mux: chapters:// and json:// metadata sinks

Two write-only file sinks that ignore the PES stream and emit the title metadata at construction (fvi-style, wired through output()): - chapters:// — chapter markers in the format the extension picks: .xml (Matroska, default), .txt/.ogm (OGM simple), .vtt (WebVTT). Reuses the existing chapters_xml/chapters_ogm writers; adds a WebVTT writer. - json:// — one title's model (playlist, duration, size, format, streams, chapters) as pretty JSON via serde_json. New mux/meta_sink.rs; StreamUrl gains Chapters/Json; codec_label + chapters_xml/ogm promoted to pub(crate) for reuse. Tests: chapters_format_selected_by_extension, title_json_carries_streams_and_chapters.
2026-07-18 17:45:39 -07:00
parent 9f33306a0a
commit 63f6909ff0
4 changed files with 280 additions and 7 deletions
@@ -0,0 +1,235 @@
+//! `chapters://` and `json://` metadata sinks.
+//!
+//! Both ignore the PES stream entirely: everything they emit is already known
+//! from the [`DiscTitle`] at construction, so each writes its whole file at
+//! `create()` and treats every `write()` frame as a no-op. They are wired
+//! through [`super::resolve::output`] like the other write-only sinks; the
+//! ISO/disc scan that builds the title is all they need.
+
+use crate::disc::{Chapter, DiscTitle, Stream as DiscStream};
+use crate::pes::{PesFrame, Stream};
+use std::fs::File;
+use std::io::{self, Write};
+use std::path::Path;
+
+// ── chapters:// ──────────────────────────────────────────────────────────────
+
+/// `HH:MM:SS.mmm` for a WebVTT cue timestamp.
+fn vtt_time(secs: f64) -> String {
+    let total_ms = (secs.max(0.0) * 1000.0).round() as u64;
+    let ms = total_ms % 1000;
+    let total_s = total_ms / 1000;
+    format!(
+        "{:02}:{:02}:{:02}.{:03}",
+        total_s / 3600,
+        (total_s / 60) % 60,
+        total_s % 60,
+        ms
+    )
+}
+
+/// WebVTT chapter cues (`.vtt`). Each chapter spans until the next one starts
+/// (the last runs to its own start — length is unknown without the title tail).
+fn chapters_vtt(chapters: &[Chapter]) -> String {
+    let mut s = String::from("WEBVTT\n\n");
+    for (i, c) in chapters.iter().enumerate() {
+        let start = c.time_secs.max(0.0);
+        let end = chapters
+            .get(i + 1)
+            .map(|n| n.time_secs.max(0.0))
+            .unwrap_or(start);
+        s.push_str(&format!(
+            "{}\n{} --> {}\nChapter {}\n\n",
+            i + 1,
+            vtt_time(start),
+            vtt_time(end),
+            c.name
+        ));
+    }
+    s
+}
+
+/// Chapter content in the format the output extension selects: `.txt`/`.ogm`
+/// (OGM simple), `.vtt` (WebVTT), else Matroska XML (`.xml` / default).
+pub(crate) fn chapters_content(chapters: &[Chapter], ext: Option<&str>) -> String {
+    match ext.map(|e| e.to_ascii_lowercase()).as_deref() {
+        Some("txt") | Some("ogm") => super::demux_sink::chapters_ogm(chapters),
+        Some("vtt") => chapters_vtt(chapters),
+        _ => super::demux_sink::chapters_xml(chapters),
+    }
+}
+
+/// `chapters://` sink: writes the title's chapter markers at construction; the
+/// PES stream is ignored.
+pub struct ChaptersSink {
+    title: DiscTitle,
+}
+
+impl ChaptersSink {
+    pub fn create(path: &Path, title: &DiscTitle) -> io::Result<Self> {
+        let ext = path.extension().and_then(|e| e.to_str());
+        let content = chapters_content(&title.chapters, ext);
+        File::create(path)?.write_all(content.as_bytes())?;
+        Ok(Self {
+            title: title.clone(),
+        })
+    }
+}
+
+impl Stream for ChaptersSink {
+    fn read(&mut self) -> io::Result<Option<PesFrame>> {
+        Err(crate::error::Error::StreamWriteOnly.into())
+    }
+    fn write(&mut self, _frame: &PesFrame) -> io::Result<()> {
+        Ok(()) // whole file written at create()
+    }
+    fn finish(&mut self) -> io::Result<()> {
+        Ok(())
+    }
+    fn info(&self) -> &DiscTitle {
+        &self.title
+    }
+}
+
+// ── json:// ──────────────────────────────────────────────────────────────────
+
+fn stream_json(s: &DiscStream) -> serde_json::Value {
+    use super::demux_sink::codec_label;
+    use serde_json::json;
+    match s {
+        DiscStream::Video(v) => json!({
+            "kind": "video",
+            "codec": codec_label(v.codec),
+            "pid": v.pid,
+        }),
+        DiscStream::Audio(a) => json!({
+            "kind": "audio",
+            "codec": codec_label(a.codec),
+            "language": a.language,
+            "pid": a.pid,
+        }),
+        DiscStream::Subtitle(t) => json!({
+            "kind": "subtitle",
+            "codec": codec_label(t.codec),
+            "language": t.language,
+            "forced": t.forced,
+            "pid": t.pid,
+        }),
+    }
+}
+
+/// The `json://` document for one title: identity, duration/size, its streams,
+/// and its chapter points. A stable, machine-readable view of one title.
