gstreamer-rs/examples/src/bin/discoverer.rs

// This example uses gstreamer's discoverer api
// https://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base-libs/html/GstDiscoverer.html
// To detect as much information from a given URI.
// The amount of time that the discoverer is allowed to use is limited by a timeout.
// This allows to handle e.g. network problems gracefully. When the timeout hits before
// discoverer was able to detect anything, discoverer will report an error.
// In this example, we catch this error and stop the application.
// Discovered information could for example contain the stream's duration or whether it is
// seekable (filesystem) or not (some http servers).

use std::env;

use anyhow::Error;
use derive_more::{Display, Error};
use gst_pbutils::{prelude::*, DiscovererInfo, DiscovererStreamInfo};

#[path = "../examples-common.rs"]
mod examples_common;

#[derive(Debug, Display, Error)]
#[display(fmt = "Discoverer error {_0}")]
struct DiscovererError(#[error(not(source))] &'static str);

fn print_tags(info: &DiscovererInfo) {
    println!("Tags:");

    let tags = info.tags();
    match tags {
        Some(taglist) => {
            println!("  {taglist}"); // FIXME use an iterator
        }
        None => {
            println!("  no tags");
        }
    }
}

fn print_stream_info(stream: &DiscovererStreamInfo) {
    println!("Stream: ");
    println!("  Stream id: {}", stream.stream_id());
    let caps_str = match stream.caps() {
        Some(caps) => caps.to_string(),
        None => String::from("--"),
    };
    println!("  Format: {caps_str}");
}

fn print_discoverer_info(info: &DiscovererInfo) -> Result<(), Error> {
    println!("URI: {}", info.uri());
    println!("Duration: {}", info.duration().display());
    print_tags(info);
    print_stream_info(
        &info
            .stream_info()
            .ok_or(DiscovererError("Error while obtaining stream info"))?,
    );

    let children = info.stream_list();
    println!("Children streams:");
    for child in children {
        print_stream_info(&child);
    }

    Ok(())
}

fn run_discoverer() -> Result<(), Error> {
    gst::init()?;

    let args: Vec<_> = env::args().collect();
    let uri: &str = if args.len() == 2 {
        args[1].as_ref()
    } else {
        println!("Usage: discoverer uri");
        std::process::exit(-1)
    };

    let timeout: gst::ClockTime = gst::ClockTime::from_seconds(15);
    let discoverer = gst_pbutils::Discoverer::new(timeout)?;
    let info = discoverer.discover_uri(uri)?;
    print_discoverer_info(&info)?;
    Ok(())
}

fn example_main() {
    match run_discoverer() {
        Ok(_) => (),
        Err(e) => eprintln!("Error: {e}"),
    }
}

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)
    examples_common::run(example_main);
}