+#include <libavformat/version.h>
+
+// This flag is only supported in FFmpeg 3.3 and up, and we only require 3.1.
+#if LIBAVFORMAT_VERSION_INT >= AV_VERSION_INT(57, 71, 100)
+#define MUX_SKIP_TRAILER "+skip_trailer"
+#else
+#define MUX_SKIP_TRAILER ""
+#endif
+
+#define OUTPUT_FREQUENCY 48000 // Currently needs to be exactly 48000, since bmusb outputs in that.