|New Training Technologies (ILO - UNEVOC, 1995, 95 p.)|
Digitizing images, sound or video can be done if the necessary hardware and software is available; here is an example of what is needed:
digitising audio (sound, music, voice):
Computer hardware is composed of an audio adapter that is placed in the PC; the same adapter is necessary to record and play back the sound. Appropriate software generally comes with the adapter and allows one to record, control the volume, etc. Audiovisual equipment consists of a microphone (some are directional, some are not, in which case one records all ambient noises, as with a camcorder) or any "line" equipment: audiocassette, radio, audio CD, CD-ROMs, videotape, videodisk, TV, camcorder, etc. Appropriate cables are needed to connect the different items together.
digitizing images, still frames:
Digitizing images requires an image capture adapter placed in the PC, which will not be needed to subsequently display the captured images, whatever the number or delivery work stations used. Software generally comes with the adapter, but is usually limited to capturing the image. If one wishes to modify the image (rotation, re-sizing, special effects, etc.) one will probably need to acquire additional specialised software.
Sources of images can be multiple: cameras, camcorders, still video cameras (e.g. ION from CANON), videotapes, videodisks, TV, CD-ROMs, scanners, slides, negatives of photographs, etc.
Compression techniques can be applied to images (still frames), but in this case a decompression hardware or software will be necessary on every delivery work station. Software decompression is only possible with PCs equipped with fast microprocessors (at least a 486).
Digitizing video is also done with a special adapter placed in the PC, generally compressing at the same time (it is also possible to do it in two steps, but recording uncompressed video on hard disks before digitizing it creates huge amounts of data and can only be performed for very short video sequences). The decompression system (hardware or software) is needed on every delivery workstation. Compression techniques and standards are the key to quality images and video digitising.
Video sequences can come from any video source: cameras, camcorders, videotapes, videodisks, TV, CD-ROMs. Some digital cameras which are now on the market, directly record video sequences in digital mode, avoiding the digitising work.
It is also possible to buy a series of images or sound files from specialised companies like MEDIASOURCE or COREL, which produce copyright-free CD-ROMs with such files. One has to check whether the images and sound formats are adequate for the software used to develop an application.