Some systems do not have ffmpeg, but have a fork

Thanks to Alessio Treglia <alessio@debian.org> for providing the basis
of this patch.

Message-ID: <700845d3-c785-2e79-5ce0-f637fdae448e@64studio.com>
Requested-by: Daniel James <daniel@64studio.com>

import

@@ -27,7 +27,15 @@ case "$FILE" in
 
 *)
 	echo "Calling fallback decoder..." >&2
-	exec ffmpeg -v 0 -i "$FILE" -f s16le -ar "$RATE" -
+
+	FFMPEG=$(which ffmpeg 2> /dev/null || which avconv 2> /dev/null)
+
+	if [ -z "$FFMPEG" ]; then
+		echo "$0: no ffmpeg or avconv available to decode file" >&2
+		exit 1
+	fi
+
+	exec "$FFMPEG" -v 0 -i "$FILE" -f s16le -ar "$RATE" -
 	;;
 
 esac