3
The New Desktop Software

The meteoric progress of desktop computing would never have happened without the catalyst of the user-friendly graphical user interface offered first on the Macintosh and later on the Windows PC. Had the capabilities of desktop machines remained cocooned within the DOS shell, with its blinking C: prompt and its arcane commands, the desktop would have remained the domain of the anorak.

Since the dawn of the GUI and its trusty companion, the mouse, progress has been signposted by a succession of landmark software developments. Early among these were word-processors like Microsoft Word and WordPerfect, spreadsheets like Lotus 123 and Excel, graphics applications like Illustrator and Freehand and DTP applications like Aldus Pagemaker and Quark XPress.

For desktop video to flourish in a similar way, it was first necessary for Apple and Microsoft to add to their respective operating systems the necessary video infrastructure and this they did – in the form of Apple’s Quicktime and Microsoft’s Video for Windows.

With the video infrastructure in place, in a close historical parallel to the evolution of DTP, developers of software for both the Mac and the PC platforms are now offering video editing applications which have borrowed heavily from their high-end professional antecedents to offer desktop users a dazzling array of features and special effects.

The different categories of software are described below:

Video and Audio Capture

Software required to capture video and/or audio clips so that these can be stored on the computer’s hard drive for later use may be provided as part of a videoediting application, may be bundled with a video or audio digitising board or may be sold as a stand-alone application.

Video Capture

Figure 3.1 shows an example of a simple video capture utility – Microsoft’s VidCap – which is supplied with Pinnacle Systems’ digitising boards. With a video source connected to the input socket of the digitising card, live video appears in the VidCap screen. Using the controls provided, individual images or complete video sequences can be captured and stored on disk by using the following procedure:

1  Connect the video source to the capture board

2  Configure the frame size and video source options (e.g. Composite or S-Video, PAL or SECAM)

3  Set up the capture file (file name and hard drive destination) and set options for the video sequence (duration and compression ratio)

4  Click on Capture/Single frame to capture the frame being displayed in the Preview window or click on Capture/Video to start the capture of a video sequence

Before capture is initiated, VidCap’s Video Settings dialog box (Figure 3.2) may be used to adjust the appearance of the image. The effect of using any one, or a combination of, sliders to adjust Brightness, Contrast, Saturation or Sharpness can be previewed in the image displayed in the capture window.

As well as features similar to those provided by VidCap, MediaStudio’s capture utility (Figure 3.3) provides the ability to play back the video which has been captured in the preview window. A set of VCR-like controls is provided to manipulate existing or newly captured clips. When capturing, the Play button changes to Freeze . This freezes the video source on one frame, but continues to play in the background. Clicking again on the Freeze button displays the video in the current position. With an MCI (Media Control Interface) device connected to the video source. Video Capture can be used to control the video source directly using the buttons on the VCR toolbar. Creating a selection from a video sequence becomes a simple matter of clicking on the Mark In and’ Mark Out buttons in the control bar

When the video source is LANC-controlled, the capture utility provided with Pinnacle Systems’ Studio 200 includes VCR or camcorder deck transport controls and an Auto-Grab button (Figure 3.4). The Auto-grab is useful for capturing a specific frame from tape when the source deck does not have a clean pause mode; clicking the Set button while viewing the moving image in the preview window button sets the grab time for the required frame; clicking on Seek causes the deck to rewind to the desired frame and, finally, clicking on Grab rewinds the tape to a time shortly before the grab time, then plays the tape and captures the desired frame ‘on the fly’. Another useful feature of Studio Grabber is its ability to capture full colour single frames at a resolution of 1500 × 1 125. Figure 3.5 shows the result of capturing a frame at this resolution, converting it to greyscale and saving it at 300 dpi. The inset shows the good distribution of grey levels retained in the captured image.

Adobe Premiere also supports the control of any device with an MCI device driver. With a controllable device, clips can also be viewed in the dialog box shown in Figure 3.6 and logged with reference to their timecode and then digitised.

Whichever capture utility is to be used, to obtain the best quality result requires some pre-planning. In general, a video board using hardware JPEG compression will produce the smoothest results. CPU availability should be maximised during capture by turning off all unnecessary applications and TSR utilities. Capture should ideally be to the fastest, defragmented, hard drive on the system.

Audio Capture

Audio is an important component of many media productions. Like video, analogue sound must be digitised, or sampled, to be used on the desk top (Figure 3.7). Digitising analogue sound breaks it up into discrete frequencies. Before digitising begins, the audio recording level must be set to avoid distortion and then a setting must be selected to determine the audio resolution or quality. The quality of digitised audio and the size of the audio file depend on the sampling rate and bit depth of the audio. The sampling rate, similar to the frame rate for digitising video, measures the number of frequencies into which the sound is subdivided. The bit depth, similar to colour depth, measures the number of tones per sample. The higher the sampling rate and bit depth, the better the sound quality.

