How to force a 16:9 ratio with getUserMedia on all devices?

When using the getUserMedia API, ensuring that video streams maintain a 16:9 aspect ratio across all devices can be achieved by specifying the ideal resolution. Here is a specific example demonstrating how to set the requested video stream resolution to a 16:9 aspect ratio.

Example Code

The following is a JavaScript example demonstrating how to request a 16:9 video resolution when using getUserMedia:

javascript
// Define the desired video aspect ratio
const aspectRatio = 16 / 9;

// Set the configuration parameters for `getUserMedia`
const constraints = {
    video: {
        aspectRatio: aspectRatio,
        width: { ideal: 1280 },  // Set the ideal width
        height: { ideal: 1280 / aspectRatio }  // Calculate the ideal height based on the 16:9 ratio
    }
};

// Call `getUserMedia` and handle the Promise
navigator.mediaDevices.getUserMedia(constraints)
    .then((stream) => {
        // Obtained the video stream; bind it to a video element for display
        const video = document.querySelector('video');
        video.srcObject = stream;
    })
    .catch((error) => {
        console.error('Failed to get video stream:', error);
    });

Analysis

In this example, I first define the desired aspect ratio aspectRatio as 16:9. Then, within the constraints object, I specify the video stream parameters. Here, I use the aspectRatio property to enforce the video stream to maintain a 16:9 aspect ratio. Additionally, I specify an ideal resolution using the width and height properties with the ideal attribute to expect a video output close to this resolution.

Notes

• Device Compatibility: Not all devices or browsers can precisely support specific resolutions or aspect ratios, so ideal is used instead of exact to allow the browser to fulfill the request as closely as possible when exact matching is not feasible.
• Error Handling: In practical applications, appropriate error handling should be implemented for the getUserMedia call to handle cases such as user denial of permission requests or device incompatibility with the specified configuration.

By using the above method, you can enforce a 16:9 video aspect ratio across different devices, enhancing user experience.