Using Multimedia on the Web

•Using Multimedia on the Web
•Enhancing a Web Site with Sound, Video, and Applets
•Objectives
•Working with Multimedia
•Working with Audio
•Linking to an Audio Clip
•Embedding an Audio Clip
•Objectives
•Working with Video
•Linking to a Video Clip
•Embedding a Video Clip
•Using a Dynamic Source
•Supporting Non-Embedded Elements
•Objectives
•Introducing Java
•Working with Applets
•Creating a Marquee with Internet Explorer
•Working with the Object Element
•Working with Multimedia
•Bandwidth is a measure of the amount of data that can be sent through a communication pipeline each second
–Consider bandwidth when working with multimedia on a Web site
•Working with Multimedia
•Multimedia can be added to a Web page two different ways:
–External media is a sound of video file that’s accessed through a link
•Useful for a low bandwidth
–Inline media is placed within a Web page as an embedded object
•Working with Multimedia
•Working with Audio
•Every sound wave is composed of two components:
–Amplitude- the height of the wave. Amplitude relates to the sound’s volume (the higher the amplitude, the louder the sound).
–Frequency- the speed at which the sound wave moves. Frequency relates to sound pitch (high frequencies have high pitches).
•Working with Audio
•Sampling Rate, Sample Resolution, and Channels
•Sound waves are analog functions (represent a continuously varying signal)
–To store the information, however, it must be converted to pieces of information.
•Digital recording measures the sound’s amplitude at discrete moments in time
–Each measurement is called a sample
•Samples per second taken is called the sampling rate
•Sampling Rate
•Sampling Rate, Sample Resolution, and Channels
•Sampling resolution indicates the precision in measuring the sound within each sample
–8-bit
–16-bit
–32-bit
•Sample Resolution
•Sample Rates and Resolution
Sampling rate and sample resolution as
related to sound quality:
Sampling Rate and Sample Resolution Sound Quality
8 KHz, 8-bit, mono Telephone
22 KHz, 16-bit, stereo Radio
44 KHz, 16-bit, stereo CD
48 KHz, 16-bit, stereo Digital Audio Tape (DAT)
•Sound File Formats
•There are different sound file formats used for different operating systems
•Different file formats provide varying levels of sound quality and sound compression
•Sound File Formats
•WAV
•Nonstreaming media
•Streaming media
•MIDI
•Sound File Formats
•MP3 is a version of the MPEG format, which compresses audio files with minor impact on sound quality
–One controversy around the MP3 format involves copyrighted material that has been copied as MP3 without the permission of the artist or producers
•Sound File Formats
•Nonstreaming media must be completely downloaded by users before being played
–May produce lengthy delays
•Sound File Formats
•Streaming media are processed in a steady and continuous stream as they are downloaded by the browser
–Both sound and video
•Sound File Formats
•MIDI (Musical Instrument Digital Interface) converts an analog signal to a series of functions describing the pitch, length, and volume of each note
–MIDI format is limited to instrumental music and cannot be used for general sounds, such as speech
•Linking to an Audio Clip
•Embedding an Audio Clip
•An embedded object is any media clip, file, program, or other object that can be run or viewed from within a Web page
–Browsers need the appropriate plug-ins to run embedded objects
•Embedding an Audio Clip
(Internet Explorer and Netscape)
To embed a sound or video clip, use the
embed element:
"height=“value” autostart=“type” />"
Where url is the location of the object, the width and height
attributes specify the width and the height of the object in pixels,
and type is either true (to start the clip automatically when the page
loads) or false (to start the clip manually).
•Playing Background Sounds
•Internet Explorer (with Version 3.0) introduced an element to play background sounds:
loop=“value” volume=“value” />
Where url is the URL of the sound file, the balance attribute defines
how the sound should be balanced between left and right
speakers, loop defines how many times the sound clip is played,
and the volume attribute indicates the background sound volume.
•Working with Video
•Video files add a visual element to a Web page as well as provide information
•Video files are composed of a series of single images called frames
•The number of frames shown in a period of time is the frame rate
•Frame Rates and Codecs
•Reducing the frame rate reduces the size of your file
–This is one way to control file size of video files
•Using a Codec (compression/decompression) is another way to control the file size

•Video File Formats
•Linking to a Video Clip
•Follow the same procedure to link a video clip as you would to link a sound clip
–Include information about the size of each video file so that users can determine whether they want to retrieve the clip
•Embedding a Video Clip
•Use the same embed element to embed a video file as you did to embed a sound clip
–You must specify a source for an embedded video clip with the src attribute and a size for the clip using the height and width attributes
•Using a Dynamic Source
•To turn inline images into dynamic video clips, use the following syntax:
"loop=“value” control=“control” / />"
Where the dynsrc attribute specifies the URL of a
dynamic (video) version of the inline image. The start attribute tells
the browser when to start the clip, the loop attribute specifies the
number of times the video will play, and the control attribute
specifies whether IE should display player controls below the inline
image to start and stop the video clip.
•Supporting Non-Embedded Elements
•If you want to support older browsers, you can add the noembed element
•The noembed element works like the noframe element for frames, providing a way to support older browsers that do not recognize embedded objects
•Using Non-Embedded Content
To provide alternate content for browsers that don’t support embedded objects, use the code
""
"" <br /> alternate content <br />""
where alternate content is the content displayed by browsers that don’t support embedded objects
•Introducing Java
•Oak was developed by Sun Microsystems as an operating system intended to be used by common appliances and devices
•Oak was renamed Java in 1995
•HotJava runs programs written in the Java language
–HotJava is a Java interpreter (it understands and runs Java languages)
•Applets and Java Interpreters
•Applets
•Applets are displayed as embedded objects on a Web page in an applet window
•Use a Java Developer’s Kit (JDK) to write your own Java applet
•Compiling changes the file into an executable file that can run by itself without the JDK
–The executable file is called a class file
•Working with Applets
•Inserting a Java Applet
•To insert a Java applet, use the code



…

Where file is the name of the Java class file, text is the
name of an applet parameter, and value is the parameter’s
value.
•Creating a Marquee with Internet Explorer
•An alternative to using an applet to create a box with scrolling text is to create a marquee element
content
Where attributes is one or more of the marquee
elements, and content is the page content that appears
in the marquee box.