feat: add initial ffmpeg implementation

src/ffmpeg.rs

@@ -0,0 +1,126 @@
+use std::{
+    path::{Path, PathBuf},
+    process::Stdio,
+};
+
+use color_eyre::eyre::{ContextCompat, Result};
+use relm4::{
+    Sender,
+    tokio::{
+        self,
+        io::{AsyncBufReadExt, BufReader},
+        process::Command,
+    },
+};
+
+use crate::ProgressMessage;
+
+#[derive(serde::Deserialize)]
+struct FfprobeOut {
+    streams: Vec<StreamInfo>,
+    format: FormatInfo,
+}
+
+#[derive(serde::Deserialize)]
+struct StreamInfo {
+    width: usize,
+    height: usize,
+}
+
+#[derive(serde::Deserialize)]
+struct FormatInfo {
+    duration: String,
+}
+
+#[derive(Debug)]
+pub struct VideoMeta {
+    pub width: usize,
+    pub height: usize,
+    pub duration_us: usize,
+}
+
+pub async fn get_video_meta(path: &Path) -> Result<VideoMeta> {
+    let output = Command::new("ffprobe")
+        .args([
+            "-v",
+            "error",
+            "-select_streams",
+            "v:0",
+            "-show_entries",
+            "stream=width,height : format=duration",
+            "-of",
+            "json",
+        ])
+        .arg(path)
+        .stdout(Stdio::piped())
+        .output()
+        .await?;
+
+    let str = String::from_utf8(output.stdout)?;
+    let output: FfprobeOut = serde_json::from_str(&str)?;
+
+    let stream = output
+        .streams
+        .first()
+        .wrap_err("could not get stream information from ffprobe")?;
+
+    let duration_sec = output.format.duration.parse::<f64>()?;
+    let duration_us = (duration_sec * 1_000_000.0).ceil() as usize;
+
+    Ok(VideoMeta {
+        width: stream.width,
+        height: stream.height,
+        duration_us,
+    })
+}
+
+pub async fn convert_video(path: &Path, sender: Sender<ProgressMessage>) -> Result<PathBuf> {
+    let out_path = PathBuf::from("/tmp/out.webm");
+
+    let mut child = Command::new("ffmpeg")
+        .arg("-i")
+        .arg(path)
+        .args([
+            "-c:a",
+            "libopus",
+            "-b:a",
+            "96k",
+            "-c:v",
+            "libsvtav1",
+            "-loglevel",
+            "error",
+            "-progress",
+            "-",
+            "-nostats",
+        ])
+        .arg(&out_path)
+        .stdout(Stdio::piped())
+        .spawn()?;
+
+    let stdout = child.stdout.take().unwrap();
+    let mut reader = BufReader::new(stdout).lines();
+
+    // make sure the process is actually started and awaited
+    tokio::spawn(async move {
+        child
+            .wait()
+            .await
+            .expect("ffmpeg process encountered an error");
+    });
+
+    while let Some(line) = reader.next_line().await? {
+        if line.starts_with("out_time_us") {
+            let (_, current_duration) = line
+                .split_once("=")
+                .wrap_err_with(|| format!("could not parse ffmpeg output: {line}"))?;
+
+            if current_duration != "N/A" {
+                sender.emit(ProgressMessage::AbsProgress(
+                    current_duration.parse::<usize>()?,
+                ));
+            }
+        }
+    }
+
+    Ok(out_path)
+}