如果视频文件损坏，MPMoviePlayerViewController 会返回错误吗？

Posted 2023-03-08

【中文标题】如果视频文件损坏，MPMoviePlayerViewController 会返回错误吗？

【英文标题】：Can MPMoviePlayerViewController return error if video file is corrupt?

【发布时间】：2012-11-27 06:38:07

【问题描述】：

我正在下载视频并将其保存在某个目录中，以便用户之后可以播放该文件。

它适用于所有情况，例如由于某些网络波动而停止下载并再次恢复。但有时文件完全下载但没有在 MPMoviePlayerViewController 中播放。

我正在使用 ASIHTTPRequest 在后台下载视频文件。

观察：可能是在下载过程中，网络不稳定，文件可能损坏。

问题：我如何知道下载的文件已损坏？ （通过 MPMoviePlayerViewControll）

有什么建议吗？下面是玩的代码：

@ACB...我使用了你的代码，但它总是处于 else 状态：

    playerViewController = [[MPMoviePlayerViewController alloc]initWithContentURL:url];

    player = [playerViewController moviePlayer];
    player.movieSourceType = MPMovieSourceTypeFile;
    [player prepareToPlay];

    if(player.loadState == MPMovieLoadStatePlayable)
    
        playerViewController.modalTransitionStyle = UIModalTransitionStyleCoverVertical;
        [self presentMoviePlayerViewControllerAnimated:playerViewController];


        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(playerInterruptByUser:) name:MPMoviePlayerPlaybackStateDidChangeNotification object:playerViewController.moviePlayer];

        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(playerFinished:) name:MPMoviePlayerPlaybackDidFinishNotification object:playerViewController.moviePlayer];

        //[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(playerFinished:) name:UIApplicationDidEnterBackgroundNotification object:playerViewController.moviePlayer];

        [player play];
    
    else
    
        corruptVideoAlert = [[UIAlertView alloc]initWithTitle:NSLocalizedString(@"Corrupt Video", nil) message:NSLocalizedString(@"This video is corrupted due to some network error. We suggest you to download again. Do you want to download it again?", nil) delegate:self cancelButtonTitle:NSLocalizedString(@"NO", nil) otherButtonTitles:NSLocalizedString(@"YES", nil),nil];
        [corruptVideoAlert show];
        [corruptVideoAlert release];
    

【参考方案1】：

我发现了类似的问题，我解决了这个问题。试试下面的代码：

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(playerPlayingErrorNotification:) name:MPMoviePlayerPlaybackDidFinishNotification object:playerViewController.moviePlayer];

 -(void)playerPlayingErrorNotification:(NSNotification*)notif


    NSNumber* reason = [[notif userInfo] objectForKey:MPMoviePlayerPlaybackDidFinishReasonUserInfoKey];
    switch ([reason intValue]) 
        case MPMovieFinishReasonPlaybackEnded:
            NSLog(@"Playback Ended");        
            break;
        case MPMovieFinishReasonPlaybackError:
            NSLog(@"Playback Error");
            [self performSelector:@selector(CorruptVideoAlertView) withObject:nil afterDelay:1.0];
            break;
        case MPMovieFinishReasonUserExited:
            NSLog(@"User Exited");
            break;
        default:
            break;
    

如果它也适合您，请接受它。祝你有美好的一天。

【讨论】：

谢谢迪利普。我去看看。

【参考方案2】：

使用

if(moviePlayer.loadState == MPMovieLoadStatePlayable)

并检查它是否可以播放。如果需要，您可以使用MPMoviePlayerLoadStateDidChangeNotification。更多详情check apple documentation.

你可以这样试试，

playerViewController = [[MPMoviePlayerViewController alloc]initWithContentURL:url];

player = [playerViewController moviePlayer];
player.movieSourceType = MPMovieSourceTypeFile;
[player prepareToPlay];

playerViewController.modalTransitionStyle = UIModalTransitionStyleCoverVertical;
[self presentMoviePlayerViewControllerAnimated:playerViewController];


[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(playerInterruptByUser:) name:MPMoviePlayerPlaybackStateDidChangeNotification object:playerViewController.moviePlayer];

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(playerFinished:) name:MPMoviePlayerPlaybackDidFinishNotification object:playerViewController.moviePlayer];

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(loadStateChanged:) name:MPMoviePlayerLoadStateDidChangeNotification object:playerViewController.moviePlayer];

    //[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(playerFinished:) name:UIApplicationDidEnterBackgroundNotification object:playerViewController.moviePlayer];

在loadStateChanged: 方法中执行以下操作，

if(player.loadState == MPMovieLoadStatePlayable)

 [player play];

else

    corruptVideoAlert = [[UIAlertView alloc]initWithTitle:NSLocalizedString(@"Corrupt Video", nil) message:NSLocalizedString(@"This video is corrupted due to some network error. We suggest you to download again. Do you want to download it again?", nil) delegate:self cancelButtonTitle:NSLocalizedString(@"NO", nil) otherButtonTitles:NSLocalizedString(@"YES", nil),nil];
    [corruptVideoAlert show];
    [corruptVideoAlert release];

【讨论】：

@swatisharma，当您尝试上述代码时会发生什么？

它打开播放器然后关闭。

我用你的方法检查了。检查我的问题的编辑代码。

@swatisharma，更新了答案。可能您正在执行它而无需等待 loadState 使用 MPMoviePlayerLoadStateDidChangeNotification 更改。

【参考方案3】：

对于我的场景，我最终记录了传入视频的预期内容长度，并确保在您尝试播放视频时文件大小匹配。

从这个意义上说，我可以更快地决定是否应该播放视频。如果文件大小不匹配，我就重新开始下载。