1 1. Introduction One of the most important elements of multimedia is digital video. The production of digital video always involves specialized software for digitizing and editing sound and moving images.
Special programs often in the form of browser plug-ins may also be required for viewing multimedia. This session is only an introduction to a complex, constantly evolving field. It uses an inexpensive video editing program called QuickTime Pro that is available for both Windows and Macintosh systems.
During this session we will: Manipulate a video segment using QuickTime Pro Save a video segment Link a video segment to web page To accomplish these tasks you should be able to: Install plug-ins Write basic HTML tags Upload files to a WWW server 2. Vocabulary amplitude depth / amplitude resolution - refers to the number of bits available to code each sample. For sound, amplitudes are typically coded with 4, 8, or 16 bits.
For video, it refers to pixel resolution and ranges from 1 bit for bitonal images to 24 bits for full color. bandwidth - generally refers to the total capacity of a network expressed in bits per second. codec - for compressor/decompressor, any technology for compressing and decompressing data.
Codecs can be ... more. less.
implemented in software, hardware, or a combination of the two. A commercial site devoted to information about codecs can be found at http://www.terran.com/CodecCentral/ index.html . compression - the process by which the description of computerized information is modified to so that the information can be stored in less space and transmitted at a faster rate.<br><br> Compression works by eliminating redundant information. It may be lossless , in which information is recovered without alteration after decompression, or lossy , in which the decompressed information is different from the original although the user may not notice the difference. computer animation - displaying on a computer screen a succession of correlated graphics giving a sensation of movement.<br><br> frame - in video, a single complete picture. The number of frames per second influences the perceived quality of the video; the television standard used in the US (NTSC) uses 30 interlaced frames per second. sampling - used to digitize analog information, a technique in which periodic csnapshots d are taken of continuous streams of information.<br><br> If the sampling rate is fast enough, the hearer/viewer can not perceive the gaps between the samples when they are played back. streaming - a way of transferring data so that it can be processed as a steady and continuous stream. This technology is important for the transfer of multimedia files over the Internet because it allows users to avoid long download times for large files.<br><br> When files are streamed, the browser (or plug-in) begins to display the data before the entire file has been downloaded. Contact(s): Curriculum Support Group e-mail email@example.com 368-8600 http://www.cwru.edu/net/csg/csg.htm Information Services Help Desk e-mail firstname.lastname@example.org 368-4357 (HELP) http://help.cwru.edu Editing Video with QuickTime Pro Case Western Reserve University Information Services 2 Editing Video w/ QuickTime Pro Curriculum Support tweening - the essential process of computer animation, this consists of generating intermediate frames between two images so that the first seems to evolve smoothly to the second. 3.<br><br> Hardware and Software The quality of your digital video files depends upon the technical quality of the content. Everyone has seen and heard cdigitally remastered d films and recordings in which old and/or damaged analog origi- nals have been transformed using digital technology. Unfortunately, this is not really possible without high-end equipment and software.<br><br> And, of course, the process begins with professional quality origi- nals. Although many of the tips hold true for all photography, others suggest ways to compensate for the resolution and frame rates commonly used in webbed multimedia. Remember, too, that different video formats (VHS, Hi8, etc.) produce different qualities when digitized.<br><br> Video is digitized using hardware video capture cards. Many Macintoshes have video capture equipment built in. (The video files for this workshop were produced by plugging an 8mm camcorder into the AV ports of a G3.) It is now also possible to use videocameras and digital camcorders to produce digitized multimedia.<br><br> In terms of computing resources, audio-video work justifies the cbigger, faster, better d rule: you will need gigs of hard drive space and the fastest computer you can find. There are even hard drives, sold as cAV d drives, that minimize the number of frames dropped when captured video is written to the hard drive. Digital audio and video files are stored in many different formats, but only some of these are commonly used on the WWW.