3.4.1 JDK Introduction
Last Version: 10/09/2025
JDK is a lightweight and efficient Multimedia Processing Platform (MPP) optimized for SpacemiT K series platform. It provides ready-to-use interfaces to access hardware features such as:
- Camera (
JdkCamera) - Video Encoding (
JdkEncoder) - Video Decoding (
JdkDecoder) - Video Output (
JdkVo)
Using these APIs, developers can quickly leverage hardware acceleration for multimedia tasks.
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
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
Build Guide
Download 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
Compile Example Programs
Navigate to the SDK root and compile all example modules:
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
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
🚨 Tips:
- Confirm the device node path based on your actual setup, e.g.,
/dev/video20.- Use the command
v4l2-ctl --list-devicesto verify device info.
The terminal will then output module initialization and image capture logs.
Sample Startup Logs
Below is a typical log output when starting the example:
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
Execution Result
After the program is executed, the camera-captured images will be displayed in real time on the monitor, as shown below:
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 |