diff --git a/src/avformat/avio.rs b/src/avformat/avio.rs
index 1e51d65..3f425b8 100644
--- a/src/avformat/avio.rs
+++ b/src/avformat/avio.rs
@@ -154,6 +154,17 @@ impl AVIOContextCustom {
             _opaque: opaque,
         }
     }
+
+    /// Re-take the ownership of the `data` passed in `alloc_context`.
+    /// The `data` inside this will be set to an empty vector.
+    pub fn take_data(&mut self) -> Vec<u8> {
+        std::mem::take(&mut self._opaque.data)
+    }
+
+    /// Get a mutable reference to the data inside this context.
+    pub fn as_mut_data(&mut self) -> &mut Vec<u8> {
+        &mut self._opaque.data
+    }
 }
 
 impl Drop for AVIOContextCustom {