AVSampleBufferDisplayLayer如何显示H.264

Question

我想分享一下我在某些日子所了解的知识。目前还没有很多可以找到的。

我对这个声音依然兴奋不已。欢迎提出意见和建议。 ;-)

Answer 1

这里是我的代码片段。声明它

@property (nonatomic, retain) AVSampleBufferDisplayLayer *videoLayer; 

在第一次设置视频层

self.videoLayer = [[AVSampleBufferDisplayLayer alloc] init]; 
self.videoLayer.bounds = self.bounds; 
self.videoLayer.position = CGPointMake(CGRectGetMidX(self.bounds), CGRectGetMidY(self.bounds)); 
self.videoLayer.videoGravity = AVLayerVideoGravityResizeAspect; 
self.videoLayer.backgroundColor = [[UIColor greenColor] CGColor]; 

//set Timebase 
CMTimebaseRef controlTimebase; 
CMTimebaseCreateWithMasterClock(CFAllocatorGetDefault(), CMClockGetHostTimeClock(), &controlTimebase); 

self.videoLayer.controlTimebase = controlTimebase; 
CMTimebaseSetTime(self.videoLayer.controlTimebase, CMTimeMake(5, 1)); 
CMTimebaseSetRate(self.videoLayer.controlTimebase, 1.0); 

// connecting the videolayer with the view 

[[self layer] addSublayer:_videoLayer]; 

提供视频数据到层

__block AVAssetReaderTrackOutput *outVideo = [AVAssetReaderTrackOutput assetReaderTrackOutputWithTrack:video outputSettings:dic]; 

if([assetReaderVideo startReading]) 
{ 
    [_videoLayer requestMediaDataWhenReadyOnQueue: assetQueue usingBlock: ^{ 
     while([_videoLayer isReadyForMoreMediaData]) 
     { 
      CMSampleBufferRef *sampleVideo = [outVideo copyNextSampleBuffer]; 

      [_videoLayer enqueueSampleBuffer:sampleVideo.data]; 
     } 
    }]; 
} 

对于进一步的细节：在WWDC 2014届513是非常丰富的。

Answer 2

我在尝试这个，但发现AVSampleBufferDisplay层没有图像。

我创建一个原始字节流的NAL单元并通过IDR和使用非IDR片：

if ([avLayer isReadyForMoreMediaData]) { 
     [avLayer enqueueSampleBuffer:sampleBuffer]; 
} 

有来自EnqueueSampleBuffer返回错误状态，因此可能很难找出它是怎么回事错误。