mythliu/py_omxilc

py_omxilc

This package defines a component class for writing OpenMAX IL client applications in Python 2.7.3 for the Raspberry Pi B/B+ board. It is mainly based on the file ilclient.c developed by Broadcom which defines an IL client side library. It is also based on the python module pyopenmax.py developed by Peter de Rivaz.

The component class omxComponent is defined in the main module omxilc.py. ctypes is used to call the core and component methods provided by the Broadcom C library libopenmaxil.so.

There are several other modules in the package. The majority of them are simply python converion of the OpenMAX IL standard C header files. omxerr.py and omxnames.py are supporting modules for omxilc.py. The converted headers are: omx_audio.py, omx_component.py, omx_core.py, omx_image.py, omx_index.py, omx_ivcommon.py, omx_other.py, omx_types.py, and omx_video.py. The module omxbcport.py defines all known port indices of the OpenMAX components in Broadcom VMCS-X release. The last module is included for reference and is not required for writing applications.

The module omxjpgdec.py is an application module. This module pairs an image_decode with a resize component to decode a JPEG image from a file to a specified color format and resize it to a specified dimension for display. Supported color formats are: 16bitRGB565, YUV420PackedPlanar and 32bitABGR8888.

There are two methods in the JPEG decoder module for setting up the components and converting a file. The first method sets up the components without the decoder-resizer tunnel before the decoder goes into state Executing. The alternate method is developed by Matt Ownby and Anthong Sale and used in their hello_jpeg demo program for the Raspberry Pi board.

There is a local variable _verbose in omxilc.py which enables the console printouts of statuses when it is set to True.

The JPEG decoder was run from the console with verbose off and 1 million continuous conversions of a single 1920x1080 JPEG file to 32-bit ABGR. The output image size is 1104x621. The total run time was 13h 51m 4s which amounts to 49.864 ms/frame or 20.055 frames/sec.

Copyright (c) 2014 Binh Bui

Redistribution and use in source and binary forms, with or without modification, are permitted.

This package requires the following C libraries:

• libopenmaxil.so
• libbcm_host.so

These libraries can be otained at: https://github.com/raspberrypi/firmware/tree/master/opt/vc/lib