generate seek index

1 files changed, 28 insertions, 0 deletions

diff --git a/matroska/src/write.rs b/matroska/src/write.rs
index 70ee06c..ee1c44c 100644
--- a/matroska/src/write.rs
+++ b/matroska/src/write.rs
@@ -26,6 +26,31 @@ impl EbmlWriter {
         Ok(())
     }
 
+    pub fn write_padding(&mut self, position: usize) -> Result<()> {
+        let mut size = position - self.position;
+        match size {
+            0 => return Ok(()),
+            1 => bail!("this is sadly not possible"),
+            _ => (),
+        }
+        size -= 1; // subtract tag size
+        size -= 4; // subtract vint size
+
+        // match size {
+        //     _ if size < (1 << 7) => size -= 1,
+        //     _ if size < (1 << 14) => size -= 2,
+        //     _ if size < (1 << 21) => size -= 3,
+        //     _ if size < (1 << 28) => size -= 4,
+        //     _ if size < (1 << 35) => size -= 5,
+        //     _ => bail!("padding to large"),
+        // }
+
+        self.write(&[0xec])?;
+        self.write_vint_len(size.try_into().unwrap(), 4)?;
+        self.write(&vec![0; size])?;
+        Ok(())
+    }
+
     pub fn write_tag(&mut self, tag: &MatroskaTag) -> Result<()> {
         let mut buf = vec![];
         tag.write_full(&mut buf)?;
@@ -44,6 +69,9 @@ impl EbmlWriter {
             }
             len += 1;
         }
+        self.write_vint_len(i, len)
+    }
+    pub fn write_vint_len(&mut self, i: u64, len: usize) -> Result<()> {
         let mut bytes = i.to_be_bytes();
         let trunc = &mut bytes[(8 - len)..];
         trunc[0] |= 1 << (8 - len);