video2srt: new crate

Cargo.toml

@@ -121,6 +121,7 @@ members = [
     "write-debian-changelog",
     "zip-or-dir",
     "zip-or-dir/dir2zip",
+    "media-utils/video2srt",
 ]
 
 exclude = ["led-box-firmware", "led-box-firmware-pico"]

media-utils/video2srt/Cargo.toml

@@ -0,0 +1,19 @@
+[package]
+name = "video2srt"
+description = "Create a subtitle .srt file from video with Strand Cam timestamps"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+clap = { version = "4.3.4", features = ["derive"] }
+color-eyre = "0.6.2"
+
+tracing = "0.1.40"
+chrono = { version = "0.4.38", features = [
+    "libc",
+    "serde",
+    "std",
+], default-features = false }
+
+env-tracing-logger = { path = "../../env-tracing-logger" }
+frame-source = { path = "../frame-source" }

media-utils/video2srt/src/main.rs

@@ -0,0 +1,115 @@
+use clap::Parser;
+use color_eyre::eyre::{self, WrapErr};
+use std::{io::Write, path::PathBuf};
+
+use frame_source::Timestamp;
+
+#[derive(Debug, Parser)]
+#[command(version, about)]
+struct Opt {
+    /// Input video filename.
+    #[arg(short, long)]
+    input: PathBuf,
+
+    /// Output srt filename. Defaults to "<INPUT>.srt"
+    #[arg(short, long)]
+    output: Option<PathBuf>,
+}
+
+trait Srt {
+    fn srt(&self) -> String;
+}
+
+impl Srt for std::time::Duration {
+    fn srt(&self) -> String {
+        // from https://en.wikipedia.org/wiki/SubRip :
+        // "hours:minutes:seconds,milliseconds with time units fixed to two
+        // zero-padded digits and fractions fixed to three zero-padded digits
+        // (00:00:00,000). The fractional separator used is the comma, since the
+        // program was written in France."
+        let total_secs = self.as_secs();
+        let hours = total_secs / (60 * 60);
+        let minutes = (total_secs % (60 * 60)) / 60;
+        let seconds = total_secs % 60;
+        dbg!(total_secs);
+        dbg!(hours);
+        dbg!(minutes);
+        dbg!(seconds);
+        debug_assert_eq!(total_secs, hours * 60 * 60 + minutes * 60 + seconds);
+        let millis = self.subsec_millis();
+        format!("{hours:02}:{minutes:02}:{seconds:02},{millis:03}")
+    }
+}
+
+fn main() -> eyre::Result<()> {
+    if std::env::var_os("RUST_LOG").is_none() {
+        std::env::set_var("RUST_LOG", "info");
+    }
+    env_tracing_logger::init();
+    let opt = Opt::parse();
+
+    let output = opt.output;
+
+    let output = output.unwrap_or_else(|| {
+        let mut output = opt.input.as_os_str().to_owned();
+        output.push(".srt");
+        output.into()
+    });
+
+    let do_decode_h264 = false;
+    let mut src = frame_source::from_path(&opt.input, do_decode_h264)
+        .with_context(|| format!("while opening path {}", opt.input.display()))?;
+
+    let start_time = src
+        .frame0_time()
+        .ok_or_else(|| eyre::eyre!("no start time found"))?;
+
+    let mut out_fd = std::fs::File::create(&output)?;
+
+    let mut prev_data: Option<(std::time::Duration, _)> = None;
+
+    let mut count = 1;
+    for (_fno, frame) in src.iter().enumerate() {
+        let frame = frame?;
+        let pts = match frame.timestamp() {
+            Timestamp::Duration(pts) => pts,
+            _ => {
+                eyre::bail!(
+                    "video has no PTS timestamps and framerate was not \
+                    specified on the command line."
+                );
+            }
+        };
+        let frame_stamp = start_time + pts;
+        if let Some((prev_pts, prev_stamp)) = prev_data.take() {
+            out_fd.write_all(
+                format!(
+                    "{}\n{} --> {}\n{}\n\n",
+                    count,
+                    prev_pts.srt(),
+                    pts.srt(),
+                    prev_stamp
+                )
+                .as_bytes(),
+            )?;
+            count += 1;
+        }
+        prev_data = Some((pts, frame_stamp));
+    }
+
+    if let Some((prev_pts, prev_stamp)) = prev_data.take() {
+        let pts = prev_pts + std::time::Duration::from_secs(1);
+        out_fd.write_all(
+            format!(
+                "{}\n{} --> {}\n{}\n\n",
+                count,
+                prev_pts.srt(),
+                pts.srt(),
+                prev_stamp
+            )
+            .as_bytes(),
+        )?;
+    }
+
+    Ok(())
+}