Quality/TestSuite/Pixel Format Library

Contents 1 Introduction 1.1 Limitations 1.2 Building packages 1.3 Using the pixel format conversion library with blts tests 1.4 Using the pixel format conversion API 2 Module Design and Architecture 2.1 Architecture diagram 3 References 4 Change History

Introduction

Blts-pixelformat package (0.1.4) provides a pixel format conversion API for the BLTS test assets.

The conversion code is based on the libswscale library of the FFMPEG project (http://www.ffmpeg.org), with modifications to remove unnecessary code. Support for additional V4L2 pixel formats has also been added.

Limitations

For some pixel formats, only limited conversion support is available:

• V4L2_PIX_FMT_SBGGR8, V4L2_PIX_FMT_SBGGR16, V4L2_PIX_FMT_SGRBG10 (Bayer formats)

* Can be converted only to V4L2_PIX_FMT_RGB24

* Cannot be used as target formats

• V4L2_PIX_FMT_RGB555X, V4L2_PIX_FMT_RGB565X (big-endian 15- & 16-bit RGB)

* Can be converted to different YUV formats and to V4L2_PIX_FMT_RGB24

* Cannot be used as target formats

Building packages

The blts-pixelformat package comes with a packaging script that can be used to build tarball out of the sources, RPM package or Debian package. To build RPM package, in the root directory execute command:

./pack.sh -r

To get packaging script help, execute command:

./pack.sh -h

The building environment requires the following RPM packages installed:

• libbltscommon-devel

Using the pixel format conversion library with blts tests

Some of blts test packages have dependency to the blts-pixelformat package and blts-pixelformat package itself has dependency to the blts-common package.

The test environment must have following packages installed:

• libbltscommon1

The library package can be installed in the device by executing the command:

rpm -ivh libbltspixelformat1_{version}.rpm 

Using the pixel format conversion API

The development package can be installed by executing the command:

rpm -ivh libbltspixelformat-devel_{version}.rpm 

The pixel format conversion API is defined in the file blts-pixelformat.h and at the moment there is only one conversion function to use convert_buffer():

#include <blts-pixelformat.h>
#include <linux/videodev2.h> //for pixel format identifiers

int convert_buffer(int width, int height, const unsigned char* srcbuffer, __u32 srcformat, unsigned char** dstbuffer, __u32 dstformat);

convert_buffer() converts the image data in srcbuffer from the source pixel format to the destination pixel format. After a successful conversion, dstbuffer contains a pointer to the converted image buffer. The buffer is allocated dynamically in the conversion function, and must be freed by the caller.

After a successful conversion, dstbuffer contains a pointer to the converted image, and the function returns the size of the converted image in bytes.

If the conversion fails, an error code is returned:

• -1 The source or destination format is not supported
• -2 Internal conversion error

The pixel formats are specified with V4L2 pixel format identifiers. The supported formats are:

• V4L2_PIX_FMT_RGB332
• V4L2_PIX_FMT_RGB444
• V4L2_PIX_FMT_RGB555
• V4L2_PIX_FMT_RGB565
• V4L2_PIX_FMT_RGB555X
• V4L2_PIX_FMT_RGB565X
• V4L2_PIX_FMT_RGB24
• V4L2_PIX_FMT_BGR24
• V4L2_PIX_FMT_BGR32
• V4L2_PIX_FMT_RGB32
• V4L2_PIX_FMT_GREY
• V4L2_PIX_FMT_Y16
• V4L2_PIX_FMT_YUYV
• V4L2_PIX_FMT_UYVY
• V4L2_PIX_FMT_Y41P
• V4L2_PIX_FMT_YVU420
• V4L2_PIX_FMT_YVU410
• V4L2_PIX_FMT_YUV422P
• V4L2_PIX_FMT_YUV411P
• V4L2_PIX_FMT_NV12
• V4L2_PIX_FMT_SBGGR8
• V4L2_PIX_FMT_SBGGR16
• V4L2_PIX_FMT_SGRBG10
• V4L2_PIX_FMT_YUV444
• V4L2_PIX_FMT_YUV555
• V4L2_PIX_FMT_YUV565
• V4L2_PIX_FMT_YUV32

Module Design and Architecture

Both Debian and RPM packaging is provided.

The blts-pixelformat package consists of libbltspixelformat1 runtime library and libbltspixelformat-devel development library.

Architecture diagram

References

blts-pixelformat	blts-pixelformat library
www.ffmpeg.org	FFmpeg project
linux.bytesex.org	video4linux website

Change History

Version	Date	Handled By	Status	Comments
0.1	15-Dec-2010	Aki Nyman	Draft	Page created (refers to blts-pixelformat package 0.1.4)