Some video digitising boards incorporate audio capturing hardware; otherwise, a separate sound card will be required to capture audio clips. Video and audio can then be captured simultaneously from a source like a camcorder by connecting Video Out and Audio Out to the video digitising board and sound board respectively. In other cases, sound in the form of a voice-over or a music clip may be captured separately for later synchronisation with video.

Sound ‘LE (Figure 3.8a) is a simple sound utility from Creative Labs which has the ability to record sounds from a range of sound sources and save them as WAV files. The sound source – e.g. a midi-compatible keyboard, an audio CD player, a line input signal from a camcorder or a microphone – is first selected from the companion utility shown in Figure 3.8b and then recording begins when the record button is clicked.

For both types of capture, options which determine the quality (and size) of the audio files are selected from a dialog box like the one in Figure 3.9. The quality of digitised audio and the size of the audio file depend on the sampling rate and bit depth of the sample. These parameters determine how accurately the analogue audio signal is reproduced when it is digitised. Audio sampled at 22 kHz and 16-bit resolution, for example, is far superior in quality to audio sampled at 11 kHz and 8-bit resolution. CD audio is normally digitized at 44 kHz and 16-bit resolution.

Video Editing Applications

Once video and audio clips have been digitised and saved on disk, applications like MediaStudio or Adobe Premiere offer the user the means of arranging these clips in the required sequence, trimming them to length, inserting sophisticated transitions between clips and adding titles. The means are also provided of superimposing tracks and implementing other special effects.

Construction and Integration

The first purpose of a video editing application is to allow the user to import and arrange video, audio or still image clips into a construction window, where they can be ordered into a logical sequence, or timeline. Figure 3.10 shows an example of MediaStudio’s construction window containing two video clips on video tracks Va and Vb, a still image clip on track Va and an audio clip on audio track Aa. When saved as a video project file, then previewed, using the Preview command from within the View menu, video clip (a) will play before video clip (b), which will play before the still image clip, i.e. the x-axis represents time within the construction window. The audio file will begin to play at the same time as video clip (a) and will continue to play over video clip (b) and then over the still image file, terminating at the end of the still image clip. Additional clips can be added to the appropriate tracks within the construction window in order to build up more complex projects.

Transitions

If the end of clip (a) was aligned vertically to coincide with the start of clip (b) then playback would result in an abrupt transition from one clip to the other; the effect of the ‘Bar-Push’ transition clip placed on track Fx between the overlapping ends of video clips (a) and (b) is to add a smoother and more visually interesting transition between the end of clip (a) and the start of clip (b). The ‘Box-Stretch’ transition clip provides the same function between clip (b) and the still image clip. MediaStudio provides a total of thirty-five transitions arranged into twelve categories. The Transition Effects menu (Figure 3.11) provides a dynamic thumbnail for each transition type which demonstrates how the transition will appear when applied to a video clip.

The way in which a transition interacts with an underlying video clip can be edited in MediaStudio by double clicking on a transition clip in the construction window to open the Transition Options dialog box shown in Figure 3.12. The Sample window in the box displays the selected transition effect. Clicking on the scroll bar activates a preview of the transition. The Transition buttons determine whether clip (a) fades to clip (b) within the transition interval, or vice-versa. The Border command may used to specify the size and colour for a border at the edges of the transition. Other controls permit editing of the softness of the transition edges, the degree of completion of the transition effect at the start and end frames, arrow keys control the direction of the effect. In the Sample window shown in Figure 3.12, the box is opening from the centre to reveal and overlay the still image of the sailing boats over video clip (b) of a fireworks display.

Tools

Reflecting the experience gained from many years of developing digital still photoediting applications like Adobe Photoshop or Corel PHOTOPAINT, videoediting applications are supplied with a range of sophisticated tools for the manipulation of video and audio clips within the construction window. Deployment and description of these tools varies from developer to developer as each seeks to find an optimum configuration, but the functions provided are broadly similar. Figure 3.13 shows the principal tools provided with MediaStudio.

In addition to these, the Display Mode tool activates the dialog box shown in Figure 3.14 which provides options for the display of video and audio clips in the construction window, the Project Window tool opens the dialog box shown in Figure 3.15 which provides thumbnails and information relating to each clip within the current project, and the Library Window tool opens the dialog box in Figure 3.16 which provides access to a library which can be used to store regularly accessed video or audio clips.

At any stage of the construction work, clicking on the Preview button opens the window shown in Figure 3.17 and choosing View/Preview initiates a live, low resolution, preview of the work in progress. The length of a video clip can be trimmed by clicking on the Trim button which opens the window in Figure 3.18 showing the end frame and the adjacent one for the currently selected clip. The mark-in and mark-out frames can be chosen visually by dragging the end point for the clip.

