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PHP camera calling skills: How to implement multi-camera switching

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Aug 04, 2023 pm 07:07 PM

CameratransferMultiple camera switching

PHP camera calling skills: How to implement multi-camera switching

Camera applications have become an important part of many web applications, such as video conferencing, real-time monitoring, etc. In PHP, we can use various technologies to call and operate the camera. This article will focus on how to implement multi-camera switching and provide some sample code to help readers better understand.

Basic of camera calling

In PHP, we can call the camera by calling the JavaScript API. Specifically, we can use the <video></video> tag and the navigator.mediaDevices.getUserMedia() method to access and operate the camera.

The following is a simple sample code to capture video data through the camera and display it on the page:

<!DOCTYPE html>
<html>
    <head>
        <script>
            function start() {
                navigator.mediaDevices.getUserMedia({ video: true })
                    .then(function(stream) {
                        var videoElement = document.getElementById('video');
                        videoElement.srcObject = stream;
                    })
                    .catch(function(error) {
                        console.error('Error accessing the camera:', error);
                    });
            }
        </script>
    </head>
    <body>
        <button onclick="start()">Start</button>
        <video id="video" autoplay></video>
    </body>
</html>

By calling the navigator.mediaDevices.getUserMedia() method And passing the { video: true } parameter, we can get the video data stream from the camera, and then assign it to the srcObject of the <video></video> tag property to display the video on the page.

Realize multi-camera switching

To implement multi-camera switching, we first need to obtain a list of all available camera devices on the system, and then switch between different cameras through the user's selection camera.

The following is a sample code that demonstrates how to implement the multi-camera switching function:

<!DOCTYPE html>
<html>
    <head>
        <script>
            function start() {
                navigator.mediaDevices.enumerateDevices()
                    .then(function(devices) {
                        var videoDevices = [];
                        devices.forEach(function(device) {
                            if (device.kind === 'videoinput') {
                                videoDevices.push(device);
                            }
                        });
                        
                        var selectElement = document.getElementById('devices');
                        videoDevices.forEach(function(device) {
                            var optionElement = document.createElement('option');
                            optionElement.value = device.deviceId;
                            optionElement.text = device.label || 'Camera ' + (selectElement.length + 1);
                            selectElement.add(optionElement);
                        });
                        
                        selectElement.onchange = function() {
                            var deviceId = selectElement.value;
                            navigator.mediaDevices.getUserMedia({ video: { deviceId: deviceId } })
                                .then(function(stream) {
                                    var videoElement = document.getElementById('video');
                                    videoElement.srcObject = stream;
                                })
                                .catch(function(error) {
                                    console.error('Error accessing the camera:', error);
                                });
                        };
                    })
                    .catch(function(error) {
                        console.error('Error enumerating devices:', error);
                    });
            }
        </script>
    </head>
    <body>
        <button onclick="start()">Start</button>
        <select id="devices"></select>
        <video id="video" autoplay></video>
    </body>
</html>

In this example, we first call navigator.mediaDevices.enumerateDevices() Method to get a list of all devices available on the system. Then, by filtering out the devices whose kind is videoinput, we save the camera device object to the videoDevices array.

Next, we dynamically create a <select></select> tag and add the camera device as an option to this drop-down list. When the user selects a different camera, switch to a different camera by calling the navigator.mediaDevices.getUserMedia() method and specifying the deviceId of the selected device.

Note: In some browsers, the navigator.mediaDevices.enumerateDevices() method may need to be accessed in a secure context (i.e. via HTTPS protocol or localhost ) to work properly.

Conclusion

By using PHP to call the camera and achieve multi-camera switching, we can add more functions and interactivity to the web application. This article introduces basic camera calling techniques and provides some sample code to help readers gain a deeper understanding. I hope readers can understand and apply it to their own projects through this article, and further expand the application scenarios of camera calling.

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