Promissory Note - Command Audio Corp. and Macrovision Corp.

    $328,948.14                                  Sunnyvale, CA 
     
    January 7th, 1997
               
      
    FOR VALUE RECEIVED, Command Audio Corporation, a California corporation,
    whose address is 805 Veterans Boulevard, Ste. 310, Redwood City,
    California, 94063 ('Maker') promises to pay to the order of Macrovision
    Corporation, whose address is 1341 Orleans Drive, Sunnyvale, CA 94089
    ('Payee'), the sum of Three Hundred Twenty Eight Thousand, Nine Hundred
    Forty Eight Dollars and Fourteen Cents ($328,948.14) together with interest
    on the unpaid principal balance at the rate of nine percent (9%) simple
    interest per annum.  Interest accrued on this Promissory Note shall be due
    and payable together with the full outstanding principal on the 1st day of
    July, 1998.
    
    Payments on this Promissory Note shall be made at the address of Payee, or
    at any other place Payee designates in writing from time to time, and shall
    be in lawful money of the United States of America. Maker waives demand for
    payment, notice of nonpayment, presentment, notice of dishonor, protest,
    and notice of protest. If Maker fails to timely make the payments required
    hereunder, Maker shall pay the costs of collection and reasonable
    attorneys' fees.  
    
    Maker may prepay this Promissory Note at any time, in whole or in part,
    with accrued interest to the date of prepayment, and without premium or
    penalty. All such payments on this Promissory Note shall be applied first
    to the payment of accrued interest and the balance shall be applied to
    principal.  
    
    This Promissory Note shall be binding upon Maker, and Maker's successors,
    and assigns. This Promissory Note shall be governed by and construed in
    accordance with the laws of the state of California.  
    
    ACCELERATION OF PAYMENT.  The entire principal amount of this Promissory
    Note, together will all accrued interest, shall immediately become due and
    payable, without demand for payment, notice of nonpayment, presentment,
    notice of dishonor, protest, notice of protest, or any other notice or
    demand, all of which Maker hereby expressly waives, if:  
    
    a. Maker has made any misrepresentation in or with respect to, or has
    breached any provision of this Promissory Note, or of any other agreement
    with Payee;
    
    b. Maker suspends payment of its obligations, or admits in writing its
    inability to pay its debts generally as they become due;
    
    c. Maker makes an assignment for the benefit of creditors, or a trustee or
    receiver of Maker or of a substantial portion of its assets is appointed,
    and the trustee or receiver is not discharged within sixty (60) days;
    
    d. Any proceeding involving Maker is voluntarily commenced by Maker under
    any bankruptcy, reorganization, insolvency, readjustment of debt,
    marshalling of 


CAC.Prom Note.doc                          1                             1/7/97
                                     CONFIDENTIAL




    assets and liabilities, dissolution, or liquidation law or
    statute of the United States or of any state, or a proceeding of such
    nature is involuntarily instituted against Maker, and Maker by any action
    indicates its approval of, or consent to, or acquiescence in, the
    proceeding, or the proceeding remains undismissed for sixty (60) days; or  
    
    e. A final judgment for the payment of money is rendered against Maker, and
    Maker does not discharge the judgment or procure a stay of execution of the
    judgment within thirty (30) days of the date of entry and service of a copy
    of the judgment, or cause execution of the judgment to be stayed during an
    appeal. 
    
    This Promissory Note shall be govern by and construed in accordance with
    the laws of the state of California. 
    
    COMMAND AUDIO CORPORATION
    
    By   /s/ Emmanuel Krakaris
       -------------------------------------
    Its  CFO
       -------------------------------------



CAC.Prom Note.doc                         2                             1/7/97
                                     CONFIDENTIAL