FFMPEG based video clipper

LICENSE

Public Domain

video_clipper.rs

pub struct VideoClipper;

impl VideoClipper {
    pub fn generate_highlights(project: &Project) -> crate::Result<()> {
        let local_path = project.video.local_path.clone();

        // ...
        // snip!
        // the snipped bit just builds up a bunch of tags which contain start/end times
        // ...

        // write out individual clips to temporary folder
        create_dir_all("temp")?;
        create_dir_all("output")?;
        let mut file_names: Vec<String> = Vec::new();

        // generate a clip for each range tag, and use video filters to burn in
        // the caption
        range_tags.iter().enumerate().for_each(|(idx, tag)| {
            let path = format!("temp/{}.mkv", idx + 1);
            file_names.push(path.clone());

            let caption = "blah a caption";

            let mut cmd = VideoClipper::get_os_cmd("ffmpeg".into());
            cmd.args(&[
                "-ss", 
                &tag.start_time.to_string()[..], // this is an f32 in seconds 
                "-t", 
                &(tag.end_time.unwrap() - tag.start_time).to_string()[..], // the tag duration in seconds, f32
                "-i", 
                &local_path[..], // the path to the video
                "-vf", 
                &format!(
                    "[in]drawtext=fontfile=OpenSans.ttf:text='{}':fontcolor=white:fontsize=48:x=10:y=10:box=1:boxcolor=black@0.5:boxborderw=5[out]",
                    caption
                )[..],
                "-y",
                &path[..]
            ]);

            let mut handle = cmd.spawn().expect("Should spawn a clipping handle");
            handle.wait().expect("Should exit eventually");
        });

        // write list of files
        let mut write_file = std::fs::File::create("file_list.txt")?;
        write_file.write_all(
            file_names
                .iter()
                .map(|f| format!("file '{}'", f))
                .collect::<Vec<_>>()
                .join("\n")
                .as_bytes(),
        )?;

        // concat the temp video files
        let mut cmd = VideoClipper::get_os_cmd("ffmpeg".into());

        cmd.args(&[
            "-f",
            "concat",
            "-i",
            "file_list.txt",
            "-c",
            "copy",
            "-y",
            "output/highlights.mkv",
        ]);

        let mut handle = cmd.spawn().expect("Cannot concat videos");
        handle.wait()?;

        // tidy up
        file_names.iter().for_each(|path| {
            let mut handle = VideoClipper::get_os_cmd(if cfg!(target_os = "windows") { "del" } else { "rm" }.into())
                .arg(if cfg!(target_os = "windows") { path.replace("/", "\\") } else { path.clone() })
                .spawn()
                .expect("Should delete file");
            handle.wait().expect("Should delete file");
        });
        
        let mut handle = VideoClipper::get_os_cmd(if cfg!(target_os = "windows") { "del" } else { "rm" }.into())
            .arg("file_list.txt")
            .spawn()
            .expect("Should delete file");
        handle.wait().expect("Should delete file");

        Ok(())
    }

    fn get_os_cmd(command: String) -> Command {
        let mut cmd = if cfg!(target_os = "windows") {
            let mut cmd = Command::new("cmd");
            cmd.arg("/C");
            cmd.arg(command);
            cmd
        } else {
            let mut cmd = Command::new("cmd");
            cmd.arg("-c");
            cmd.arg(command);
            cmd
        };

        cmd.stdout(Stdio::inherit());

        cmd
    }
}