Transcript ppt file
Audio and Video CGS 3066 Some Common Audio Formats Format MIDI MPEG RealAudio Wave Use instrumental music songs live broadcasts sound clips Extension .mid .mp3 .ra .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 features Very 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 AVI MPEG QuickTime File extension .avi * .mpg or mpeg .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.M aterials/Multimedia/OnLine.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!”