<br><br> When creating or digitizing sound and video files, remember to save your final product in a WWW-friendly format. Video formats include: ASF - Active Streaming Format, the standard file format of Windows Media files. Video for Windows - (also called cAVI d) Microsoft 9s initial multimedia architecture primarily aimed at CD-ROM video.<br><br> MPEG - Moving Picture Experts Group - often used to refer to the standard file format and set of compression algorithms developed to handle video and audio. MPEG-1 - format which produces high quality video and audio streams at approximately 2x CD- ROM data rates. Standard MPEG-1 is full frame rate (24 - 30 fps, depending on the source) with a quarter size image (352x240), and is useful for playback on most desktop computers.<br><br> MPEG-2 - format which produces high data rate, full broadcast quality files. MPEG-2 playback re- quires an extremely fast computer and video card, or a hardware accelerator card. MPEG-2 is the format for DVD-Video and many home satellite dish systems.<br><br> Standard MPEG-2 is full frame rate (24 - 30 fps) and full screen resolution (720x480). DV - Digital Video, format that is recorded by a digital video camera directly as digital signal, that does not degrade with time, or suffer generation loss. Since Digital Video files are already digitized, they only need to be moved from the camera to the computer.<br><br> QuickTime -a media system developed by Apple Computer that is commonly used to distribute audio and video on the WWW because it is understood by both Macs and PCs and supports most encoding formats. QuickTime Pro is an inexpensive editing system for media files. QuickTime VR is an enhanced version of QuickTime, adding the ability to display and rotate objects in 3D.<br><br> RealVideo -the technology developed by RealNetworks for transmitting video over the Internet. 4. Basic Commands Ò To use the QuickTime Pro editing system, open QuickTime Player.<br><br> (In Windows, Start > Pro- grams > QuickTime > QuickTime Player ). 3 Editing Video w/ QuickTime Pro Curriculum Support Ò Movies and image sequences are created, opened, and saved via the File menu. Other important commands in the File menu are Import (to bring non-QuickTime data into your movies) and Export (to convert your movies to other formats).<br><br> Ò If you have several movies open simultaneously, you may want to go to Edit> Preferences> General to play sound from only one movie. Ò The Present Movie command under File allows you to select the amount of screen space the movie uses. You may also choose to view your movie as a slide show, i.e., to advance frame by frame using the mouse.<br><br> Selecting Present Movie hides everything else on your desktop and shows the movie. You must press the Escap e key to end the presentation. Ò Basic editing functions ( Select All , Cut , Copy , Paste ) are found under Edit and work as they do in any other application.<br><br> 5. Editing Commands Edit Segments To avoid irreparable harm to your carefully digitized video, you should always work with a copy of your movie. QuickTime Pro has limited cundo d abilities.<br><br> To select segments to copy, cut, paste, use in new movies, etc., use the diamond-shaped selector at the bottom of the Movie Player screen. To select only one frame, position the selector on the frame. To select more than one frame, hold down the Shift key as you drag the selector.<br><br> For finer control over your selection, you may click on the left selector or right select at the left of the Play bar and use the arrow keys to move them. The selected portion of the movie will be shown in a dark color on the Play bar. Note : The image that is on the screen once you are done selecting is the frame which the selector is on and has no relation to the actual selection.<br><br> You can cancel a selection at any time by clicking in the play bar or by clicking Select None in the Edit menu. Once you have made your selection, use the Edit menu to Cut or Copy . Play bar 4 Editing Video w/ QuickTime Pro Curriculum Support Other useful editing commands are Clear , Trim , and Replace : Clear deletes the selected portion of a movie.<br><br> It is under the standard Edit menu. Trim clears everything except the selection. To find the Trim command, hold <control>-<alt> in Windows or <option> on a Mac while you go to the Edit menu.<br><br> Bug : in Windows, the Trim command clears the selection! Replace , as its name implies, lets you replace one selection with another. To find the Replace command, hold the Shift key while selecting the Edit menu.