Video-Editing TechniquesGuilford County Sci Vis

V204.03

Video Post-Production. Creating an animation

using a program such as 3D Studio Max or trueSpace is often just a part of a total video production process.

Video editing software (such as Adobe Premiere) offers the opportunity to enhance animation productions with sound, still images, and scene transitions.

Video Post-Production. The addition of sound

can add realism and interest to a video production.

Titles and single images (static or scrolling) provide additional information.

Digital Versus Analog Analog (linear) devices

record light and sound as continuously changing electrical signals described by a continuous change of voltage.

Digital recordings are composed of a series of specific, discrete values which are recorded and manipulated as bits of information, which can be accessed or modified one bit at the time or in selected groups of bits.

Digital media is stored in a format that a computer can read and process directly. Digital cameras, scanners,

and digital audio recorders can be used to save images and sound in a format that can be recognized by computer programs.

Digital media may come from images created or sound recorded directly by computer programs.

Digital Versus Analog

Digital Versus Analog Analog media must be digitized or converted to

a digital format before using a computer Analog images may be obtained from such

sources as older video cameras working with VHS or SVHS. Analog sounds may come from sources such as audiotapes and recordings.

Hardware devices such as a video capture card must be attached to the computer to bring analog materials into computer video editing programs.

Sufficient computer resources are needed for digital video editing. Fast processors

needed to process the video.

Additional RAM beyond customary requirements is needed.

Digital Versus Analog

Digital Versus Analog Very large hard

drives are needed. Few minutes of footage require vast amounts of storage.

Video cards should be capable of working with 24-bit color depth displays.

Large monitors are better due to the need to work with numerous software displays.

Specifying Project Settings Selecting settings can be a

complex task requiring an understanding of input resources and output goals.

The ability to make good decisions regarding capture, edit, and output settings require an understanding of topics such as frame rates, compression, and audio.

Numerous books can help but Experience is still a really good teacher.

Specifying Project Settings Timebase specifies

time divisions used to calculate the time position of each edit, expressed in frames per second (fps). 24 is used for

editing motion-picture film

25 for editing PAL (European standard)

29.97 for editing NTSC (North American standard) video (television)

Specifying Project Settings Frame rate indicates to the

number of frames per second contained in the source or the exported video. Whenever possible, the timebase and frame rate agree. The frame rate does not affect the speed of the video, only how smoothly it displays.

Timecode is a way of specifying time. Timecode is displayed in hours, minutes, second and frames (00;00;00;00). The timecode number gives each frame a unique address.

Specifying Project Settings Frame size specifies the dimensions (in pixels) for

frames. Choose the frame size that matches your source video. Common frames sizes include: 640 x 480–standard for low-end video cards 720 x 486–standard-resolution professional video 720 x 480–DV standard 720 x 576–PAL video standard (Used in Europe.)

Specifying Project Settings Aspect ratio is the ratio of width to

height of the video display. Pixel aspect ratio is the ratio for a pixel

while the frame aspect ratio is the width to height relationship for an image.

4:3 is the standard for conventional television and analog video.

16:9 is the motion picture standard. Distortion can occur when a source

image has a different pixel aspect ratio from the one used by your display monitor. Some software may correct for the distortion.

CODECs (compressor/decompressor) specify the compression system used for reducing the size of digital files. Digital video and audio files are very large and must be reduced for use on anything other than powerful computer systems. Some common CODECS include systems for QuickTime or Windows.

Specifying Project Settings

QuickTime (movie-playing format for both the Mac and Windows platform) - Cinepak, DV-NTSC, Motion JPEG A and B, Video

Video for Windows (movie-playing format available only for the Windows platform) – Cinepak, Intel Indeo, Microrsoft DV, Microsoft Video1

Specifying Project Settings

Specifying Project Settings Color bit depth is the number of colors to be

included. The more colors that you choose to work with, the larger the file size and in turn, the more computer resources required. 8-bit color (256 colors) might be used for displays on the

Web. 24-bit color (millions of colors) produces the best image

quality. 32-bit color (millions of colors) allows the use of an alpha

channel .

