d", secondAsset.exportable);

    //setup composition and track
    AVMutableComposition *composition = [[AVMutableComposition alloc]init];
    AVMutableCompositionTrack *track = [composition addMutableTrackWithMediaType:AVAssetExportPresetPassthrough preferredTrackID:kCMPersistentTrackID_Invalid];

    //add assets to track
    [track insertTimeRange:CMTimeRangeMake(kCMTimeZero, firstAsset.duration) ofTrack:[[firstAsset tracksWithMediaType:AVMediaTypeVideo]objectAtIndex:0] atTime:kCMTimeZero error:nil];

    [track insertTimeRange:CMTimeRangeMake(kCMTimeZero, secondAsset.duration) ofTrack:[[secondAsset tracksWithMediaType:AVMediaTypeVideo]objectAtIndex:0] atTime:firstAsset.duration error:nil];

    // 5 - Create exporter
    AVAssetExportSession *exporter = [[AVAssetExportSession alloc]initWithAsset:composition presetName:AVAssetExportPresetPassthrough];

    NSString *outputURL = [NSString stringWithFormat:@"%@mergedvid.mp4", NSTemporaryDirectory()];

    NSLog(@"%@", exporter.supportedFileTypes);
    exporter.outputURL=[NSURL fileURLWithPath:outputURL];

    exporter.outputFileType = AVFileTypeMPEG4;
    [exporter exportAsynchronouslyWithCompletionHandler:^{
        dispatch_async(dispatch_get_main_queue(), ^{
            [self exportDidFinish:exporter];
        });
    }];

}

-(void)exportDidFinish:(AVAssetExportSession*)session {

    NSLog(@"export method");
    NSLog(@"%i", session.status);
    NSLog(@"%@", session.error);
}

输出如下:

- FirstAsset Is Readable = 1
- FirstAsset Is playable = 1
- FirstAsset Is exportable = 1
- SecondAsset Is Readable = 1
- SecondAsset Is playable = 1
- SecondAsset Is exportable = 1
- (
"com.apple.quicktime-movie",
"com.apple.m4a-audio",
"public.mpeg-4",
"com.apple.m4v-video",
"public.3gpp",
"org.3gpp.adaptive-multi-rate-audio",
"com.microsoft.waveform-audio",
"public.aiff-audio",
"public.aifc-audio",
"com.apple.coreaudio-format"
)
-export method
- 4
- Error Domain=AVFoundationErrorDomain Code=-11838 "Operation Stopped" UserInfo=0x155f76f0 {NSLocalizedDescription=Operation Stopped, NSLocalizedFailureReason=The operation is not supported for this media.}

好的，根据输出，我的文件是可以导出的，并且mp4是受支持的输出类型。

有人知道为什么它会给我错误信息“此媒体不支持该操作”吗？

Answer 1

我认为这是你的罪魁祸首

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

在这里，您传递了 AVAssetExportPresetPassthrough，您应该在其中使用 AVMediaTypeVideo或 AVMediaTypeAudio