Video projects can become very complex, consisting of many files and different effects. To assist in project management, as well as the Project Window and the Clip Library, MediaStudio provides cues as a means of marking significant points within the project. There are two types of cue; project cues appear in the bottom of the ruler and can apply to any part of a project; clip cues can only be assigned to video or audio clips, appearing in the cue bar below the track occupied by the clip. The Video Scratch Pad (Figure 3.19) can be used to create, edit and view named cues within any video clip. As well as marking significant points in a project, cues can also be used, for example, to synchronize an audio, overlay, or special effect with another track. The Audio Scratch Pad (Figure 3.20) provides a similar facility for setting named audio cues. The Image Scratch Pad (Figure 3.21) is provided for viewing and changing the length of an image clip.

All the commands for working with project cues are available from the Cue Manager command in the View menu. Cue times and names appear in the Cue Manager dialog box (Figure 3.22). In a complex project, the Go To key provides an easy way of finding a specific event within the project.

Although differing in detail from those of MediaStudio, the construction windows and tool sets offered by Adobe Premiere and Corel Lumiere are similar in function. Premiere’s construction window, shown in Figure 3.23, with two video clips, an image clip, two transition clips and an audio clip laid out on the timeline in the same configuration as we saw in MediaStudio’s construction window (Figure 3.10). Premiere also provides a Project window which displays thumbnails and information about the clips being used in the active project, a Transitions window from which transition clips can be dragged and dropped into the transition track, a Clip window for selecting and trimming individual clips and a Preview window for displaying a movie of the project at any point in its construction.

The toolbar appears at the bottom left of the construction window; Figure 3.24 summarises the function of the tools.

Corel Lumiere’s construction window, shown in Figure 3.25, again shows a set of video, transition, still and audio clips laid out along the time line. The Media Catalog window serves the same purpose as the Project windows in MediaStudio and Premiere, providing a registry of all files in use, but it also doubles as a library window, like that of MediaStudio, with the help of the file tools at the top of the window.

Lumiere’s tools are shown in Figure 3.26. Most have functions similar to those described for MediaStudio, but others need some explanation.

The speed tool is used to change the speed of a clip by adjusting its duration. Dragging either edge of a clip with this tool adjust the speed of all the frames contained within the duration of the clip. Shortening the duration of a clip will increase its speed and vice-versa.

The virtual clip tool creates a virtual clip (a single clip which points to, or represents, all the clips in a segment of a movie) by dragging over a section of the active project. The virtual clip is placed on either a video track or a superimpose track in the construction window.

The sound wizard accesses a sound editing facility which will be explained later.

The transparency tool changes the transparency settings for the selected clip. The use of transparency will be explained later.

Titles

All of the applications described in this chapter provide the means of adding an impressive range of titles to a project. Figure 3.27 shows MediaStudio’s Insert Title Clip dialog box; title text is typed into the window in the bottom left of the dialog box and attributes can be set using the menus and buttons provided; a sample window shows how the text will appear. Clicking on the Effects tab opens the options shown in Figure 3.28. Clicking on the Opaque button activates the Background option which can be used to place a colour matte behind the title.

A title clip placed on a normal video track (Va or Vb in MediaStudio) will show the title by itself against a default white background, which can be changed to a colour matte. A title clip placed on a video superimposition track (e.g. V1 in MediaStudio), on the other hand, will appear superimposed over an underlying video clip. Figure 3.29 shows two examples; an introductory title clip on track Va displays ‘Isle of Man Tourist Trophy’ in white text on a solid black background, while a second title clip on track V1 displays ‘YAMAHA 1000 cc Privateer’ superimposed on the video clip of the motorcyclist on track Va (see the overlay effect in the Preview window in Figure 3.30).

Adobe Premiere’s Title dialog box (Figure 3.31) provides a simple tool set which can be used to create title clips containing type, straight lines, and various geometric shapes. Premiere automatically assigns anti-aliased alpha channels to type and graphics generated in the Title window. As in MediaStudio, a full-frame matte of a solid colour can be created as a background, for example, for scrolling titles or credits.

Corel Lumiere provides an even more comprehensive range of titling options. Opening the Titler menu activates the titling toolset shown in Figure 3.32. As well as the obvious tools, the toolbar includes tools for editing the points on polylines, adding shadows, and adjusting the transparency of objects in the title clip relative to the underlying video clip. By default the backdrop for the Titler is white, but the white backdrop can be replaced with a frame from a video clip. Text and objects in the Titler will then appear superimposed on the videoframe selected by placing the Time Marker in the timeline above the chosen frame. Figure 3.33 shows an example in which the title ‘Digital Video’ has been superimposed, in white, on a track from the clapper board clip entitled ANESUMM.AVI in Figure 3.25.

