<PAGE>

                                                                 Exhibit 4(C)
                                  FOURTH AMENDMENT 

                                          TO

                   AMENDED AND RESTATED LOAN AND SECURITY AGREEMENT



    THIS FOURTH AMENDMENT ("Amendment") is entered into as of May 7, 1997, by
and among UNITEL VIDEO, INC., a Delaware corporation having its principal place
of business at 555 West 57th Street, New York, New York 10019 ("Borrower"), R
SQUARED, INC., a California Corporation having its principal place of business
at  3330 Cahuenga Boulevard West, Los Angeles, California 90068 ("Corporate
Guarantor") and HELLER FINANCIAL, INC., a Delaware corporation having an office
at  500 West Monroe Street, Chicago, Illinois 60661, as agent ("Agent") for
Lender (as hereafter defined).

                                      BACKGROUND

    Borrower, Corporate Guarantor, Agent and Heller Financial, Inc. ("Lender")
are parties to an Amended and Restated Loan and Security Agreement dated as of
December 12, 1995 (as amended, supplemented or otherwise modified from time to
time, the "Loan Agreement") pursuant to which Lender provides Borrower with
certain financial accommodations.

    Borrower has requested that Lender amend the Loan Agreement and Lender is
willing to do so on the terms and conditions hereafter set forth.

    NOW, THEREFORE, in consideration of any loan or advance or grant of credit
heretofore or hereafter made to or for the account of Borrower by Lender, and
for other good and valuable consideration, the receipt and sufficiency of which
are hereby acknowledged, the parties hereto hereby agree as follows:

    1.   Definitions.  All capitalized terms not otherwise defined herein shall
have the meanings given to them in the Loan Agreement.

    2.   Amendment to Loan Agreement.  Subject to satisfaction of the
conditions precedent set forth in Section 3 below, the Loan Agreement is hereby
amended as follows:

    (a)  Section 1.1 of the Loan Agreement is hereby amended by:
 
    (i)  adding the following defined term in its appropriate alphabetical
    order:

    "Fourth Amendment Effective Date" means May 7, 1997."

    (ii) amending the defined term "Permitted Term Loan B Repayment Source" to
    provide as follows:

<PAGE>

    "Permitted Term Loan B Repayment Source" means Specified Fixed Asset
    Dispositions relating solely to Borrower's Editel-Los Angeles and Unitel
    Hollywood divisions; provided, however, the aggregate Orderly Liquidation
    Value of Appraised Assets sold or otherwise disposed of in such Specified
    Fixed Asset Dispositions may not exceed the Threshold Amount; provided,
    further, Specified Fixed Asset Dispositions relating to Borrower's
    Editel-Los Angeles division shall only be utilized as a Permitted Term Loan
    B Repayment Source in the event the Appraised Assets of Borrower's
    Editel-Los Angeles division so sold are replaced with Appraised Assets of
    Borrower's Unitel Hollywood division having an Orderly Liquidation Value of
    not less than the amount of the Appraised Assets of Borrower's Editel-Los
    Angeles division so sold.

    (iii) amending the defined term "Amended and Restated Term Note" or
    "Amended and Restated Term Notes" to provide as follows:

    "Amended and Restated Term Note" or "Amended and Restated Term Notes" means
    each promissory note of Borrower in substantially the form of Exhibits
    2.1(A)(1), (A)(2) and (A)(3) issued in connection with the term loans
    referenced in Section 2.1(A).

    (b)  Sections 2.1(A)(1) and 2.1(A)(2) of the Loan Agreement are hereby
amended in their entirety to provide as follows:

    (A)(1)    Term Loan A.  Subject to the terms and conditions of this
    Agreement and in reliance upon the representations and warranties of
    Borrower herein set forth, each Lender, severally, agrees to lend to
    Borrower on the Fourth Amendment Effective Date such Lender's Pro Rata
    Share of $9,000,000 minus $6,071,424, such that after giving effect to the
    loan to be made to Borrower under this subsection 2.1(A)(1) on the Fourth
    Amendment Effective Date the aggregate outstanding amount of Term Loan A
    shall equal $9,000,000.  Amounts borrowed under this subsection 2.1(A)(1)
    and repaid may not be reborrowed.  Borrower shall make principal payments
    in the amount of the applicable Scheduled Installment of Term Loan A (or
    such lesser principal amount of Term Loan A as shall then be outstanding)
    on the dates and in the amounts set forth below.

         "Scheduled Installment of Term Loan A" means each of the fifty-six
    (56) consecutive monthly principal installments commencing on June 1, 1997
    and continuing on the first day of each month thereafter, the first
    fifty-five (55) of which shall, subject to the provisions of subsection
    2.4(B), be in an amount equal to $100,000; and the final installment due on
    December 12, 2001, or the

                                       -2-

<PAGE>

    earlier to occur of (a) the Termination Date or (b) acceleration of the
    Obligations in accordance with the provisions of subsection 8.3, in an
    amount equal to the unpaid principal amount of Term Loan A plus accrued
    interest thereon.

