updateSequence, updateSequence

Load SlowFast Video Classifier

sf = slowFastVideoClassifier();

Setup Video Player and Video Reader

Specify the video file name to stream video frames.

videoFilename = "pushup.mp4";

Create a VideoReader to read video.

reader = VideoReader(videoFilename);

Setup a video player.

player = vision.VideoPlayer;

Classify Video Sequences

Specify how frequently the classifier should be applied to incoming video frames.

classifyInterval = 10;

A value of 10 balances runtime performance against classification performance. Increase this value to improve runtime performance at the cost of missing actions from the video file.

Obtain the sequence length of the SlowFast Video Classifier. Classify only after capturing at least sequenceLength number of frames from the video file.

sequenceLength = sf.InputSize(4);

Read video frames using the hasFrame and readFrame functions of the VideoReader. Using the updateSequence function update the video classifier's sequence. Using the classifySequence function classify the updated sequence.

numFrames = 0;
text = "";

while hasFrame(reader)
    frame = readFrame(reader);
    numFrames = numFrames + 1;

    % Update the sequence with the next video frame.
    sf = updateSequence(sf,frame);

    % Classify the sequence only at every classifyInterval number of frames.
    if mod(numFrames, classifyInterval) == 0 && numFrames >= sequenceLength
        [label,score] = classifySequence(sf);
        text = string(label) + "; " + num2str(score, "%0.2f");
    end
    frame = insertText(frame,[30,30],text,'FontSize',24);
    step(player,frame);
end