Compressed Video Stream Switching Apparatus for Conference Systems
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Solution Overview
Problem
Existing conference systems face challenges in switching between compressed video streams in real-time applications, leading to non-deterministic and resource-consuming processes, particularly in scenarios where immediate switching is required without causing video delays or freezing.
Innovation Solution
A switching apparatus that operates on compressed video streams by switching between input streams without decoding, utilizing a switching module to stop and start video transmissions with key frames, and employing a cache module and time stamp module to manage frame transitions and timestamps, ensuring seamless and synchronized video output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If video streams are decoded and re-encoded during switching, then switching flexibility and format compatibility are improved, but processing time and resource consumption increase significantly
Solution Approach 1:
The patent extracts the essential switching function from the complex decode-re-encode process. By taking out only the necessary frame data from the compressed input stream and inserting it directly into the output stream, the system achieves switching without the time-consuming decode-re-encode cycle, thus resolving the contradiction between format compatibility and switching speed
Solution Approach 2:
The patent introduces an intermediary switching apparatus that operates on compressed video streams directly. This intermediary device receives compressed frames from one input stream and inserts them into the output stream without full decoding, acting as a mediator that enables fast switching while maintaining compatibility with standard video codecs
2Speed
If switching occurs during frame transmission, then real-time switching capability is improved, but video artifacts and decoding errors occur
Solution Approach 1:
The patent applies preliminary action by identifying and switching at key frame boundaries before problematic inter-frame dependencies occur. The switching apparatus detects key frames in advance and schedules switching operations to occur between key frames, preventing video artifacts while maintaining real-time switching capability
Solution Approach 2:
The patent implements feedback mechanisms where the switching apparatus monitors the incoming compressed video stream for key frame indicators and adjusts switching timing accordingly. This feedback loop ensures that switching operations are synchronized with the frame structure, preventing decoding errors and maintaining video quality
3Reliability
If key frames are transmitted frequently to ensure independent decoding, then video quality and reliability are improved, but bandwidth consumption and transmission time increase
Solution Approach 1:
The patent applies local quality by transmitting full key frames only at switching points rather than frequently throughout the stream. During normal operation within a key frame group, the system transmits compressed inter-frames that reference the key frame, reducing overall data volume while maintaining decoding independence when switching occurs
Data Source
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AI summary
Conference systems are used to support discussions in meeting rooms or plenary halls, whereby the conference systems usually comprise a plurality of delegate units for participants of the discussion. It is furthermore known, that conference systems comprise a display for displaying the active speaker in a conference. Especially in large conferences with a plurality of participants more than one camera is used for viewing the different active speakers to be displayed on the display. A switching apparatus (9) for switching compressed video streams, the switching apparatus (9) comprising: at least two inputs IN1, IN2, each input being operable to receive an input video stream from a camera (7), an output OUT for outputting an output video stream, whereby the input video streams are compressed video streams, whereby each compressed video stream is represented by a sequence of groups of frames GoF, whereby each group of frames GoF comprises a key frame I and at least one inter frame X, a switching module (12) operable to receive a switch request SR and to switch the input video streams in the output video stream, so that a first video stream of the input video streams is stopped and a second video stream of the input video streams is started, whereby the output video stream is a compressed video stream.