diff --git a/src/api.rs b/src/api.rs
index 604a8e06b21b52482ae50744b94cd6d295e814a4..6579eb5c46107c29407cba4a96099e00d27cd49e 100644
--- a/src/api.rs
+++ b/src/api.rs
@@ -3,6 +3,7 @@ use context::CDFContext;
 use partition::LAST_FRAME;
 
 use std::collections::VecDeque;
+use std::fmt;
 use std::sync::Arc;
 
 // TODO: use the num crate?
@@ -148,3 +149,9 @@ impl Context {
     self.frame_q.push_back(None);
   }
 }
+
+impl fmt::Display for Context {
+  fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+    write!(f, "Frame {} - {}", self.fi.number, self.fi.frame_type)
+  }
+}
diff --git a/src/bin/common.rs b/src/bin/common.rs
index 04f20c6c840f68fb9acf3a78f97406fd39e48646..d43038ab5c072a7d5b5f2b1ec377cc9348d18353 100644
--- a/src/bin/common.rs
+++ b/src/bin/common.rs
@@ -126,6 +126,7 @@ pub fn process_frame(ctx: &mut Context,
                 _ => panic! ("unknown input bit depth!"),
             }
 
+            eprintln!("{}", ctx);
             let _ = ctx.send_frame(input);
 
             let pkt = ctx.receive_packet().unwrap();