<PAGE>

                                                                   EXHIBIT 10.20

CONFIDENTIAL TREATMENT REQUESTED. CONFIDENTIAL PORTIONS OF THIS DOCUMENT HAVE
BEEN REDACTED AND HAVE BEEN SEPARATELY FILED WITH THE SECURITIES AND EXCHANGE
COMMISSION.

                    ADDENDUM TO TECHNOLOGY LICENSE AGREEMENT
                                     BETWEEN
                              OAK TECHNOLOGY, INC.
                                       AND
                                   TVIA, INC.

THIS ADDENDUM No. 1 is made this 25th day of April, 2001 ("Addendum Effective
Date"), by and between OAK TECHNOLOGY, INC., hereinafter called the "Oak", and
TVIA, INC., hereinafter called "Licensee", and is intended by Oak and Licensee
to amend the terms and conditions of the Technology License Agreement dated
December 29, 2000 ("Controlling Agreement"), for the purpose of allowing
additional technology and software to be licensed to Licensee under the terms of
this Addendum incorporating the unmodified terms of the Controlling Agreement.

WITNESSETH, that Oak and Licensee agree the terms and conditions of the
Controlling Agreement and its Exhibits shall be amended as follows and
incorporated into and made part of this Addendum to allow for the licensing of
Oak's OTI-2650 and OT-I8215 technology by Licensee under the terms of this
Addendum:

1.      In Section 1.2, the definition of "Chip Technology", shall be amended as
        follows to allow for the licensing of the OTI-2650 technology under the
        terms of this Addendum:

        "Chip Technology" shall mean Oak Technology's OTI-2650 MPEG 2
        technology, including the OTI-8215 reference design, and related working
        directories as further described in Exhibit A-1 provided in Source Code
        and SGN Format. Chip Technology does not include Excluded Technology.

2.      In Section 1.12 the definition of "Software Technology" shall be amended
        as follows to allow for the licensing of the OTI-2650 technology under
        the terms of this Addendum:

        "Software Technology" shall mean the design database Source Code as
        described in Exhibit A-1, as well as all Object Code and firmware
        delivered to Licensee, as also specified in Exhibit A-1, as part of the
        Licensed Technology deliverables. Software Technology does not include
        Excluded Technology.

3.      A new Section 1.16 shall be added as follows:

"Excluded Technology" shall mean the following third party technology and/or
software that is incorporated into and made part of the OTI 2650 device and
OTI-8215 device but which will not be/cannot be licensed by Oak under this
Addendum. The following is a list of technology and/or information that will be
excluded from the Chip Technology and Software Technology deliverables:
MACROVISION, CSS, USPARC, DVD FORUM MEMBERSHIP, ***, Q-SOUND, DOLBY DIGITAL
(AC3), DOLBY PROLOGIC, THREADX RTOS, GREEN HILLS USPARC DEVELOPMENT TOOLS,
VIRTUAL SILICON .25UM LIBRARY, AND TSMC I/O FORMAT.

*** CONFIDENTIAL MATERIAL REDACTED AND FILED SEPARATELY WITH THE SECURITIES AND
    EXCHANGE COMMISSION.


<PAGE>
        INCLUDED IN THE SCOPE OF EXCLUDED TECHNOLOGY, UNTIL APPROVAL IS OBTAINED
BY LICENSEE FROM CSS AND SUCH APPROVAL IS PROVIDED TO OAK, IS THE OTI-2650
DESIGN LAYOUT FOR THE CSS MODULE, AND THE GDSII AND MASK SET FOR THE OTI-2650
DEVICE, DUE TO THE INCLUSION IN THESE ITEMS OF OAK'S LICENSED AND
NON-TRANSFERABLE CSS MASTER KEY. LICENSEE UNDERSTANDS THAT A SEPARATE LICENSE
MUST BE EXECUTED WITH THE OWNERS OF SUCH TECHNOLOGY AND/OR SOFTWARE IN ORDER TO
RIGHTFULLY USE THE THIRD PARTY COMPONENTS OF THE OTI 2650 AND OTI-8215 DEVICES.

