You can find a PDF version of the Linux DVB API version 3 in the download area.
A browsable online version of the Linux DVB API version 3 documentation (generated with latex2html from TeX sources in the CVS) is here.
You can also find an experimental online version of the DVB API version 3 documentation generated from the new DocBook undergoing port.
A small collection of READMEs and FAQs is included in the Linux kernel source tree in linux/Documentation/dvb/ ( browse docs in the mercurial repository).
A browsable online version of Video4Linux2 API is at here.
Although it is possible to generate a PDF version of the Video4Linux2 API, the generated PDF is not very useful, since some tables and pictures are larger than the output page. So the better is to use the browable documentation.
For developers, LWN.net is writing a V4L2 series of articles focusing at the development of a Linux V4L2 driver.
There's a new V4L Drivers guide at
here.
PS.: This is a newer document and might be suject to some errors. Contributions are wanted. Also notice that the main guide shall always be V4L API2.
Video4Linux API version 1 is obsolete. Driver and application
developers are requested to migrate their work to V4L2 API.
There's an effort in course to remove its support from
the drivers, keeping just a conversion module for keeping
compatibility for the old binary-only V4L1 applications.