Post 03: Creating a video with gstreamer and C++/Rust

sudo apt-get install -y gcc pkg-config curl

sudo dnf install -y gcc pkgconf-pkg-config curl

sudo pacman -S --needed gcc pkgconf curl

mkdir gstreamer-cpp
cd gstreamer-cpp
code main.cpp

#include <gst/gst.h>

int main(int argc, char *argv[]) {
    gst_init(&argc, &argv);

    GstElement *pipeline = gst_pipeline_new("test-pipeline");
    GstElement *src = gst_element_factory_make("videotestsrc", "src");
    GstElement *capsfilter = gst_element_factory_make("capsfilter", "capsfilter");
    GstElement *enc = gst_element_factory_make("x264enc", "enc");
    GstElement *parse = gst_element_factory_make("h264parse", "parse");
    GstElement *mux = gst_element_factory_make("matroskamux", "mux");
    GstElement *sink = gst_element_factory_make("filesink", "sink");

    if (!pipeline || !src || !capsfilter || !enc || !parse || !mux || !sink) {
        g_printerr("Failed to create elements\n");
        return -1;
    }

    g_object_set(src, "num-buffers", 90, nullptr);
    g_object_set(sink, "location", "test.mkv", nullptr);

    GstCaps *caps = gst_caps_new_simple("video/x-raw",
        "width", G_TYPE_INT, 1280,
        "height", G_TYPE_INT, 720,
        "framerate", GST_TYPE_FRACTION, 30, 1,
        nullptr);
    g_object_set(capsfilter, "caps", caps, nullptr);
    gst_caps_unref(caps);

    gst_bin_add_many(GST_BIN(pipeline), src, capsfilter, enc, parse, mux, sink, nullptr);

    if (!gst_element_link_many(src, capsfilter, enc, parse, mux, sink, nullptr)) {
        g_printerr("Failed to link elements\n");
        gst_object_unref(pipeline);
        return -1;
    }

    GstStateChangeReturn ret = gst_element_set_state(pipeline, GST_STATE_PLAYING);
    if (ret == GST_STATE_CHANGE_FAILURE) {
        g_printerr("Failed to set pipeline to PLAYING\n");
        gst_object_unref(pipeline);
        return -1;
    }

    GstBus *bus = gst_element_get_bus(pipeline);
    GstMessage *msg = gst_bus_timed_pop_filtered(bus, GST_CLOCK_TIME_NONE,
        (GstMessageType)(GST_MESSAGE_ERROR | GST_MESSAGE_EOS));

    if (msg != nullptr) {
        GError *err;
        gchar *debug_info;
        switch (GST_MESSAGE_TYPE(msg)) {
            case GST_MESSAGE_ERROR:
                gst_message_parse_error(msg, &err, &debug_info);
                g_printerr("Error: %s\n", err->message);
                g_clear_error(&err);
                g_free(debug_info);
                break;
            case GST_MESSAGE_EOS:
                g_print("End of stream\n");
                break;
            default:
                break;
        }
        gst_message_unref(msg);
    }

    // -e flag behavior: send EOS before stopping
    gst_element_send_event(pipeline, gst_event_new_eos());

    gst_object_unref(bus);
    gst_element_set_state(pipeline, GST_STATE_NULL);
    gst_object_unref(pipeline);

    return 0;
}

g++ main.cpp -o gstreamer-cpp `pkg-config --cflags --libs gstreamer-1.0`
./gstreamer-cpp

cargo new gstreamer-rust
cd gstreamer-rust
cargo add gstreamer
code src/main.rs

use gst::prelude::*;
use gstreamer as gst;

fn main() {
    gst::init().unwrap();

    let pipeline = gst::Pipeline::new();

    let src = gst::ElementFactory::make("videotestsrc")
        .property("num-buffers", 90)
        .build()
        .expect("Failed to create videotestsrc");

    let capsfilter = gst::ElementFactory::make("capsfilter")
        .property(
            "caps",
            gst::Caps::builder("video/x-raw")
                .field("width", 1280)
                .field("height", 720)
                .field("framerate", gst::Fraction::new(30, 1))
                .build(),
        )
        .build()
        .expect("Failed to create capsfilter");

    let enc = gst::ElementFactory::make("x264enc")
        .build()
        .expect("Failed to create x264enc");

    let parse = gst::ElementFactory::make("h264parse")
        .build()
        .expect("Failed to create h264parse");

    let mux = gst::ElementFactory::make("matroskamux")
        .build()
        .expect("Failed to create matroskamux");

    let sink = gst::ElementFactory::make("filesink")
        .property("location", "test.mkv")
        .build()
        .expect("Failed to create filesink");

    pipeline
        .add_many([&src, &capsfilter, &enc, &parse, &mux, &sink])
        .unwrap();

    gst::Element::link_many([&src, &capsfilter, &enc, &parse, &mux, &sink])
        .expect("Failed to link elements");

    pipeline
        .set_state(gst::State::Playing)
        .expect("Unable to set pipeline to Playing");

    let bus = pipeline.bus().unwrap();

    for msg in bus.iter_timed(gst::ClockTime::NONE) {
        use gst::MessageView;

        match msg.view() {
            MessageView::Eos(..) => {
                println!("End of stream");
                break;
            }
            MessageView::Error(err) => {
                eprintln!(
                    "Error from {:?}: {} ({:?})",
                    err.src().map(|s| s.path_string()),
                    err.error(),
                    err.debug()
                );
                break;
            }
            _ => (),
        }
    }

    pipeline
        .set_state(gst::State::Null)
        .expect("Unable to set pipeline to Null");
}

cargo run

gst_init(&argc, &argv);

gst::init().unwrap();

auto* pipeline = gst_pipeline_new("pipeline");

let pipeline = gst::Pipeline::new();

gst_bin_add_many(
    GST_BIN(pipeline),
    source,
    encoder,
    muxer,
    sink,
    nullptr);

pipeline
    .add_many([&src, &capsfilter, &enc, &parse, &mux, &sink])
    .unwrap();

gst_element_link_many(
    source,
    encoder,
    muxer,
    sink,
    nullptr);

gst::Element::link_many([&src, &capsfilter, &enc, &parse, &mux, &sink])
    .expect("Failed to link elements");

g_object_set(
    source,
    "pattern",
    1,
    nullptr);

let src = gst::ElementFactory::make("videotestsrc")
    .property("num-buffers", 90)
    .build()
    .expect("Failed to create videotestsrc");

gst_element_set_state(
    pipeline,
    GST_STATE_PLAYING);

pipeline
    .set_state(gst::State::Playing)
    .expect("Unable to set pipeline to Playing");