VideoEffect doesn't run execute function

[abhinandan-chakraborty]

Hi, first of all, thank you very much for this amazing library and keeping it up-to-date and supporting so many features out of the box. I have been playing around with this library for a couple of days but I can't seem to figure out why VideoEffect "execute" function never gets called. Here is an example:

private class ContentModel: ObservableObject, IOStreamObserver, IOStreamDelegate {
    @Published var stream:RTMPStream?
    private let connection = RTMPConnection()
    
    init() {
            let session = AVAudioSession.sharedInstance()
        do {
            try session.setCategory(.playAndRecord, mode: .default, options: [.defaultToSpeaker, .allowBluetooth])
            try session.setActive(true)
                
            stream = RTMPStream(connection: connection)
            stream?.videoOrientation = .portrait

            stream?.sessionPreset = .hd1280x720
            stream?.videoSettings.profileLevel = kVTProfileLevel_H264_Baseline_AutoLevel as String
            stream?.videoSettings.videoSize = CGSize(width: 720, height: 1280)
            stream?.videoSettings.bitRate = 4 * 1000 * 1000
            stream?.frameRate = 30

            stream!.attachAudio(AVCaptureDevice.default(for: .audio)) { _, error in
              if let error {
                  print("errr 1: \(error.localizedDescription)")
              }
            }
                        
            stream!.attachCamera(AVCaptureDevice.default(.builtInWideAngleCamera, for: .video, position: .back)) { videoUnit, error in
              if let error {
                  print("errr 2: \(error.localizedDescription)")
              } 
            }
            
            stream?.addObserver(self)
            stream?.delegate = self
            
            let _ = stream?.registerVideoEffect(SepiaEffect()) //here attempts to use Video effect
            
        } catch(let err) {
            print("error :\(err)")
        }
    }
    
    
    //on button click
    public func startStream() {
        connection.connect("rtmp://192.168.1.38/live")
        stream?.publish("hello")
    }
}

and now for the my video effect class:

final class SepiaEffect: VideoEffect {
    let filter = CIFilter.sepiaTone()
    
    override init() {
        print("sepiaeffect ") // this gets called successfully
    }

    override func execute(_ image: CIImage, info: CMSampleBuffer?) -> CIImage {
        print("called here") //never gets called
        filter.inputImage = image
        filter.intensity = 0.9
        return filter.outputImage!
    }
}

now talking about my true intention, I don't really need to use CIFilter in my actual project, as I just want to access CMSampleBuffer and send it to VTDecompressionSessionDecodeFrame to decode multi-frame MV-HEVC and then process it and send it back as either a modified CMSampleBuffer or CIImage (If I use VideoEffect).

There is another way where I can access CMSampleBuffer:

func stream(_ stream: HaishinKit.IOStream, track: UInt8, didInput video: CMSampleBuffer) {
  //do some processing and then:
  stream?.append(newSampleBuffer, track: track)
|

but this method causes the MTHKView to flicker ( assuming append makes the stream add same buffer instead of replacing original buffer with the new CMSampleBuffer object ). I also tried to use another RTMPStream object that would publish the stream but there the stream is very unstable. All in all, I think VideoEffect sounds like the right way to deal with this situation, but I am not sure why execute is never called.

[shogo4405]

If you are using version 1.9.x, you need to specify the following value. The default is .passthrough.

stream.videoMixerSettings.mode = .offscreen

[abhinandan-chakraborty]

Ah, what a beauty! It works so good. I just had to add these lines:

   stream?.videoMixerSettings.mode = .offscreen
   stream?.screen.startRunning()
   stream?.registerVideoEffect(SepiaEffect())

Just one last question, Is it possible to publish these filtered streams to the server but without displaying these effects on top of MTHKView?

Thank you for so fast response.

[shogo4405]

I did not design it that way. However, it is possible to display a raw CMSampleBuffer in MTKView. In this case, calling hkView.attachStream is not necessary.

func stream(_ stream: HaishinKit.IOStream, track: UInt8, didInput video: CMSampleBuffer) {
  //do some processing and then:
  if track == 0 {
      hkView?.enqueue(sampleBuffer)
  }
|

[abhinandan-chakraborty]

Wow, this is just so cool. It works perfectly fine. Thank you so much for your help!