diff --git a/src/codec/packet/mod.rs b/src/codec/packet/mod.rs
index 8fad4c9..c22dd91 100644
--- a/src/codec/packet/mod.rs
+++ b/src/codec/packet/mod.rs
@@ -191,4 +191,12 @@ impl<'a> Iterator for SideDataIter<'a> {
 			}
 		}
 	}
+
+	fn size_hint(&self) -> (usize, Option<usize>) {
+		unsafe {
+			((*self.ptr).side_data_elems as usize, Some((*self.ptr).side_data_elems as usize))
+		}
+	}
 }
+
+impl<'a> ExactSizeIterator for SideDataIter<'a> { }
diff --git a/src/codec/subtitle/mod.rs b/src/codec/subtitle/mod.rs
index af78c21..9d61823 100644
--- a/src/codec/subtitle/mod.rs
+++ b/src/codec/subtitle/mod.rs
@@ -118,8 +118,16 @@ impl<'a> Iterator for RectIter<'a> {
 			}
 		}
 	}
+
+	fn size_hint(&self) -> (usize, Option<usize>) {
+		unsafe {
+			((*self.ptr).num_rects as usize, Some((*self.ptr).num_rects as usize))
+		}
+	}
 }
 
+impl<'a> ExactSizeIterator for RectIter<'a> { }
+
 pub enum Rect<'a> {
 	None,
 	Bitmap(Bitmap<'a>),
diff --git a/src/device/extensions.rs b/src/device/extensions.rs
index e396509..c518055 100644
--- a/src/device/extensions.rs
+++ b/src/device/extensions.rs
@@ -66,4 +66,12 @@ impl<'a> Iterator for DeviceIter<'a> {
 			}
 		}
 	}
+
+	fn size_hint(&self) -> (usize, Option<usize>) {
+		unsafe {
+			((*self.ptr).nb_devices as usize, Some((*self.ptr).nb_devices as usize))
+		}
+	}
 }
+
+impl<'a> ExactSizeIterator for DeviceIter<'a> { }
diff --git a/src/format/context.rs b/src/format/context.rs
index d5b24ef..ee26e83 100644
--- a/src/format/context.rs
+++ b/src/format/context.rs
@@ -216,8 +216,16 @@ impl<'a> Iterator for StreamIter<'a> {
 			}
 		}
 	}
+
+	fn size_hint(&self) -> (usize, Option<usize>) {
+		unsafe {
+			((*self.ptr).nb_streams as usize, Some((*self.ptr).nb_streams as usize))
+		}
+	}
 }
 
+impl<'a> ExactSizeIterator for StreamIter<'a> { }
+
 pub struct StreamIterMut<'a> {
 	ptr: *const AVFormatContext,
 	cur: c_uint,
@@ -245,8 +253,16 @@ impl<'a> Iterator for StreamIterMut<'a> {
 			}
 		}
 	}
+
+	fn size_hint(&self) -> (usize, Option<usize>) {
+		unsafe {
+			((*self.ptr).nb_streams as usize, Some((*self.ptr).nb_streams as usize))
+		}
+	}
 }
 
+impl<'a> ExactSizeIterator for StreamIterMut<'a> { }
+
 pub struct PacketIter<'a> {
 	context: &'a mut Context,
 }
diff --git a/src/format/stream/stream.rs b/src/format/stream/stream.rs
index efc04ad..7204ed1 100644
--- a/src/format/stream/stream.rs
+++ b/src/format/stream/stream.rs
@@ -113,4 +113,12 @@ impl<'a> Iterator for SideDataIter<'a> {
 			}
 		}
 	}
+
+	fn size_hint(&self) -> (usize, Option<usize>) {
+		unsafe {
+			((*self.ptr).nb_side_data as usize, Some((*self.ptr).nb_side_data as usize))
+		}
+	}
 }
+
+impl<'a> ExactSizeIterator for SideDataIter<'a> { }