This way they can vouch for the performance and features of their product as well as support it in the knowledge what the customer actually has in front of them.
Some manufactures offer their software only with propriety hardware (industrial grade rack PCs with high-end graphics cards as well as fast and resilient hard disk configurations). The fact that the hardware is crucial to the acceptable and predictable performance of the software is generally true and comes into focus when looking at the most popular type of software used in theater today, the so-called media server.
They tend to be free or open source (with the exception of touch designer) and have a large community of users. I have also heard the term visual development platform in this context. As the name suggests these require programming in a specific way that is particular to the software environment. There are also programming environments that are completely customizable for the use in theatre. The software can only works as well as the hardware allows it to. That is why they tend to have minimum hardware requirements. It is important to note that all the software mentioned relies on adequate hardware (Computer, hard drives, graphics card) to function. The available software keeps developing and changing so I have only listed the popular ones that are currently used based on what I know. Another example of repurposing software from another field of work would be VJ software. Popular examples are powerpoint and keynote. A large variety of software has been re-utilized for the purpose of outputting to screens in the theater but was originally conceived for a different purpose, for example presentation software. There are stand-alone hardware solutions like Hard Drive players, flash memory players used for presentation Kiosks or the humble DVD player. Therfore it helps to try a few different products over time to learn what they are capable of and how they address the needs of the projection designer differently. With demand for sophisticated control and features usually also comes an increased complexity to use or program these solutions. There are solutions which are realtively easy to use and quick to learn and products which require days of tutorials if not many weeks of practice. Usually media can be copied ot transfered to the playback system and once on the system it can be played back and send out via a cable to the projector or monitor. The part of the projection system which facilitates this aspect is the playback component. For the purpose of clarity this is the reason: The artwork, content or imagery needs to be send to a projector or screen in order to be seen by the audiennce. Of course initially it is important to understand why you need them in the first place. The variety and number of options that is being offered these days is somewhat dizzying. However some have evolved over the years to cater to the theater community. Most of these products have not been conceived for the use in theater. There are many types of playback solutions in use today and this little article's goal is to provide an introduction to this type of system component because no projection design can be realized without it.
The subject of playback solutions used in the live entertainment industry warrants a little booklet or at least a chapter of a book, but for the purpose of this website and as a brief introduction to the subject I hope this will do.