    (A)(2)    Term Loan B.   Subject to the terms and conditions of this
    Agreement and in reliance upon the representations and warranties of
    Borrower herein set forth, each Lender, severally, agrees to lend to
    Borrower its Pro Rata Share of Term Loan B in an aggregate amount not to
    exceed $2,151,660.27 (all of which is outstanding as of the Fourth
    Amendment Effective Date).  Amounts borrowed under this subsection
    2.1(A)(2) and repaid may not be reborrowed.  Borrower shall make principal
    payments in the amounts of the applicable Scheduled Installment of Term
    Loan B (or such lesser principal amount of Term Loan B as shall then be
    outstanding) on the dates and in the amounts set forth below; provided,
    however, unless Agent otherwise consents in writing, Borrower may only make
    principal payments on Term Loan B from a Permitted Term Loan B Repayment
    Source.

         "Scheduled Installment of Term Loan B" means each of the following two
    (2) principal installments, the first of which is payable, subject to the
    provisions of subsection 2.4(B), on or before July 1, 1997 in an amount
    equal to $651,660.27 and the second of which is payable, subject to the
    provisions of subsection 2.4(B), on or before September 30, 1997 in an
    amount equal to the entire unpaid principal amount of Term Loan B plus
    accrued interest thereon (it being understood that Borrower may prepay Term
    Loan B, in whole or in part, from time to time, but only from a Permitted
    Term Loan B Repayment Source), or, in each case, upon the earlier to occur
    of (i) the Termination Date or (ii) acceleration of the Obligations in
    accordance with the provisions of subsection 8.3, at which time the entire
    unpaid principal amount of Term Loan B plus accrued interest thereon shall
    be due and payable.  Borrower hereby acknowledges that in the event any
    Scheduled Installment of Term Loan B is not made on the dates and in the
    amounts set forth herein, then it shall pay to Agent (which amount Agent
    may charge to Borrower's account) a contingency fee in an amount equal to
    (a) ten percent (10%) times (b) such unpaid Scheduled Installment of Term
    Loan B; provided, however, Borrower's failure to pay a Scheduled
    Installment of Term Loan B when due shall constitute an Event of Default
    and shall entitle Agent to exercise all rights and remedies available to
    Agent under this Agreement, the Loan Documents and applicable law,
    notwithstanding payment of the aforementioned contingency fee.

                                       -3-

<PAGE>

    (c)  A new Section 2.1(A)(3) is hereby added to the Loan Agreement to
provide as follows:

    (A)(3)    Term Loan C.   Subject to the terms and conditions of this
    Agreement and in reliance upon the representations and warranties of
    Borrower herein set forth, each Lender, severally, agrees to lend to
    Borrower, upon Borrower's request therefor in accordance with the borrowing
    procedures for Revolving Loan requests set forth in Section 2.1(D) hereof,
    its Pro Rata Share of Term Loan C in an aggregate amount not to exceed
    $3,500,000.  Amounts borrowed under this subsection 2.1(A)(3) and repaid
    may not be reborrowed.  Borrower shall make a principal payment in the
    amount of the applicable Scheduled Installment of Term Loan C (or such
    lesser principal amount of Term Loan C as shall then be outstanding) on the
    date and in the amount set forth below.  Term Loan C shall bear interest
    from the date such Loan is made to the date paid in full at a rate per
    annum equal to the interest rate set forth in Section 2.2(A) applicable to
    Term Loan A.

         "Scheduled Installment of Term Loan C" means the principal installment
    in an amount equal to $3,500,000, payable, subject to the provisions of
    subsection 2.4(B), on or before July 31, 1997, together with all accrued
    interest thereon (it being understood that Borrower may prepay Term Loan B,
    in whole or in part, from time to time), or the earlier to occur of (i) the
    Termination Date or (ii) acceleration of the Obligations in accordance with
    the provisions of subsection 8.3 at which time the entire unpaid principal
    amount of Term Loan C plus accrued interest thereon shall be due and
    payable.

    (d)  Clause "(i)" of the first sentence of Section 2.1(E) is hereby amended
to provide as follows:

    "(i) a Second Amended and Restated Term Note A, a Second Amended and
    Restated Term Note B and Term Note C to evidence such Lender's portion of
    the Term Loans, such notes to be in the principal amount of the respective
    Term Loan Commitments of such Lender and with other appropriate insertions
    and".

    (e)  Section 2.3(C) of the Loan Agreement is hereby amended by deleting all
references to "the second Loan Year" and replacing the same with the following: 
"the period commencing on the first day of the second Loan Year and ending on
April 30, 1999".

