Keyframe Mitigation for Multi-Receiver Video Streams
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Solution Overview
Problem
In low-latency video communication, keyframes are often of lower quality due to bandwidth constraints, affecting the visual experience of receivers, especially in multi-receiver scenarios where continuous content is disrupted, and existing compression techniques cannot achieve optimal quality without increasing latency.
Innovation Solution
The proposed solution involves generating an encoded bitstream that includes information from pre-keyframe video frames to enhance the quality of keyframes and subsequent frames, using a 'sync-layer' and 'improvement layer' combination, where 'enabled' receivers can utilize supplemental syntax to generate improvement frames, blending them with sync-layer frames to produce higher quality display frames, while 'non-enabled' receivers receive standard keyframes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If keyframe size is reduced to meet bandwidth constraints, then transmission delay is reduced, but keyframe quality deteriorates
Solution Approach 1:
The video stream is segmented into sync-layer frames and improvement-layer frames. The sync-layer contains essential information for all receivers, while the improvement-layer contains additional data to enhance quality for receivers that have not experienced packet loss. This segmentation allows the system to transmit smaller keyframes (reducing delay) while still providing quality improvement options for eligible receivers.
Solution Approach 2:
Different quality levels are provided to different receivers based on their specific needs and conditions. Receivers that have experienced packet loss or are new participants receive standard sync-layer keyframes with lower quality but faster transmission. Receivers with continuous stream reception can utilize improvement-layer data to generate higher quality display frames locally, achieving local quality enhancement without increasing overall transmission delay.
2Manufacturing precision
If keyframe quality is improved through higher compression, then keyframe visual quality is improved, but bandwidth consumption increases
Solution Approach 1:
Instead of transmitting full high-quality keyframes to all receivers, the system transmits partial information (sync-layer) to all receivers and additional improvement information only to receivers that can benefit from it. This partial action approach improves keyframe quality for eligible receivers without proportionally increasing bandwidth consumption for all receivers.
Solution Approach 2:
The system changes the parameter of keyframe transmission by introducing a dual-layer structure with different quality levels. The sync-layer uses standard compression, while the improvement-layer uses enhanced compression techniques. Receivers dynamically select which layer to use based on their reception status, allowing quality improvement without linear bandwidth increase.
3Reliability
If a keyframe is sent to resynchronize a specific receiver, then that receiver's stream is repaired, but other receivers experience temporary quality degradation
Solution Approach 1:
The keyframe transmission is segmented into sync-layer (for all receivers) and improvement-layer (for specific receivers). When a receiver needs resynchronization, the sync-layer keyframe is transmitted to all receivers to restore stream continuity, while the improvement-layer is selectively transmitted only to the receiver that needs quality enhancement, preventing unnecessary quality degradation for other receivers.
Solution Approach 2:
The improvement-layer acts as an intermediary that bridges the gap between sync-layer transmission and individual receiver needs. It allows the system to provide targeted quality enhancement to specific receivers without forcing all receivers to receive and process high-bandwidth improvement data, thus preventing unnecessary quality degradation for receivers that don't need it.
Data Source
AI summary
In one embodiment, a video encoder generates an encoded bitstream representing a sequence of video frames including a keyframe. The encoder generates information for use by a decoder that receives the encoded bitstream to enable the decoder to generate display frames from a pre-keyframe video frame that is prior to the keyframe in the sequence of video frames. The encoded bitstream is sent to the decoder. In another embodiment, a video decoder receives from an encoder an encoded bitstream representing a sequence of video frames including a keyframe. The keyframe includes information to enable the decoder to generate display frames from a pre-keyframe video frame that was received prior to the keyframe in the sequence of video frames. The decoder generates display frames using the pre-keyframe video frame, information included with the keyframe and information included with an encoder-determined number of decoded frames subsequent to the keyframe.