Image Coding Apparatus Dynamic Mode Selection for Buffer Overflow
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Solution Overview
Problem
Conventional image coding techniques face challenges in ensuring that the accumulated amount of coded data does not exceed a target amount, leading to potential stream buffer failures and degradation in image quality due to the need to switch to minimum data encoding.
Innovation Solution
An image coding apparatus with a decision section that dynamically selects between two coding modes: a first mode for regular encoding and a second mode that generates a predetermined amount of coded data, ensuring the total data remains within the target by adjusting encoding processes and quantization parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the maximum amount of coded data is generated from a macro block, then the image quality is maintained, but the stream buffer may be failed and the bit stream size exceeds the target
Solution Approach 1:
The patent performs preliminary calculation of the maximum coded data amount for each macro block before actual encoding. By predicting the bit stream size in advance and comparing it with the target amount, the system can proactively adjust encoding parameters to prevent buffer overflow, rather than reacting after the overflow occurs.
Solution Approach 2:
The patent dynamically switches between normal encoding mode and minimum coded data mode based on real-time buffer status and predicted data amounts. The encoding parameters are adjusted dynamically during the encoding process to balance image quality and buffer reliability, rather than using a fixed encoding strategy throughout.
2Quantity of substance
If the coding process is switched to generate the minimum amount of coded data when the stream buffer is failed, then the bit stream size is reduced, but the image quality is largely degraded
Solution Approach 1:
The patent applies different encoding qualities to different macro blocks based on local conditions. Only macro blocks that would cause buffer overflow are encoded with minimum data mode, while other macro blocks maintain normal encoding quality. This localized quality adjustment prevents overall image quality degradation while still managing the bit stream size.
Solution Approach 2:
The patent changes encoding parameters (quantization scale, coding mode) based on the calculated maximum coded data amount and target amount ratio. When the ratio exceeds a threshold, parameters are adjusted to reduce data amount; otherwise, normal parameters are used to maintain quality.
3Reliability
If a margin of the maximum amount of coded data is equivalently reserved, then the stream buffer reliability is improved, but the coding process by the minimum amount of coded data is apt to be selected
Solution Approach 1:
The patent calculates the maximum coded data amount and compares it with the target amount before encoding each macro block. This preliminary assessment allows the system to determine whether normal or minimum encoding should be used, avoiding unnecessary quality degradation while still ensuring buffer reliability.
Solution Approach 2:
The patent uses the ratio of maximum coded data amount to target amount as a decision criterion for parameter selection. When the ratio is within an acceptable range, normal encoding parameters are used; when it exceeds the range, minimum encoding parameters are selected. This adaptive parameter selection optimizes the balance between reliability and quality.
Data Source
AI summary
First coded data are generated from a target block by a first coding mode. Second coded data having predetermined amount are generated from the target block by a second coding mode. Whether to encode by the first coding mode or the second coding mode is decided. Based on the decision result, any of the first coded data and the second coded data is selected. If a total amount of coded data of a segment is over a target amount, encoding by the second coding mode is decided. The segment comprises blocks including the target block. The total amount is sum of an amount of coded data generated from blocks prior to the target block in the segment, an amount of the first coded data, an amount of coded data to be generated from remained blocks in the segment by the second coding mode.