Special Effects

After video and audio clips have been assembled in the construction window of one of our video editing applications, and transitions have been placed in position and title clips added, a number of special effects are available to add further interest to the finished result.

Adding Motion

One of the most advanced features found in the new video editing applications is the moving path. Moving paths can be applied to video clips to make them follow two dimensional paths or to flip, rotate or spin in three dimensions; paths can also be used to zoom in or out, or to create fast or slow motion effects.

As explained earlier (Figure 3.13), five of the buttons on MediaStudio’s toolbar are used to activate motion filters. A motion filter is used to impart movement to a clip – e.g. to cause the text credits at the end of a project to scroll from the bottom to the top of the screen while the movie is playing. Moving paths can be applied to any clip in a video track and can add visual interest to a project. Uses include creating moving pictures from still images – for example, a car moving across the screen – or producing multiple-image screens.

Figure 3.34 shows the dialog box for MediaStudio’s simplest motion filter, the 2D Basic Moving Path. Figure 3.35 shows the function of the editing tools provided within the dialog box. In the preview window at the top of the dialog box, ‘S’ and ‘E’ denote the Start and End points of the path and the video clip, to which the path is being applied, can be seen midway between the two. Either or both Start and End points can be outside the field of view (as in Figure 3.34) or inside the field of view.

Width and Height controls are provided for adjustment of the clip dimensions and the X and Y controls determine the horizontal and vertical locations of the selected control point within the frame. Changes to the frame dimensions apply only at the reference point where the clip is located when the changes are made, so by altering the frame size from point to point, zoom in or zoom out effects can be created as the clip traverses a path. If the Start and End points are dragged to overlap at some point within the field of view, and if the Start width and length are made small compared to the End width and length, then the clip will appear to zoom from a fixed position as the clip plays.

The nine handles in the Reference Point box in the lower right hand side of the dialog box relate to the same nine points within the video clip; clicking one of these specifies the reference point on the frame for movement along the path. If required, colour, stroke width and softness can be specified for a border around the edges of the clip. Once created, paths can be saved for later reuse.

The 2D Advanced Moving Path ‘motion filter adds the possibility of rotating a clip either at rest or as it traverses along a path, as well as the option to distort the clip, for example to introduce a perspective effect as shown in Figure 3.36. The angle of rotation is set either using the thumbwheel or by entering a value in the Rotate window. In the Distortion window, the handles can be dragged independently to alter the clip dimensions.

Figure 3.37 shows just the extra controls available in the dialog boxes which appear when the 3D Path (a), 3D Sphere Path (b) and 3D Cylinder Path (c) filters are selected.

The 3D Path X, Y and Z buttons select the axis of rotation. The angle of rotation around the selected axis can be set either by using the thumbwheel or by entering a value in the appropriate box. Rotation Order specifies the order in which the rotation takes place, while Perspective changes the perceived distance of the rotation axis; the higher the value, the closer the axis appears.

In the 3D Sphere Path dialog box, Radius determines the invisible sphere size around which the clip is wrapped. Rotate determines the sphere rotation and the × and Y settings locate the sphere horizontally and vertically in the frame; Clip Angle 1 locates the clip vertically (on the XY plane) on the sphere’s surface and C//p Angle 2 locates the clip horizontally (on the XZ plane) on the sphere’s surface; Adjust selects the category to adjust with the thumbwheel.

Finally, in the 3D Cylinder Path dialog box, Radius determines the cylinder width, Rotate defines the rotation of the clip in its plane and X locates the cylinder horizontally in the frame; on the left of the dialog box, Rotate determines the cylinder rotation about the z axis. Angle locates the clip horizontally on the cylinder surface and Y locates the clip vertically on the cylinder surface.

Adobe Premiere provides motion controls similar to those of MediaStudio, but manages to squeeze them into a single dialog box (Figure 3.38). Clips can be moved in two dimensions along a path, rotated, zoomed and distorted. Near the bottom of the dialog box, the Delay setting, as the name suggests, can be used to introduce a pause into the motion of a clip as it traverses a path, while the Motion menu contains the options Linear, Accelerate and Decelerate; selecting Accelerate, for example, will cause the rate of movement of the clip to accelerate as it moves along its path.

Premiere also provides a set of named preset motion settings which can be accessed via the Load button in the dialog box. These include examples like Bounce In, Leaf (which causes the clip to adopt the shape of a leaf, falling alternately from left to right and top to bottom of the screen), Spin Out, Spiral, Whoosh and Zoom Left.