<br><br> When you want to make a new movie out of pieces of other material, you need to open a new, blank movie. To do this, go to File>New . This will produce an empty movie.<br><br> You can the use Edit>Paste to place material in this move. You can, of course, paste material into any movie, not just a new one. 6.<br><br> Working with Several Tracks Separating Tracks Separating video and audio tracks--so you can use only the sound, for example-- is easy to do in either of two ways: 1. Extracting a track opens a new movie file containing only the track you want it to. To do this, go to Edit>Extract Tracks .<br><br> Choose a track. A new untitled movie with just the selected track is created. Manipulate this track at your leisure.<br><br> 2. Deleting a track is accomplished by choosing Edit>Delete Tracks and selecting a track. Remem- ber, however, that you may lose the track you delete.<br><br> Merging Tracks You can add material in between other parts of the movie or you can add material on top of other material (tracks) to play concurrently. Edit>Paste places new material between portions of existing material but does not overlap anything. For example, if you extract the sound track, edit it, and copy the whole thing back into the original movie using the Paste command, you will have only sound 4with a blank screen 4followed by the movie--with no sound.<br><br> To overlap tracks, you must use the Edit > Add command. Hold down <control>-<alt> in Windows or <option> on the Mac while you select the Edit menu to see Add . Place the selector at the starting point for the material and choose Add .<br><br> The selection will overlap the existing track. If you want to overlap only a certain segment, select the segment (using shift - selector) you want it to overlap, then hold down <shift>-<control>-<alt> (in Windows ) or <shift>-<option> (on Macs ) and choose Edit > Add Scaled . This will extend or compress the material to fit into whatever segment you selected.<br><br> 7. Adding Text and Stills to Movies 1. Using any text editor (we suggest Notepad for Windows and SimpleText for Macs), write the text you want to import into your movie.<br><br> Remember to save the file as a text file. 2. Then go to File > Import in QuickTime.<br><br> Find the text file, click on Convert , and save it as a converted movie. You will have a text-only movie that can be manipulated as you would any other. An almost identical procedure enables you to import a picture into your movie: 1.<br><br> Go to File > Import , and choose a picture 2. Click Convert , then Save . The new movie with just the picture track will appear.<br><br> Again, manipulate it as you would any other movie. 5 Editing Video w/ QuickTime Pro Curriculum Support 01/22/2001 edtech 8. Saving Movies Go to File > Save .<br><br> For use on the WWW, choose Make movie self-contained . To work with different types of file compression, choose File > Export , select a format from the pull-down menu, and click on the Options button. You may then work with different codecs and frame rates to balance quality and file size.<br><br> 9. Linking QuickTime Movies to Your Web Pages Once you have edited and saved a multimedia file, you can link it to a web page. You can use the following HTML or Netscape Composer.<br><br> Note: Multimedia files are quite large and may take some time to upload. If you have many of these files, you may find it useful to store them in a special directory. In these examples, the directory is called cav d and the format for the links is av/filename.extension.<br><br> HTML Tags for linking multimedia look much like those for any other links using the < a href > tag: <a href= dhttp://starwars.apple.com/quicktime/trailers/fox/episode-i/ trailer_b/menace_480.mov d> Cool Star Wars movie </a> Composer 1. Highlight the image or text that will provide the link to the sound or video file. 2.<br><br> Click on the Link button on the toolbar . The Character Properties (Windows) or Format (Mac) window appears. 3.<br><br> Click on the Link tab and look in the Link to section. 4. In the Link to a page location or local file (Win) or URL (Page Location) or File (Mac) box, type in the URL of the file to which you are linking, or the path name of a local document (if that document is in the same folder as your current one, simply type in the name of the document).<br><br> 5. Click Apply and OK . 6.<br><br> When you view the page in the web browser and click on the link, it should load the video or sound file. 10. For More Information Apple QuickTime Home Page http://www.apple.com/quicktime How to Embed QuickTime in a Web Page http://www.apple.com/quicktime/authoring/embed.html Step by Step guide on using QuickTime Pro http://www.apple.com/quicktime/resources/qt4/us/help/QuickTime%20Help.htm<br><br>