Obviousness

Obviousness Analysis of US Patent 7,724,818 under 35 U.S.C. § 103

This analysis identifies combinations of prior art references that would render the claims of US Patent 7,724,818 obvious to a person having ordinary skill in the art (PHOSITA) as of the priority date, April 30, 2003. The primary reference for this analysis is ITU-T document VCEG-N55, also known as "Joint Video Team (JVT) of ISO/IEC MPEG & ITU-T VCEG - Working Draft Number 2, Revision 0 (WD2 Rev. 0)," dated November 22, 2002. This document is explicitly referenced in the background of US7724818 as introducing the parameter set concept that replaces traditional video headers.

Background of the Invention and Admitted Prior Art

US7724818 describes a method for coding sequences of pictures using a hierarchical parameter set structure. The patent acknowledges that the "JVT coding standard" (which aimed to become ITU-T Recommendation H.264 and ISO/IEC International Standard 14496-10) introduced a concept of parameter sets, replacing traditional picture, Group of Pictures (GOP), or sequence headers. Specifically, it states that "a concept of a parameter set, introduced in ITU-T document VCEG-N55, replaces such headers." The patent further notes that these parameter sets include "all picture, GOP, and sequence level data such as picture size, display window, optional coding modes employed, macroblock allocation map, and others." It also admits that "each slice header includes a reference to a parameter set identifier, and the parameter values of the referred parameter set are used when decoding the slice." These statements establish VCEG-N55 and the general principles of the JVT parameter set concept as prior art.

The claimed invention focuses on a specific division of parameters into:

1. A sequence parameter set (SPS) for sequence-level parameters.
2. A picture parameter set (PPS) for picture-level parameters.
3. A slice header containing at least one "picture parameter value" that remains unchanged across all slice headers of one picture.

Obviousness of Independent Claims (Claims 1, 6, 10, 11, 12, 14, 15, 16, 20, 21, 22, 23)

Primary Reference: ITU-T document VCEG-N55 (JVT Working Draft 2, Revision 0, November 22, 2002).

Analysis of Claim 1 (Encoding Method) and related apparatus/bitstream claims (10, 14, 16, 20, 22):

Claim 1 recites a method for encoding sequences of pictures comprising:

• "defining, in an encoder, parameter values in a sequence parameter set for a sequence of pictures;"
• "defining, in the encoder, parameter values in a picture parameter set for a picture;" and
• "defining, in the encoder, at least one picture parameter value in a slice header, the picture parameter value remaining unchanged at least in all slice headers of one picture."

VCEG-N55, as the working draft for what became the H.264/AVC standard, explicitly discloses this structure:

• VCEG-N55 defines the Sequence Parameter Set (SPS) to contain parameters applicable to an entire video sequence.
• VCEG-N55 defines the Picture Parameter Set (PPS) to contain parameters applicable to a picture.
• VCEG-N55 specifies that the slice header includes certain syntax elements, such as frame_num and information related to PicOrderCnt (e.g., pic_order_cnt_lsb). These elements are "picture parameter values" in the sense that they identify and characterize the picture as a whole, not just a specific slice. The design of VCEG-N55 inherently requires that these values (frame_num and the resulting PicOrderCnt) are consistent and remain unchanged across all slices that belong to the same coded picture. Without such consistency, the temporal identification and ordering of pictures would be ambiguous, leading to incorrect decoding.

Thus, VCEG-N55 anticipates or renders obvious all the elements of Claim 1. The corresponding decoding method (Claim 6), encoder (Claims 10, 14, 22), decoder (Claims 11, 15, 23), system (Claim 12), bitstream (Claim 16), and computer-readable storage media (Claims 20, 21) would similarly be obvious as they describe the implementation or result of this already disclosed method and structure.

Motivation for Combining Elements (inherent in VCEG-N55 design):
A PHOSITA in video coding in April 2003 would have been actively involved with or aware of the JVT standardization efforts and documents like VCEG-N55. The motivation for the hierarchical parameter set structure was clearly understood:

• Improved Compression Efficiency: By separating infrequently changing parameters (sequence, picture level) from frequently changing ones (slice level), redundancy in the bitstream is reduced, as these parameters do not need to be repeated in every slice. The patent itself highlights this benefit.
• Enhanced Error Resilience: Decoupling parameter transmission allows for out-of-band transmission or repeated in-band transmission of critical, less-frequently changing parameters, improving robustness against transmission errors. This is also noted in the patent.
• Clarity and Consistency: Defining clear persistency rules for parameters at different levels simplifies codec design and ensures reliable decoding. Placing picture-level identifiers like frame_num and PicOrderCnt in the slice header, while maintaining their consistency across all slices of a picture, provides immediate access to crucial temporal information while preserving the logical integrity of the picture. The patent also emphasizes clarifying "persistency rules of parameter values."

These motivations were well-known and directly drove the design choices embodied in VCEG-N55, making the claimed hierarchical structure and parameter placement an obvious design for a PHOSITA.

Obviousness of Dependent Claims

• Claim 2 (Slice header refers to PPS) and 17 (Bitstream): VCEG-N55 explicitly defines that each slice header includes a reference to a Picture Parameter Set identifier (pic_parameter_set_id).
• Claim 3 (PPS refers to SPS) and 18 (Bitstream): VCEG-N55 describes the Picture Parameter Set (PPS) referring to a Sequence Parameter Set (SPS).
• Claim 4 (Picture parameter value is POC or frame number) and 9, 19 (Bitstream): As detailed, VCEG-N55 includes frame_num and pic_order_cnt_lsb (for deriving Picture Order Count) directly in the slice header, which are prime examples of picture parameter values that must remain consistent across all slices of a picture.
• Claim 5 (SPS and PPS transmitted less often than once per each picture): The primary purpose of parameter sets in VCEG-N55, as admitted by the patent, is to "decouple the transmission and decoding order of infrequently changing picture, GOP, and sequence level data." This directly implies that these parameter sets are transmitted less often than once per picture, which was a fundamental design goal for efficiency.
• Claim 13 (Parameter set stored in encoder and decoder): Storing parameters in memory for subsequent use by both encoding and decoding devices is a standard practice in video processing. The patent itself notes that "the encoder and decoder can maintain a list of more than one Parameter Set." A PHOSITA would find it obvious to store such parameters for efficient access.

Conclusion

All claims of US Patent 7,724,818 are rendered obvious by the teachings of ITU-T document VCEG-N55 (JVT Working Draft 2, Revision 0, November 22, 2002). This document, which forms the basis for the H.264/AVC video coding standard, directly discloses the hierarchical use of sequence parameter sets, picture parameter sets, and the inclusion of picture-level parameters like frame_num and Picture Order Count information within slice headers, with the inherent understanding that these values remain consistent for all slices of a given picture. The motivations for such a design—improved compression, enhanced error resilience, and clearer persistency rules—were well-known and were the driving forces behind the development of the JVT standard itself. No inventive step beyond the ordinary skill of a PHOSITA is demonstrated by the claims over this prior art.