Guidelines on creating videos

Videos are increasingly being used to showcase software. This wiki page provides some recommendations for creating videos for use on the OMII-UK website.

Videos on the OMII-UK website

The OMII-UK policy for dealing with videos is to upload the video to our YouTube channel and then embed the video into the OMII-UK website. This process is described below.

If absolutely necessary, it is also possible to add videos directly to the OMII-UK website. However, this practice is not recommended since it tends to distribute the videos around the website and make it more difficult to keep the content up to date.

Embedding a video from YouTube

The code used to embed a YouTube video is as follows:

%%center
[{Flash src='http://www.youtube.com/v/<Video ID>&hl=en&fs=1' width='650' 
controls='true' play='false' loop='false' border='2'}]
%%

Where <Video ID> is an alphanumeric code used to locate the video. It can be found from the URL of the YouTube video, which follows the format:

http://www.youtube.com/watch?v=<Video ID>

Where <Video ID> is of the form LBIiSZFuqvQ.

Video constraints

What to show?

The most interesting videos generally show people talking about the project or software with which they are involved. However, videos of software demonstrations are also useful. These must be narrated, either by over-dubbing or by overlaying text, so that the viewer understands what the video is attempting to show.

Duration

It is difficult to retain a viewer's attention for more than five to ten minutes, so the duration of a video should reflect this fact.

Videos uploaded to YouTube must be less than ten minutes in duration (and also less than 2Gb in size), meaning that any video lasting longer than ten minutes must be cut into ten-minute long sections.

Screen size

If the video is to be uploaded to YouTube, the screen size is not particularly important, because it will be automatically re-sized during upload.

If the video is to be directly added to the OMII-UK website, the screen width must be less than 700 pixels (i.e. narrower than the full width of the website which is 800 pixels).

Aspect ratio

An aspect ratio of 4:3 is preferred for OMII-UK videos. (YouTube now advocates the use of a 16:9 widescreen aspect ratio, but this format does not display well on the OMII-UK website.)

Recommended formats and codecs

Codec

OMII-UK generally uses the h.264 codec, because it provides good quality compression and is widely available.

Formats

The recommended format for OMII-UK's videos is the same as that recommended for YouTube (see YouTube). Namely:

• .WMV (Windows Media Video)
• .3GP (cell phones)
• .AVI (windows)
• .MOV (mac)
• .MP4 (ipod/psp)
• .MPEG
• .FLV (adobe flash)
• .MKV

Overview of the requirements for producing YouTube videos

1. Duration less than ten minutes
2. File size less than 2Gb
3. Aspect ratio of 4:3 preferred for OMII-UK website
4. File type as described above

Converting video

If possible, avoid video conversion by producing videos in one of the recommended formats. However, if video conversion is necessary, we recommend using the open-source package ffmpeg. It is easy to use and produces very good results.

Software used by OMII-UK for video production

There are many different packages that can be used for video production, editing and conversion. The following packages are the ones used by OMII-UK.

ffmpeg

The open-source ffmpeg tool is a fantastic video resource. It converts video formats quickly and without losing quality, converts images to video and is a quick way to cut long videos to meet the YouTube duration limit. And it's free!

Useful ffmpeg commands

• Get video information

ffmpeg -i [input_file].mov

• Convert video (to a .mov in this example)

ffmpeg -sameq -i [input_file].wmv [outputfile].mov

• Convert images to video

ffmpeg -f image2 -i image%d.jpg [outputfile].mov

• Cut video

ffmpeg -sameq -ss [start_seconds] /
-t [duration_seconds] -i [input_file] [outputfile]

Capturing screencasts

Wink

Wink is a free, easy-to-use, open-source package for producing flash videos (.swf) from a screen capture. The screen is captured as a series of images, which can be over-dubbed with audio narration or overlaid with text narration.

• Note the flash files produced by Wink are a series of images and not a video. For viewing purposes, this makes no difference. However, it does mean that the .swf produced by Wink cannot be converted to other video formats using video conversion software. However, there is a work around:

• Using Wink, export the video as html, which will produce an html file and a folder containing the video as a series of images
• The attached simple script uses ffmpeg to convert the images into video and also allows pauses to be added to individual frames of the video (pauses are used in Wink to allow sufficient time for the user to read narration and the script replicates this functionality)

Jing

Jing is another easy-to-use flash package with both a free and paid-for version.

• Note that Jing limits all videos to under five-minutes in duration.

Video conversion

• ffmpeg. The only video conversion tool you will need.

Video editing

All video editing at OMII-UK is performed using an iMac and its proprietary software iMovie. Similar packages are available on Windows.

Adding a video directly to the OMII-UK website

As discussed above, the preferred way to add videos to the OMII-UK website is to embed a video that has been uploaded to the OMII-UK YouTube channel. However, if absolutely necessary the following procedure can be used to add a video directly to the OMII-UK website.

Only two formats of video can be added directly to the OMII-UK website: swf and flv. The preferred method is to use swf, because it can be added to a wiki page. Adding a .flv video requires the creation of a new jsp page on the website, which is a more involved process.

Adding a swf to a wiki page.

1. Attach the .swf video to the wiki page to which the video will added
2. Go to the attachment and copy the full URL for the video
3. Enter the following code in the wiki page

%%center
[{Flash src='<full URL for video>' width='650' controls='true' play='false' loop='false' border='2'}]
%%

• Note that videos attached to the website must be no greater than 650 pixels in width. In practice, this means that the video must be recorded at 650 in width, because converting a flash video's size inevitably ends up causing significant loss of video quality.

Adding a .flv to the website

An .flv video can only be added to the website by an OMII-UK staff member with login rights to the website server. The process for adding the video is provided on the maintenance page (only viewable by staff members).