Video, video, every where,
Devices for you and me;
Video, video, every where,
But none that we can see.

Flip cameras. Cell phones. DVDs. iTunes. Netflix. YouTube. We get video from many sources these days. We shoot our own clips, we buy movies online, and we convert our videotapes into digital form. Video is everywhere. But it doesn't always work. We want the video to play on all of our devices: computers, tablets, and mobile phones; but it doesn't. We want to post it online for our students to view, but that seldom works universally.

Of all the types of materials destined for student learning, videos and podcasts present the toughest usability issues. We are frustrated when the video we get on one device won't play on another, or when we post it online for our students but only a few of them can see it. Or when we create an original video with our brand new camera and find that the file is so large that it won't fit on our computer. This week's article looks past the huge file sizes profusion of formats to make some concrete recommendations for making digital video useful for teaching and learning.

Goal

We want to make our videos and podcasts accessible, playable and usable for all of our students on all platforms: desktop, laptop, and mobile. We want the videos to arrive safely and swiftly to the users; we want them to play well on whatever device is in their hands; and we want the quality to be adequate to the educational purpose. After helping dozens of schools and colleges wrestle toward this goal, we have arrived at these five considerations for working with video online.

Considerations

File Format

We should publish video and podcasts in the ISO open standard MPEG-4 format, unless it is impossible to do so. Using non-standard, proprietary formats is asking for trouble. Best results ensue by compressing your video into the format agreed to by the International Standards Organization and designed by the world's best video engineers. That standard is called MPEG-4, which stands for Motion Picture Experts Group, the aforementioned engineers recognized by the ISO. Any device can be made to display MPEG-4 videos. Any other format is proprietary, and should not be used: AVI, WMV, FLV, SWF, and so forth. Follow the MPEG standard, and use the H.264 codec for video, and AAC for audio.

Video Display Size

We should publish each video and podcast at a display size no bigger than it needs to be to convey the information. 320x240 pixels at a minimum; 800x600 maximum. Anything bigger won't fit onto the screens of most users, and will create enormous files. A Flip camera shoots video at 1920 by 1080 pixels, much more than necessary for educational work; the display size of a standard laptop computer, or an iPad, is 1024 by 768 pixels; of the best mobile phones 480 by 360. Most of the videos we use for educational purposes provide little additional benefit by adding more pixels than necessary. We need to compress our videos to a proper useful size before we post them.

Frame Rate

We should publish video materials at a frame rate no faster then necessary to convey the information. 12 frames per second is adequate for most educational material. Unless you are capturing fast-motion events, the normal 30 frames per second is unnecessary; your students will not notice the difference. And you will reduce the file size by more than half if you compress your videos to 12 fps.

Data Rate

We should keep the data rate of a multimedia file as low as possible to convey the necessary information. Most educational material can be compressed to a data rate of less than 500 kbps, which is suitable for delivery through the school network as well as to our students at home. Data rate is a function of display size, frame rate, and compression type; reducing all of these to their optimal values as described above should get your frame rate down to something useful online, with swift delivery over the network, and reasonable file size.

Streaming Method

We should publish our media files in the fast-start download format for files less than 50 Megabytes, and for anything that's copyable to mobile media. We should use the open-standard RTSP hinted streaming format for larger files or copyright material. Unless the material is copyright fair use, we should publish it in such a way as to allow students to download it onto a mobile device.

Compressing your videos

How do we get our videos into the optimal format for use online? Schools have produced good results with two software tools: QuickTime Pro, and MPEG Streamclip.

with QuickTime Pro

1. Download and install QuickTime 7, a $30 program for compressing video files, on WIndows or Mac. Get it from http://www.apple.com/quicktime/extending/index.html

2. Copy your video file from your camera to your computer.

3. In QuickTime, choose from the menubar File --> Open File.

4. Open your video file.

5. Choose File --> Export from the menubar.

6. Choose Export: Movie to QuickTime Movie.

7. Click the Options button.

8. In the dialog box, make the settings look like the picture below. They are:

• Compression: H.264
• Quality: High
• Limit Data Rate: Automatic
• Frame rate: 12
• Sound: AAC
• Frame Size: 320 x 240 up to 800x600
• Fast Start: check
• All other settings: defaults

9. Click the OK button on the lower right.

10. Save this compressed video file to a place on your computer that you will remember.

11. This will create a compressed file ready for uploading to the video server.

with MPEG Streamclip

1. Download and install MPEG Streamclip, a free program for compressing video files, on Windows or Mac. Get it from http://www.squared5.com/

2. Copy your video file from your camera to your computer.

3. In MPEG Streamclip, choose from the menubar File --> Open Files.

4. Open your video file.

5. Choose File --> Export to Quicktime from the menubar.

6. In the dialog box, make the settngs look like the picture below. They are:

• Compression: H.264
• Limit Data Rate: 400 Kbps
• Sound: MPEG-4 AAC
• Frame Size: 320 x 240
• Fast Start: check
• All other settings: defaults

7. Click the Make Movie button on the lower right.

8. Save this compressed video file to a place on your computer that you will remember.

9. This will create a compressed file ready for uploading to the video server.

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From The Rime of the Ancient Mariner
by Samuel Taylor Coleridge

Water, water, every where,
And all the boards did shrink;
Water, water, every where,
Nor any drop to drink.