Video Rate Control via Target Frame Size Computation
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Solution Overview
Problem
Current video coding standards, such as H.263, face limitations in rate control, failing to accurately manage both average and maximum bitrates, leading to potential bitrate exceedance and compromised video quality due to inadequate control over Intra and Inter frame sizes.
Innovation Solution
A method and device for improved rate control in video coding that computes target frame sizes and buffer levels for each Inter frame relative to nearby Intra frames, optimizing transmission to meet both average and maximum bitrates by dynamically adjusting Quantization Parameters and proactively dropping frames if necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current rate control algorithms (e.g., TMN8) are used to manage bitrate, then average bitrate can be met, but maximum bitrate cannot be guaranteed and frame sizes cannot be precisely controlled
Solution Approach 1:
The patent computes target frame sizes for Inter frames in advance, considering the positions of previous and upcoming Intra frames. This preliminary calculation ensures that frame sizes are controlled before encoding, preventing bitrate exceedance while maintaining average bitrate compliance.
Solution Approach 2:
The rate control mechanism uses feedback from buffer levels and frame position information to dynamically adjust target frame sizes. By monitoring the buffer state and considering the temporal relationship between Intra and Inter frames, the system adaptively controls encoding parameters to meet both average and maximum bitrate constraints.
2Reliability
If Intra frames are used to represent whole pictures, then video quality is maintained, but bandwidth consumption increases
Solution Approach 1:
The patent segments the video stream into Intra frames and Inter frames with specific positioning strategies. By carefully controlling the frequency and placement of Intra frames and calculating appropriate target sizes for Inter frames, the system maintains video quality where needed while reducing overall bandwidth consumption through efficient differential encoding.
Solution Approach 2:
Different frame types are assigned different quality levels and target sizes based on their position in the sequence. Intra frames maintain full quality as reference points, while Inter frames use predictive encoding with adjusted target sizes to optimize the balance between quality and bandwidth usage in different local regions of the video stream.
3Quantity of substance
If Inter frames are used to compress video by encoding only differences, then bandwidth is saved, but control over frame size and bitrate becomes more difficult
Solution Approach 1:
The patent computes target frame sizes for Inter frames in advance, before the actual encoding process. This preliminary calculation considers the buffer state, frame position relative to Intra frames, and bitrate constraints, thereby simplifying the encoding process by providing clear size targets rather than requiring complex post-encoding adjustments.
Solution Approach 2:
The rate control system dynamically adjusts target frame sizes for Inter frames based on changing buffer conditions and frame positions. The control parameters are updated adaptively to reflect the current state of the encoding process, allowing the system to maintain efficiency while responding to varying video content complexity and channel conditions.
Data Source
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AI summary
A method and device for improving rate controlling in video coding of sequences including a series of Inter frames separated by Intra frames, when a decoding delay is considered, comprise for each Inter frame of the series: computing a target frame size, computing a maximum buffer level related to a position of each Inter frame relative to a previous Intra frame and an upcoming Intra frame, and optimizing a transmission buffer level in response to the computed target frame size and the computed maximum buffer level.