CMSampleBufferGetImageBuffer返回null

Question

我试图从CMSampleBufferRef中检索CVPixelBufferRef,以便改变CVPixelBufferRef以动态覆盖水印.

我正在使用CMSampleBufferGetImageBuffer(sampleBuffer)以实现这一目标.我正在打印返回的CVPixelBufferRef的结果,但它始终为null.

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection {

    CVPixelBufferRef pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);

    NSLog(@"PixelBuffer %@",pixelBuffer);
...

}

我有什么我想念的吗？

Answer 1

经过数小时的调试,结果表明样本可能是视频或音频样本.因此,尝试从音频缓冲区获取CVPixelBufferRef将返回null.

我在继续之前通过检查样本类型来解决它.由于我对音频样本不感兴趣,所以我只是在它的音频样本时返回.

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection {

    CVPixelBufferRef pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);

    CMFormatDescriptionRef formatDesc = CMSampleBufferGetFormatDescription(sampleBuffer);
    CMMediaType mediaType = CMFormatDescriptionGetMediaType(formatDesc);

    //Checking sample type before proceeding
    if (mediaType == kCMMediaType_Audio)
    {return;}

//Processing the sample...

}