Reverse Trick Mode Video Playback Using Supplemental Frames
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Solution Overview
Problem
Current video encoding standards, such as MPEG, VC-1, and others, are designed for forward playback only, making it difficult to achieve smooth reverse playback in trick modes, as they rely on predictive frames that require decoding and processing in a specific order, leading to resource-intensive memory and time requirements.
Innovation Solution
The method involves creating an auxiliary video stream by copying and replacing uni-directional predicted frames with supplemental frames, arranged in reverse processing order, which can be recorded and played back efficiently, allowing for smooth reverse trick mode playback without the need to read entire GOPs into memory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If predictive frames are used for video encoding, then compression efficiency is improved, but reverse playback capability deteriorates
Solution Approach 1:
The video stream is segmented into forward-playback portions (using predictive frames) and reverse-playback portions (using supplemental frames). The encoder selectively switches between encoding modes based on playback direction requirements, allowing compression efficiency for forward playback while enabling reverse playback capability through supplemental frame insertion.
Solution Approach 2:
Instead of attempting to decode predictive frames in reverse order (which is problematic), the invention inverts the approach by generating supplemental frames that are inherently suitable for reverse playback. These supplemental frames are encoded in a manner that allows direct decoding in reverse sequence without requiring complex reordering or reprocessing of predictive frames.
2Manufacturing precision
If entire GOPs are read into memory for reverse playback, then playback quality is maintained, but memory usage increases
Solution Approach 1:
The invention extracts only the essential information needed for reverse playback by generating supplemental frames that contain the necessary reference data in a condensed form. Instead of loading entire GOPs (Groups of Pictures) into memory, the supplemental frames provide just-enough reference information to maintain playback quality while using minimal memory resources.
Solution Approach 2:
The supplemental frames are prepared in advance during encoding with pre-calculated reference information embedded within them. This preliminary preparation eliminates the need for complex runtime memory operations and allows smooth reverse playback with minimal memory buffering, as the necessary data is already organized and available in the supplemental frame structure.
3Measurement precision
If predictive frames are processed in specific order, then decoding accuracy is improved, but processing time increases
Solution Approach 1:
The invention inverts the processing approach by creating supplemental frames that are naturally ordered for reverse playback from the outset. During encoding, supplemental frames are generated with reference to future frames in the forward sequence, but they are structured to be decoded in reverse order. This inversion eliminates the need for complex reordering operations during reverse playback, maintaining decoding accuracy while reducing processing time.
Solution Approach 2:
The encoder performs preliminary calculations and frame generation in advance, creating supplemental frames with all necessary reference information pre-computed and embedded. This preliminary action ensures that during reverse playback, the decoder can process frames in the natural reverse sequence without requiring additional processing steps for reordering or re-referencing, thus maintaining accuracy while minimizing processing time.
Data Source
AI summary
A method for producing an auxiliary video stream arranged for reverse trick mode playback from a video stream including a plurality of uni-directional predicted frames, the method including producing the auxiliary video stream by performing the following steps copying each uni-directional predicted frame included in the video stream into a memory, thereby producing a plurality of copied frames in the memory, replacing each one of the plurality of copied frames with one corresponding supplemental frame, thereby producing a plurality of corresponding supplemental frames, and producing a copy of the video stream arranged in reverse processing order, the producing a copy including replacing each frame which corresponds to one of the plurality of copied frames with the one corresponding supplemental frame from among the plurality of corresponding supplemental frames. Related methods and systems are also described.