3.4.1 Introduction to JDK

JDK is a lightweight and efficient multimedia processing library (MPP) tailored for the Spacemit K1/K2 platforms. It provides encapsulated access interfaces to hardware features such as camera (JdkCamera), video encoding (JdkEncoder), decoding (JdkDecoder), and video output (JdkVo), enabling developers to quickly utilize hardware capabilities.

1.Environment Setup

• Operating System: Bianbu 2.2
• Compiler: GCC version 9 or later (recommended to use the native compiler pre-installed on the development board)

Required dependencies installation:

sudo apt install build-essential cmake libv4l-dev libdrm-dev libjpeg-dev uuid-dev

2.Project Structure Overview

jdk_examples
├── jdk_cam       # Camera module
├── jdk_client    # Client module
├── jdk_drm       # DRM-related module
├── jdk_frame     # Frame processing module
├── jdk_infer     # Inference module
├── jdk_server    # Server module
├── jdk_v2d       # 2D video module
├── jdk_vdec      # Video decoding module
├── jdk_venc      # Video encoding module
└── jdk_vo        # Video output module

3.Build Guide

3.1Download and Install the JDK SDK

wget https://archive.spacemit.com/ros2/code/jdk_sdk.tar.gz
sudo tar xvf jdk_sdk.tar.gz

Directory structure:

jdk_sdk
├── include
│   ├── data_type.hpp
│   ├── IConver.hpp
│   ├── IEngine.hpp
│   ├── IPlugin.hpp
│   ├── ITensor.hpp
│   ├── JdkCamera.hpp
│   ├── JdkDecoder.hpp
│   ├── JdkDma.hpp
│   ├── JdkDrm.hpp
│   ├── JdkEncoder.hpp
│   ├── JdkFrame.hpp
│   ├── jdk_log.h
│   ├── JdkUsbCam.hpp
│   ├── jdkV2d.hpp
│   ├── JdkVo.hpp
│   ├── json.hpp
│   └── Tensor.hpp
├── jdk_examples
│   ├── jdk_cam
│   ├── jdk_client
│   ├── jdk_drm
│   ├── jdk_frame
│   ├── jdk_infer
│   ├── jdk_infer@rtsp
│   ├── jdk_server
│   ├── jdk_usbcam
│   ├── jdk_v2d
│   ├── jdk_vdec
│   ├── jdk_venc
│   └── jdk_vo
├── ko
│   └── jdk_dma.ko
├── lib
│   ├── libengine.so
│   ├── libjdk_cam.so
│   ├── libjdk_dma.so
│   ├── libjdk_drm.so
│   ├── libjdk_frame.so
│   ├── libjdk_usbcam.so
│   ├── libjdk_v2d.so
│   ├── libjdk_vdec.so
│   ├── libjdk_venc.so
│   ├── libjdk_vo.so
│   ├── libnet_client.so
│   └── libnet_server.so
├── Makefile
└── README.md

3.2 Compile Example Programs

Navigate to the camera module directory and compile:

cd jdk_sdk
make all

Sample output:

make -C jdk_examples/jdk_cam all
make[1]: Entering directory '/home/work/jdk_sdk/jdk_examples/jdk_cam'
Compile depends C++ src/main.cpp
Compile CXX src/main.cpp
Link workspace/jdk_cam

3.3 Run Example

Before running the JDK example, you need to install the JDK DMA driver:

insmod ./ko/jdk_dma.ko
cd jdk_examples/jdk_usbcam
./workspace/jdk_usbcam /dev/video20

🚨 Tip: Confirm the device node path based on your actual setup, e.g., /dev/video20. Use the command v4l2-ctl --list-devices to verify device info.

The terminal will then output module initialization and image capture logs.

