将使用计算机摄像头捕获的视频从网站发送到服务器

Question

我正在尝试让计算机或安卓设备从摄像头录制视频并将其发送到将存储它的服务器。该系统必须是基于网络的，并且需要连续发送视频片段。

这是javascript中的代码：

var camera = (function() {
    var options;
    var video, canvas, context;
    var renderTimer;

    function initVideoStream() {
        video = document.createElement("video");
        video.setAttribute('width', options.width);
        video.setAttribute('height', options.height);

        navigator.getUserMedia = navigator.getUserMedia || navigator.webkitGetUserMedia || navigator.mozGetUserMedia || navigator.msGetUserMedia;
        window.URL = window.URL || window.webkitURL || window.mozURL || window.msURL;

        if (navigator.getUserMedia) {
            navigator.getUserMedia({
                video: true
            }, function(stream) {
                options.onSuccess();

                if (video.mozSrcObject !== undefined) { // hack for Firefox < 19
                    video.mozSrcObject = stream;
                } else {
                    video.src = (window.URL && window.URL.createObjectURL(stream)) || stream;
                }

                initCanvas();
            }, options.onError);
        } else {
            options.onNotSupported();
        }
    }

    function initCanvas() {
        canvas = document.getElementById("canvas");//options.targetCanvas || document.createElement("canvas");
        canvas.setAttribute('width', options.width);
        canvas.setAttribute('height', options.height);

        context = canvas.getContext('2d');

        // mirror video
        if (options.mirror) {
            context.translate(canvas.width, 0);
            context.scale(-1, 1);
        }

        startCapture();
    }

    function startCapture() {
        video.play();

        renderTimer = setInterval(function() {
            try {
                context.drawImage(video, 0, 0, video.width, video.height);
                options.onFrame(canvas);
            } catch (e) {
                // TODO
            }
        }, Math.round(1000 / options.fps));
    }

    function stopCapture() {
        pauseCapture();

        if (video.mozSrcObject !== undefined) {
            video.mozSrcObject = null;
        } else {
            video.src = "";
        }
    }

    function pauseCapture() {
        if (renderTimer) clearInterval(renderTimer);
        video.pause();
    }

    return {
        init: function(captureOptions) {
            var doNothing = function(){};

            options = captureOptions || {};

            options.fps = options.fps || 30;
            options.width = options.width || 640;
            options.height = options.height || 480;
            options.mirror = options.mirror || false;
            options.targetCanvas = options.targetCanvas || null; // TODO: is the element actually a <canvas> ?

            initVideoStream();
        },

        start: startCapture,

        pause: pauseCapture,

        stop: stopCapture
    };
})();

var imgSender = (function() {
    function imgsFromCanvas(canvas, options) {
        var context = canvas.getContext("2d");
        var canvasWidth = canvas.width; //# pixels horizontally
        var canvasHeight = canvas.height; //# pixels vertically
        var imageData = context.getImageData(0, 0, canvasWidth, canvasHeight); //Vector of all pixels
        options.callback(canvasWidth, canvasHeight, imageData.data);
    }

    return {
        fromCanvas: function(canvas, options) {
            options = options || {};
            options.callback = options.callback || doNothing;
            return imgsFromCanvas(canvas, options);
        }
    };
})();

var FPS = 30; //fps
var minVideoTime = 5; //Seconds that every video clip sent will take
var arrayImgs = []; //Array with all the images that will be sent to the server
var videoTime = 0; //Number of seconds of video stored in videoTime
(function() {
    var capturing = false;

    camera.init({
        width: 160,
        height: 120,
        fps: FPS,
        mirror: true,

        onFrame: function(canvas) {
            imgSender.fromCanvas(canvas, {
                callback: function(w,h,image) {
                    arrayImgs.push(image);
                    videoTime += 1/FPS;
                    if (minVideoTime <= videoTime) {
                        sendToPhp(w,h,videoTime*FPS);
                        arrayImgs = [];
                        videoTime = 0;

                        function sendToPhp(width,height,numFrames) {
                            $.ajax({
                                type: "POST",
                                url: "sendToServer.php",
                                data: {
                                    arrayImgs: arrayImgs,
                                    width: w,
                                    height: h,
                                    nframes: numFrames
                                },

                                async: true, // If set to non-async, browser shows page as "Loading.."
                                cache: false,
                                timeout:500, // Timeout in ms (0.5s)

                                success: function(answer){
                                    console.log("SUCCESS: ", answer);
                                },
                                error: function(XMLHttpRequest, textStatus, errorThrown){
                                    console.log("ERROR: ", textStatus, " , ", errorThrown);                             }
                            });
                        }
                    }
                }
            });
        },

        onSuccess: function() {
            document.getElementById("info").style.display = "none";

            capturing = true;
            document.getElementById("pause").style.display = "block";
            document.getElementById("pause").onclick = function() {
                if (capturing) {
                    camera.pause();
                } else {
                    camera.start();
                }
                capturing = !capturing;
            };
        },

        onError: function(error) {
            // TODO: log error
        },

        onNotSupported: function() {
            document.getElementById("info").style.display = "none";
            document.getElementById("notSupported").style.display = "block";
        }
    });
})();

如您所见，我正在使用 getUserMedia 来获取视频，并且我正在对数组中的图像进行采样，直到获得 5 秒的视频，然后我将其发送到一个 php 文件，该文件将其发送到服务器。

我的问题：所有 ajax 请求都有很多延迟，而且我也有大小问题，ajax 请求不会同时接受这么多数据，所以我有以降低 fps 和发送视频的长度。

有没有更好的方法来做到这一点？到目前为止，我丢失了超过 50% 的视频！也许是通过 WebRTC？请帮忙

谢谢！

Answer 1

对于您的用例，您应该使用MediaRecorder API。这将允许您将视频记录为 WebM 块，您可以在后台上传到服务器。 WebM/VP8（或 mp4）在压缩视频方面比您现在使用的 ad-hoc MJPEG 做得更好。

另请参阅RecordRTC，其中包括尚未实现此功能的浏览器的兼容层等。