Strategies for Drafting and Amending Bitstream-Related Claims in the Field of Video Coding and Decoding for Cross-Border Patent Prosecution

Introduction

In the field of digital video coding and decoding (e.g., HEVC, VVC, AVS, AV1), a longstanding practical challenge has been whether a bitstream itself qualifies as a patentable subject matter. The inventor’s core contribution lies in designing a sophisticated encoding algorithm, the direct output of which is a specific bitstream conforming to a standard syntax. However, in past examination practices, claim categories such as “a video bitstream” or “a medium storing a video bitstream” were often rejected by examiners as falling under the exclusions of “rules and methods of intellectual activity” (Article 25 of the Chinese Patent Law) or as failing to meet the definition of a “technical solution” under Article 2(2). The underlying rationale was that a bitstream is regarded as mere information content or a data encoding format, i.e., an expression of information rather than a technical means.

The 2026 Amendment to the Patent Examination Guidelines

On April 30, 2025, the China National Intellectual Property Administration (CNIPA) published the draft amendment to the Patent Examination Guidelines for public comment. Subsequently, the final version was officially promulgated via CNIPA Decree No. 84 on November 10, 2025, effective as of January 1, 2026. The amended Guidelines add a new Section 7 to Part II, Chapter 9, specifically providing examination rules for patent applications directed to bitstreams. The amendment clarifies the circumstances under which bitstream-containing inventions are patentable: in the field of digital video coding/decoding, where a particular video coding/decoding method that generates a bitstream constitutes a technical solution, then the bitstream-defined storage medium, storage method, or transmission method also falls within the scope of patentable subject matter. Thus, storage media, storage methods, and transmission methods defined by a specific coding/decoding method are brought into the fold of patentable subject matter.

This amendment is not an isolated textual adjustment but represents an important step in aligning China’s IP system with the development of the digital economy and streaming media technologies, while benchmarking international examination practices. It provides a direct examination basis for allowing bitstream-related claims in the video coding/decoding field. By clarifying the requirements for patent eligibility of video coding/decoding bitstreams, China has signaled that its protection for inventions in the Information and Communication Technology (ICT) field is now on par with the highest international standards. For cross-border applicants, this change removes legal obstacles to obtaining full-chain protection (from encoder, to bitstream, to medium) in China. Previously, patentees could only claim “encoding methods” or “decoding methods.” In a globally distributed environment, the encoding side might reside in a chip design company, while infringing activities often occur on the distribution side, such as content delivery networks (CDNs) or physical optical discs. Without protection of the bitstream product itself, patentees could not directly sue entities that merely sell optical discs containing the infringing bitstream or provide streaming media services using that specific format. This amendment is intended to open a remedy path from “algorithm invention” to “product protection.”

Since the draft amendment was published on April 30, 2025, the author has accumulated practical experience in prosecuting cross-border patent applications, particularly those involving bitstream protection. The practical strategies developed are summarized below for the benefit of applicants and those in the relevant art, and any comments or corrections are welcome.

1. Drafting Suggestions for the First Filing

When drafting a patent application, it is advisable to explicitly and quantitatively describe in the specification the effects of the specific method on storage or transmission resource optimization, such as bandwidth reduction percentage, storage footprint reduction, decoding latency reduction, CPU resource consumption, or energy consumption improvement. The beneficial technical effects brought by the bitstream structure should be concretely indicated. If the original specification does not sufficiently disclose these effects, later amendments may face a “lack of sufficient disclosure” rejection. Where possible, comparative experimental data against existing standards or conventional methods should be provided to strongly support the “technical effect” assertion. In addition, various implementation forms (e.g., software, hardware accelerators, network protocol stack implementations) and their optional variants should be described in detail to broaden the scope of protection and reduce the risk of design-around. The specification should also include exemplary bitstream syntax descriptions, such as specific and limited syntax elements and their order, and explain how they improve decoding efficiency. In summary, the original specification and claims should lay a solid technical foundation for subsequent amendments in various jurisdictions.

2. Recommended Claim Drafting Structure

· Main independent claim set A (video encoding/decoding method): An independent method claim directed to a specific “video encoding/decoding method for generating a bitstream,” defining key steps such as frame partitioning, prediction mode, transform/quantization parameters, entropy coding flow, order of generating specific syntax elements, etc.

