How to apply filter on saved video and save it again using MetalPetal ? [Urgent]

[metalpetal]

How to apply filter on saved video and save it again using MetalPetal ? [Urgent]

[YuAo]

You need to use AVAssetReader and writer. Here’s an example for you https://github.com/rs/SDAVAssetExportSession . It also has a delegate method where you can insert your render code.

[commando24]

@YuAo sorry to interrupt But can you please guide me or provide me a simple code to write in the delegate method ? I wanna just test it with MetalPetal sample project. I have also tried to understand SDAVAssetExportSession but i was unable to understand this .

[YuAo]

All you need to do is to process the video buffer in the delegate method.
You may want to look at MetalPetal's CameraViewController demo.

Something like:

- (void)exportSession:(SDAVAssetExportSession *)exportSession renderFrame:(CVPixelBufferRef)pixelBuffer withPresentationTime:(CMTime)presentationTime toBuffer:(CVPixelBufferRef)renderBuffer {
        MTIImage *inputImage = [[MTIImage alloc] initWithCVPixelBuffer:pixelBuffer alphaType:MTIAlphaTypeAlphaIsOne];
        self.filter.inputImage = inputImage;
        MTIImage *outputImage = self.filter.outputImage;
        NSError *error;
        [self.context renderImage:outputImage toCVPixelBuffer:renderBuffer error:&error];
}

Things about using SDAVAssetExportSession are not good topics here. You may want to create a question on "stackoverflow".

[commando24]

@YuAo thanks for your help. But my reason to use MetalPetal still not fullfilled. I thought using this will reduce video processing time but it's not . Can you tell me why this is happening ? Like we are using GPU for video processing but still its time same result as CPU.

[YuAo]

I think it’s better to create a sample project demonstrating the issue you’ve encountered. And post a question about what you’re doing / what is your expectation on a Q&A site like stackoverflow. So people can discuss the question in a more open and efficient way.