Error detection/correction and fault detection/recovery – Pulse or data error handling – Digital logic testing
Reexamination Certificate
1998-04-20
2001-05-08
Decady, Albert (Department: 2133)
Error detection/correction and fault detection/recovery
Pulse or data error handling
Digital logic testing
Reexamination Certificate
active
06230295
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the field of testing bitstream devices, and in particular to a system for efficiently creating data streams which can be used for device testing.
2. Description of the Related Art
Electronic systems which perform data stream processing are being developed for many applications including video and audio compression such as MPEG, JPEG, and AC3, high-speed interconnection such as Fibre Channel and 1394, and digital communication such as wireless, Ethernet, V34 modems and ATM. By necessity, the development of systems for these applications includes testing and verification of system designs, and in particular, testing and verification of the system's implementation of the data stream syntax.
Data stream processing systems convert a stream of data to or from a structured sequence of data having a syntax. The syntax causes the portions of the data stream to assume meaning, i.e. the structured sequence cannot be treated as a stream of random data. Rather, the syntax is expected to be present, and structured data sequences must be used to test that data stream processing systems properly implement their functions.
A testing approach used in the past relies on a library of sample sequences which are constructed to test specific syntax rules, specific combinations of syntax rules, or performance on “typical” sequences. This approach has the drawback of requiring an enormous amount of storage space in order to provide a moderate amount of test coverage in today's increasingly sophisticated encoding and decoding algorithms. Furthermore, these libraries are difficult to produce and difficult to modify when syntax rules change. Also, simply combining libraries to test a device which incorporates multiple syntax sets does not provide adequate or efficient test coverage.
The importance of finding an efficient, user-friendly method of generating structured sequences cannot be overstated for testing compliance to standards such as DVD which provide for an extreme degree of flexibility. Functionality verification requires a wide variety of sequences be generated and applied to a device, and a way to manage and track the resulting overabundance of data streams is needed. For complete verification, it is often necessary to change a single bit in a single field in a two-hour (>2 GB!) data stream. Clearly an efficient method for specifying the content of data streams is needed.
In addition to compressed audio and video substreams, the DVD standard provides for a “navigation” substream which specifies ways in which a DVD system user can interact with the entertainment program. In many respects, the structure of the navigation substream resembles a software program for specifying a user interface. Verifying the functionality of a DVD system which implements the navigation substream requires the ability to efficiently generate a huge number of navigation substreams.
SUMMARY OF THE INVENTION
Accordingly, there is provided herein a system and method for verifying the functionality of a multimedia device. In one embodiment, the system includes a device under test and a computer configured to test the device by providing test bitstreams and sequences of user actions to the device. The computer uses bitstream profiles to describe, edit, and generate multimedia bitstreams. The profiles are part of a bitstream management system which includes tools for generating profiles from existing multimedia bitstreams and for generating multimedia bitstreams from profiles. The profiles are used to describe in human-intelligible form the values of various fields of interest in multimedia bitstreams. Since the fields of interest vary between verification tests, the profile form is subject to change.
Typically the multimedia device under test will comprise hardware for converting presentation data in the multimedia bitstream into audio and video signals, and software for implementing navigation functions related to the presentation material. The navigation functions may be specified in a navigation substream interleaved with other substreams in the multimedia bitstream. The navigation substream comprises many navigation instructions which may be flexibly placed to specify the desired navigation functions. Bitstream profiles for verification of the multimedia device software may comprise instruction mnemonics and associated operands which specify the navigation instructions in the test bitstreams. A profile compiler may be provided for converting the bitstream profile into bitstream field values, and a combiner may be provided for combining the bitstream field values with an existing bitstream to generate test bitstreams for verification. Additionally, a bitstream de-compiler may be provided for generating a bitstream profile from an existing bitstream. This profile could then be edited and compiled to generate a new test bitstream which has changed in the desired manner. A test generation tool may be provided for automating this process to generate a set of test bitstreams which verifies all specified functionalities.
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“L64020 Single-Chip DVD Decoder Scenario™ Family of DVD PC Reference” Copyright 1995-1998 by LSI Logic Corporation.
De'cady Albert
Lamarre Guy
LSI Logic Corporation
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