Corel Lumiere’s approach to motion control is similar to that of Premiere. Figure 3.39 shows its dialog box in which a Cartwheel preset is being applied to a title clip; the cartwheeling title can be seen superimposed on an underlying video clip in the Preview window on the right. Editing tools are ranged on the left side of the dialog box and windows for entering numerical values are in the lower right hand corner.

Panning to Create Motion in Still Image

The ability to interpose still images (e.g. scanned photographs or clipart images) with moving video clips when building a project extends considerably the range of creative possibilities in video production. A useful technique which can increase the visual interest of a still image is panning, which simulates the effect obtained when a traditional movie camera or video camera is swept across a static scene. Figure 3.40 shows an example of this use of panning, available as one of Corel Lumiere’s Special video filters. The Start frame in the dialog box shows a still image of a bullfighting scene, with the matador confronting the bull. In the End frame, the handles at the four corners have been dragged to create a smaller frame around the matador. When the clip is played back and viewed in the Preview window to the right of the dialog box, the ‘camera’ filming the scene starts with a full shot of the bullring and then appears to travel to the right while zooming in to close-up on the matador.

Pan can also be used to create rolling credits – a list of names which scroll across the screen, usually from top to bottom. A Titler utility is first used to produce a long page with the appropriate list of names, and then the Titler file is placed on a superimpose track. By default, the pan frames in the Start and End windows of the dialog box are both set to the size of the credits page. The Start frame is first reset to the size of a standard frame (so that just the first few credits can be seen) and then the Copy Frame button is used to copy the Start frame to the End window of the dialog box. Now in the End window, the copy of the Start frame can be dragged down until it encloses just the last of the credits. When the project is previewed, the credits now roll smoothly from the bottom of the screen to the top!

Other Motion Effects

Other motion editing features provided by videoediting applications include adjustment of the speed of playback, direction reversal, holding on a selected frame and frame skipping.

Figure 3.41 shows Premiere’s Clip Speed dialog box. By selecting a video clip and reducing its clip speed – e.g. to 25% as shown – the clip will play at a quarter of its original speed, creating a slow-motion effect and extending the playback time (in this case to four times the original length). Conversely, increasing the clip speed will compress the playback time of the clip, speeding up the action contained within the clip. Caution has to be used when changing clip speed as doing so effectively reduces or multiplies the number of frames in the original clip and can affect the quality of motion in the clip.

Changing a clip’s direction – so that it plays in reverse – is achieved simply by inserting a minus sign (–) in front of the percentage figure in the Clip Speed dialog box.

In both Premiere and Lumiere, Frame Hold can be used to select a particular frame within a clip to be played for the duration of the clip; this could be useful, for example, when that frame is to provide a static background behind an overlayed title frame. In Premiere’s Video Filters/Special dialog box (Figure 3.42). Clicking the Select Frame button displays the Video Control dialog box shown in Figure 3.43; dragging the Time Marker advances the clip until the desired frame is displayed in the preview window

The Skip command can be used, for example, to convert flowing movement in a video clip to jerky, staccato, movement. To skip frames, the Skip button is activated in Premiere’s Video Filters I Special dialog box and the number of frames to be skipped is entered in the window provided (Figure 3.44). For example, if the figure of 10 is entered, the project will show the first frame of the clip, skip frames 2 to 11, show frame 12, then skip another 10 frames, and so on.

Cutting and Mixing

Thanks to the latest compression techniques and the large storage capacity of modern hard drives, it is possible to capture many minutes or even hours of video from a VCR or camcorder. To reduce the problems of manipulating such large files, the footage can be captured as a series of sequential files which can then be edited individually before being printed back sequentially to tape (more on this in the chapter entitled The production process).

In many practical cases, however, where the editing required may be confined to the cutting out of unwanted footage, rearranging and mixing video sequences from different tapes or adding simple titles or credits, a simpler solution is to use an editing package such as Pinnacle Systems’ Studio 200 Video Director.

Studio 200 provides the hardware and MCI software necessary to control the video source and destination devices from virtual tape decks on the PC screen. Instead of capturing hours of footage to disk, only the first frame of each clip on the tape is captured, together with the length of the clip and the time codes corresponding to the start and finish of the clip. Thumbnails of the clips are then displayed in a library window in the same order in which they appeared in the original tape. From the library window, those required can be dragged to an Event List where they can be sorted into a final sequence. At this stage transitions, titles and sound effects can be added, if required.

When the Event List is complete, a simple Make Tape command initiates a process whereby Studio 200 begins to assemble the final tape by scanning forward through the camcorder source tape to find the first clip in the Event List sequence. As the clip starts to play, the destination deck is automatically set to record, so that the clip is copied from the tape in the source deck to the tape in destination deck. Any special effects will be added at the same time. When the first clip has been completed, the next clip is automatically located and the process is repeated. If the next clip is on a different tape from the one currently in the source deck, then a Mount New Tape message appears. The current tape is ejected from the source deck, the next tape is loaded and the process continues to completion.