4.      In Section 3.1 the Fee for the licensing of the OTI-2650 technology
        under the terms of this Addendum shall be as follows: *** Dollars
        ($***), paid as follows: (i) *** ($ ***) paid by ***; and *** (ii)
        ($***) paid by ***.

5.      In Section 6, a new Section 6(g) shall be added as follows:

        For a period of One (1) year after the Effective Date of this Agreement
as modified pursuant to this Addendum, both Licensee and Oak agree that they
shall not, directly or indirectly, (i) hire or employ; (ii) knowingly permit any
entity, company or business organization which is directly or indirectly
controlled by either party to hire or employ; (iii) recruit or attempt to
recruit, solicit or attempt to solicit, attempt to hire, interfere with or
endeavor to entice away; or (iv) assist any entity, company or business
organization to recruit or attempt to recruit, solicit or attempt to solicit,
attempt to hire, interfere with or endeavor to entice away any person who is
employed by Licensee or Oak unless prior written consent is obtained from the
other party.

6.      For the purposes of this Addendum and solely with respect to the
        licensing of the Chip Technology and Software Technology, as defined in
        this Addendum, the following Support terms are provided:

        Support of the hardware and software development environments for Chip
Technology and Software Technology:

        1.      One designated person, acting as an independent consultant for
                Oak and identified below, shall be the sole contact for all
                support needs, which shall be limited to understanding the Chip
                Technology and Software Technology. The designated consultant
                will: (i) answer directly Licensee's support questions, using
                his skill and experience with the OTI-2650 design, or (ii)
                solicit from Oak engineers the answers to Licensee's support
                questions if he cannot personally answer the support question.
                Licensee understands and agrees Oak shall have no direct support
                obligations or liability under this Addendum.

        2.      Licensee further understands and agrees that Oak engineers may
                not be able to provide immediate response to such questions, due
                to internal development schedules, and that some questions
                cannot be answered by Oak, requiring

*** CONFIDENTIAL MATERIAL REDACTED AND FILED SEPARATELY WITH THE SECURITIES AND
    EXCHANGE COMMISSION.


<PAGE>
                Licensee to secure on its own behalf additional support from
                third parties. The designated individual will use his best
                efforts to identify persons or entities not affiliated with Oak
                that are capable of providing the needed support, and introduce
                Licensee as a customer for such support. Any arrangements with
                third parties for additional support assistance will be
                negotiated by Licensee directly with such third parties, and
                Licensee shall be responsible for all costs associated with
                securing the additional support. Oak shall have no obligation or
                liability for such fees. Licensee shall ensure that any
                arrangements with third parties for additional support are
                conducted under an appropriate written agreement protecting the
                confidentiality and intellectual property rights of Oak.

        3.      The designated person shall perform support services, which
                shall be limited to assisting Licensee in understanding the Chip
                Technology and Software Technology, for a period not to extend
                beyond August 31, 2001, and limited to: (i) a maximum of 320
                hours (including time of Oak employees and any outside
                additional support obtained through the efforts of the
                designated support person); and (ii) a maximum of ten (10) hours
                per week by any single Oak employee. Licensee shall arrange
                contact information and support times directly with the
                designated person for the support services.

        4.      If the designated person fails to provide the support services
                specified herein to Licensee, Licensee will notify Oak of such
                failure and Oak will in turn notify the designated person that
                he is in default and demand the designated person cure the
                default. If the designated person fails to provide a cure, Oak's
                sole obligation and liability to Licensee will be to: (i)
                terminate its contract with the designated person, and withhold
                the fees reserved under the contract for the support services;
                and (ii) attempt to identify a replacement that can continue to
                provide support services to Licensee. Licensee understands and
                agrees that other than the withholding of fees, and attempting
                to find a replacement for the designated person, Oak shall have
                no responsibility for the failure of the designated person to
                provide support or otherwise satisfactorily meet the support
                services specified herein. Licensee further understand that any
                replacement that may be found may not have technical expertise
                and familiarity with the OTI-2650 design, and their ability to
                provide support assistance could be limited in scope.

