Audio and Video

CGS 3066

Some Common Audio Formats

Format Use Extension

MIDI instrumental music .mid

MPEG songs .mp3

RealAudio live broadcasts .ra

Wave sound clips .wav

MIDI (slide 1)(Musical Instrument Digital Interface)

-developed in the early eighties to allow synthesizers and other digital devices to communicate with one another. 

- MIDI is a representation of sound -describing

the note and the instrument that renders it 

- Voice and acoustic instruments cannot be recorded in MIDI

MIDI - The Advantages

- MIDI files are significantly smaller than digital audio files

needs less storage space and has a shorter download time

- MIDI files can be edited and rearranged

MIDI - the Disadvantages

Sounds are not uniform system to system:

- Why? because the sound card or playing device of the computer in use defines the sound

- Voice and acoustic instruments cannot be recorded

Places to start for MIDI links

http://www.mididb.com/

http://aitech.ac.jp/~ckelly/midi/good.html

MPEG (Motion Pictures Expert Group)

Established for video

but because of good file compression is often used when transferring whole music recordings (as opposed to clips)

MP3 is the most recent MPEG standard

More on MP3

THE most common sound file format on the Web

No security featuresVery easy to share

Beyond the web: MP3 is also used in car stereos and portable

music players

RealAudio

Designed for real-time playing- like radio

Smaller than au or wav files but quality

Is not as high

WAV

Developed for Windows

One of the most common forms on the web

(but not THE most- that’s MP3)

(Macs use AIFF or SND files)

(unix uses au files)

What’s Required for an Audio File to be played?

- the user's system must have the appropriate plug-in for the audio type (WAV, MP3, etc.) 

- Browsers identify the plug-in to play the audio file

by looking up the file extension in MIME -- (Multipurpose Internet Mail Extensions) in the browser's preferences settings. 

- The user’s server must also be configured to

support the mime type of the audio element.

Some Web Sites with Sound Clips

http://www.earthstation1.com/

http://www.soundamerica.com/

(240,000 clips by category)

http://www.wavcentral.com/

http://www.musicloops.com/

http://www.coolfreebies.com/wav.html

To add audio to your page

Download free audio clips

Right click on the audio link Save as Link

on a Mac: hold down the Ctrl key and click on link. 

To link to the sound clip from your Web page: <a href=“radio.url">listen to this! </a>

(Remember to use the path for the link if it’s not on the current directory)

How to play an audio clip directly from your page

The <EMBED> tag

The full command….

<EMBED SRC=“url” WIDTH=“value” ALIGN=”value” AUTOSTART=“startvalue”

EMBED attributes

Width and height in pixels allows for the size of the controls to be

displayed so the user can play the clip

Align places the controls on the page (default is text

flows below the controls)

Autostart =true means clip starts when page is loaded =false means wait for the user to click

A final word on EMBED

The same parameters can be used to play video clips

Some Common Video Types

Type File extensionAVI .avi *MPEG .mpg or mpegQuickTime .mov

*The latest MPEG, MPEG4, has .avi extension different from this

Some Places to Find Video

http://www.jurassicpunk.com/http://spacelink.nasa.gov/Instructional.Materials/Multimedia/On-Line.Multimedia/Video.Archives/.index.html

To add video to your page

<a href=“video.avi">see this! </a>

Look familiar?

It’s the same technique as audio!

How to play an video clip directly from your page

The <EMBED> tag

The full command….

<EMBED SRC=“yourclip.avi” WIDTH=“value”

AUTOSTART=“startvalue” LOOP=true>

Video EMBED attributes

Width and height in pixels allows for the video to fit the browser window

Autostart =true means clip starts when page is loaded =false means wait for the user to click

Loop =true means the video will play continuously until the

user does something

Some pointers on Multimedia

- Tell users what the file size/download time the clip represents

- If possible, give them more than one option (sample vs whole thing)

And…

Always Make multimedia an OPTION!

Never set up your Web site or e-mail to begin playing audio or video automatically,

This may startle and annoy people

Instead, entice people to fetch the audio with a message such as:

"Click below to hear 5 secrets!" or “Here’s how the experts do it!”