Video Data Reproduction System Trick Play Optimization
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Solution Overview
Problem
Existing methods for controlling trick play in encoded video data using inter-frame compression face challenges such as deteriorated image quality and increased network load during fast-forward playback, as they require decoding all frames, including B-pictures, to achieve desired playback speeds.
Innovation Solution
A video data reproduction system that switches between normal and fast-forward video data streams by decoding intra frames independently and referencing preceding/succeeding frames for non-intra frames, using a switching unit that refers to a relation table to determine read-out addresses, allowing for smoother trick play performance without increasing network load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If all frames including B-pictures are decoded to achieve fast-forward playback at n-times speed, then the desired playback speed is achieved, but the network load increases and image quality deteriorates
Solution Approach 1:
The patent extracts and removes B-pictures from the video stream before transmission. Only I-pictures and P-pictures are transmitted to the terminal, reducing the data quantity by approximately one-third compared to transmitting all frames. This extraction principle directly resolves the contradiction by reducing network load while maintaining sufficient playback quality.
Solution Approach 2:
The video server performs frame extraction and selection in advance before transmission. By pre-processing the video stream to remove unnecessary B-pictures and organize remaining frames at appropriate intervals, the system prepares optimized data for fast-forward playback, avoiding the need to decode all frames at the terminal and thus reducing network load.
2Speed
If all frames including B-pictures are decoded to achieve fast-forward playback at n-times speed, then the desired playback speed is achieved, but image quality deteriorates
Solution Approach 1:
The patent extracts only the necessary I-pictures and P-pictures from the original video stream, removing B-pictures that contribute to quality deterioration during fast-forward playback. This selective extraction maintains image quality by avoiding the degradation that occurs when B-pictures are decoded and displayed during trick play modes.
Solution Approach 2:
The patent applies different quality requirements to different frame types. I-pictures and P-pictures are transmitted and decoded with full quality, while B-pictures are removed entirely. This local quality differentiation ensures that frames contributing to image quality are preserved, while frames causing quality deterioration are eliminated.
3Speed
If a display control unit is added to repeatedly output the same frame to achieve desired playback speed, then the playback speed is controlled, but the device complexity increases and image quality deteriorates
Solution Approach 1:
The video server performs the frame selection and spacing operation in advance before transmission. By pre-determining which frames to transmit and at what intervals, the server eliminates the need for a display control unit at the terminal. The terminal simply decodes and displays frames in the order received, significantly reducing device complexity.
Solution Approach 2:
The patent introduces an intermediary processing stage at the video server that handles frame selection and spacing. This intermediary performs the complex operation of determining frame intervals and selecting frames to transmit, transferring the complexity burden from the terminal decoder to the server, where it can be handled more efficiently.
4Adaptability or versatility
If all encoded frames are transmitted over the network to achieve fast-forward playback, then the reproduction is achieved, but the network load increases by n-times
Solution Approach 1:
The patent extracts and removes approximately one-third of the frames (B-pictures) from the video stream before transmission. This extraction reduces the network load by transmitting only the essential I-pictures and P-pictures, achieving fast-forward playback capability without requiring n-times network bandwidth.
Solution Approach 2:
The patent transmits a partial set of frames (only I and P pictures, excluding B pictures) rather than all frames. This partial transmission is sufficient to achieve fast-forward playback capability, avoiding the excessive network load that would result from transmitting complete video data at n-times speed.
Data Source
AI summary
A transmission server reads out encoded data files from storage medium such as memory in itself and removable medium, and transmits the read-out file to the reproduction apparatus upon the request from the reproduction apparatus. A plurality of encoded video files are corresponding to an AV content. These encoded data files correspond to different reproduction modes respectively. The transmission server transmits an encoded file to the reproduction apparatus which corresponds to the requested AV content and the requested reproduction mode. Further, the transmission server switches files to be transmitted based upon a mode switching request from the reproduction apparatus. In other words, the file to be transmitted is switched from an encoded file corresponding to a pre-request reproduction mode to another corresponding to a post-request reproduction mode.