Cover Image
close this bookNew Training Technologies (ILO - UNEVOC, 1995, 95 p.)
View the document(introduction...)
View the documentIntroduction
View the documentChapter 1 New Technologies and Training
close this folderChapter 2 Delivery mechanisms and available NTTs
View the document(introduction...)
close this folderDelivery mechanisms
View the document1. Group learning
View the document2. Individual learning
close this folderAvailable NTTs
View the document1. NTTs and group learning
View the document2. NTTs and individual learning
View the documentSoft technologies
close this folderChapter 3 Selecting the appropriate NTTs
View the document(introduction...)
View the documentPolitical or strategic decision
View the documentThe teaching/learning environment analysis
close this folderCost/benefit analysis
View the document(introduction...)
View the document1. Courseware analysis and development
View the document2. Course distribution
View the document3. Delivery costs
View the document4. Update costs
View the document5. Intangible costs and benefits
View the document6. A simplified cost model
close this folderChapter 4 Implementing NTTs in a training environment
View the document(introduction...)
View the document1. Demonstrations
View the document2. Order and install equipment
View the document3. Hands-on workshops
View the document4. Train the trainers and developers
View the document5. Prototypes
View the document6. Develop titles
View the document7. Organize help, support
View the documentChapter 5 Trends in NTTs
View the documentConclusion
close this folderAppendix A Compatibility
View the document(introduction...)
View the documentPC buses (architecture)
View the documentMicroprocessors
View the documentOperating systems
View the documentGraphic modes
View the documentDigital images, sound and video files
View the documentColour standards
View the documentVideotape formats
View the documentAppendix B Suggested PC configurations
View the documentAppendix C Laser technology
View the documentAppendix D Digital versus analogue
View the documentAppendix E Digitizing
View the documentAppendix F Telecommunications and training
View the documentAppendix G More technologies for training
View the documentAppendix H Training the disabled
View the documentGlossary23

Digital images, sound and video files

1. Images

Not only can image files have different resolutions but they are saved by different software in different file formats: file name extension may be PCX, BMP, WMF, TIF, etc...

Software exists that can translate, convert a certain number of file formats into others, but not all conversions are possible. Such a conversion necessarily induces a quality loss. Software also exists that handles images in many ways: rotating, resizing, etc., with a possible quality loss, which means that whenever possible, one should directly digitize the quality and size one intends to use, in order to get the best possible result.

Image files may be uncompressed, or compacted or compressed. Compacted images are slightly compressed without quality loss; it is only another way of recording areas of similar colour; the compression ratios are rather poor. Compressed images, with the current state of the compression algorithms, may have a compression ratio as high as 140:1 (about 2:1), but this always represents a loss of quality.

2. Sound

Digital sound also exists in different qualities expressed in sample width (bits) and in sampling rates (samples/sec or Hz); the higher the quality, the bigger the file; compression techniques may be applied, but their results are less spectacular than those for images. Sample width (8 or 16 bits) is combined with the sampling rate (8, 11, 22 or 44 million samples/sec or MHz), which produces files of 8 to 44 Kb/sec for 8-bit mono sound, and 16 to 22 Kb/sec for 16-bit mono sound; stereo sound is represented by files twice as big!

Sound files are also saved in different formats (e.g. AUD, WAV); software exists that can convert them into another format.

3. Video

Digital video data can be saved and played in different sizes (e.g. full screen, 1/4 screen) and resolutions (320x200, etc.); they exist in different formats (e.g. AVIS AVI); they are generally compressed because of their rather huge size, using different compression algorithms (e.g. DVI, MPEG, etc.). As an example, the Digital Video Interactive (DVI) system of INTEL allows the user to compress "live" (if the PC is equipped with the adequate compression adapter) in Real Time Video (RTV) mode, with a low compression ratio, or to get the file compressed by a specialized company in Production Level Video (PLV) with a ratio around 140:1 and a much better quality.

Video decompression needs on every work station a decompression adapter, or a decompression software (much cheaper) provided the PC is equipped with a fast enough microprocessor (a 486 as a minimum).