Adaptive Pre-Filter for Video Encoder Bit-Rate Management
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Solution Overview
Problem
Video encoding systems face challenges in maintaining efficient bit-rate allocation, leading to undesirable artifacts like jerkiness due to excessive frame skipping caused by bit-rate overflow or underflow, especially in high complexity video frames.
Innovation Solution
An adaptive filtering technique is implemented in the video front end (VFE) of a video recording system, where an adaptive pre-filter is configured based on performance feedback from the video back end (VBE) to reduce video complexity and enhance encoder performance, thereby managing bit-rate overflow/underflow and improving visual quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the video encoder increases compression to meet target bit rate, then recording efficiency is improved, but frame skipping increases causing jerkiness
Solution Approach 1:
The patent applies a pre-filter to the video signal before encoding to reduce complexity in advance. This preliminary action reduces the computational burden on the encoder, allowing it to maintain higher quality encoding without exceeding the target bit rate, thereby reducing frame skipping and improving video quality while maintaining recording efficiency.
Solution Approach 2:
The pre-filter selectively reduces complexity in specific regions of the video signal where it is most beneficial, rather than uniformly processing all regions. This local approach allows the encoder to allocate bits more efficiently to important regions, improving overall video quality while staying within the target bit rate constraint.
2Reliability
If the video encoder reduces compression to maintain frame rate, then video quality is improved, but bit rate overflow increases
Solution Approach 1:
By applying the pre-filter before encoding, the patent reduces the complexity of the video signal in advance, which decreases the number of bits required to encode the video while maintaining visual quality. This preliminary complexity reduction prevents bit rate overflow while preserving video quality and frame rate.
Solution Approach 2:
The pre-filter modifies the frequency content parameters of the video signal by attenuating high-frequency components that are less perceptible to humans. This parameter change reduces the entropy of the signal, allowing for more efficient compression and preventing bit rate overflow while maintaining perceived video quality.
3Productivity
If the adaptive pre-filter reduces video complexity, then encoder performance is improved, but some video information is lost
Solution Approach 1:
The adaptive pre-filter selectively applies filtering only to frequency regions and spatial areas where it provides the most benefit without significantly impacting visual quality. This local approach minimizes information loss while still achieving the desired complexity reduction to improve encoder performance.
Solution Approach 2:
The patent converts the potential harm of information loss into a benefit by deliberately removing high-frequency components that are less perceptible to humans. This selective information removal reduces complexity and improves encoder performance while the lost information is imperceptible, effectively transforming a negative into a positive outcome.
4Reliability
If the system applies adaptive filtering to reduce bit-rate overflow, then frame skipping is minimized, but device complexity increases
Solution Approach 1:
By performing the filtering operation in advance before the encoding process, the patent simplifies the overall system architecture. The pre-filter is a relatively simple operation that reduces complexity before the more complex encoding stage, thereby minimizing frame skipping without significantly increasing overall device complexity.
Solution Approach 2:
The patent segments the video processing pipeline into distinct stages: a simple pre-filtering stage followed by the encoding stage. This segmentation allows each stage to be optimized independently, with the pre-filter handling complexity reduction and the encoder handling compression, thereby improving frame continuity without excessive overall system complexity.
Data Source
AI summary
This disclosure describes adaptive filtering techniques to improve the quality of captured imagery, such as video or still images. In particular, this disclosure describes adaptive filtering techniques that filter each pixel as a function of a set of surrounding pixels. An adaptive image filter may compare image information associated with a pixel of interest to image information associated with a set of surrounding pixels by, for example, computing differences between the image information associated with the pixel of interest and each of the surrounding pixels of the set. The computed differences can be used in a variety of ways to filter image information of the pixel of interest. In some embodiments, for example, the adaptive image filter may include both a low pass component and high pass component that adjust as a function of the computed differences.