Escape Pixel Value Restriction in Palette Mode Video Coding
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Solution Overview
Problem
Traditional video coding techniques are inefficient for compressing computer-generated screen content with discrete-tone and high contrast features, as they assume continuous-tone and smoothness, leading to suboptimal compression performance in applications like remote desktop and wireless display.
Innovation Solution
Implementing palette-based coding techniques, which create a table of colors (palette) to represent video data, allowing pixels to be encoded using palette indices rather than actual pixel values, and restricting escape pixel values and quantization parameters to improve encoding and decoding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional video coding techniques are used for computer-generated screen content, then the encoding process is simple, but compression efficiency is poor due to the continuous-tone assumption not matching discrete-tone content
Solution Approach 1:
The patent changes the fundamental parameter representation from continuous-tone pixel values to discrete palette indices. This parameter transformation allows the encoder to exploit the discrete-tone nature of screen content by mapping pixels to a limited set of palette entries, thereby achieving superior compression efficiency while adapting to the specific characteristics of computer-generated content
Solution Approach 2:
The patent segments the color space into discrete palette entries that represent the actual colors present in screen content. By dividing the continuous color range into a finite set of representative colors and assigning indices to them, the encoder can efficiently represent discrete-tone content with reduced bitrates
2Productivity
If escape pixel values are unrestricted in palette mode, then all pixel values can be represented, but bitstream length increases and decoding efficiency decreases
Solution Approach 1:
The patent applies parameter changes by restricting escape pixel values to fall within the range of existing palette entries rather than allowing arbitrary values. This restriction transforms the escape value representation from unbounded to bounded, reducing the number of bits required to encode escape pixels and improving decoding efficiency while maintaining all necessary color information
Data Source
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AI summary
An apparatus configured to decode video data that comprises a memory configured to store the video data; and one or more processors. The one or more processors are configured to: receive a bitstream that is constrained such that escape values used in a palette mode for decoding the video data are no greater than a maximum value, wherein the bitstream includes information for determining at least one escape value representing a sample in a block of the video data to be decoded; and reconstruct the sample in the block of the video data using the information for determining the at least one escape value.