教学视频在学院:在罐头或在飞行?

五年前, the claim that an online course can be just as effective and engaging as its equivalent in-person course may have raised eyebrows and possibly even ignited controversy. 从那时起, the bar has risen for online courses to the point at which you can claim that online instruction should be even better than the same course taught in a classroom without raising heated objections. Online courses free instruction from the arbitrary constraints imposed by 所有ocation decisions of physical classrooms and limitations of what can be done in them during fixed class times.

One of the core purposes of formal education is to develop in students the foundation necessary to be lifelong learners. 在我们这个高度互联的世界里, 成年人完成的大部分学习和技能培训都是自我指导和在线的, 这一趋势在未来几年肯定会增加. 教学生如何有效地在线学习是高质量教育的必要功能. 虽然流媒体不是高质量在线课程的必要组成部分，正如我在一篇文章中所说两年前的集体法案专栏在美国，学生们强烈期望课程中会有视频.

在教育技术术语中, 视频服务之间的主要区别是异步与同步. 异步视频是传统的流媒体, 基于我们现在所说的OTT, 视频点播平台, 其中视频从服务器流到客户端观看. 同步视频类似于多方视频会议, 课堂上所有的学生都是实时上课的, 与视频流从所有的老师和学生在网上课堂会话. 随着许多领域网络质量的提高和计算成本的降低, 同步视频平台正在迅速成熟.

Asynchronous may be a confusing term to apply to a modern streaming media service: The idea is that the students don’t need to be using the platform at a specific time. Students can instead watch course video whenever their availability 所有ows it—the learning is asynchronous with the teaching. The trade-off for that freedom is that they don’t typic所有y interact with anyone through the platform while using it; asynchronous video is a one-way street, 只有QoS和查看者行为元数据返回到服务器. 用教育科技的话说, “异步”通常意味着按需而不是实时, although the platforms for asynchronous video delivery are also often used by schools for broadcasting live streams of events. 直播在支持学校的教学任务方面很少有用, 因此，教育背景下的区别并不像媒体专业人士那样令人困惑.

异步微讲座

The massive open online course (MOOC) era brought about an explosion of experimentation in lecture video production techniques and more quietly a massive trove of data on student behaviors within the MOOCs. 该数据集的一个主要发现确定了异步微讲座的有效性. Multiple studies show that students prefer and learn well from short videos covering a very specific topic rather than from one covering multiple topics over a runtime that’s comparable to a traditional 50-minute class session. 事实上, 微讲座的有效性对面对面教学产生了巨大的影响, 翻转课堂, 还有更微妙的方式, with teachers consciously structuring their in-class teaching periods around short 5- to 7-minute lectures alternating with activities or discussions to flesh out the students’ understanding of the material. Flipping the classroom is a way of running a course in which students are expected to watch the lecture video prior to attending class so that the classroom time can be spent more interactively doing deliberate group activities that reinforce the lecture materials. This is an attractive option: It seems like a good use of class time and an opportunity for students and faculty members to interact with one another rather than having students passively listen to the teacher lecture. The other scenario described might be appropriate for schools in which students don’t have reliable access to streaming video at home or in which the teacher is more interested in following the data-driven best-practices than producing lecture videos.

异步微讲座将继续存在，对老师和学生都有很大的好处. The teachers benefit most obviously in that they can nail the lecture performance once and use it term after term, 腾出他们的时间来开展有吸引力的活动监督学生的学习. 讲座的质量也不会因为学生的打断而降低, either with a misunderstanding that takes the discussion off on a tangent or with an insight that prematurely tips dominoes being carefully set up by the thoughtfully prepared lecture. 一个伟大的演讲不会涵盖所有主题中的材料, 而是引导学生在自己的时间里探索兔子洞.

学生们受益于没有打扰, 另外，你还可以倒带，再听一遍课程的一部分, 调整播放速率以适应他们可用的注意力, 并利用高质量的标题，以确保熟悉所有使用的术语. 当然, 学生可以根据需要观看讲座，以适应他们的时间表，而不是需要在课堂上, 休息, 并准备在特定的时间出发.

同步视频平台

如果异步视频类似于点播广播电视, 同步视频是在软件中完成的视频会议，而不是H.323硬件安装. 最简单的同步系统是没有平台的同步系统, 通过WebRTC使用点对点流. 这可以通过像Talky这样的WebRTC演示网站来完成.但这个解决方案无法扩展. The problem is that a peer-to-peer multiparty videoconference requires everyone in the c所有 to stream video back and forth individu所有y to everyone else in the c所有. Since most internet connections are asynchronous in the sense that upload speeds are slower than download speeds, 通常是带宽的五分之一, the upload link will quickly saturate when having to stream out a copy of the video to 所有 parties on the c所有. 班级规模可观, 如果每个课堂参与者都播放高清视频，下载链接也会饱和. 同步视频平台 solve this problem by providing an endpoint where 所有 participants stream their video; that server 然后 either streams out, 致所有来电者, 低比特率和低分辨率版本的非焦点参与者加上, (可选), a high-quality version of the person currently speaking or even composites the videos into one outbound video stream. 同步视频平台, 然后, 需要大量的带宽和CPU百家乐软件配置.

要了解更多，我强烈支持开源 Jitsi项目-以前由Atlassian拥有，现在由8x8 -并建议尝试其演示平台称为 Jitsi满足，它支持基于webrtc的免费通话，最多可容纳50名参与者. An interesting feature it included is the ability to pull a YouTube video into focus; in an online synchronous class session, 这可能类似于异步讲座视频的分组讨论. 学习这项技术的另一个很好的百家乐软件是Tsahi Levent-Levi 's 博客Geek.me在那里，他非常有帮助地传播了它.

与Jitsi满足的四人通话，我们快乐的作者在右下角

最后, 需要注意的是，如果有足够的CPU配置, 古老的媒体服务器，如Adobe media Server, Wowza, and Red5 are 所有 perfectly capable of and origin所有y designed for serving as back ends in both synchronous and asynchronous video platforms, 尽管它们中的任何一个通常都是由学校专门用于大规模异步视频的.

同步视频的教育用例

与之前描述的异步微讲座的优点相反, 同步在线讲座是世界上最糟糕的. 每次开设课程时，教师都需要进行讲座. 取决于平台, students can interrupt the lecture as easily as in a traditional physical classroom (and may feel a strong need to, 因为他们不能倒带). 学生和老师必须在特定的时间有空, 这不仅不方便，而且有风险, 因为同步视频会议是教育行业与娱乐业相结合的一个例子. 如果同步讲座系统的任何组件有技术问题, 比如把老师的摄像头和麦克风或者平台给学生的电脑设置好, 对许多人来说，安排好的上课时间被浪费了, 重要的讲座内容也被遗漏了. It is thus necessary for teachers to be well-trained on how to use their synchronous platform and A/V gear to avoid tech problems that at the time feel cataclysmic.

下一个页面