从GPUImage视频帧生成UIImage

问题描述

我正在尝试从GPUImage捕获的视频帧中生成UIImage.我已经做了很多AVFoundation视频工作，但是我是使用GPUImage的新手.我已经subclassed GPUImageVideoCamera并添加了此方法，但是UIImage始终为nil.如果有人能告诉我我哪里出了这么大的错误，我将非常感激！

I'm trying to generate a UIImage from a video frame captured by GPUImage. I've done a lot of AVFoundation video work, but i'm new to using GPUImage. I've subclassed GPUImageVideoCamera and added this method, but the UIImage is always nil. If anyone can tell me where i've gone so horribly wrong, i'd be very appreciative!

- (void)processVideoSampleBuffer:( CMSampleBufferRef )sampleBuffer

{ [super processVideoSampleBuffer:sampleBuffer]; //让GPUImage首先进行处理

{ [super processVideoSampleBuffer:sampleBuffer]; // to let GPUImage do it's processing first

if (!self.thumbnailGenerated)
{
    CMTime timestamp = CMSampleBufferGetPresentationTimeStamp(sampleBuffer);
    NSLog(@"%f", (float)timestamp.value / timestamp.timescale);

    self.thumbnailGenerated = YES;

    dispatch_sync(dispatch_get_main_queue(), ^
                  {
                      // generate a preview frame from the last filter in the camera filter chain

                      UIImage *thumbnailImage = [UIImage imageWithCGImage:[[self.targets lastObject] newCGImageFromCurrentlyProcessedOutput]];
                      NSString *pathToMovie = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents/Thumbnail.png"];
                      [UIImagePNGRepresentation(thumbnailImage) writeToFile:pathToMovie atomically:YES];
                  });
}
}

推荐答案

我不确定这是否有帮助，但是在处理视频时会出现缩略图.为此，我使用

I'm not sure if that is of any help, but I'm getting thumbnail while processing video. For this purpose I'm using

 videoInput --> someMyOperations --> fileOutput
 someMyOperations --> imageOutput //imageOutput is PictureOutput()
 videoInput.start() //that needs to be called!
 imageOutput.saveNextFrameToUrl(coverUrl, format: .jpg) { file in
     //here goes the code what to do with thumbnail
     videoInput.cancel() //quite probably here you want this
 }

这是猜测-我看不到您的代码，但对我来说这可行.

That's guessing - I don't see your code, but for me this works.

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