Configuring Studio 200

Figure 3.45 shows the Studio 200 mixer unit and its I/O ports. Figure 3.46 shows the unit connected up in a typical editing configuration. When using a LANC source deck, a special cable with three separate connectors is supplied with Studio 200; two of the connections link a serial port on the PC to the LANC socket on the video deck; the third connector incorporates an infrared device which uses infrared signals, in the same way that a VCR remote control unit does, to send appropriate infrared pulses to the record deck for commands such as Start, Stop, Pause and Record.

The video-out jack on the source deck is connected to a socket labelled From Source Deck on the Studio 200 Mixer, using either an S-Video or composite cable. A second cable is used to connect the socket labelled To Record Deck on the Studio 200 Mixer to the video-in jack on the record deck. The audio and video out jacks from the record deck are then connected to the audio and video in jacks of your television monitor. The television monitor is used to view title and transition effects or to view the edited tapes from your record deck. Video from your source deck can be viewed using Studio 200’s Video Preview window.

To record video and audio together, the audio out jacks of the source deck are connected to the audio in jack on the PC sound card. The audio out jack of the PC sound card is connected to the audio in jacks on the record deck.

The Studio 200 editing window is shown in Figure 3.47. The basic sequence of events is controlled by the three large buttons (1. Log, 2. Edit, 3. Make Tape ) immediately below the menus at the top of the window.

After loading a tape into the source deck and naming it, using the dialog box in Figure 3.48, the VCR-like controls in the Source Deck window (top left corner of the screen in Figure 3.47) are used to control the source deck. Clicking Log initiates the process of Auto-Logging all the clips on the tape (Figure 3.49), adding a frame representing each clip to the Tape Library window as the logging proceeds (see clip thumbnails in the Tape Library window in Figure 3.47). If clips from another tape are to be included in the new project, then the first tape is replaced by the second in the source deck and logging of the second tape proceeds. Once in the library, individual clips can be selected and trimmed, if required, using the Modify button at the top of the Tape Library window, which opens the editing window shown in Figure 3.50. Stan and End time codes can be altered manually, or alternatively, by clicking the button the tape can be automatically rewound to the start of the dip and previewed before trimming Information about any logged clip can be obtained by clicking on the info button in the Tape Library window (Figure 3.51).

When all the required tapes have been logged, clicking on the Edit button opens the Event List window shown in Figure 3.49. It is in this window that logged clips which are to appear on the final tape are arranged in order, like in a story board, by simply dragging the corresponding clip thumbnails from the 7ape Library window into the Event List. To assist in the planning and conlrol of a project, annotations can be added at significant points in the Event List; Figure 3.52 shows the list displayed in text format, instead of thumbnail format, with a note which has been added by clicking on the Note button.

Once in the Event List window, transitions and other effects can be applied; clicking on the Effects button opens the dialog box in Figure 3.53 which provides access to a variety of audio and video effects, including transitions (Figure 3.54), over a hundred of which are provided.

Studio 200’s Title Editor (Figure 3.55) has a comprehensive set of editing tools. Titles can be displayed full screen against an imported background, as shown, or overlayed on a video clip. Overlay titles can also be animated to move over the underlying video.

When the event list is complete, clicking on the Make Tape button in the toolbar sets up the process for production of the finished tape, opening up all the relevant windows – Source Deck, Record Deck, Make Tape, and Event List (Figure 3.56). Clicking Go in the Make Tape window opens the dialog box in Figure 3.57, which asks for final confirmation of the clips to be assembled and provides the means of adjusting the audio level during the recording process.

Once recording has begun, Studio 200 copies the clips and effects in the event list from the source tapes to the record tape. The only time intervention required is when a prompt appears in the Make Tape window requesting a change of source tape (in the event that the clips being assembled exist on more than one tape).

As the recording process proceeds, status information is displayed in the Make Tape window; the name of the current clip is displayed at the top of the window. Each clip is also highlighted in turn in the event list window as it is recorded, so that progress can be monitored on a real time basis (Figure 3.58).

Beneath the clip name display is the Status field which provides details on exactly what Studio 200 is doing at all times during the Make Tape process, e.g. ‘Preparing to record’, ‘Seeking to position’, ‘Recording clip’ or ‘Recording complete’. At the bottom of the Make Tape window two progress bars display the status of the current clip being copied and the overall progress of the Make Tape process. At every stage, the source tape timecode data is displayed in the Source Deck window and the status of the record deck – Stop, Rec/Pause or Record – is displayed in the Record Deck window.

