Guide to Submitting a Video as Supplementary Material
This guide provides information for preparing a supplementary digital video for submission to any of the CHI venues where videos are accepted. For submissions to the video showcase, please see the Video Showcase Call for Participation.
A submission that includes a supplementary digital video must not exceed 100 MB in total size (paper + video) for it to be included in the ACM Digital Library.
We strongly suggest an MP4 encoding using the H.264 codec for your digital video submission. Most video editing software provides an exporting option to MP4/H.264 (for example, iMovie, Adobe Premiere, Camtasia, and Final Cut Pro can all export to MP4/H.264). If you prefer to use free software, x264 can encode any video into H.264. If you compress your video with unusual software or codecs you risk the possibility that reviewers will not be able to watch your video, and it may need to be re-encoded for the ACM Digital Library. CHI does not accept software applications or digital video clips requiring a specific computing platform or additional software to play.
We strongly recommend using a 16:9 aspect ratio. Encode your video using square pixels for the pixel aspect ratio to avoid your movie looking stretched when projected.
Supplementary video figures do not have a specified limit, although we recommend staying within 5 minutes.
Please remember to review the meta-data properties of your digital file. For submission to an anonymized venue, all meta-data that could identify the authors should be removed. The camera-ready version of your video submission should contain a title slide with the title, authors, and affiliations.
Authors retain copyright to videos, but ACM requires that you sign an agreement allowing ACM to distribute the material.
Suggestions for Creating a Successful Video Figure
This section contains guidelines and hints for those who are new to video production, particularly in creating videos for CHI. None of the following suggestions are required reading.
Organization and Structure
There are many ways to organize a video presentation, just as there are many ways to write prose. You should select a theme for the video and present the research in a way that contributes to this goal. It is generally not a good idea to simply show all the features of your system; you should identify what is novel and interesting. Emphasize the problems or issues being addressed. Present the concepts and principles upon which the work is based. Always clearly state the status of what is being shown. If you are simulating any aspect of the system, be sure to mention this.
Your video should be understandable by itself; you should not assume that the viewer has read your printed submission. Therefore, most videos will need a short introduction explaining the goals and context of the work. Your video should also be understandable to viewers who are not familiar with the subject.
Videos require much more planning and preparation than most people think. Before recording begins, prepare a detailed script of the video, including a written version of any voiceover text at each scene. A common and often effective strategy for videos that use voice narration is to record the entire narration at a comfortable pace, leaving gaps in the audio for important visual transitions, and fit the video accordingly. This is not how one would record a feature film, but it’s a very effective strategy for research videos that can simplify the process.
Once you’ve written a voiceover script, find someone who doesn’t understand what you do and make your presentation to them, just like you were practicing a talk. Incorporate their feedback before you record your voiceover.
Exposition and Presentation
The expository style of your video presentation will greatly affect its impact. Use both video and audio. Always explain what is about to happen or what is most interesting: as the narrator, tell the viewer where to look and what to look for. Visual aids, such as callouts, annotations and captions, can help orient the viewer. Make your point once, and make it effectively; avoid being repetitive.
When appropriate, seek a variety of images: switch between face, screen, hands, and slides to keep the viewer’s interest. If possible, start out with an establishing shot, which shows the context of the subject and/or group. This might be a wide shot of the group in a meeting room, a split-screen shot of users in different locations, a wide shot of a meeting participant at the computer or of the entire computer screen. This helps the viewer stay oriented. Periodically return to an establishing shot to prevent viewer confusion.
Pay attention to the background and colors; the eye is drawn to the most brightly colored part of the scene; make sure the brightest point is the point of interest. Carefully consider lighting and make sure that there are no distracting shadows, especially on faces (a common occurrence with overhead lighting).
Avoid visual distractions, such as idly moving the mouse in a screen-captured video.
Fades to black can be used as transitions between scenes, but they should not be overused. A full screen fade usually indicates a change in subject, time or place, and can be confusing when used elsewhere.
Video is different from a lecture or a demonstration. A recording of a live demonstration will often appear too slow. A large number of sudden cuts may create too fast a pace. And please remember that your digital video will be accessed by an international audience, so speak clearly and more slowly than is natural to successfully convey your message.
Your video need not employ professional actors, although you may wish to use professional readers to obtain the best audio results. Usually the most realistic and convincing advocate of an idea is the person responsible for the work being reported. Whoever provides voice content should speak naturally, and should not appear to be reading.
Record in the highest possible quality and resolution, even though you will compress the final video. Maintain the quality of the original recording throughout the editing process; leave compression to the last step.
Keeping the camera stable and level is vital. Tripods are a low-cost way to get the most out of your camera; use a tripod whenever possible. Remember that camera jiggles are more apparent in telephoto shots; take extra care in zooms and close-ups.
Lighting makes a huge difference in perceived quality. For indoor recordings, if you have access to a diffuse light source, use it. Avoid overhead lights that cast shadows in the scene, and avoid light sources that are directly visible to the camera. Lighting for video is closely related to lighting for photography, so if you have friends who are hobbyist photographers, ask them for advice on how they might light a scene.
Audio quality is as important as image quality to the overall impact of your video. Try to avoid recording the noise of computer fans and disks. It is generally better to record the audio separately, by doing a voice-over in a studio or other quiet room.
A decent-quality microphone will make a huge difference in your recording quality relative to a typical computer microphone. A large-diaphragm condenser microphone will generally be best for recording voiceovers, and nearly any university A/V expert or hobbyist musician will have one; borrow one if you can (musicians respond well to free food). Even if you choose to buy a microphone, you don’t need to spend hundreds of dollars to get a quality condenser microphone; the cheapest large-diaphragm condenser microphone you can find will likely provide a huge benefit in audio quality relative to your desktop, laptop, or phone microphone.
Avoid holding a microphone in your hand while recording; support it with a microphone stand. A hand-held microphone will inevitably lead to uneven volume in the recording.
If it is important to hear key clicks or computer audio output (beeps), record these on a separate audio track, and mix them with the voice-over in your editing software. Similarly, if you are adding music to the video, place it on a separate track, so it will be easy to fade out music when narration begins, etc.
Recording Computer Screens
Because of incompatibilities of resolution, refresh rate, and interlacing, it can be difficult to get good shots of computer screens on video. As such, we highly recommend recording video of a computer screen using screen capture software, such as Camtasia.
If you are using screen capture software, make sure that it is able to capture the screen at a satisfactory frame rate and does not affect the performance of your application. Most software can capture the whole screen or a specific area such as a window. Since performance is often affected by the size of the area being captured, you should try to focus the capture on the area of interest. This will also reduce the artifacts if you later compress and rescale the image. Finally, remember that screen capture only captures the screen (!): you may want to add wider shots taken with a camcorder to show the user interacting with the system; you should also consider adding click sounds when the user clicks the mouse to make such interactions more explicit (some capture software can do that automatically).
Raw analog or digital footage can be 1 gigabyte per minute in data size. Editing digital video generally requires twice the disk space as the video itself. Choose what you want to preserve carefully when editing, and compress your video as a final step.
Test your video for usability just as you would any other product. You can start off by testing your script with colleagues and friends. Is it interesting and understandable? Next you may want to storyboard your video. Do the cuts and transitions make sense? Can you visualize how it will look? As well as being useful for usability testing, the storyboard should be an important part of your planning process. A storyboard is a great stage at which to test with colleagues and friends again, since the most time-consuming aspect is likely video capture and editing, and you’ll save yourself a great deal of headache if you solicit feedback before shooting.
Finally, to ensure that your digital video file will play on a variety of computers and mobile devices.