+pub(crate) fn title_json(title: &DiscTitle) -> serde_json::Value {
+    use serde_json::json;
+    let streams: Vec<_> = title.streams.iter().map(stream_json).collect();
+    let chapters: Vec<_> = title
+        .chapters
+        .iter()
+        .enumerate()
+        .map(|(i, c)| json!({ "n": i + 1, "start_secs": c.time_secs }))
+        .collect();
+    json!({
+        "playlist": title.playlist,
+        "playlist_id": title.playlist_id,
+        "duration_secs": title.duration_secs,
+        "size_bytes": title.size_bytes,
+        "format": format!("{:?}", title.content_format),
+        "streams": streams,
+        "chapters": chapters,
+    })
+}
+
+/// `json://` sink: writes the title's structured metadata at construction; the
+/// PES stream is ignored.
+pub struct JsonSink {
+    title: DiscTitle,
+}
+
+impl JsonSink {
+    pub fn create(path: &Path, title: &DiscTitle) -> io::Result<Self> {
+        let doc =
+            serde_json::to_string_pretty(&title_json(title)).unwrap_or_else(|_| "{}".to_string());
+        let mut f = File::create(path)?;
+        f.write_all(doc.as_bytes())?;
+        f.write_all(b"\n")?;
+        Ok(Self {
+            title: title.clone(),
+        })
+    }
+}
+
+impl Stream for JsonSink {
+    fn read(&mut self) -> io::Result<Option<PesFrame>> {
+        Err(crate::error::Error::StreamWriteOnly.into())
+    }
+    fn write(&mut self, _frame: &PesFrame) -> io::Result<()> {
+        Ok(())
+    }
+    fn finish(&mut self) -> io::Result<()> {
+        Ok(())
+    }
+    fn info(&self) -> &DiscTitle {
+        &self.title
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::disc::Chapter;
+
+    fn chaps() -> Vec<Chapter> {
+        vec![
+            Chapter {
+                time_secs: 0.0,
+                name: "1".into(),
+            },
+            Chapter {
+                time_secs: 62.5,
+                name: "2".into(),
+            },
+        ]
+    }
+
+    #[test]
+    fn chapters_format_selected_by_extension() {
+        let xml = chapters_content(&chaps(), Some("xml"));
+        assert!(xml.contains("<Chapters>"), "xml chosen for .xml");
+        let ogm = chapters_content(&chaps(), Some("txt"));
+        assert!(ogm.contains("CHAPTER01="), "ogm chosen for .txt");
+        let vtt = chapters_content(&chaps(), Some("vtt"));
+        assert!(
+            vtt.starts_with("WEBVTT") && vtt.contains("00:01:02.500"),
+            "vtt chosen for .vtt, with cue timing"
+        );
+        // Unknown / missing extension defaults to XML.
+        assert!(chapters_content(&chaps(), None).contains("<Chapters>"));
+    }
+
+    #[test]
+    fn title_json_carries_streams_and_chapters() {
+        use crate::disc::{AudioChannels, AudioStream, Codec, DiscTitle};
+        use crate::disc::{LabelPurpose, SampleRate, Stream as DiscStream};
+        let mut t = DiscTitle::empty();
+        t.playlist = "MAIN".into();
+        t.chapters = chaps();
+        t.streams = vec![DiscStream::Audio(AudioStream {
+            pid: 0x1100,
+            codec: Codec::TrueHd,
+            channels: AudioChannels::Stereo,
+            language: "eng".into(),
+            sample_rate: SampleRate::S48,
+            secondary: false,
+            purpose: LabelPurpose::Normal,
+            label: String::new(),
+        })];
+        let v = title_json(&t);
+        assert_eq!(v["playlist"], "MAIN");
+        assert_eq!(v["streams"][0]["kind"], "audio");
+        assert_eq!(v["streams"][0]["codec"], "TrueHD");
+        assert_eq!(v["streams"][0]["language"], "eng");
+        assert_eq!(v["chapters"][1]["n"], 2);
+        assert_eq!(v["chapters"][1]["start_secs"], 62.5);
+    }
+}