I. Introduction
II. Digital media: What is it? Examples.
III. The difference between analog and digital media
A. Analog
1. An analog signal represents an infinite number of smooth gradations
between given levels.
2. Most audio or video content you want to serve-- whether it's
a video tape from a conference, a live video feed from a performance,
or tape from a standard video camera-- exists in an analog format.
3. Traditional devices for playing back analog (such as speakers)
audio use electrical or mechanical means to recreate these infinite
levels
4. However, this introduces "noise" into the signal.
It also means that each time the signal is copied, more noise
is added so the quality of copies degrades.
B. Digital
1. computers operate in the binary world, so these levels must
be assigned numbers in order for the computer to manipulate and
display them.
The more data the computer generates about the original levels,
the more accurate the digital representation will be. Similar
to plotting points on a curve.
The more data, the more storage space and processor power is
required.
Digital files can be copied infinite number of times without
degradation because no noise is introduced.
iV. Compression
A. Removing data from a file to make it smaller. Uncompressed
video can require up to 20MB/s. Uncompressed audio files can require
up to
B. Compression can be done several ways
1. temporally - by tracking changes from frame to frame of
the file over time
2. spatially - by generalizing large homogenous areas of the
file instead of descibing each pixel of that area individually
3. filtering - removing data that is not vital to presenting
the data; for example, inaudible frequencies in MP3 files.
V. Helix Producer
VI. Tips for improving your digital audio/video
A. Source media
1. format: varying quality, VHS tapes are the lowest, Beta
tapes the highest.
2. DV is becoming a more frequent option.
3. Creating vs. "repurposing" content.
B. Camera technique and/or things to beware of when using pre-existing
content:
1. Short cuts rather than pans or zooms will translate into
better digital video.
2. Well lighted, but not sharply lighted (soft lighting is
best).
3. Simple backgrounds rather than complex details. If background
is complex, situate subject far enough in front so the background
blurs.
4. Transitions, fades, fast panning don't translate well on
low-end computers or connections.
5. Pictures of images (video of a screen or slideshow) and
subtitle are generally too small/blurry to be useful.
C. Other considerations:
1. Look for compelling subject material- don't put up video
just to do it..
2. Consider whether video and audio are necessary, or if audio
alone will serve the purpose.
3. Consider what is practical given your audience's network
access.
VII. Next Steps: Publishing Streaming Media
