gstreamer-rs/tutorials/src/bin/playback-tutorial-1.rs

use std::{thread, time};

use anyhow::Error;
use glib::FlagsClass;
use gst::prelude::*;
use termion::{event::Key, input::TermRead};

#[path = "../tutorials-common.rs"]
mod tutorials_common;

fn analyze_streams(playbin: &gst::Element) {
    let n_video = playbin.property::<i32>("n-video");
    let n_audio = playbin.property::<i32>("n-audio");
    let n_text = playbin.property::<i32>("n-text");
    println!("{n_video} video stream(s), {n_audio} audio stream(s), {n_text} text stream(s)");

    for i in 0..n_video {
        let tags = playbin.emit_by_name::<Option<gst::TagList>>("get-video-tags", &[&i]);

        if let Some(tags) = tags {
            println!("video stream {i}:");
            if let Some(codec) = tags.get::<gst::tags::VideoCodec>() {
                println!("    codec: {}", codec.get());
            }
        }
    }

    for i in 0..n_audio {
        let tags = playbin.emit_by_name::<Option<gst::TagList>>("get-audio-tags", &[&i]);

        if let Some(tags) = tags {
            println!("audio stream {i}:");
            if let Some(codec) = tags.get::<gst::tags::AudioCodec>() {
                println!("    codec: {}", codec.get());
            }
            if let Some(codec) = tags.get::<gst::tags::LanguageCode>() {
                println!("    language: {}", codec.get());
            }
            if let Some(codec) = tags.get::<gst::tags::Bitrate>() {
                println!("    bitrate: {}", codec.get());
            }
        }
    }

    for i in 0..n_text {
        let tags = playbin.emit_by_name::<Option<gst::TagList>>("get-text-tags", &[&i]);

        if let Some(tags) = tags {
            println!("subtitle stream {i}:");
            if let Some(codec) = tags.get::<gst::tags::LanguageCode>() {
                println!("    language: {}", codec.get());
            }
        }
    }

    let current_video = playbin.property::<i32>("current-video");
    let current_audio = playbin.property::<i32>("current-audio");
    let current_text = playbin.property::<i32>("current-text");
    println!(
        "Currently playing video stream {current_video}, audio stream {current_audio}, text stream {current_text}"
    );
    println!("Type any number and hit ENTER to select a different audio stream");
}

fn handle_keyboard(playbin: &gst::Element, main_loop: &glib::MainLoop) {
    let mut stdin = termion::async_stdin().keys();

    loop {
        if let Some(Ok(input)) = stdin.next() {
            match input {
                Key::Char(index) => {
                    if let Some(index) = index.to_digit(10) {
                        // Here index can only be 0-9
                        let index = index as i32;
                        let n_audio = playbin.property::<i32>("n-audio");

                        if index < n_audio {
                            println!("Setting current audio stream to {index}");
                            playbin.set_property("current-audio", index);
                        } else {
                            eprintln!("Index out of bounds");
                        }
                    }
                }
                Key::Ctrl('c') => {
                    main_loop.quit();
                    break;
                }
                _ => continue,
            };
        }
        thread::sleep(time::Duration::from_millis(50));
    }
}

fn tutorial_main() -> Result<(), Error> {
    // Set up main loop
    let main_loop = glib::MainLoop::new(None, false);

    // Initialize GStreamer
    gst::init()?;

    let uri =
        "https://www.freedesktop.org/software/gstreamer-sdk/data/media/sintel_cropped_multilingual.webm";

    // Create PlayBin element
    let playbin = gst::ElementFactory::make("playbin")
        .name("playbin")
        // Set URI to play
        .property("uri", uri)
        // Set connection speed. This will affect some internal decisions of playbin
        .property("connection-speed", 56u64)
        .build()?;

    // Set flags to show Audio and Video but ignore Subtitles
    let flags = playbin.property_value("flags");
    let flags_class = FlagsClass::new(flags.type_()).unwrap();

    let flags = flags_class
        .builder_with_value(flags)
        .unwrap()
        .set_by_nick("audio")
        .set_by_nick("video")
        .unset_by_nick("text")
        .build()
        .unwrap();
    playbin.set_property_from_value("flags", &flags);

    // Handle keyboard input
    let playbin_clone = playbin.clone();
    let main_loop_clone = main_loop.clone();
    thread::spawn(move || handle_keyboard(&playbin_clone, &main_loop_clone));

    // Add a bus watch, so we get notified when a message arrives
    let playbin_clone = playbin.clone();
    let main_loop_clone = main_loop.clone();
    let bus = playbin.bus().unwrap();
    let _bus_watch = bus.add_watch(move |_bus, message| {
        use gst::MessageView;
        match message.view() {
            MessageView::Error(err) => {
                eprintln!(
                    "Error received from element {:?} {}",
                    err.src().map(|s| s.path_string()),
                    err.error()
                );
                eprintln!("Debugging information: {:?}", err.debug());
                main_loop_clone.quit();
                Continue(false)
            }
            MessageView::StateChanged(state_changed) => {
                if state_changed
                    .src()
                    .map(|s| s == &playbin_clone)
                    .unwrap_or(false)
                    && state_changed.current() == gst::State::Playing
                {
                    analyze_streams(&playbin_clone);
                }
                Continue(true)
            }
            MessageView::Eos(..) => {
                println!("Reached end of stream");
                main_loop_clone.quit();
                Continue(false)
            }
            _ => Continue(true),
        }
    })?;

    // Set to PLAYING
    playbin.set_state(gst::State::Playing)?;

    // Set GLib mainlooop to run
    main_loop.run();

    // Clean up
    playbin.set_state(gst::State::Null)?;

    Ok(())
}

fn main() {
    // tutorials_common::run is only required to set up the application environment on macOS
    // (but not necessary in normal Cocoa applications where this is set up automatically)
    match tutorials_common::run(tutorial_main) {
        Ok(_) => {}
        Err(err) => eprintln!("Failed: {err}"),
    };
}