Sound File Types
Windows Sound Recorder and a microphone can be used to record sounds including narration, nature sounds, and performances. The sampling rate and the length of the sound will determine its file size. Sampling rate is the number of samples per time, expressed in kHz. Fr example, telephone sound is sampled at 4 kHz, FM radio at 16 kHz, CD audio at 22 kHz. As a rule of thumb, 5 kHz takes 5 kbyte per second; 22 kHz takes 22 Kbytes per sec. Once a sound is captured, named and saved, it can be edited using software such as GoldWave. Sound files may be inserted in PowerPoint slides or Web pages, or attached to email.
To record a sound, make sure a microphone is connected. Start Sound Recorder from Start-Programs-Accessories-Multimedia. The red button begins the recording, and the black square stops recording. After recording, move the slider to the left, and click the single triangle to play the sound. The Edit menu allows you to change the sampling rate, and to delete portions of the recording before or after the slider. For fun, experiment with the options in the Effects menu. Save the recorded sound using File-Save As.
Sources of Sounds
Graphics are image files used for visual display in documents, presentations, and Web pages. Graphics files can be attached to email.
Graphics can be obtained from the clip art files of many applications, or saved from the Web. Saving images from the Web begins with right-clicking over the image. Choose Save Image As from the pop-up menu, then choose a name and location.
To create your own images, use a drawing program such as PhotoShop, Paint It, Color It, or Paintbrush. Windows Accessories includes Paint, for creating bitmaps. Existing images can be edited or converted to another file type using software such as Lview.
To capture images, peripherals such as scanners or digital cameras are used. An object or printed image can be scanned and saved as an image file. Digital cameras capture digital photographs that are transferred to a computer for editing and saving.
Sources of Graphic Images
Video and Animation
Digital video and animation can also add realism to presentations and Web pages. Video can be saved from the Web or created using software and hardware. Video capture cards or digital video cameras will capture digital video from an analog source such as a VCR or TV. Digital video cameras can capture live video which can be saved as a digital movie file.
Animation is a sequence of still images (usually GIF images). Software such as GIF Construction Set or GIF Animator is used to combine images into a file.
Video File Types
A video signal is 10,000 times larger than a voice signal of the same duration. A frame of digitized video can occupy over 750 KB; 1.3 GB for 30 fps! Video files are compressed to reduce file size, makes storage easier, shorten loading time. When choosing frame-rate, compare to 30 frames per second for real-time. Use a smaller video display window to speed processing and improve resolution (reduce pixelation).
Sources of Video
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