vcs-controller/src/ui/gstreamer_pipeline.rs

use gstreamer::prelude::{ElementExt, ElementExtManual, GstBinExtManual, PadExt};
use gstreamer::{Element, ElementFactory, Pipeline, State};

#[derive(Clone)]
pub struct WebcamPipeline {
    pub pipeline: Pipeline,

    pub src: Element,
    pub converter: Element,
    pub tee: Element,
    pub sink_paintable: Element,

    pub resize: Element,
    pub decode: Element,
    pub sink_frame: Element,
}

impl WebcamPipeline {
    pub fn new() -> WebcamPipeline {
        let pipeline = Pipeline::with_name("webcam_pipeline");

        let source = ElementFactory::make("mfvideosrc")
            .build()
            .expect("Could not build video source for GStreamer");
        let convert = ElementFactory::make("videoconvert")
            .build()
            .expect("Could not build video convert for GStreamer");

        let tee = ElementFactory::make("tee")
            .build()
            .expect("Could not create tee element");

        let sink_paintable = ElementFactory::make("gtk4paintablesink")
            .build()
            .expect("Could not build gtk sink for GStreamer");

        let resize = ElementFactory::make("videoscale")
            .build()
            .expect("Could not build videoscale for GStreamer");

        todo!("Video XRaw is not actually working yet");
        let decode = ElementFactory::make("video/x-raw,width=650,height=480")
            .build()
            .expect("Could not create decoder");

        let sink_frame = ElementFactory::make("appsink name=frame_sink")
            .build()
            .expect("Could not build appsrc for GStreamer");

        pipeline.add_many(&[
            &source,
            &convert,
            &tee,
            &sink_paintable,
            &resize,
            &sink_frame,
        ]).expect("Could not link the elements to the pipeline");

        source
            .link(&convert)
            .expect("Could not link video source to converter");
        convert.link(&tee).expect("Could not link converter to tee");

        let tee_pad_template = tee
            .pad_template("src_%u")
            .expect("Could not get pad templates");

        let tee_src_1 = tee
            .request_pad(&tee_pad_template, Some("paintable_src_pad"), None)
            .expect("Could not create src pad 1");
        let sink_paintable_sinkpad = sink_paintable
            .static_pad("sink")
            .expect("Could not get sink pad for paintablesink");
        tee_src_1
            .link(&sink_paintable_sinkpad)
            .expect("Could not link tee srcpad 1 to paintablesink pad");

        let tee_src_2 = tee
            .request_pad(&tee_pad_template, Some("output_src_pad"), None)
            .expect("Could not create src pad 2");
        let sink_frameoutput_sinkpad = sink_frame
            .static_pad("sink")
            .expect("Could not get sink pad for frameoutput sink");
        tee_src_2
            .link(&sink_frameoutput_sinkpad)
            .expect("Could not link tee srcpad 2 to frame output sink pad");

        resize
            .link(&decode)
            .expect("Could not bind resize to decoder");
        decode
            .link(&sink_frame)
            .expect("Could not bind decoder to webcam frame output");

        WebcamPipeline {
            pipeline,
            src: source,
            converter: convert,
            tee,
            sink_paintable,
            resize,
            decode,
            sink_frame,
        }
    }
}

impl Drop for WebcamPipeline {
    fn drop(&mut self) {
        self.pipeline
            .set_state(State::Null)
            .expect("Could not close pipeline during window deconstruction");
    }
}