HTML5 video 上传预览图片视频如何设置、预览视频某秒的海报帧

当一收到上传图片视频并可以动态设置视频显示的海报帧的需求时，主要想的是怎么样解析视频并获取保存每帧的图片，百度出来的大多是类似下面这种需要播放video并点击截图的，或者是用php ffmpeg扩展，跟需求不一致，有点抓狂了，然后就先做了视频图片的预览功能，进而对设置海报帧换了种思路，通过输入设置video开始播放的时间，取消自动播放和控制条，这样用户看到的就是一张图片

/*预览*/
              $('.qtuploader__items').on('click', '[name="viewVideoPicBtn"]', function() {
    var parent = $(this).closest('.qtab__page');
    var video = $(this).closest('.qtuploader__itemsbd').find('video');
    var srcStr = '', htmlStr = '';
    if($(this).siblings('.qtuploader__picinputbox').hasClass('is-error')){
      $.fn.toast({
        'parentDom': parent,
        'classes': 'isorange',
        'top': '0',
        'spacing': 0,
        'toastContent': '请设置正确范围的海报帧',
        'autoHide': 3000,
        'position': {
          'top': '5px',
          'left': '50%'
        }
      });
      return;
    }
    if (video.length > 0) {
      var thumbHeight = setSize(video)[0];
      var thumbWidth = setSize(video)[1];
      srcStr = video.attr('src');
      htmlStr = '
';
    }
    parent.append(htmlStr);
    parent.find('.qtuploader__view video')[0].currentTime = $(this).siblings('.qtuploader__picinputbox').find('.qtuploader__picinput').val();
    parent.find('.qtuploader__view').fadeIn();
  });
  /*设置海报帧预览时间*/
  $('.qtuploader__items').on('keyup', '.qtuploader__picinput', function() {
    var parent = $(this).closest('.qtuploader__picinputbox');
    var video = $(this).closest('.qtuploader__itemsbd').find('video');
    var strVal = $.trim($(this).val());
    console.log(strVal)
    if (strVal == '') {
      parent.addClass('is-error');
      parent.find('.qverify__font').text('请设置海报帧');
    } else if (!(/^[0-9]*$/.test(strVal))) {
      parent.addClass('is-error');
      parent.find('.qverify__font').text('请输入数字');
    } else if (video.length > 0 && strVal > video[0].duration) {
      parent.addClass('is-error');
      parent.find('.qverify__font').text('不超过(' + video[0].duration + ')');
      console.log('111---' + video[0].duration)
    } else {
      parent.removeClass('is-error');
      parent.find('.qverify__font').text('请设置海报帧');
    }
  })
  /*关闭预览*/
  $(document).undelegate('.qtuploader__mask', 'click');
  $(document).delegate('.qtuploader__mask', 'click', function() {
    $(this).closest('.qtuploader__view').fadeOut('normal', function() {
      $(this).closest('.qtuploader__view').remove();
    })
  })
  /*设置预览大小*/
  function setSize(element) {
    var thumbWidth = 0, thumbHeight = 0, arr = [];
    var winWidth = $(window).width(), winHeight = $(window).height();
    var imgWidth = element.width(), imgHeight = element.height();
    if (imgWidth > imgHeight) {
      thumbHeight = parseInt(winHeight - 200);
      thumbWidth = parseInt((1920 * thumbHeight) / 1080);
    } else {
      thumbHeight = parseInt(winHeight - 200);
      thumbWidth = parseInt((1080 * thumbHeight) / 1920);
    }
    arr.push(thumbHeight, thumbWidth)
    return arr;
  }