DVD Smooth Rewind Frame Buffer Segmentation

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Solution Overview

Problem

Conventional DVD players face challenges in achieving smooth backwards playback, single frame stepping, and smooth transitions between playback rates due to limitations in MPEG-2 compression and memory resources, resulting in jerky playback and inability to decode P or B frames when playing backwards.

Innovation Solution

The use of at least seven frame buffers to reconstruct and display all frames during backwards playback, allowing for smooth rewind, single frame stepping, and smooth search transitions by decoding frames in a manner consistent with forward decoding and interpolating frame rates for seamless transitions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If conventional DVD players decode only I-frames during backwards playback to save memory resources, then memory usage is reduced, but playback smoothness deteriorates resulting in jerky playback

Engineering Contradiction:

Improvememory resourcesVSAvoidplayback smoothness

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent segments the frame buffering requirement into distinct functional groups: current frame buffer, displayed frame buffer, reference frame buffers for forward prediction, reference frame buffers for backward prediction, and reconstructed frame buffers. This segmentation allows systematic management of memory resources while ensuring all necessary frames are available for smooth backwards playback.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent adds a temporal dimension to frame buffering by maintaining multiple reference frames from different time positions (forward and backward references) and using reconstruction buffers to generate intermediate frames. This multi-temporal approach enables smooth playback by providing reference data from both directions around the current playback position.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Device complexity

If DVD players use only four frame buffers to limit memory resources, then device complexity is reduced, but the ability to perform smooth backwards playback deteriorates

Engineering Contradiction:

Improveframe buffer quantityVSAvoidbackwards playback capability

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent divides the frame buffering system into six distinct buffer segments, each serving a specific function in the playback process. This segmentation transforms the complex requirement of smooth backwards playback into manageable buffer management tasks.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The frame buffers in the patent serve multiple functions: storing current frames, displayed frames, forward reference frames, backward reference frames, and reconstructed frames. This multi-functionality allows the buffer system to support both forward and backward playback modes with a unified buffer architecture.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Power

If P-frames and B-frames are not decoded during backwards playback to conserve resources, then processing power is reduced, but frame decoding completeness deteriorates

Engineering Contradiction:

Improveprocessing capacityVSAvoidframe decoding completeness

Core Design Contradiction:

PowerVSLoss of information

Solution Approach 1:

The patent performs preliminary decoding of reference frames (both forward and backward) before attempting to decode dependent P-frames or B-frames during backwards playback. This preliminary action ensures that all necessary reference data is available in memory, enabling complete frame decoding when resources permit.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses feedback from the playback position and frame type analysis to dynamically determine which frames to decode and which reference frames to maintain in memory. This feedback mechanism optimizes processing capacity utilization while ensuring decoding completeness.

Inventive Principle:

Principle #23Feedback

4Device complexity

If conventional players avoid decoding dependent frames backwards, then memory management is simplified, but playback quality deteriorates

Engineering Contradiction:

Improvememory management complexityVSAvoidplayback quality

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent segments memory management into distinct buffer zones with clear allocation rules, simplifying the complexity of managing dependent frames. Each buffer segment has a defined purpose and lifetime, making memory management systematic rather than ad hoc.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system changes the parameter of frame dependency handling by maintaining reference frames from both forward and backward directions, rather than only forward references. This parameter change in reference frame management enables quality backwards playback while keeping memory management organized.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS8958688B2Method and system for DVD smooth rewind

Publication Date: 2015.02.17 NVIDIA CORP

AI summary

Aspects of performing smooth backwards playback in a DVD system are described. The aspects include reconstructing frame data for every frame in a set of frames of an original playback, the set of frames preceding a currently displayed frame. Further included is the utilization of at least seven frame buffers to store frame data during the reconstructing step. The reconstructed frame data is then displayed in reverse order of the original playback for the set of frames.