snippet subtitles are working.

1 files changed, 18 insertions, 4 deletions

diff --git a/remuxer/src/segment_extractor.rs b/remuxer/src/segment_extractor.rs
index bc5b44f..d176b3a 100644
--- a/remuxer/src/segment_extractor.rs
+++ b/remuxer/src/segment_extractor.rs
@@ -17,7 +17,11 @@ impl<'a> SegmentExtractIter<'a> {
         Self { segment, extract }
     }
 
-    pub fn next(&mut self) -> Result<Block> {
+    /// Returns the next block and sometimes its duration too.
+    pub fn next(&mut self) -> Result<(Block, Option<u64>)> {
+        let mut duration = None;
+        let mut group = false;
+        let mut saved_block = None;
         loop {
             let item = self.segment.next().ok_or(anyhow!("eof"))??;
             match item {
@@ -25,13 +29,23 @@ impl<'a> SegmentExtractIter<'a> {
                 MatroskaTag::Crc32(_) => (),
                 MatroskaTag::Cluster(_) => (),
                 MatroskaTag::Timestamp(_) => (),
-                MatroskaTag::BlockGroup(_) => (),
-                MatroskaTag::BlockDuration(_) => (),
+                MatroskaTag::BlockGroup(Master::Start) => group = true,
+                MatroskaTag::BlockGroup(Master::End) => {
+                    assert!(group, "group end without start");
+                    let block = saved_block.expect("blockgroup without any block");
+                    return Ok((block, duration));
+                }
+                MatroskaTag::BlockDuration(d) => duration = Some(d),
                 MatroskaTag::SimpleBlock(buf) | MatroskaTag::Block(buf) => {
                     let block = Block::parse(&buf)?;
                     if block.track == self.extract {
                         trace!("block: track={} tso={}", block.track, block.timestamp_off);
-                        return Ok(block);
+                        if group {
+                            // can't return yet; there might be a BlockDuration coming
+                            saved_block = Some(block);
+                        } else {
+                            return Ok((block, duration));
+                        }
                     }
                 }
                 MatroskaTag::Cues(_) => bail!("reached cues, this is the end"),