Adaptive Video Streaming via Critical Point Scheduling
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Solution Overview
Problem
Traditional constant bit rate (CBR) video encoding leads to sub-optimal user experience due to variable video quality, while variable bit rate (VBR) encoding faces challenges in ensuring timely delivery over networks, causing buffer underflow and interruptions.
Innovation Solution
A method that calculates data transfer rates for variable bit rate encoded video data to select optimal quality levels by using pre-calculated critical points on a decoding schedule, ensuring timely delivery and preventing buffer underflow, allowing for seamless video streaming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If variable bit rate (VBR) encoded video is delivered over a network, then video quality is improved, but buffer underflow and interruptions may occur due to high instantaneous data rate requirements
Solution Approach 1:
The patent pre-calculates critical points on the decoding schedule before video delivery, identifying points where the bit rate decreases and where the delivery schedule equals the decoding schedule. These pre-calculated critical points are stored and used during actual delivery to determine appropriate data transfer rates, allowing the system to proactively adjust delivery rates to prevent buffer underflow while maintaining high video quality.
2Ease of operation
If constant bit rate (CBR) encoding is used, then delivery over network is simplified, but video quality becomes sub-optimal due to time varying quality to meet bit rate constraint
Solution Approach 1:
The patent implements a dynamic delivery approach where the data transfer rate is adjusted in real-time based on the actual delivery rate and pre-calculated critical points. The system transitions from static CBR delivery to adaptive VBR delivery, where the delivery rate changes dynamically to match the encoded video's bit rate variations while preventing buffer underflow, thus achieving both high video quality and reliable delivery.
3Stability of the object's composition
If fixed bit rate independent of content genre is used, then encoding consistency is maintained, but some genres such as fast moving sport and music videos can only be coded poorly
Solution Approach 1:
The patent applies local quality by allowing different bit rates for different portions of the video content. Instead of using a single fixed bit rate for the entire video, the system uses VBR encoding where each scene or segment can have an appropriate bit rate based on its complexity and content requirements. The pre-calculated critical points capture these local variations, enabling the delivery system to allocate bandwidth dynamically to match content requirements.
Data Source
AI summary
A client device receives streamed encoded content data, such as encoded video data, which has been encoded at a constant perceptual quality. Several different versions of the content are available to be streamed to the device, at different perceptual quality levels. In order to decide which quality level to request from a content server at intervals the device calculates the delivery rates that would be required for each level of quality. The calculation of the delivery levels is made in dependence on whether the actual delivery rate that has been received so far is greater than or less than a constant bit rate delivery schedule that decreases monotonically but which guarantees to deliver the encoded data in a timely manner such that no buffer underflow and interruption of reproduction takes place. The monotonically decreasing bit rate schedule is defined by one or more “critical points”, which are the points at which the bit rates are decreased, and correspond to the points where the delivery schedule is just equal to the decoding schedule of the encoded data. At such points there would be no encoded data in a buffer at the client. If the delivery rate has been greater than the constant bit rate schedule for a quality then the delivery rate required going forward for a particular quality level can be calculated from the critical point information, and no more complicated calculation is required.