Recurrent Neural Network for Real-Time Video Action Detection

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Solution Overview

Problem

Existing action detection models are inefficient in real-time recognition and forecasting of actions, particularly in streaming videos, as they require full observation of actions and struggle with uncertain action lengths, leading to high computational costs and delayed detection.

Innovation Solution

An on-line action detection scheme using a recurrent neural network (RNN) with long short-term memory (LSTM) neurons is proposed, which extracts features from current and preceding frames to predict action labels and forecast start and end points of actions, enabling frame-wise recognition and reducing latency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional action detection models observe full actions before detection, then detection accuracy is improved, but detection latency and computational cost increase significantly

Engineering Contradiction:
Improvedetection accuracyVSAvoiddetection latency
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The model performs preliminary feature extraction and processing on individual frames as they arrive, preparing representation information in advance. This allows the system to have detection-ready features available before the complete action sequence is observed, reducing the waiting time for detection while maintaining accuracy through progressive refinement of predictions as more frames become available.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If traditional models wait for complete action observation, then reliable detection is achieved, but real-time processing capability deteriorates

Engineering Contradiction:
Improvedetection reliabilityVSAvoidreal-time processing speed
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The video stream is segmented into individual frames that are processed independently and sequentially. Each frame's representation information is extracted and fed into the RNN model separately, allowing parallel processing capabilities and reducing the bottleneck of waiting for complete action sequences. This segmentation enables real-time processing while maintaining detection reliability through the temporal modeling capabilities of the RNN.

Inventive Principle:
Principle #1Segmentation

3Loss of information

If computational models process entire video sequences, then comprehensive action understanding is achieved, but computational complexity increases

Engineering Contradiction:
Improveaction context understandingVSAvoidcomputational complexity
Core Design Contradiction:
Loss of informationVSDevice complexity

Solution Approach 1:

The model extracts only the essential representation information from each frame using pre-trained convolutional neural networks, separating the feature extraction task from the temporal modeling task. This extraction approach reduces the dimensionality and complexity of input data fed into the RNN, making computational processing more efficient while preserving the critical action-related information needed for comprehensive understanding.

Inventive Principle:
Principle #2Taking out (Extraction)

4Ease of manufacture

If action detection requires fixed observation windows, then processing simplicity is maintained, but adaptability to varying action lengths deteriorates

Engineering Contradiction:
Improveprocessing simplicityVSAvoidadaptability to action length variations
Core Design Contradiction:
Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The RNN model dynamically adjusts its processing to accommodate varying action lengths by maintaining a continuous temporal state that adapts to the actual duration of observed actions. Unlike fixed-window approaches, the RNN can process frames sequentially without predetermined window constraints, automatically adapting to actions of any length while maintaining processing simplicity through its recurrent structure that naturally handles variable-length sequences.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentUS10789482B2On-line action detection using recurrent neural network
Publication Date: 2020.09.29 MICROSOFT TECHNOLOGY LICENSING LLC
  • US10789482B2 patent drawing
  • US10789482B2 patent drawing
  • US10789482B2 patent drawing

AI summary

In implementations of the subject matter described herein, an action detection scheme using a recurrent neural network (RNN) is proposed. Representation information of an incoming frame of a video and a predefined action label for the frame are obtained to train a learning network including RNN elements and a classification element. The representation information represents an observed entity in the frame. Specifically, parameters for the RNN elements are determined based on the representation information and the predefined action label. With the determined parameters, the RNN elements are caused to extract features for the frame based on the representation information and features for a preceding frame. Parameters for the classification element are determined based on the extracted features and the predefined action label. The classification element with the determined parameters generates a probability of the frame being associated with the predefined action label. The parameters for the RNN elements are updated according to the probability.