    (f)  The first sentence of Section 2.4(C) of the Loan Agreement is hereby
amended by adding the following immediately preceding the reference to "2.1(B)":
"2.1(A)(2), 2.1(A)(3),".

                                       -4-

<PAGE>

    (g)  The first sentence of Section 2.5 of the Loan Agreement is hereby
amended to provide as follows:  "This Agreement shall be effective until
December 12, 2001 (the "Termination Date")."

    (h)  Section 6.1 of the Loan Agreement is hereby amended to provide as
follows:

    6.1  Tangible Net Worth.  Borrower shall at all times during the fiscal
    quarters set forth below maintain Tangible Net Worth plus Subordinated Debt
    of not less than the amounts set forth opposite such fiscal quarters:

    Fiscal Quarter End                 Amount

      May 31, 1997                   $18,000,000
      August 31, 1997                $17,000,000
      November 30, 1997              $17,500,000
      February 28, 1998              $18,000,000
      May 31, 1998                   $18,500,000
      August 31, 1998                $19,500,000
      November 30, 1998 and
         each fiscal quarter
         end thereafter              $20,000,000

    (i)  Notwithstanding anything contained in Section 6.2 of the Loan
Agreement to the contrary, the Annual Amount applicable to Borrower's 1997
Fiscal Year shall be $15,000,000.

    (j)  Section 6.3 of the Loan Agreement is hereby amended to provide as
follows:

    6.3  Fixed Charge Coverage.  Borrower shall not permit its Fixed Charge
    Coverage to be less than (a) .80 to 1.00 at all times during the three
    fiscal quarters ending May 31, 1997, (b) .50 to 1.00 at all times during
    the four fiscal quarters ending August 31, 1997, (c) .50 to 1.00 at all
    times during the fiscal quarter ending November 30, 1997, calculated on a
    rolling four quarter basis, (d) .50 to 1.00 at all times during the fiscal
    quarter ending February 28, 1998, calculated on a rolling four quarter
    basis, (e) .75 to 1.00 at all times during the fiscal quarter ending May
    31, 1998, calculated on a rolling four quarter basis, (f) 1.00 to 1.00 at
    all times during the fiscal quarter ending August 31, 1998, calculated on a
    rolling four quarter basis and (g) 1.00 to 1.00 at all times during each
    fiscal quarter ending thereafter, calculated on a rolling four quarter
    basis.

    For purposes of the covenant calculations under this Section 6.3, Operating
    Cash Flow shall exclude financed Capital Expenditures utilized by Borrower
    to finance its construction of mobile teleproduction units with the

                                       -5-

<PAGE>


    proceeds of industrial revenue bonds to be issued by the Allegheny County
    Industrial Development Authority.

    (k)  Section 6.4 of the Loan Agreement is hereby amended to provide as
follows:

    6.4  Leverage Ratio.  Borrower shall not permit its Leverage Ratio at the
    end of each fiscal quarter set forth below (calculated on a rolling four
    quarter basis) to be greater than the amount set forth below for such
    fiscal quarter end:

         Fiscal Quarter End            Ratio

         May 31, 1997                  3.75 to 1.00
         August 31, 1997               3.75 to 1.00
         November 30, 1997             3.25 to 1.00
         February 28, 1998             3.00 to 1.00
         May 31, 1998                  2.75 to 1.00
         August 31, 1998 and
            each fiscal quarter end
            thereafter                 2.75 to 1.00

    (l)  Section 6.5 to the Loan Agreement is hereby deleted in its entirety
and replaced with the following:

    6.5  Interest Coverage.  During each fiscal period when Borrower's Fixed
    Charge Coverage is less than 1.00 to 1.00, Borrower shall not permit the
    ratio of (a) Operating Cash Flow to (b) Interest Expense to be less than
    1.30 to 1.00.  For purposes of the covenant calculations under this Section
    6.5, Operating Cash Flow shall exclude financed Capital Expenditures
    utilized by Borrower to finance its construction of mobile teleproduction
    units with the proceeds of industrial revenue bonds to be issued by the
    Allegheny County Industrial Development Authority.

    (m)  Exhibits 2.1(A)(1) and 2.1(A)(2) to the Loan Agreement are hereby
replaced with Exhibits 2.1(A)(1) and 2.1(A)(2) to this Amendment.

    (n)  Exhibit 2.1(A)(3) to this Amendment is hereby added to the Loan
Agreement as Exhibit 2.1(A)(3).

    3.   Conditions of Effectiveness.  This Amendment shall become effective
when and only when Agent shall have received (a) four (4) copies of this
Amendment executed by Borrower and Corporate Guarantor, (b) an amendment fee for
Agent's account in an amount equal to $75,000, which may be charged by Agent to
Borrower's account (the "Amendment Fee") and (c) such other certificates,
instruments, documents, agreements and opinions of counsel as may be required by
Agent or its counsel, each of which

                                       -6-

<PAGE>


shall be in form and substance satisfactory to Lender and its counsel.