3.4 Sample Startup Logs

VIDIOC_STREAMON succeeded
[MPP-DEBUG] 10800:module_init:159 +++++++++++++++ module init, module type = 9
[MPP-DEBUG] 10800:find_v4l2_linlonv5v7_plugin:83 yeah! we have v4l2_linlonv5v7_codec plugin---------------
[MPP-DEBUG] 10800:module_init:199 ++++++++++ V4L2_LINLONV5V7 (/usr/lib/libv4l2_linlonv5v7_codec.so)
[MPP-DEBUG] 10800:module_init:199 ++++++++++ open (/usr/lib/libv4l2_linlonv5v7_codec.so) success !
[MPP-DEBUG] 10800:al_dec_create:337 init create
[MPP-DEBUG] 10800:al_dec_init:398 input para check: foramt:0x4745504a output format:0x3231564e input buffer num:12 output buffer num:8
[MPP-DEBUG] 10800:al_dec_init:421 video fd = 4, device path = '/dev/video0'
[MPP-DEBUG] 10800:createCodec:115 create a codec, width=1280 height=720 align=1 inputtype=2 outputtype=9 inputformat=4745504a outputformat=3231564e inputbufnum=12 outputbufnum=8
[MPP-DEBUG] 10800:createPort:80 create a port, type=2 format_fourcc=1195724874
[MPP-DEBUG] 10800:createPort:80 create a port, type=9 format_fourcc=842094158
[MPP-DEBUG] 10800:getTrySetFormat:196 width=1280 height=720 align=1 pixel_format=4745504a
[MPP-DEBUG] 10800:printFormat:294 PRINTFORMAT ===== type: 2, format: 1195724874, width: 1280, height: 720, bytesperline: 0, sizeimage: 1048576
[MPP-DEBUG] 10800:getTrySetFormat:196 width=1280 height=720 align=1 pixel_format=3231564e
[MPP-DEBUG] 10800:printFormat:283 PRINTFORMAT ===== type: 9, format: 842094158, width: 1280, height: 720, nplanes: 2, bytesperline: [1280 1280 0], sizeimage: [921600 460800 0]
[MPP-DEBUG] 10800:allocateBuffers:340 Request buffers. type:2 count:12(12) memory:1
[MPP-DEBUG] 10800:allocateBuffers:340 Request buffers. type:9 count:8(8) memory:4
[MPP-DEBUG] 10800:streamon:558 Stream on 1751956058513
[MPP-DEBUG] 10800:streamon:558 Stream on 1751956058513
[MPP-DEBUG] 10800:al_dec_init:449 init finish
[MPP-DEBUG] 10800:VO_CreateChannel:43 create VO Channel success!
[MPP-DEBUG] 10800:module_init:159 +++++++++++++++ module init, module type = 101
[MPP-DEBUG] 10800:check_vo_sdl2:121 yeah! have vo_sdl2---------------
[MPP-DEBUG] 10800:find_vo_sdl2_plugin:86 yeah! we have vo_sdl2_plugin plugin---------------
[MPP-DEBUG] 10800:module_init:207 ++++++++++ VO_SDL2 (/usr/lib/libvo_sdl2_plugin.so)
[MPP-DEBUG] 10800:module_init:207 ++++++++++ open (/usr/lib/libvo_sdl2_plugin.so) success !
[MPP-ERROR] 10800:al_vo_init:93 SDL could not initialize! SDL_Error: wayland not available
[MPP-ERROR] 10800:al_vo_init:128 k1 vo_sdl2 init fail
[MPP-DEBUG] 10800:VO_Init:66 init VO Channel, ret = -400
[MPP-ERROR] 10800:JdkVo:32 VO_init failed, please check!
[MPP-INFO] 10801:runpoll:321 Now k1 hardware decoding ...
select: Resource temporarily unavailable
Failed to capture frame 0
NO data, return.
[MPP-DEBUG] 10801:handleEvent:453 get V4L2_EVENT_SOURCE_CHANGE event, do notify!
[MPP-DEBUG] 10800:handleOutputBuffer:1509 Resolution changed:0 new size: 1280 x 720
[MPP-DEBUG] 10800:streamoff:571 Stream off 1751956060839
[MPP-DEBUG] 10800:allocateBuffers:340 Request buffers. type:9 count:0(0) memory:4
[MPP-DEBUG] 10800:getTrySetFormat:196 width=1280 height=720 align=1 pixel_format=3231564e
[MPP-DEBUG] 10800:printFormat:283 PRINTFORMAT ===== type: 9, format: 842094158, width: 1280, height: 720, nplanes: 2, bytesperline: [1280 1280 0], sizeimage: [921600 460800 0]
[MPP-DEBUG] 10800:allocateBuffers:340 Request buffers. type:9 count:12(12) memory:4
[MPP-DEBUG] 10800:streamon:558 Stream on 1751956060850
[MPP-ERROR] 10800:queueBuffer:461 Failed to queue buffer. type = 9 (Invalid argument)
[MPP-ERROR] 10800:al_dec_return_output_frame:652 queueBuffer failed, this should not happen, please check!
[MPP-DEBUG] 10800:VO_Process:82 vo one packet, ret = 0
index:1,dma_fd:33 width:1280,height:720,size:1382400
[MPP-DEBUG] 10800:VO_Process:82 vo one packet, ret = 0
index:2,dma_fd:33 width:1280,height:720,size:1382400
[MPP-DEBUG] 10800:VO_Process:82 vo one packet, ret = 0
index:3,dma_fd:33 width:1280,height:720,size:1382400

4.Execution Result

After the program is executed, the camera-captured images will be displayed in real time on the monitor, as shown below:

5.Common Issues and Recommendations

Issue	Description
Camera not detected	Check USB connection, try other ports, or verify the camera model
Camera won't open	Possibly not recognized or unsupported by driver
SDL error	Missing graphical library dependency; does not affect image capture
No image display	Check vo initialization logs and verify display channel & permissions