How to use/learn Video4Linux2 (On Screen Display) Output APIs?

My latest microprocessor( Freescale iMX233 ) has 8 hardware overlay plus inbuilt YUV to RGB conversion functionality.开发者_如何学Python They have exposed these functionality through v4l2 driver. v4l2 Documentation doesn't say it properly that how to use it. Is there any tutorial available or any reference code which I can use to learn v4l2 apis?

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The V4L2 API isn't the greatest API out there and it is not very easy to use it.

There are however a few resources available.

The first one is the "official" V4L2 doc

The series of article written on lwn focus more on the driver side of V4L2, but still they are a very interesting reading if you want to understand how V4L2 works and to use it right.

Finally, this simple but quite complete video capture example is a good code basis for anyone wanting to use the V4L2 API. It shows the 3 ways (memory mapped buffers, read() calls and application allocated buffers) of acquiring data through a camera sensor.