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QNX Software Development Platform
QNX SDP is a cross-compiling and debugging environment, including an IDE and command-line tools, for building binary images and programs for target boards running the QNX OS 8.0.
Graphics
Image Library Reference
Image API
img_decode_begin()
Prepare to decode one or more frames from a stream

QNX Momentics IDE User's Guide
This User's Guide describes version 8.0 of the Integrated Development Environment (IDE) that's part of the QNX Tool Suite.
QNX Software Development Platform
QNX SDP is a cross-compiling and debugging environment, including an IDE and command-line tools, for building binary images and programs for target boards running the QNX OS 8.0.
- Quickstart Guide
- System Architecture
  The System Architecture guide accompanies the QNX OS and is intended for both application developers and end-users.
- OS Components & Operations
- Graphics
  - Gestures Library Reference
    The Gestures library provides gesture recognizers to detect gestures through touch events that occur when you place one or more fingers on a touch screen.
  - Image Library Reference
    - Working with Images
    - Image API
      - img_cfg_read()
        Read a configuration file and load codecs
      - img_codec_get_criteria()
        Get the extension and mime information for a given codec
      - img_codec_list()
        Enumerate codecs
      - img_codec_list_byext()
        Enumerate codecs by file extension
      - img_codec_list_bymime()
        Enumerate codecs by MIME type
      - img_convert_data()
        Convert data from one image format to another
      - img_convert_getfunc()
        Get a function to convert one image format to another
      - img_crop()
        Crop an image
      - img_decode_begin()
        Prepare to decode one or more frames from a stream
      - img_decode_callouts_t
        Decoder callout table
      - img_decode_finish()
        Release decode resources
      - img_decode_frame()
        Decode a frame
      - img_decode_validate()
        Find a codec for decoding
      - img_dtransform()
        Convert an image from one format to another
      - img_dtransform_apply()
        Apply a data transform
      - img_dtransform_create()
        Prepare to transform an image
      - img_dtransform_free()
        Free a transform structure
      - img_encode_begin()
        Prepare to encode one or more frames to a stream
      - img_encode_callouts_t
        Encoder callout table
      - img_encode_finish()
        Release encode resources
      - img_encode_frame()
        Encode a frame
      - img_expand_getfunc()
        Get a function to convert a palette format to a direct format
      - IMG_FMT_BPL()
        Calculate the minimum number of bytes required to represent a pixel run
      - IMG_FMT_BPP()
        Determine the number of bits per pixel for the specified format
      - img_format_t
        Image formats
      - img_lib_attach()
        Initialize the image library
      - img_lib_detach()
        Detach from the library
      - img_load()
        Decode a frame from a stream
      - img_load_file()
        Decode a frame from a file on the filesystem
      - img_load_resize()
        Decode and resize a frame from a stream
      - img_load_resize_file()
        Decode and resize a frame from a file on the filesystem
      - img_resize_fs()
        Resize an image
      - img_rotate_ortho()
        Rotate an image by 90-degree increments
      - img_write()
        Encode a frame to an output stream on the filesystem
      - img_write_file()
        Encode a frame to a file on the filesystem
      - img_t
        Information describing an image
      - io_close()
        Release an input stream
      - io_open()
        Initialize an IO stream
  - Input Events Library Reference
    The Input Events library provides the framework necessary for Screen Graphics Subsystem to communicate with your touch driver.
  - OpenWF Configuration Developer's Guide
    If you are integrating a new display, you must configure and provide the parameters of your display based on its specifications via the OpenWF Display Configuration API (Wfdcfg Library).
  - OpenWF Display Server User's Guide
    The OpenWF Display Server (wfd-server) is a resource manager that provides applications the ability to show image buffers directly to the display controller via the OpenWF Display API.
  - Screen Graphics Subsystem Developer's Guide
    QNX Screen Graphics Subsystem is a graphics framework that provides all the functionality necessary to develop interactive user experiences.
  - Video Capture Developer's Guide
    The video capture framework provides applications the ability to capture frames from a video input source. These frames can be passed to a graphics component such as Screen for display.
- Programming
- System Security Guide
  The QNX System Security Guide is intended for both system integrators who are responsible for the security of a QNX OS system and developers who want to create a QNX OS resource manager free from vulnerabilities.
- Utilities & Libraries
- Migrating to QNX OS 8.0
QNX Software in the Cloud
QNX Software in the Cloud enables developers to use the QNX OS in the Amazon cloud environment.
QNX Toolkit for Visual Studio Code
This User's Guide describes the QNX^® Toolkit for Visual Studio Code. The guide introduces you to the QNX Toolkit by explaining the QNX development environment and how to build, run, and debug your QNX^® Operating System (OS) applications and systems.
QNX Hypervisor User's Guide
This User's Guide explains the QNX hypervisor architecture and provides instructions for installing and running a QNX Hypervisor system, changing system components and configuration, and using hypervisor features such as virtual devices (vdevs).
Typographical Conventions, Support, and Licensing
This section describes the typographical conventions used throughout the documentation, explains how to obtain technical support, and provides some information about licensing.

img_decode_begin()

QNX SDP8.0Image Library ReferenceAPIDeveloperProgramming

Prepare to decode one or more frames from a stream

Synopsis:

#include <img/img.h>

int img_decode_begin( img_codec_t  codec,
                      io_stream_t *input,
                      uintptr_t    *decode_data );

Arguments:

codec: The codec to use. To figure out a codec to use, see img_codec_list, list_byext, list_bymime, and img_decode_validate.
input: The input source.
decode_data: An address of a uintptr_t which the decoder uses to store data it needs across the decode process. You should not pass NULL, but instead pass a valid address of a uintptr_t initialized to 0.

Library:

libimg

Use the -l img option to qcc to link against this library.

Description:

This function prepares to decode a frame (or series of frames) from a stream.

Returns:

IMG_ERR_OK: Success.
IMG_ERR_NOTIMPL: The codec doesn't provide an implementation for this function.
Other: Any other code that a decoder's begin() function may pass back to flag an error (see img_errno.h for a list of defined errors).

Classification:

Image library


Safety:
Signal handler	No
Thread	No

Page updated: March 05, 2025