Graphics, Audio & Video

ACS 367

Sources:http://members.home.net/chris.bagwell/

AudioFormats-3.html

Computer Graphics Picture, drawings, illustrations, clip

art, and animations can help to explain or exemplify the text included in your interface.

Pictures File size File format (PNG, JPG) Image resolution

72DPI for screen 400 or higher DPI for printed artwork

Drawings File Format (PNG, GIF)

PNG (10k)

GIF (6k)

Problems with JPG

Emphasized

Animation Animation can describe two-dimensional

(2D) or three-dimensional (3D) objects. processes, or phenomena in ways not possible in the "real world".

Animation can describe events or processes that cannot be easily videotaped such as global networks, biochemical processes, or prehistoric ecological systems.

Animation may be better suited than video for portraying sensitive or complex events. For example, showing a car part assembly process in animation provides a clearer, more focused view than videotaping the process with all of the other parts an associated dirt and grime in the way.

Audio Researchers at MIT 's Media Lab have

found sound to be more important than once thought-even in visual media.

In tests with identical televisions, unknowing test subjects consistently choose the television with the best sound system as having superior picture.

Audio – Things to consider Sound effects can provide

humorous or serious punctuation to events and content in a project, but use them wisely and sparingly.

Products full of sound cues can often frustrate or annoy the user. Experiment with different effects and

choose those that capture the mood or trigger the reaction you desire.

Sound Morphing Sound morphing, if used carefully, can

be an appropriate effect. Sound morphing combines two or more

sound objects to create a blend with elements of each. For example, words in a poem can be

morphed to give them an onomatopoetic effect that sounds like what they describe. The phrase "Water drips and drops" can be morphed with sounds of water dripping to color the phrase with the sound.

Sounds & Music Well chosen sounds can verify or reinforce

user actions. Sounds can alert the user to new conditions or

convey information. Music can be an emotional and alluring

enhancement to a project. It can be used for ambient background sounds or

be a prominent focal point of a project. The model for music in many multimedia projects

is how music is used in film making. Sweeping, engaging music has long been used in movies to draw in an affect the audience.

Text-to-speech processing offers a workable but not always aesthetic or natural solution for generating voice.

Synthesizing speech as needed rather than storing sampled voice data may save disk space, but the quality may not meet requirements for a particular project. Synthesized speech tends to sound tinny,

artificial, and robot-like.

Audio Inclusion Do not design audio cues to interfere

with reading from the text and vice versa. To be most effective, audio and text should

complement, not compete with, each other. Users generally prefer not to have to

read long text passages off a screen. Do not put a lot of text on a single screen. Research data indicates that users find it

easier to complete lessons which use audio extensively to present information.

If audio is used, provide users with headphones. Users in a lab environment will not be

distracted by the audio from other user stations if headphones are provided.

Experiment with different voice actors, ages, genders, accents, and intonations. Be sure to choose final voice styling that

reflect the content, the audience, and the project's purpose which in turn should be communicated clearly to the voice talent.

Audio File Formats Audio data is characterized by the

following parameters, which correspond to settings of the A/D converter when the data was recorded. Naturally, the same settings must be used to play the data. sampling rate (in samples per second), e.g.

8000 or 44100 number of bits per sample, e.g. 8 or 16 number of channels (1 for mono, 2 for

stereo, etc.)

Audio requirements When digitizing your sounds,

sample them at 44.100 KHz

Stereo CD quality requires a 16 bits sample size

22.050 KHz 11.025 kHz

Popular sampling rates

5500 One fourth of the Mac sampling rate (rarely seen).

7333 One third of the Mac sampling rate (rarely seen).

8000 Exactly 8000 samples/sec is a telephony standard.

11 k or 11025 a quarter of the CD sampling rate, or half the Mac

sampling rate (perhaps the most popular rate on the Mac).

16000 Used by the G.722 compression

standard. 18.9 k

CD-ROM/XA standard. 22 k Either 22050

half the CD sampling rate, or the Mac rate; the latter is precisely 22254.545454545454 but usually misquoted as 22000.

32000 Used in digital radio, NICAM (Nearly

Instantaneous Compandable Audio Matrix [IBA/BREMA/BBC]) and other TV work, at least in the UK; also long play DAT and Japanese HDTV.

37.8 k CD-ROM/XA standard for higher quality.

44056 This weird rate is used by professional audio

equipment to fit an integral number of samples in a video frame.

44100 The CD sampling rate. (DAT players

recording digitally from CD also use this rate.)

48000 The DAT (Digital Audio Tape) sampling rate for domestic use.

Self-Describing File Format

Headerless File Format

Video The inclusion of video sequences could

significantly improve the user's consistency in the decision making process (Vila, et all, 1995).

Video can be used to teach by example and show processes that are difficult to describe in text.

Video – Things to consider Depending on the subject matter, video

can more easily cross linguistic and cultural boundaries. Video can be used to communicate to a wider audience than text or speech can reach.

Video can also be an effective means of communicating to hearing or learning impaired people.

Video – Things to consider To establish visual orientation, present

video in three-shot sequences (long, medium, and close-up).

To grab student's attention and imply that something is important, use close-up shots.

When showing something new, focus on the subject long enough for the audience to register what is being shown.

The eye focuses on lighted instead of dark areas and movement instead of static images.

Shooting Video Always consider the hiring of professional

videographers or video production house to shoot the video sequences for you.

Use subdued colors for all of your set's backgrounds and talent's attire.

Highly saturated colors such as red or blue will reduce the overall quality of a digitized video.

Video – Things to consider Make sure that the lighting of your set is

even. The subject you are focusing on should neither

be washed out or in a shadow.

Think about the size of your video window when shooting. You may want to capture a slight tighter shot

than normal to compensate for the smaller viewing area you will be working with inside your computer.

Video – Things to consider Keep your camera movements smooth and

stay away from too many pans or zooms. If you will be digitizing your video at 15 frames per second (fps) excessive camera movements may cause the shot to look jittery.

Use high quality audio. Most consumer cameras come with a mounted microphone. However, if the audio information on your video is important to you it is best to buy a microphone that clips onto your talent's lapel or sits very close to the original sound source.

Video – Things to consider Use audio and video to reinforce each other.

Design a visual message appropriate to the content and make sure that each visual ties in directly to the accompanying audio.

Never present two unrelated or clashing pieces of information at the same time. Presenting unrelated or clashing information or

an inappropriate visual will often confuse the user.

Video – Things to consider Use special effects to enhance video footage

that otherwise may be in poor or ordinary condition. For example, rotoscoping, a technique that converts

video into outline drawings that can appear as animation. Morphing is another effect that creates the impression of one or more images being transformed into another.

Use still frames if production resources are limited or there are storage limitations with hardware.