Trick Play via I-Slice Assembly in MPEG Streams
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Solution Overview
Problem
Existing methods for implementing trick play modes in progressive I-slice refreshed MPEG data streams require large buffers or additional decoding and re-encoding, leading to high costs and loss of quality, especially during fast forward and rewind operations.
Innovation Solution
A display device with a syntax parser, storage, and processor that locates and assembles I-slices into constructed I-frames, allowing for decoding and enabling trick play features without the need for extensive buffering or re-encoding, thereby reducing bandwidth and maintaining visual continuity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If large buffers are used to store several pictures worth of data for trick play modes, then trick play functionality is enabled, but device complexity and memory requirements increase significantly
Solution Approach 1:
The I-frame is segmented into multiple I-slices that are distributed across different P-frames in the MPEG data stream. Instead of storing complete I-frames in large buffers, the system locates and assembles these distributed I-slices from multiple P-frames to reconstruct I-frames on-demand during trick play operations, significantly reducing buffer requirements while maintaining trick play functionality
Solution Approach 2:
The I-slices are pre-distributed across P-frames during encoding, and their locations are recorded in navigation data. During trick play, the system uses this pre-stored location information to quickly locate and assemble the required I-slices without needing to buffer entire pictures, enabling fast seeking and frame construction
2Adaptability or versatility
If the stream is fully decoded and re-encoded as an I-frame based stream to enable trick play modes, then trick play functionality is achieved, but processing time and hardware requirements increase
Solution Approach 1:
The system extracts only the necessary I-slices from the progressive I-slice refreshed stream based on navigation data, rather than fully decoding and re-encoding the entire stream. This selective extraction approach enables trick play modes while avoiding the computational overhead of complete re-encoding
Solution Approach 2:
Instead of creating a new I-frame based stream through full decoding and re-encoding, the system copies and assembles the existing I-slice data from distributed P-frames to construct I-frames on-demand, significantly reducing processing requirements while maintaining visual quality
3Quantity of substance
If I-slices are distributed across multiple P-frames to equalize bit rate, then bandwidth efficiency is improved, but the ability to perform trick play modes deteriorates
Solution Approach 1:
Navigation data is prepared in advance during encoding, storing the locations of I-slices within each P-frame and the P-frame numbers where they appear. This preliminary organization of location information enables efficient trick play operations by allowing the system to quickly locate and assemble I-slices without full stream analysis
Solution Approach 2:
The navigation data structure acts as an intermediary between the distributed I-slices and the trick play functionality. It provides the mapping information needed to locate I-slices across multiple P-frames, enabling trick play modes without requiring the I-slices to be contiguous or requiring complex stream analysis
Data Source
AI summary
A display device with personal versatile recorder capabilities is provided which is capable of processing progressive I-slice refreshed MPEG data streams to enable trick play mode features. The display device comprises a receiver for receiving a progressive I-slice refreshed MPEG data stream having I-slices distributed over multiple P-frames. The display device further comprises a syntax parser for parsing the data stream to locate I-slices which make up an I-frame. A storage device is provided for storing the data stream. The display device also comprises an interface for receiving a command for a trick play mode feature. A processor associated with the syntax parser recovers the located I-slices from the storage device and assembles the recovered I-slices into one or more constructed I-frames. A decoder is provided for decoding the constructed I-frames to enable the trick play mode features.