                        Designated Person: Tuan Nguyen

The terms and conditions of the Controlling Agreement are incorporated into and
made part of this Addendum, and to the extent any of the terms and condition of
this Controlling Agreement conflict with the terms and conditions of this
Addendum, the terms and conditions of this Addendum shall control.


<PAGE>
Understood and Agreed

TVIA, INC.                                  FOR OAK TECHNOLOGY, INC.

By: /s/ Jack Guedj                          By:  /s/ David J. Power
   --------------------------------            --------------------------------

Name:  JACK GUEDJ                           Name: David J. Power
     ------------------------------              ------------------------------

Title:  President                           Title: V.P. & Gen Counsel
      -----------------------------               -----------------------------

Date:  05/11/01                             Date:  11 May 01
     ------------------------------              ------------------------------


<PAGE>
                                   EXHIBIT A-1

                     CHIP TECHNOLOGY AND SOFTWARE TECHNOLOGY

                                  DELIVERABLES

UNLESS OTHERWISE IDENTIFIED AS EXCLUDED TECHNOLOGY, DUE TO OWNERSHIP RIGHTS HELD
BY THIRD PARTIES, the Chip Technology and Software Technology deliverables, as
specified below, include necessary documentation, libraries, models, scripts and
code necessary to perform synthesis, simulation, emulation, verification,
fabrication and validation, and the necessary software. All documents should be
delivered as Microsoft Word (.doc) files to the extent available.

The OTI-2650A0 is also known as Magellan, OTI-265B0, or OTI-261, and the parts
are marked as OTI-2650AA.

I.       CHIP TECHNOLOGY

1.       IC DATABASE- OTI-2650 REVA0 SILICON

        A.      Architecture Specification and documents referenced therein.

        B.      Micro-architecture specifications

        C.      Detailed Module documentation, block diagrams, flow charts,
                state diagrams, waveforms

        D.      Complete design database, including, but not limited to:

                1.      Directory Structure with description

                2.      Verilog RTL code(1),(2)

                3.      Simulation environment and test vectors, chip level and
                        module level

                4.      Local Test Benches and script files

                5.      C Code and Models with run scripts

                6.      Synthesis scripts, block level and chip level

                7.      Timing scripts, block level and chip level

                8.      Gate level netlist(1),(2)

                9.      Models for Custom Macros

        E.      QuickTurn

                1.      Emulation board

                2.      Database

                3.      Schematics, Gerber files, BOM

                4.      Test Programs, script files, utility programs such as
                        loader, linker, available documents, etc

        F.      Engineering Samples

                1.      100 untested units for protype use


                                       1


<PAGE>
NOTES: REFERENCE TO EXCLUDED TECHNOLOGY

1)      Tvia must obtain Macrovision license to receive TVEncoder RTL & Gate
        level netlist

2)      CSS module contains Oak's Master Key, therefore CSS RTL will have the
        Master Key removed, and the CSS gate level netlist can not be released
        to Tvia. To obtain physical databases, Tvia must get legal clearance
        before databases can be released.

3)      This is subject to Tvia getting approval from all necessary library
        vendors to receive the physical databases (Virtual Silicon,.25um
        libraries and TSMC .25um I/O library).

4)      Tvia will not receive, until written approval is first obtained from
        CSS, the following: (a) Avant! layout database(1),(2),(3) (see above
        notes) with back annotation files and documentation of tools flow and
        procedure for physical design; and (b) GDSII database(1),(2),(3) (see
        above notes).


2.      SYSTEM DEVELOPMENT BOARD

        A.      Working PCI board and database, including schematic files, PADS
                layout job files, Gerber files, BOM, User's Manual, demo
                software for OTI-2650 with Titanic stream, utility programs and
                files.

