Synchronizer Circuit for Video Codec Memory Latency
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Solution Overview
Problem
In video codec systems, memory latency is a significant contributor to overall system latency due to extensive memory access by multiple component devices, necessitating optimization of memory access synchronization.
Innovation Solution
A synchronizer circuit monitors bus transactions between memory and devices to determine an occupancy threshold, allowing read transactions only when the memory is available, thereby reducing latency by enabling immediate data fetching by consumer devices after write transactions are completed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional interrupt-based synchronization is used for memory access between capture and encoder devices, then system reliability is maintained through proper data availability checking, but encoding latency increases significantly due to interrupt handling overhead at every frame boundary
Solution Approach 1:
The patent extracts the synchronization control function from the interrupt-based software handling and relocates it to a dedicated hardware synchronizer circuit. This circuit continuously monitors the occupancy threshold of the memory buffer and automatically controls the timing of read transactions, eliminating the need for interrupt handlers to check data availability at every frame boundary. The hardware circuit operates autonomously to enable immediate data fetching when memory is available, reducing encoding latency from 20ms to 3ms while maintaining reliable synchronization.
Solution Approach 2:
The synchronizer circuit acts as an intermediary component between the capture device (producer) and the encoder device (consumer). It monitors the memory buffer occupancy through the first bus and controls read transaction timing through the second bus, mediating the data flow between producer and consumer. This intermediary hardware layer eliminates the need for software interrupt handling while ensuring that read operations only occur when data is available, thus maintaining reliability without the latency penalty of interrupt-based synchronization.
2Adaptability or versatility
If multiple component devices access the same memory extensively in a video codec system, then system functionality and versatility are enhanced, but memory access latency increases due to contention and synchronization overhead
Solution Approach 1:
The patent implements dynamic control of memory read access timing based on real-time monitoring of buffer occupancy. The synchronizer circuit continuously adjusts the timing of read transactions by comparing the current occupancy level against a predefined threshold, enabling the system to adaptively optimize memory access patterns. This dynamic approach allows multiple devices to access memory efficiently without fixed timing constraints, reducing latency while maintaining system versatility.
Solution Approach 2:
The synchronizer circuit employs feedback control by continuously monitoring the occupancy threshold of the memory buffer through the first bus and using this information to control the timing of read transactions on the second bus. When the occupancy level indicates data availability, the circuit enables read transactions; when occupancy is low, it prevents reads. This feedback mechanism optimizes memory access timing dynamically, reducing latency for multiple component devices while maintaining proper synchronization.
3Measurement precision
If processor handles interrupts at every frame boundary for synchronization, then precise control over memory access is achieved, but processor workload increases significantly
Solution Approach 1:
The synchronizer circuit is designed to autonomously perform synchronization control without requiring processor intervention. It independently monitors memory occupancy through the first bus, determines when the threshold is met, and controls read transaction timing through the second bus. This self-service hardware circuit eliminates the need for the processor to handle interrupts at every frame boundary, maintaining precise synchronization control while dramatically reducing processor workload and freeing the processor for other computational tasks.
Data Source
AI summary
A system includes a synchronizer circuit configured to monitor a first bus coupled between a memory and a first device to determine an occupancy threshold of the memory based on one or more write requests from the first device. The synchronizer circuit monitors a second bus between the memory and a second device to receive a first read transaction of a read request from the second device. The synchronizer circuit determines that the first read transaction is allowed to be sent to the memory based on the occupancy threshold of the memory. In response to the determination, the first read transaction is sent to the memory.