Share the Video

Once a video is created, there are numerous options for sharing the video with students and other educators.

Many digital video cameras can be attached to a television to display the video through the monitor. This is a simple way to share the video within a classroom setting. Other options for sharing a digital video are to master the digital video on CD-R or DVD-R. You can also share the video over the Internet as a downloadable file or a streaming video. I actually recommend a hybrid approach of mastering a gold CD or gold DVD to serve as a backup file, as well as sharing a digital video over the Web.

The benefits of sharing a digital video over the Web is to provide the opportunity for your students and other teachers and students to view the video at any time, from home or within a school or library setting.

The benefits of creating CDs or DVDs are:

1. A website is not required. Many Internet Service Providers will provide a small amount of space for a website within your standard monthly fee. Usually this space is in the range of 10 MB. You will quickly exceed your space limit with digital video, thus requiring you to pay extra for website hosting. Your school may provide space on the school’s server at no extra cost. In contrast, recordable CD and DVD media is quite inexpensive. You can create a single file of fairly high quality that you can share in the classroom or that students can view at home on computers with at least 64 KB of RAM (although 128 KB of RAM or higher is recommended). A CD-ROM has about 700 MB of space and can hold about 45 minutes of VHS quality video (MPEG-1 encoding), while a DVD has about 4.7 GB of space and can store about 2.5 hours of MPEG-2 encoded video. [4]
2. You can provide standardized video of consistent quality without transcoding, editing and compressing for the Web.
3. You have more control over your intellectual property, and also the safeguarding of privacy for participants. Video that can be downloaded over the Web can be copied and reused without your knowledge or authorization.
4. Gold CD-R and DVD-R is a fairly stable medium that can store your video file for at least five years. You should store your CD or DVD in a cool, dry environment and check the video files for errors at least annually.

Sharing via the Web:

One of the significant challenges with digital video is the amount of physical storage required for digital video files. A minute of uncompressed digital video may require more than 500 MB of space. [5]. In addition to storage concerns, the MPEG video standards, in particular, require considerable bandwidth for transport. The 1.5 Mbit/second required for transporting a standard MPEG-1 VHS quality video at 30 frames/second can strain the capabilities of a local area network, particularly when competing for shared bandwidth with other applications. Storage and transport together represent a significant challenge for digital video access over a local area network or across the Internet.

A server is generally employed to store and share a video over a network, since even a few digital video files may quickly overwhelm the ability of an individual workstation to store and share video files. Digital video may be delivered to the viewer’s computer in two ways—streaming or non-streaming. Non-streaming video requires that the entire video be downloaded before viewing. Non-streaming video may reside on any server; video server software is not required to store and serve non-streaming digital video. Non-streaming or downloaded video is an option when the time required for the download process, which can range from several minutes to several hours depending on connection speed and file size, is not an issue for the end user.

Streaming video requires video server and client software. A streamed video begins playback on client software as soon as enough of the video has loaded to begin and sustain playback at a continuous rate. A cache is established from Random Access Memory (RAM) on the client computer and is used to receive the file, insure that frames are in the correct order, establish timing, refresh compressed frames and check for dropped packets. The video file continues to download into the client cache even as the beginning of the video is being viewed. Video streaming is a collaborative effort between the video server and the client software to receive and assemble a video in which all data bits play smoothly, in progressive frame order.

Common streaming video server software, available in both free and commercial applications include the Helix server for Real Video and the Darwin server for Quicktime video files.

Real Video is a streaming video architecture that provides a free downloadable encoder to create RealVideo from digital video files. Real Video can be encoded to support a range of bandwidths by dropping back to a lower data rate or stepping up to a higher data rate, depending on the bandwidth of the client’s Internet connection.

Quicktime is the native file system for Mac. It can be streamed or downloaded. Quicktime can be encoded with several codecs. The highest quality is provided by the Sorenson codec, which is available as a plug in for video editing software such as Media Cleaner Pro.

Microsoft also offers native Windows Media formats for download or streaming. Windows video formats, depending on the operating system in use, include avi (audio video interleave), Video for Windows, and Windows Media Video (wvm)

An emerging standard for video shared over the Web is MPEG-4, which includes multiple simultaneous text tracks, editing of objects within video frames, and many other features. Robust commercial players and MPEG-4 applications are just beginning to emerge.

Digital video must generally be edited to support a range of bandwidths. Bandwidth requirements for streaming video are a function of data bit rate and frame rate. A rule of thumb is to create a digital video file that utilizes a data rate of not more than two thirds of the available bandwidth. Also be aware that not all the bandwidth provided by a device such as a 56 KB modem is actually available for applications. Some bandwidth is reserved for error correction, etc.

Ways to reduce file size and bandwidth requirements include reducing the audio from stereo to mono at 22 KHz or less, reducing the frame rate to 15 frames per second or less, and reducing the frame size to 320 x 240 or 160 x 120. Experiment with various frame rates and frame sizes to find the best tradeoffs for sound quality (audio that does not sound muffled or fuzzy), visual clarity, and smooth, crisp movements.