在使用AVFoundation框架播放视频时出现问题

Question

我使用AVAssetReader从视频文件一个接一个地获得帧缓冲区，并对帧进行一些操作，然后使用AVAssetWritter将新帧保存到临时文件。现在我有一个临时文件路径，所有的新帧一个接一个地保存。有没有办法播放视频的时间框架是不断添加到临时文件?

下面是从临时路径播放视频的代码(帧数不断增加):

(void)loadAssetFromFile {
AVURLAsset *asset = [AVURLAsset URLAssetWithURL:[NSURL fileURLWithPath:[(mMediaReader.mCameraRecorder) tempVideoFilePath ]] options:nil];
NSString *tracksKey = @"tracks";
[asset loadValuesAsynchronouslyForKeys:[NSArray arrayWithObject:tracksKey] completionHandler:
 ^{
     // Completion handler block.
     dispatch_async(dispatch_get_main_queue(),
                    ^{
                        NSError *error = nil;
                        AVKeyValueStatus status = [asset statusOfValueForKey:tracksKey error:&error];
                        if (status == AVKeyValueStatusLoaded) {
                            self.mPlayerItem = [AVPlayerItem playerItemWithAsset:asset];
                            [mPlayerItem addObserver:self forKeyPath:@"status"
                                            options:0 context:&ItemStatusContext];
                            [[NSNotificationCenter defaultCenter] addObserver:self
                                                                     selector:@selector(playerItemDidReachEnd:)
                                                                         name:AVPlayerItemDidPlayToEndTimeNotification
                                                                       object:mPlayerItem];
                           self.mPlayer = [AVPlayer playerWithPlayerItem:mPlayerItem];
                            [mPlayerView setPlayer:mPlayer];
                            [self play:nil];
                        }
                        else {
                            // You should deal with the error appropriately.
                            NSLog(@"The asset's tracks were not loaded:n%@", [error localizedDescription]);
                        }
                    });
 }];
}
(IBAction)play:sender {
[mPlayer play];
}

并且块内的代码永远不会运行。

Answer 1

你可以将AVAssetReader返回的CMSampleBuffer转换为CGImage，然后是UIImage，并在UIImageView中显示，以渲染从原始视频文件中拉出的帧。

在AVFoundation编程指南中有示例代码，展示了如何进行此转换。