[GL] <MMovieWriter.mm:476::-[MMovieWriter appendAudioSampleBufferInternal:]> INFO: audio writer status 3, desc Error Domain=AVFoundationErrorDomain Code=-11800 "这项操作无法完成" UserInfo=0x11495910 {NSLocalizedDescription=这项操作无法完成, NSUnderlyingError=0x1146e8d0 "The operation couldn’t be completed. (OSStatus error -12633.)", NSLocalizedFailureReason=发生未知错误（-12633）}

//m_writer.movieFragmentInterval = CMTimeMakeWithSeconds(1.0, 1000); // AVAssetWriter

NSURL* videoUrl = [NSURL fileURLWithPath:m_path isDirectory:NO];
m_playItem = [AVPlayerItem playerItemWithURL:videoUrl];

// 监听playItem的status属性
[m_playItem addObserver:self forKeyPath:@"status" 
    options:NSKeyValueObservingOptionNew context:nil];

// AVPlayer
m_player = [AVPlayer playerWithPlayerItem:m_playItem];
m_player.actionAtItemEnd = AVPlayerActionAtItemEndNone;

// AVPlayerLayerView
m_playerView = [[AVPlayerLayerView alloc] initWithFrame:self.bounds];
[self addSubview:m_playerView];

// 把AVPlayer添加到AVPlayerLayer
[(AVPlayerLayer*)[m_playerView layer] setPlayer:m_player];

// 观察AVPlayerItem播放结束的通知
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(itemPlayEnded:) 
    name:AVPlayerItemDidPlayToEndTimeNotification object:m_playItem];

AVAssetReader* reader = [[AVAssetReader alloc] initWithAsset:m_asset error:&error];
NSArray* videoTracks = [m_asset tracksWithMediaType:AVMediaTypeVideo];
AVAssetTrack* videoTrack = [videoTracks objectAtIndex:0];

// 视频播放时，m_pixelFormatType=kCVPixelFormatType_32BGRA
// 其他用途，如视频压缩，m_pixelFormatType=kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange
NSDictionary* options = [NSDictionary dictionaryWithObject:[NSNumber numberWithInt:
        (int)m_pixelFormatType] forKey:(id)kCVPixelBufferPixelFormatTypeKey];
AVAssetReaderTrackOutput* videoReaderOutput = [[AVAssetReaderTrackOutput alloc] 
        initWithTrack:videoTrack outputSettings:options];
[reader addOutput:videoReaderOutput];
[reader startReading];

// 要确保nominalFrameRate>0，之前出现过android拍的0帧视频
while ([reader status] == AVAssetReaderStatusReading && videoTrack.nominalFrameRate > 0) {
    // 读取video sample
    CMSampleBufferRef videoBuffer = [videoReaderOutput copyNextSampleBuffer];
    [m_delegate mMovieDecoder:self onNewVideoFrameReady:videoBuffer);
    CFRelease(videoBuffer);    
    // 根据需要休眠一段时间；比如上层播放视频时每帧之间是有间隔的
    [NSThread sleepForTimeInterval:sampleInternal];
}
    
// 告诉上层视频解码结束
[m_delegate mMovieDecoderOnDecodeFinished:self];