Expanded-State Video TCQ With Compact Dequantization Mapping
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Solution Overview
Problem
Existing video coding systems face inefficiencies in quantization processes, particularly with trellis coded quantization (TCQ), due to limitations in the number of quantization and dequantization states, leading to suboptimal compression and transmission efficiency.
Innovation Solution
Implementing a state transition table for TCQ with more than eight quantization states, allowing for enhanced states-dependent quantization, where the number of quantization states exceeds dequantization states, and using multiple scalar quantizers with odd and even indices, and selecting quantization states based on block characteristics such as size, prediction mode, and color component.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of quantization states is increased beyond eight states in TCQ, then compression efficiency and rate-distortion performance are improved, but decoder complexity and memory requirements increase
Solution Approach 1:
The quantization process is segmented into multiple independent scalar quantizers (first scalar quantizer for odd indices, second scalar quantizer for even indices). Each quantizer handles a subset of the quantization states, allowing the decoder to process fewer states at any given time while still achieving the benefits of having access to a larger total number of quantization states through state transitions.
Solution Approach 2:
The system dynamically transitions between different quantization states during the quantization process. The state transition table enables the encoder and decoder to switch between states based on the current quantization context, allowing adaptive selection of appropriate quantization precision without requiring the decoder to maintain all high-number states simultaneously in memory.
2Measurement precision
If more quantization states are used than dequantization states, then quantization precision is improved, but memory requirements and processing overhead increase
Solution Approach 1:
The dequantization process is segmented into multiple dequantization states that are fewer in number than the total quantization states. The system uses state transition indexing to map from a larger quantization state space to a smaller dequantization state space, maintaining precision through the transition logic rather than through direct one-to-one state mapping.
Solution Approach 2:
The system changes the parameter of state representation by using parity-based indexing (odd/even indices) to select between different scalar quantizers. This parameter transformation allows the system to efficiently navigate a large quantization state space using a compact dequantization state representation, reducing memory requirements while preserving quantization precision.
3Productivity
If multiple scalar quantizers are used with odd and even indices, then rate-distortion performance is improved, but computational complexity increases
Solution Approach 1:
Different scalar quantizers are applied to different local regions of the quantization space (odd indices vs. even indices). Each scalar quantizer is optimized for its specific subset of states, allowing the system to achieve high rate-distortion performance through specialized local processing rather than requiring a single complex universal quantizer.
Solution Approach 2:
Instead of using a single complex quantizer that handles all states uniformly, the system inverts the approach by using multiple simple scalar quantizers that each handle specific subsets of states. The complexity is inverted from the quantization function to the state transition and selection logic, simplifying the actual quantization operations while maintaining overall system performance.
Data Source
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AI summary
Systems, methods, and instrumentalities may be configured for states dependent quantization. A video encoding device may determine to use a quantization state transition table for trellis coded quantization (TCQ) including a multiple quantization states. The state transition table includes more than eight quantization states. The number of quantization states may be greater than the number dequantization states (e.g., the number of dequantization states available at a decoding device). The device may select a quantization state from the multiple quantization states. The device may determine, based on the selected quantization state, a dequantization index based on a parity associated with the selected quantization state. The determined dequantization index may be associated with a dequantization state list that may include multiple dequantization states. There may be more quantization states than dequantization states. The device may perform quantization based on the selected quantization state.