Using PHP to Capture Camera Video and Perform Emotion Recognition

Camera devices are ubiquitous, and recognizing human emotions via camera is challenging, but AI advances make it feasible. This article explains how to use PHP to control a camera, capture video frames, and analyze facial expressions for emotion detection.

1. Preparation

Install the PHP GD extension and V4L2 utilities on a Linux system.

sudo apt-get install php7.4-gd
sudo apt-get install v4l-utils

2. Getting the video stream

Use PHP's shell_exec to run an FFmpeg command that captures a single frame from /dev/video0 and saves it as an image.

<?php
function getVideoStream() {
    $cmd = "ffmpeg -i /dev/video0 -vf fps=1 -s 1280x720 -f image2 -frames 1 /path/to/image.jpg";
    shell_exec($cmd);
    return "/path/to/image.jpg";
}
$videoStream = getVideoStream();
echo "<img src='$videoStream'>";
?>

3. Emotion recognition

Integrate the open‑source Fer2013 facial‑emotion model by invoking a Python script from PHP.

<?php
function getEmotion($imagePath) {
    $modelPath = "path/to/Fer2013/model.hdf5";
    $cmd = "python3 scripts/emotion_classification.py $modelPath $imagePath";
    $emotion = shell_exec($cmd);
    return $emotion;
}
$emotion = getEmotion($videoStream);
echo "Current emotion: $emotion";
?>

4. Full example

The combined script captures a frame, runs emotion classification, and displays both the image and the detected emotion.

<?php
function getVideoStream() {
    $cmd = "ffmpeg -i /dev/video0 -vf fps=1 -s 1280x720 -f image2 -frames 1 /path/to/image.jpg";
    shell_exec($cmd);
    return "/path/to/image.jpg";
}
function getEmotion($imagePath) {
    $modelPath = "path/to/Fer2013/model.hdf5";
    $cmd = "python3 scripts/emotion_classification.py $modelPath $imagePath";
    $emotion = shell_exec($cmd);
    return $emotion;
}
$videoStream = getVideoStream();
$emotion = getEmotion($videoStream);
echo "<img src='$videoStream'>";
echo "当前的情绪：$emotion";
?>

Running this example shows a live camera snapshot on a web page and prints the inferred emotional state, providing a starter guide for integrating camera‑based emotion recognition into PHP projects.