Specifying Project Settings Audio bit depth is the

number of bits used to describe the audio sample. 8-bit mono is similar to

FM radio 16-bit is similar to CD

audio Audio interleave

specifies how often audio information is inserted among the video frames.

Audio compression reduces file size and is needed when you plan to export very large audio files to CD-ROMs or the Internet.

Audio formats include WAV, MP3, and MIDI files. MIDI files do not include vocals. MPEG files can also include audio.

Specifying Project Settings

The Editing Process Visual and audio source media are referred to as

clips, which is a film industry metaphor referring to short segments of a film project. Clips may be either computer-generated or

live-action images or sounds that may last from a few frames to several minutes.

Bins are used store and organize clips in a small screen space. Bin is another film industry metaphor, which is where editors hung strips of film until added to the total production.

Premiere UI

Editing Tools Opening and viewing clips

Images must be in a format that the video editing software can recognize such as an avi (for animation), wav (for sound), or jpg (for still image) before it can be imported.

Many software programs provide both a “source” window and a separate “program” window where the entire production can be monitored.

Sound clips may be displayed as a waveform where sounds are shown as spikes in a graph.

Editing Tools Playback controls are a part of most viewing

windows. Play, Stop, Frame back, frame forward are typical of window commands.

The Timeline helps cue the user as to the relative position and duration of a particular clip (or frame) within the program by graphically showing the clips as colored bars whose length is an indication of the duration. As clip positions are moved along the timeline, their position within the program is changed.

Editing Tools Typically the timeline will include rows or

individual tracks for images, audio, and scene transition clips. The tracks often include a time ruler for measurement of the clips duration.

Some programs allow the duration of a clip to be changed by altering the length of the bar representing the clip. Scenes within the program may be slowed or the speed increased using this stretch method.

Editing Tools Cutting and joining clips

Software tools are typically available for selecting a clip on the timeline and then cutting the bar that represents the clip. Using this process, segments of “film” may be separated, deleted, moved, or joined with other clips.

Cutting and joining may be used on audio or video.

Editing Tools Transitions allow you to make a

gradual or interesting change from one clip to another by using special effects. Transitions might include dissolve,

page peels, slides, and stretches. The number and types of transitions

available depend upon the software you are using.

Audio mixing is the process of making adjustments to sound clips.

Editing Tools Title clips

Alpha channel allows you superimpose the title

Title rolls allow text to move from the bottom of the screen to beyond the top used for credits.

Editing Tools A title crawl moves the text

horizontally across the screen. News bulletins along the bottom of the television are an example of this type of effect.

Text and graphics may be created in other programs and inserted. Video editing programs are usually limited in their ability to create and manipulate text and graphics.

Editing Tools By using layering techniques, adjusting opacity,

and creating transparency, composite clips can be created. Bluescreen (greenscreen) and track

hierarchy allow background scenes to be overlaid and image editing to occur.

Keying makes only certain parts of a clip transparent which can then be filled with other images (clips on the lower tracks of the timeline.)

Creating Output Output may be to

videotape for display on a television or to a digital file for display through a computer output device.

Output may be put into other presentation programs such as PowerPoint.

Creating Output Export goals will determine the

output settings that you choose. Does the production need to

operate on Windows and/or Mac platforms?

What software will be used to play your production?

What image quality is required? How big can the file size be? Will the production be displayed

on the Web?

Creating Output Common digital outputs

Audio Video Interleave (avi) – for use on Windows only computers, good for short digital movies.

QuickTime – a cross platform Apple format that is popular for Web video.

RealVideo – RealNetworks streaming video is an extremely popular format.

Video editing programs may be exported to other multimedia programs (such as Macromedia Director or Authorware) for addition editing or integration with other materials such as Flash programs.