DirectFB: Linux API for video mixing

This book is about DirectFB - an open source Linux API for graphics and video mixing.

In it I explain why and how DirectFB’s API can be used to achieve different effects.

It is an introduction to the concepts that lie behind DirectFB’s functions and interfaces, rather than a reference book.
DirectFB, like much open source software, grew to do what its developers wanted it to do - which is not always a fully coherent and logical construct. In this book I address these issues, to clarify and resolve inconsistencies as well as explaining why they arose.

This is not a text book or a reference. Nor does it teach programming or the implementation details of DirectFB. Its aim is to give you a basic and intuitive understanding that will inform your application of the tools, and enable you to apply them more effectively and with sharper insight.

This eBook – written specifically for the Amazon Kindle – is meant to be read as you would a novel: starting at the beginning, reading through in sequence, following the narrative. Not stopping to make notes, nor working through exercises or assignments, just reading it for enjoyment and to gain a better understanding of the subject.

DirectFB is a powerful library with many features, and its applications of drawing and mixing are themselves complex and subtle. It is developed in the Open Source community and continues to evolve to meet new needs and to support new platforms.
Because the library, and its applications, are subtle and complex it can be hard to see how a given function or feature should be used to best effect. Often you need to know a lot of background before you can understand what a function does and how best to use it.

DirectFB’s own Reference details each of its functions and data types but does not explain their application very fully, and has many examples of ‘student comments’ (as for example the explanation for SetCooperativeLevel(): “puts the interface into the specified cooperative level”) that are not very helpful.

In this book I try to explain DirectFB’s features, functions and use in a way that makes things as clear as possible and that explains the background to the application where necessary. I try to explain the purpose and application of functions, not just the syntax of their usage.

DirectFB is a big project and is developed through an Open Source collaboration. Its size and the looseness of control over its content lead to features that can be frustrating or unwise. It has some features that address very specific needs with functions that are clever but rarely used. It has some features that I think are frankly unwise (like the Lock() and Unlock() functions that give you direct access to data buffers). It has some ‘shortcut’ features that I find simply horrid (like the ‘primary Surface’). These are frustrations and annoyances around a library that is mainly very sound and very useful. Where I explain such features I express my reservations and try to outline ways to avoid using them but I leave the choice up to you since Linux programming is almost by definition a realm where programmers can exercise their freedom to the utmost limit of endurance.