Skip to content

JPEG Encoder

Name

jpegenc - jpeg encoding

Description

KNEO Pi provides an application called jpegenc designed for JPEG encoding demostrations. This application reads a YUV file and encode it into a jpeg file.

Before starting the encoding process, ensure the appropriate drivers are loaded.

Configuration File (config.ini)

  • inputpath: Path to the input YUV file.
  • outputpath: Path where the encode jpeg file will be saved.
  • img_width: input frame width.
  • img_height: input frame height.
  • img_qp: output frame quantization parameter. Valid range is 0 ~ 200. Smaller value means better picture quality.
inputpath = "sample_1920x1080.yuv"
outputpath = "sample_1920x1080.jpg"
img_width = 1920
img_height = 1080
img_qp = 100

Use the following command to start the encoding process: 

jpegenc -c config.ini

Build Example

Use ${kneopi-example}/hardware_control/${example}/build.sh script to compile the binary.

$ cd ${kneopi-example}/hardware_control/jpegenc/
$ sh build.sh

Synopsis

The JPEG encode sample uses VMF_SNAP_ProcessOneFrame_YUV and VMF_SNAP_CROP_PARAMS_T. It reads a YUV frame, fills VMF_SNAP_CROP_PARAMS_T with the output buffer/size, crop rectangle (dwStartX, dwStartY, dwCropWidth, dwCropHeight), and quality (dwQp), then calls VMF_SNAP_ProcessOneFrame_YUV(ssm, &crop) to encode. On success, the function returns the JPEG size (bytes) and writes the encoded image into pOutBuffer.

The simple encoder app flow is shown below:

Options

-c Specify the encoding configuration file

Example

To decode the specified video file according to the parameters defined in the config.ini file and output a YUV file 

jpegenc -c config.ini

# config.ini
[config]
inputpath = "sample_1920x1080.yuv"
outputpath = "sample_1920x1080.jpg"
img_width = 1920
img_height = 1080
img_qp = 100