Compression Software

While perhaps less exciting than those covered so far in this chapter, a software category which makes an important contribution to the feasibility of desktop video is that of compression software. Compression is the process of removing or restructuring data to decrease the size of a file. As already discussed, digital video files are intrinsically very large, requiring high data transfer rates during capture and playback. When a completed video project is compiled and saved in AVI or MOV format, the data is compressed to reduce the file size and to facilitate the playback of the movie. As the movie plays back, the data is decompressed ‘on the fly’.

A compression algorithm is a method of compressing data. Video compression algorithms are specifically designed to handle the data created by digitising full-motion video. No single algorithm can satisfy every video compression requirement; different algorithms are designed with different objectives, some being optimised for quality at the expense of file size and data rate and others, conversely, being optimised to minimise file size and data rate with some sacrifice of quality.

Real-time, symmetrical, compression means that video is captured and compressed at full video frame rates (PAL = 25 frames per second). Video can also be compressed asymmetrically. Asymmetric compression means that the compression process is carried out after the capture has taken place. Asymmetric compression processes differ in their degree of asymmetry. This degree, or level, is usually referred to by a ratio, e.g. 100:1. A compression process with 100:1 asymmetry will take 100 minutes to compress 1 minute of video.

Several compression/decompression algorithms, known as codecs, are available for compressing Video for Windows and QuickTime movies. Codecs can be software-based or hardware-based. Hardware compression, as discussed in the previous chapter, is significantly faster than software compression but requires a special digitising card. The performance of the codec used affects the visual quality of the movie and the speed with which it plays back. Software codecs are normally used for video files to be played back from CD-ROMs, so that clips can be viewed without specialised hardware.

MOV and AVI movies can be compressed from within the videoediting applications we have been reviewing in this chapter, using any of the software codecs that come with Video for Windows, Quicktime, or the applications themselves. Third-party codecs can also be installed to provide a variety of compression formats from which to choose. Some codecs are optimised for image quality compression while others are optimized for speed. The choice of codec depends on the type of original images being processed and on and the desired results.

Video for Windows Software Compressors

The following software codecs are shipped with Video for Windows and appear in the videoediting application Compression dialog box (Figure 3.59 shows MediaStudio’s dialog box). The dropdown menu of compressors includes, at the bottom, the Miro Video DC10 MPEG compressor supplied with the Miro DC 10 digitising board.

Microsoft Video 1 Codec

Use for compressing analogue video. The Video 1 compressor is a lossy, spatial compressor which supports pixel depths of 8 or 16 bits.

Microsoft RLE Codec

Used for compressing animation and computer-synthesized images. The RLE compressor is a spatial 8-bit compressor that uses run-length encoding techniques.

Cinepak Codec

Available on both Windows and Macintosh computers, the Radius Cinepac codec is used when compressing 24-bit video for playback from CD-ROM discs. The Cinepak codec attains higher compression ratios, better image quality, and faster playback speeds than the Microsoft Video 1 codec. Cinepak is a highly asymmetric codec, which means that decompression is much faster than compression.

Intel Indeo Video R3.2 Codec

Also available on both Windows and Macintosh computers, this codec is used when compressing 24-bit video for playback from CD-ROM disks. This codec attains higher compression ratios, better image quality, and faster playback speeds than the Microsoft Video 1 codec and produces results comparable in quality to those compressed with the Cinepak codec.

Intel Indeo Video Raw Codec

Used for capturing uncompressed video, this codec provides excellent image quality as no compression is applied! Its advantage is that captured video files are smaller than those captured with the None option.

QuickTime Software Compressors

As already stated, the Cinepac codec and Intel Indeo Video R3.2 codec are available for both Windows and Macintosh systems.

Video Codec

Used for capture and compression of analogue video, high-quality playback from hard disk, and reasonable quality playback from CD-ROM. This codec supports both spatial and temporal compression of 16-bit video and can play back at rates of 10 fps or more. The Video codec allows recompression with little quality degradation.

MPEG

Named after the group which conceived it – the Moving Pictures Expert Group – MPEG is an ISO supported standard for compression and decompression of digital video and audio.

As explained already, many formats are lossy, which means that some of the video information is discarded during compression. Many work by comparing a series of frames and only storing the data which actually changes from one frame to the next. For example, suppose a child is filmed standing in front of a plain, fixed background. The child might be moving but the background doesn’t change at all from frame to frame, so there is no need to store the image data for the background in each separate frame. Eliminating this unnecessary data allows the compressor to reduce significantly the size of the video file without affecting the overall image quality (Figure 3.60a). Contrast this with the scene in Figure 3.60b which contains many moving figures in the foreground and in the background which are changing from frame to frame.