· Independent claim set B (system/device): Claims directed to an encoder/decoder device architecture, module partitioning, cache/buffer management, network interfaces, and signal processing units associated with the bitstream, specifying hardware or software implementation details.

· Independent claim set C (computer-readable storage medium; bitstream storage or transmission method defined by the specific coding/decoding method): A non-transitory computer-readable storage medium claims, recite “storing instructions that, when executed, cause device computer to perform said encoding method.” Avoid “pure information” language, and emphasize “non-transitory” and “executable instructions.”

· Dependent claims: Sequentially define features such as bitstream syntax, header fields, NAL unit structure, timestamp processing, error correction or redundancy strategies, encapsulation formats (e.g., specific container formats, fragmentation/reassembly methods), and concrete parameter ranges.

3. Practical Response Strategies in Chinese Patent Prosecution

Where a patent application enters China through Paris Convention Route or a PCT Route, and the claims include subject matter such as “a bitstream” or “a medium storing a video bitstream,” it is recommended to first consider amending such claims in accordance with the amended Patent Examination Guidelines to preserve such protection. Alternatively, when responding to an office action where claims directed to “a bitstream” or “a medium storing a video bitstream” are rejected as falling under the non-statutory subject matter exclusions of Article 25 or failing to meet the “technical solution” definition of Article 2(2), the recommended approach is to amend the claims in line with the amended Guidelines rather than simply cancelling such claims.

Specific amendment suggestions are as follows:

1) Modify “a bitstream” to:

“A computer-readable storage medium for storing a bitstream generated by the method according to claim X.”

or

“A non-transitory computer-readable storage medium, stored thereon a bitstream decoded by the method according to claim X.”

· Advantage: Avoids using “program” as an intermediate and directly protects “a bitstream defined by a method.”

· Disadvantage: May be considered unclear by some examiners as it deviates from the conventional drafting practice of “computer program + when executed by a computer/processor.”

2) Modify “a bitstream” to:

“A computer-readable storage medium for storing a computer program and a bitstream, when the computer program runs on a computer, causes the computer to perform the method according to claim X, to generate said bitstream,” where claim X is an encoding method.

· Advantage: High allowance rate and complies with the conventional drafting practice of “computer program + when executed by a computer/processor”; widely accepted by examiners in practice.

· Disadvantage: Introduces “program” as an intermediate and thus does not directly protect “a method-defined bitstream.”

3) Modify “a bitstream” to:

“A method for storing a bitstream, by storing said bitstream onto a digital storage medium, wherein said bitstream is generated by a video encoding method comprising: …”

· Advantage: Extends protection to “a method for storing a method-defined bitstream.”

4) Modify “a bitstream” to:

“A method for transmitting a bitstream, wherein said bitstream is generated by the method according to claim X …”

· Advantage: Extends protection to “a transmission method for a method-defined bitstream.”

5) Modify “a data stream” to:

“A method for processing a data stream into which a media content is encoded, wherein said data stream is generated by the method according to claim X …”

· In practice, where a specific encoding/decoding method or encoder/decoder scheme is patentable, the corresponding “method for processing a data stream” is also deemed allowable.

4. Distinction Between “Bitstream” and “Data Stream”

It should be noted that in everyday technical language, “bitstream” and “data stream” may be used interchangeably. However, in the context of patent law, particularly when examining subject matter eligibility under Article 2(2) of the Chinese Patent Law, the two terms must be strictly distinguished. Generally speaking, “bitstream” refers to the physical layer, underlying binary sequence, whereas “data stream” is a logical layer that includes protocol and encapsulation. The main differences lie in technical aspects such as granularity and protocol dependence. Briefly, a “data stream” contains or encapsulates a “bitstream.”

When responding to a Chinese office action where a non-statutory subject matter rejection is raised, a key strategy to secure allowance is to narrow or clarify the “data stream” term to “a data stream containing/defined by a bitstream generated by a specific encoding/decoding method,” making precise adjustments in accordance with the amended Patent Examination Guidelines.

5. Conclusion

In summary, by leveraging the provisions of the amended Patent Examination Guidelines and following the above amendment examples and practical tips, cross-border applicants can, when amending patent applications entering China based on a priority or PCT application, or when subsequently responding to office actions or filing divisional applications, extend the scope of protection for bitstream-related subject matter from methods to storage media and data streams involved in the distribution chain. This significantly enhances the commercial value of the patent portfolio and the enforceability of the patent rights.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.