is it possible to "feed" the library with a manipulated video?

[haemi]

I would like to modify the video coming from the device - is this possible somehow? E.g. with OpenCV?

[iobroyles]

You should be able to create a chain of filters using GPUImage which this project uses.

https://github.com/BradLarson/GPUImage#filtering-live-video

[haemi]

sorry, I don't get it yet; can you give a short example for how to achieve that?

[longbai]

here is sample
GPUImageVideoCamera *videoCamera = [[GPUImageVideoCamera alloc] initWithSessionPreset:AVCaptureSessionPreset640x480 cameraPosition:AVCaptureDevicePositionBack];
videoCamera.outputImageOrientation = UIInterfaceOrientationPortrait;

// 创建一个 filter
GPUImageSketchFilter *filter = [[GPUImageSketchFilter alloc] init];
__weak typeof(self) wself = self;
filter.frameProcessingCompletionBlock = ^(GPUImageOutput *output, CMTime time) {
__strong typeof(wself) strongSelf = wself;
if (strongSelf && PLStreamStateConnected == strongSelf.session.streamState) {
// 从 filter 中读取 GPUImageFramebuffer 对象
GPUImageFramebuffer *imageFramebuffer = output.framebufferForOutput;

    // 通过上面添加的方法获取到 CVPixelBufferReft
    CVPixelBufferRef pixelBuffer = [imageFramebuffer renderTarget];

    if (pixelBuffer) {
        CVPixelBufferLockBaseAddress(pixelBuffer, 0);
        CVPixelBufferRetain(pixelBuffer);

        // 发送视频数据
        [strongSelf.session pushPixelBuffer:pixelBuffer completion:^{
            CVPixelBufferRelease(pixelBuffer);
            CVPixelBufferUnlockBaseAddress(pixelBuffer, 0);
        }];
    }
}

};

GPUImageView *filteredVideoView = [[GPUImageView alloc] initWithFrame:(CGRect){0, 64, width, height}];

// Add the view somewhere so it's visible
[self.view addSubview:filteredVideoView];

[videoCamera addTarget:filter];
[filter addTarget:filteredVideoView];

[videoCamera startCameraCapture];

[haemi]

there is no renderTarget method on GPUImageFramebuffer - how can I achieve this conversion?

[longbai]

you can modify the GPUimageFilter and add this method