Adaptive Resolution Change in Video Bitstreams
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Solution Overview
Problem
Modern video codecs face challenges in efficiently managing varying instantaneous bandwidth during video transmission, as existing methods like rate control and rate scaling are inadequate for dramatic changes in bandwidth, and require normative elements in the bitstream to handle resolution changes, especially for VVC standards.
Innovation Solution
The implementation of adaptive resolution change (ARC) mechanisms in video bitstreams, where the video encoder and decoder signal and apply resampling at the sequence and picture parameter sets levels, allowing for flexible rescaling of video frames to match changing bandwidth conditions, including support for arbitrary rational resampling ratios and reference picture resampling based on dimensional ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If rate control and rate scaling methods are used to manage bandwidth changes, then video transmission can be maintained under normal conditions, but they are inadequate for dramatic changes in instantaneous bandwidth
Solution Approach 1:
The patent implements dynamic resolution adjustment where video frames are resampled at different resolutions based on current bandwidth conditions. The encoder can switch between multiple resolution levels (e.g., full resolution, half resolution, quarter resolution) dynamically, allowing the system to adapt to dramatic bandwidth changes while maintaining reliable transmission. This is achieved through resampling flags and resolution indicators in the bitstream that enable the decoder to perform corresponding resampling operations.
2Productivity
If the resolution of video frames is changed to adapt to bandwidth variations, then bandwidth efficiency is improved, but normative elements in the bitstream are required which increases complexity
Solution Approach 1:
The patent changes the resolution parameter of video frames dynamically by introducing resampling flags and resolution indicators in the bitstream. These parameters allow the encoder to signal to the decoder whether resampling should be performed and at what resolution level, enabling flexible bitrate adaptation without requiring complete redefinition of the coding standard. The approach modifies existing parameter structures (PPS, SPS) to include resolution-related flags and values.
3Ease of operation
If I frames are repeated intermittently to enable random access, then fast forward and rewind functionality is provided, but I frames require far more bandwidth than predicted frames
Solution Approach 1:
The patent segments the video stream into different resolution levels, allowing selective transmission of frames at reduced resolution. By dividing the video content into segments that can be decoded at different quality levels, the system can maintain random access capability through periodic keyframes while reducing their bandwidth consumption through resolution reduction. This segmentation approach allows the system to balance random access requirements with bandwidth efficiency.
Data Source
AI summary
A video coding system in which video images of a video bitstream are rescaled prior to encoding, and again at the decoder upon reception. When encoding a given video frame, the video encoder deduces a level of resampling to apply to a reference frame in order to properly predict blocks in the given video frame or the full given video frame, and carries out one or more predictions by first applying a resampling process on the reference frame data at the deduced level. To decode the given video frame of the bitstream, a video decoder compares a size of the given video frame to sizes of a reference frame to determine a level of resampling for the reference frame data, and carries out predictions to generate predicted data by first applying the determined level of resampling to the reference frame data.