Invalidity dossier
US 5821887
Method and apparatus for decoding variable length codes
Current assignee: Intel Corp
Added 9/23/2026, 1:57:48 PM
Active provider: DeepSeek · deepseek-flash
Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview — US 5821887 A
Title: Method and apparatus for decoding variable length codes
Patent number: US 5,821,887 A
Application number: US 08/747,980
Inventor: Chunrong Zhu
Assignee: Intel Corporation (original and current assignee per the source)
Priority/filing date: 1996-11-12
Publication (grant) date: 1998-10-13
Legal status shown: Expired – Lifetime; anticipated expiration 2016-11-12
Classification: H03M 7/40, H03M 7/42, H03M 7/425 (conversion to/from variable length codes; table look-up decoding)
Purpose
The patent relates generally to video signal processing, and more specifically to real-time decoding of encoded digital video signals that use variable length codes (VLCs), such as Huffman codes.
Plain-language scope
Encoding and decoding are described as table-driven: a table associates variable length codes with fixed length codes. For decoding, a table is indexed by the variable length code, and its entries hold the corresponding fixed length codes and/or indirect values. In the described one-level lookup table stored in main memory, each VLC has an entry containing an index for run length decode, an index for inverse quantization, and a "bits" field. The variable length decode table is indexed by a VLC field; its indirect values are used as indices into other tables, such as a run length decode table. Decoding reverses a video encoding pipeline involving motion estimation and compensation, DCT, quantization, zig-zag scan, run length coding, variable length coding, and bitstream assembly. The description notes that the codec may be implemented, for example, by a general purpose processor running programs or by ASICs. The source lists litigation-related links, but these are outside the permitted scope of this overview.
Source: https://patents.google.com/patent/US5821887/en (fetched 2026-09-23)
What the excerpt does not establish
The supplied text is an excerpt. It does not include the full claims, abstract, complete description, or the referenced figures (e.g., FIGS. 1–3) and tables (e.g., Table 1, H.263 codebook). It therefore does not establish the precise claimed scope, claim count, or the specifics of embodiments not reproduced above. Dates, inventor, and assignee are taken as stated in the source and are not independently verified here.
Generated 10/1/2026, 9:52:41 PM
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Litigation summary
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Proceedings on file (0)
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PTAB challenges
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Assignment history
Inventors, original assignee, and the chain of ownership recorded with the USPTO — including the correspondent attorney who recorded each assignment, since shell-LLC chains often share one repeat-player attorney even when the entity names look unrelated. Surfaces NPE / patent-troll patterns: shell-entity transfers, known asserters in the chain, repeat correspondent fingerprints, pre-litigation assignments, and bankruptcy fire-sales.
Prior art
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Obviousness
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Extensions
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Derivative works
Defensive disclosure: derivative variations of each claim designed to render future incremental improvements obvious or non-novel.