    4.   Lender Acknowledgments.  Lender hereby acknowledges that (i)
Borrower's payment of the Amendment Fee shall compensate Lender for its
accommodations provided under this Amendment and a fifth amendment to the Loan
Agreement (the "Fifth Amendment") to be executed by the parties hereto on or
prior to July 31, 1997 so long as the Fifth Amendment is solely to provide for a
letter of credit facility and other accommodations by Lender for the benefit of
Borrower in connection with certain industrial revenue bonds to be issued by the
Allegheny County Industrial Development Authority to finance Borrower's
construction of mobile teleproduction units, on terms and conditions acceptable
to Lender, and Lender shall not charge Borrower any additional amendment fee in
connection with the execution and delivery of the Fifth Amendment; provided,
however, Lender hereby reserves its rights to charge an additional amendment fee
in connection with the Fifth Amendment if at the time of its execution either
(a) an Event of Default shall be in existence or (b) the matters covered by the
Fifth Amendment are additional to those specifically set forth above; provided,
further, that Lender shall be under no obligation to enter into the Fifth
Amendment if an Event of Default shall then be in existence; (ii) the Special
Reserve established under the First Amendment to the Loan Agreement is no longer
applicable to Borrower and (iii) upon Lender's receipt of the fully executed and
notarized original promissory notes attached to this Amendment, the Amended and
Restated Term Note A and the Amended and Restated Term Note B, each dated
December 12, 1995 and made by Borrower in favor of Agent shall be of no further
force and effect and Lender shall promptly thereafter deliver originals of the
same to Borrower marked cancelled.

    5.   Representations and Warranties.  Borrower hereby represents and
warrants as follows:

         (a)  This Amendment and the Agreement, as amended hereby, constitute
    legal, valid and binding obligations of Borrower and are enforceable
    against Borrower in accordance with their respective terms.

         (b)  Upon the effectiveness of this Amendment, Borrower hereby
    reaffirms that all covenants, representations and warranties made in the
    Loan Agreement to the extent the same are not specifically amended hereby
    are correct in all material respects and agrees that all covenants,
    representations and warranties shall be deemed to have been remade as of
    the effective date of this Amendment.

         (c)  No Event of Default or Default has occurred and is continuing or
    would exist after giving effect to this Amendment.

                                       -7-

<PAGE>


         (d)  Borrower has no defense, counterclaim or offset with respect to
    the Loan Agreement or the Obligations thereunder.

    6.   Effect on the Loan Agreement.

         (a)  Upon the effectiveness of Section 2 hereof, each reference in the
Loan Agreement to "this Agreement," "hereunder," "hereof," "herein" or words of
like import shall mean and be a reference to the Loan Agreement as amended
hereby.

         (b)  Except as specifically amended herein, the Loan Agreement, and
all other documents, instruments and agreements executed and/or delivered in
connection therewith, shall remain in full force and effect, and are hereby
ratified and confirmed.

         (c)  The execution, delivery and effectiveness of this Amendment shall
not operate as a waiver of any right, power or remedy of Agent or Lender, nor
constitute a waiver of any provision of the Loan Agreement, or any other
documents, instruments or agreements executed and/or delivered under or in
connection therewith.

    7.   Governing Law.  This Amendment shall be binding upon and inure to the
benefit of the parties hereto and their respective successors and assigns and
shall be governed by and construed in accordance with the laws of the State of
New York.

    8.   Headings.  Section headings in this Amendment are included herein for
convenience of reference only and shall not constitute a part of this Amendment
for any other purpose.

    9.   Counterparts.  This Amendment may be executed by the parties hereto in
one or more counterparts, each of which shall be deemed an original and all of
which taken together shall be deemed to constitute one and the same agreement. 
Any signature received by facsimile transmission shall be deemed an original
signature hereto.
                         [SIGNATURE LINES ON FOLLOWING PAGE] 

                                       -8-

<PAGE>


    IN WITNESS WHEREOF, this Amendment has been duly executed as of the day and
year first written above.


                        UNITEL VIDEO, INC., as Borrower

                        By: /s/Barry Knepper
                           --------------------------------
                        Name: Barry Knepper
                             ------------------------------
                        Title: CEO
                              -----------------------------


                        R SQUARED, INC., as Corporate                     
                          Guarantor

                        By: /s/Barry Knepper
                           -------------------------------
                        Name: Barry Knepper
                             -----------------------------
                        Title: CEO
                              ----------------------------


                        HELLER FINANCIAL, INC., as Agent and              
                         Lender

                        By: /s/Jerome Sepich
                           ------------------------------
                        Name: Jerome Sepich
                             ----------------------------
                        Title: Vice President
                              ---------------------------

 



                                       -9-