Media Stream Synchronization via Delay Compensation
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Solution Overview
Problem
In mobile communication systems, the synchronization of media streams with different end-to-end delays, such as video and voice streams, is challenging due to their transmission over separate paths with varying delays, leading to unsynchronized presentation at the receiving terminal, which affects user experience.
Innovation Solution
The method involves delaying the presentation of the media stream with the longer end-to-end delay at the sending terminal by an amount corresponding to the difference between the end-to-end delays of the two streams, ensuring synchronized playback at the receiving terminal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If video streams are transmitted over packet switched channels with long buffering times to ensure data quality, then data quality is improved, but end-to-end delay increases significantly compared to circuit switched voice streams
Solution Approach 1:
The patent applies preliminary action by estimating the end-to-end delay for both video and voice streams in advance, before actual transmission. This allows the system to pre-calculate the delay difference and apply appropriate buffering to the voice stream proactively, ensuring synchronization is achieved without real-time adjustments.
Solution Approach 2:
The patent introduces an intermediary mechanism by using a delay estimation and compensation system that acts as a mediator between the video and voice transmission paths. This intermediary calculates the delay difference and applies compensatory buffering to the voice stream, effectively synchronizing the two different transmission paths.
2Adaptability or versatility
If different media streams use separate transmission paths (circuit switched for voice, packet switched for video), then service functionality is improved, but synchronization between streams deteriorates
Solution Approach 1:
The patent implements feedback by continuously monitoring and estimating the end-to-end delay characteristics of both video and voice streams. This feedback information is used to adjust the buffering time for the voice stream, creating a closed-loop control system that maintains synchronization despite the different transmission paths.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting the buffering time parameter for the voice stream based on the estimated delay difference between video and voice paths. This parameter adjustment compensates for the inherent timing differences caused by using separate circuit switched and packet switched transmission paths.
3Reliability
If buffering time for packet switched video data is increased to handle interruptions and jitter, then data quality is improved, but the delay difference between voice and video streams increases
Solution Approach 1:
The patent applies preliminary action by estimating the total end-to-end delay for video streams in advance, including the necessary buffering time for handling interruptions and jitter. This pre-estimation allows the system to calculate the exact delay difference that needs to be compensated for in the voice stream, rather than adding excessive buffering.
Solution Approach 2:
The patent replaces the mechanical approach of simply increasing video buffering time with a more sophisticated delay estimation and compensation system. Instead of blindly increasing buffers, the system uses delay measurement and calculation to precisely determine the compensation needed, substituting brute-force buffering with intelligent delay management.
Data Source
AI summary
For some mobile communication services, a media stream such as video, will be combined with another media stream such as voice. For example, a user of a first terminal (101) is involved in a voice call over e.g. a circuit switched network (103) with a friend. During the voice call, the user of the first terminal decides to start transmitting another media stream, such as live streamed video, which may be transmitted over a packet switched network (104), to the friend's terminal (102). In such a case there is problem in that the two media streams voice and video may have quite different end-to-end time delays, i.e. the time from a part of the media stream is transmitted from the first user's terminal (101) until that part of the media stream is presented at the friend's terminal (102). Since comments from the first user will be presented to the user's friend earlier than the commented part of the video this will be quite annoying to the friend. To avoid this problem this invention presents the video to the user of the first terminal (101) delayed with a time dependent on the time difference between the end-to-end time delay of video and the end-to-end time delay of voice. Thereby, comments from the user of the first terminal (101) regarding the video will be received at the friend's terminal (102) approximately synchronized with the video.