1 files changed, 84 insertions, 0 deletions
diff --git a/remuxer/src/matroska_to_webm.rs b/remuxer/src/matroska_to_webm.rs
new file mode 100644
index 0000000..b9a1819
--- /dev/null
+++ b/remuxer/src/matroska_to_webm.rs
@@ -0,0 +1,84 @@
+use crate::ebml_track_entry;
+use anyhow::Context;
+use ebml_struct::{
+    ids::*,
+    matroska::{Cluster, Ebml, Info, Tracks},
+    read::{EbmlReadExt, TagRead},
+    write::TagWrite,
+};
+use jellymatroska::{read::EbmlReader, write::EbmlWriter, Master, MatroskaTag};
+use log::warn;
+use std::io::{BufReader, BufWriter, ErrorKind, Read, Seek, Write};
+
+pub fn matroska_to_webm(
+    input: impl Read + Seek + 'static,
+    output: impl Write,
+) -> anyhow::Result<()> {
+    let mut output = EbmlWriter::new(BufWriter::new(output), 0);
+    let mut input = EbmlReader::new(BufReader::new(input));
+
+    Ebml {
+        ebml_version: 1,
+        ebml_read_version: 1,
+        ebml_max_id_length: 4,
+        ebml_max_size_length: 8,
+        doc_type: "webm".to_string(),
+        doc_type_version: 4,
+        doc_type_read_version: 2,
+        doc_type_extensions: vec![],
+    }
+    .write(&mut output)?;
+    output.write_tag(&MatroskaTag::Segment(Master::Start))?;
+
+    let (x, mut ebml) = input.read_tag()?;
+    assert_eq!(x, EL_EBML);
+    let ebml = Ebml::read(&mut ebml).unwrap();
+    assert!(ebml.doc_type == "matroska" || ebml.doc_type == "webm");
+    let (x, mut segment) = input.read_tag()?;
+    assert_eq!(x, EL_SEGMENT);
+
+    loop {
+        let (x, mut seg) = match segment.read_tag() {
+            Ok(o) => o,
+            Err(e) if e.kind() == ErrorKind::UnexpectedEof => break,
+            Err(e) => return Err(e.into()),
+        };
+        match x {
+            EL_INFO => {
+                let info = Info::read(&mut seg).context("info")?;
+                output.write_tag(&{
+                    MatroskaTag::Info(Master::Collected(vec![
+                        MatroskaTag::TimestampScale(info.timestamp_scale),
+                        MatroskaTag::Duration(info.duration.unwrap_or_default()),
+                        MatroskaTag::Title(info.title.unwrap_or_default()),
+                        MatroskaTag::MuxingApp("jellyremux".to_string()),
+                        MatroskaTag::WritingApp("jellything".to_string()),
+                    ]))
+                })?;
+            }
+            EL_TRACKS => {
+                let tracks = Tracks::read(&mut seg).context("tracks")?;
+                output.write_tag(&MatroskaTag::Tracks(Master::Collected(
+                    tracks
+                        .entries
+                        .into_iter()
+                        .map(|t| ebml_track_entry(t.track_number, &t))
+                        .collect(),
+                )))?;
+            }
+            EL_VOID | EL_CRC32 | EL_CUES | EL_SEEKHEAD | EL_ATTACHMENTS | EL_TAGS => {
+                seg.consume()?;
+            }
+            EL_CLUSTER => {
+                let cluster = Cluster::read(&mut seg).context("cluster")?;
+                // TODO mixing both ebml libraries :)))
+                cluster.write(&mut output)?;
+            }
+            id => {
+                warn!("unknown top-level element {id:x}");
+                seg.consume()?;
+            }
+        }
+    }
+    Ok(())
+}