\section{Hard case 1}
-$C_V$ is not a DCI rate, $C_A$ is. e.g.\ if $C_V = 25$, $C_A =
+$C_V$ is not a DCI rate, $C_A$ is, e.g.\ if $C_V = 25$, $C_A =
48\times{}10^3$. We will run the video at a nearby DCI rate $F_V$,
meaning that it will run faster or slower than it should. We resample
the audio to $C_V C_A / F_V$ and mark it as $C_A$ so that it, too,