Getting duration of a partial file

[skoove]

Hello! I am trying to get the duration of a file, without having the entire file. I know that this is bitrate / duration but I cannot figure out how to get the metadata of a parital file without getting unexpected end of stream.

/// Returns the length of an mp3 given the url
async fn get_content_length(url: &str) -> reqwest::Result<Duration> {
    let client = Client::new();

    let client_clone = client.clone();
    let url_owned = url.to_string();

    let content_length = tokio::spawn(async move {
        let response = client_clone.get(url_owned).send().await;
        match response {
            Ok(r) => Ok(r
                .headers()
                .get(CONTENT_LENGTH)
                .and_then(|val| val.to_str().ok())
                .and_then(|s| s.parse::<u32>().ok())
                .expect("content length in header")),
            Err(e) => Err(e),
        }
    });

    let url_owned = url.to_string();
    let file_part = tokio::spawn(async move {
        Ok(client
            .get(url_owned)
            // only grab first 64 kb
            // .header("Range", "bytes=0-64000")
            .send()
            .await?
            .bytes())
    });

    println!("attempting to parse partial file to get bitrate");

    let codecs = symphonia::default::get_codecs();
    let probe = symphonia::default::get_probe();
    let cursor = Cursor::new(file_part.await.expect("to join")?.await?);
    let stream = MediaSourceStream::new(Box::new(cursor), MediaSourceStreamOptions::default());

    probe
        .format(
            &Hint::new().with_extension("mp3"),
            stream,
            &FormatOptions::default(),
            &MetadataOptions::default(),
        )
        .unwrap();

    println!("content_length = {}", content_length.await.unwrap()?);

    // to get compiler to be quiet
    Ok(Duration::from_secs(1))
}