Multimedia Picture Encoding Bit Allocation
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Solution Overview
Problem
The challenge lies in accurately estimating bit allocation for encoding multimedia pictures to prevent buffer underflow or overflow in decoder buffers, which vary in size and are subjected to different transmission bit rates, leading to potential stalls or data loss during multimedia playback.
Innovation Solution
A method and system that estimate the occupancy level of a coded picture buffer associated with a hypothetical reference decoder to dynamically allocate bits for encoding, using tracking of access unit arrival and removal times and transmission channel bit rates, and adjusting quantization parameters to prevent buffer underflow, while allowing for skip-macroblock encoding if necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a large number of bits is allocated for encoding multimedia pictures, then multimedia picture quality is improved, but buffer underflow occurs at the decoder buffer
Solution Approach 1:
The encoder performs preliminary estimation of the decoder buffer occupancy level before encoding each multimedia picture. By tracking arrival and removal times of access units and calculating buffer occupancy in advance, the encoder determines the maximum allowable bits that can be allocated without causing buffer underflow. This preliminary action enables the encoder to set appropriate bit allocation limits before the actual encoding process begins.
Solution Approach 2:
The system dynamically adjusts bit allocation for each multimedia picture based on real-time buffer occupancy conditions. Instead of using a fixed bit allocation strategy, the encoder continuously updates the maximum bit limit by tracking the decoder buffer state, arrival times, and removal times. This dynamic adaptation allows the system to optimize picture quality while preventing buffer underflow under varying transmission conditions.
2Reliability
If a small number of bits is allocated for encoding multimedia pictures, then buffer overflow is prevented, but multimedia picture quality deteriorates
Solution Approach 1:
The system changes the bit allocation parameter dynamically based on buffer occupancy conditions. By calculating the maximum bit limit as a function of buffer occupancy, arrival time, and removal time, the system adapts the bit allocation parameter to match current decoder buffer conditions. This ensures that bit allocation is neither excessively large nor unnecessarily small, optimizing both buffer stability and picture quality.
3Device complexity
If fixed bit allocation is used for encoding, then encoding process is simplified, but buffer underflow or overflow cannot be prevented under varying transmission conditions
Solution Approach 1:
The encoder implements a feedback mechanism by tracking the decoder buffer occupancy level, arrival times, and removal times of access units. This feedback information is used to continuously update the maximum bit allocation limit for each multimedia picture. The feedback loop ensures that bit allocation adapts to varying transmission conditions and decoder buffer states, preventing both buffer underflow and overflow while maintaining encoding process manageability.
Data Source
AI summary
Several methods and systems for encoding of multimedia pictures are disclosed. In an embodiment, an occupancy level of a coded picture buffer (CPB) associated with a hypothetical reference decoder (HRD) is estimated at an instant of removal of an access unit corresponding to a multimedia picture from the CPB for decoding the access unit. A number of bits for encoding the multimedia picture is allocated based on the estimated occupancy level of the CPB. The multimedia picture is encoded based on the allocated number of bits.