Originally the equipment used for AV was as simple as a single slide projector, with maybe a pre-recorded sound track with cues so that the slide changes could be made manually at the appropriate time.
The use of two projectors with a means to fade between them was a big step forward. The Duofade was a manual device which allowed control of two diaphragms in front of the projector lens. It was realised that by judicious selection of slide, a transient ‘third image’ could be created as the change occurred.
Various sytems were developed to allow automatic control of the fading and changing of the projectors. One popular with AV workers was the Imatronic.
Developed in the 1980s the Imatronic system used a four-track tape recorder, two slide projectors and a special 'dissolve' unit. The left and right channels of stereo sound were recorded on two tracks of the four-track tape and a modulated control signal was recorded on the fourth track.
When the tape was played, the sound signal on the first two tracks was fed to an amplifier and speakers. The signal from the fourth track was fed to the dissolve unit where it was decoded and used to control both the brightness and the slide changes of the two projectors. This permitted a true dissolve between one slide and the next, fully synchronised with the audio.
As with conventional photography the arrival of the digital age changed everything. Both soundtrack and images could now be handled digitally on a computer. Whilst developing the AV it could be viewed on the monitor but for showing to an audience a digital projector was the solution. Although initially expensive, only one projector was required and it gave superior sharpness and no problems of alignment.
Specialised computer software was developed to help in the creation of AVs. The simple dissolve was now only one of many transition effects that could be used.
The latest AV software allows images and text to be animated and video clips to be used as well as still images. The final AV can be created as an executable file that can be played on any computer without installing additional software. The same AV can also be generated as a DVD or a YouTube video which makes sharing of AVs very easy.
See the links page for details of the software mentioned on this page.
One of the most popular and successful examples of AV software is PicturesToExe. This has evolved through many versions in close consultation with its users through an active forum. There is a lot of information relating to PicturesToExe on the resources page. Other software includes the Proshow range, DGFects Discovery and M.Objects
Digital also changed the way in which the soundtrack was produced. Analogue multitrack mixers and cassette recorders were replaced by sound editing and mixing software. CoolEdit was one of the early examples but was eventually bought by Adobe and became the much more expensive Adobe Audition which is still available. There are now many free sound editing programs, such as Audacity.
The latest versions of PicturesTo Exe incorporate most of the sound mixing functions that are required for an AV. Together with the ready availability of downloadable sound, this makes a separate sound editing software unnecessary.
Experimenting with AV has never been simpler. Most people already have a digital camera and a computer so it only requires the addition of some relatively inexpensive software before you are ready to have a go yourself. The What is AV? page has more information on the AV community, AV groups and competitions.
AV is a distinct form of art, and, like all art, it is about communication. Even though the equipment and capabilities have changed radically, successful AVs are still those with a clear message.