The MPEG format is a good example of a compression method which can significantly compress redundant information. It is now used to store full-length feature films on CD-ROM or the new DVD disks. Using a suitable software video player, MPEG files can be played fullscreen at 30 fps, providing picture and stereo sound quality comparable with that of a TV broadcast. Figure 3.61 shows the interface of such a player which ATI supplies with a number of its graphics cards. When loaded on the author’s system, the ATI player delivered impressive stereo sound and full 20 inch screen video from a 32 speed CD ROM without a glitch. File size reduction using MPEG compression is significant; 5 minutes of 640 × 480, 25 fps video and 22 KHz, 16-bit, stereo sound occupies less than 2 Gb of hard drive space.

Video editing, of course, requires the ability to work with the detail contained within individual frames and this is not feasible if much of the visual data for each frame has been lost during compression. Because of this, capture cards intended for professional work often use a compression called motion-JPEG (M-JPEG). As the name implies, this is basically a version of the JPEG compression used to store still images. M-JPEG compression has no inter-frame compression so a clip can be captured with single-frame precision. Video files are often captured and edited using M-JPEG, then converted into MPEG when editing is complete.

Video Conferencing

Until very recently, videoconferencing was a domain exclusive to big business, due to its high cost and complex equipment requirements. Now the advent of low cost videoconferencing software applications designed for use over the Internet is changing all that.

One of the most popular applications – around a million users are claimed – is the appropriately-named CU-SeeMe, available as a free download from the site of Cornell University (http://cu-seeme.cornell.edu) which owns the copyright. With CU-SeeMe, which runs on either a Mac or a Windows PC, it is possible to videoconference with another site located anywhere around the world for the cost of a local call. In addition, by using what is called reflector software, multiple parties at different locations can participate in a conference, each from his or her own desktop computer.

The philosophy of the Cornell project was to extend the use of videoconferencing using available, affordable hardware and to stimulate creative thinking and create a wide base of user experience. Because CU-SeeMe uses simple but efficient video frame-differencing and compression algorithms, it opens networked videoconferencing capability to users of lower cost desktop computers, and enables broader participation in desktop video technology.

CU-SeeMee displays 4-bit greyscale video windows at 160 × 120 pixels or at double that diameter, and now includes audio. A participant can choose to be a receiver, a sender, or both. Receiving requires only a Mac with a screen capable of displaying 16 greys, or a PC with a screen capable of displaying 256 colours, and a connection to the Internet. Sending requires the addition of a digitising board and a low cost ‘web camera’. A popular example of such a camera, the QuickCam from Connectix (Figure 2.12), is now available with a USB interface. The USB version is hot-pluggable, meaning that users may attach or detach the camera without shutting down the system. The USB interface also simplifies wiring by using only one cable for both power and data. Connectix’ second generation Video Digitally Enhanced Compression (VIDEO, combined with the increased bandwidth offered by USB, extends frame rates to twice the speed of earlier models. Users are no longer limited to postage stamp sized views. USB QuickCam offers full motion video at CIF resolution (352 × 288), approximately one quarter VGA, at 15 frames per second plus.

To send and receive video requires a video capture board which supports Microsoft Video For Windows and a video camera to plug into the video capture board. To send and receive audio requires a Windows sound board which conforms to the Windows MultiMedia specification (full duplex audio is desirable), plus speakers (or headphones) and a microphone. Video and audio interaction can be supplemented with written communication in a talk window – for example, a written piece of text could be presented for group comment. An individual microphone icon allows private conversations during a group videoconference without disrupting the flow of the discussion.

Figure 3.62 shows Cornell’s visual user’s guide to the application. The participants in a conference are listed in the main application window, which also displays data related to the transmission. The participant, or participants, within the field of view of the cameras at the two locations appear in separate local and remote video windows. Two other windows are used to control direct audio transmission and the display of text. More information on use of the application can be found at the following Internet location: http://www.jungle.com/msattler/sci-tech/comp/CU-SeeMe/users-guide/index.html.

Summary

The range and function of video and audio software available for the desktop is growing rapidly as application developers respond to increasing user interest in this sector of the market. In particular, advances in compression software have combined with development of the kind of video digitising hardware described in Chapter 2 to narrow considerably the gap between today’s desktop video and true broadcast quality.

The editing software now available – of which we have looked at a representative range of examples – is capable of satisfying a range of needs, from simply remixing clips from different sources, to adding titles and transitions, to applying sophisticated special effects and creating hybrid multimedia productions. And all of this in a flexible, non-linear, environment.

We are already seeing results of the adoption of digital technology by the professional community in the form of exciting new films and television productions, while early Internet users have seen the Web transform from a static and relatively black and white environment to one which is increasingly vibrant with colour and animation. Video is set to play an increasing role in the realms of education, business and entertainment. Thanks to the availability of the latest video software, the desktop user has the chance to participate in these exciting new developments.