当我在将视频上传到服务器之前尝试获取屏幕截图并将其另存为PNG时,我遇到了以下问题

我希望你能解决我的问题......
/*Output image show view*/
$('#file_browse').change(function(e){
getVideo(this);
});
var capbtn = document.querySelector('#video_capture');
var video = document.querySelector('video');
var canvas = document.querySelector('canvas');
var context = canvas.getContext('2d');
var w, h, ratio;
video.addEventListener('loadedmetadata', function() {
ratio = video.videoWidth / video.videoHeight;
w = video.videoWidth - 100;
h = parseInt(w / ratio, 10);
canvas.width = w;
canvas.height = h;
}, false);
capbtn.addEventListener("click", function(){
context.fillRect(0, 0, w, h);
context.drawImage(video, 0, 0, w, h);
var objImageData = canvas.toDataURL("data:image/png;");
});
function getVideo(input) {
if (input.files && input.files[0]) { …Run Code Online (Sandbox Code Playgroud)