        B.      Partial Reference Design:

                1.      Schematics of BEA1-A (2650 back-end PCB)

                2.      Schematics of DVDAV03-B (A/V output PCB)

                3.      Schematics of 265DVD_PANEL02-A (front-panel PCB)

                4.      Schematics of PW_D010-D (power supply PCB)

        C.      OTI-2650 Demonstration Boards

                1.      5 PCI boards: 1 working board and 4 best available
                        boards.

3.      OTI-8215 AS REFERENCE

        A.      Complete RTL design database of the Transport/Program Stream
                Demultiplexor section that includes STC Recovery scheme from
                OTI-8215B0 design.

        B.      Architecture Specification and design documents for Transport
                Stream Demultiplexor and Video Decoder.

        C.      Micro-architecture specifications thereof.

        D.      Best effort to retrieve 8211 Reference Design and Demo Software
                Source Code and Files for Applications Layer, System Control
                Layer, Basic Function Layer and Hardware Access Layer (from UK
                company) as available.

4.      AVAILABLE MARKETING DOCUMENTATIONS


                                       2


<PAGE>
II.     SOFTWARE TECHNOLOGY

1.      CORE SOFTWARE (EXCLUDED TECHNOLOGY)

Tvia understands and agrees that in order to obtain complete software
deliverables, Tvia must obtain the following licenses prior to delivery:

1.      DVD

2.      CSS

3.      ***

4.      Q-Sound

5.      Dolby Digital (AC3)

6.      Dolby ProLogic

7.      ThreadX RTOS

8.      Green Hills (mu)SPARC development tools

A.      AUDIO DSP SOFTWARE

        1.      2-channel MPEG-1/2, layer I & II

        2.      MPEG-1/2 layer III

        3.      5.1 channel Dolby AC-3

        4.      Dolby Pro Logic

        5.      Various (up to 8-channel) LPCM outputs

        6.      Various cross-channel downmixing modes

        7.      SPDIF channel status bit stream support

        8.      ***

        9.      Q-sound surround sound (QMSS/Qxpander)

        10.     Post Processing effects -Pitch-shift, Echo, Surround,
                Treble/Bass control, audio resampling

B.      AUDIO DSP DEVELOPMENT SOFTWARE

        1.      In-house 24-bit assembler, linker, loader, libraries and
                utilities

        2.      *** Simulator/C Model

        3.      *** Debugger

        4.      Test bit-streams and demonstration software

        5.      Source code for all software

        6.      Documentation/Manual for DSP development environment/software to
                the extent of availability

*** CONFIDENTIAL MATERIAL REDACTED AND FILED SEPARATELY WITH THE SECURITIES AND
    EXCHANGE COMMISSION.


                                       3


<PAGE>
2.      SYSTEM SOFTWARE

A.      DOCUMENTS (Electronic versions and hard copies)

        1.      System Specification of New Orleans DVD Player ver.0.8

        2.      System Software Specifications of New Orleans DVD Player ver.0.8

        3.      Core Software Specification

        4.      Application Notes

        5.      DRAM Partition Note

        6.      OTI-265/OTI-2650 Data Book

        7.      Software Module documentation including descriptions, block
                diagrams, flowcharts, state diagrams to the extent of
                availability

        8.      Documents and Reference C-Codes for the OTI-2650 Audio
                Post-processing

B.      SOFTWARE

        1.      Complete software design database and source codes of OTI-2650
                including:

                A.      Source Safe data base and project files

                B.      uSparc C Code files

                C.      uSparc Assembly Code files

                D.      uSparc Header files

                E.      Script files

                F.      Libraries

                G.      Makefiles.

                H.      Simulation environment, test programs and test vectors

        2.      System software should include the following:

                A.      UI

                B.      Navigator

                C.      Main Program

        3.      Utilities

                a.      OTI-2650 uSPARC ROM monitor

                b.      Debugging, Demo Programs, Video Format Conversion to the
                        extent of availability



                                       4