VCodecJetPack C++ library

v2.0.4

Table of contents

• Overview
• Versions
• VCodecJetPack class description
  • VCodecJetPack class declaration
  • transcode method
  • setParam method
  • getParam method
  • executeCommand method
• Build and connect to your project
• Simple example
• Test application

Overview

VCodecJetPack C++ library provides hardware video encoding for H264 and HEVC codecs for Jetson platforms based on Jetson Multimedia API. VCodecJetPack class inherits interface and data structures from open source VCodec library (provides interface for video codecs, source code included, Apache 2.0 license) and also includes Logger open source library (provides function for print logs, source code included, Apache 2.0 license). VCodecJetPack uses Jetson Jetson Multimedia API. The library provides simple programming interface to be implemented in different C++ projects. The library was written with C++17 standard. The libraries are supplied as source code only in form of CMake project. Encoding time on Jetson Orin NX:

codec / resolution	2560x1440	1920x1080	1280x720	640x512
H264	14.4 msec	8.6 msec	4.2 msec	2 msec
HEVC	13.8 msec	8.4 msec	4.2 msec	2 msec

Versions

Table 1 - Library versions.

Version	Release date	What’s new
1.0.0	09.12.2022	First version.
1.0.1	10.04.2023	- support for non-standard resolution
2.0.0	19.09.2023	- Interface changes to VCodec. - Test application updated. - Added example application.
2.0.1	10.01.2024	- VCodec interface updated. - Examples updated. - Documentation updated.
2.0.2	17.05.2024	- Documentation updated. - Submodules updated.
2.0.3	06.08.2024	- Submodules updated.
2.0.4	06.08.2024	- Update VCodec interface with variable bitrate params.

Library files

The library is supplied only by source code. The user is given a set of files in the form of a CMake project (repository). The repository structure is shown below:

CMakeLists.txt ----------------- Main CMake file of the library.
3rdparty ----------------------- Folder with third-party libraries.
    CMakeLists.txt ------------- CMake file which includes third-party libraries.
    Logger --------------------- Source code of Logger library.
    VCodec --------------------- Source code of VCodec library.
src ---------------------------- Folder with source code of the library.
    CMakeLists.txt ------------- CMake file of the library.
    VCodecJetPack.cpp ---------- C++ implementation file.
    VCodecJetPack.h ------------ Header file which includes VCodecJetPack class declaration.
    VCodecJetPackVersion.h ----- Header file which includes version of the library.
    VCodecJetPackVersion.h.in -- CMake service file to generate version file.
test --------------------------- Folder with codec test application.
    CMakeLists.txt ------------- CMake file for codec test application.
    main.cpp ------------------- Source code file of codec test application.
example ------------------------ Folder with simple example of VCodecJetPack usage.
    CMakeLists.txt ------------- CMake file for example application.
    main.cpp ------------------- Source code file of example application.

VCodecJetPack class description

VCodecJetPack class declaration

VCodecJetPack class declared in VCodecJetPack.h file. Class declaration:

class VCodecJetPack : public VCodec
{
public:

    /// Class constructor.
    VCodecJetPack();

    /// Class destructor.
    ~VCodecJetPack();

    /// Get string of current library version.
    static std::string getVersion();

    /// Encode frame.
    bool transcode(Frame& src, Frame& dst) override;

    /// Set codec parameter.
    bool setParam(VCodecParam id, float value) override;

    /// Get parameter value.
    float getParam(VCodecParam id) override;

    /// Execute command.
    bool executeCommand(VCodecCommand id) override;
};

getVersion method

The getVersion() method returns string of current version of VCodecJetPack class. Method declaration:

static std::string getVersion();

Method can be used without **VCodecJetPack ** class instance:

cout << "VCodecJetPack class version: " << VCodecJetPack::getVersion() << endl;

Console output:

VCodecJetPack class version: 2.0.4

transcode method

The transcode(…) method intended to encode video frame (Frame class). Video codec encodes video frames frame-by-frame. Method declaration:

bool transcode(Frame& src, Frame& dst) override;

Parameter	Value
src	Source video frame (see Frame class description). To encode video data src frame must have NV12 pixel format.
dst	Result video frame (see Frame class description). To encode video data src frame must have compressed pixel format (field fourcc of Frame class): H264 or HEVC.

Returns: TRUE if frame was encoded or FALSE if not.

setParam method

The setParam(…) method designed to set new video codec parameters value. Method declaration:

bool setParam(VCodecParam id, float value) override;

Parameter	Description
id	Video codec parameter ID according to VCodecParam enum.
value	Video codec parameter value. Valid values depends on parameter ID.

Returns: TRUE is the parameter was set or FALSE if not.

VCodec.h file of VCodec library defines IDs for parameters (VCodecParam enum) and IDs for commands (VCodecCommand enum). VCodecParam declaration:

namespace cr
{
namespace video
{
enum class VCodecParam
{
    /// [read/write] Log level: 0-Disable, 1-Console, 2-File, 3-Console and file.
    LOG_LEVEL = 1,
    /// [read/write] Bitrate, kbps. For H264 and H265 codecs.
    BITRATE_KBPS,
    /// [read/write] Minimum bitrate, kbps. For variable bitrate mode.
    MIN_BITRATE_KBPS,
    /// [read/write] Maximum bitrate, kbps. For variable bitrate mode.
    MAX_BITRATE_KBPS,
    /// [read/write] Bitrate mode: 0 - constant bitrate, 1 - variable bitrate.
    BITRATE_MODE,
    /// [read/write] Quality 0-100%. For JPEG codecs.
    QUALITY,
    /// [read/write] FPS. For H264 and H265 codecs.
    FPS,
    /// [read/write] GOP size. For H264 and H265 codecs.
    GOP,
    /// [read/write] H264 profile: 0 - Baseline, 1 - Main, 2 - High.
    H264_PROFILE,
    /// [read/write] Codec type. Depends on implementation.
    TYPE,
    /// Custom 1. Depends on implementation.
    CUSTOM_1,
    /// Custom 2. Depends on implementation.
    CUSTOM_2,
    /// Custom 3. Depends on implementation.
    CUSTOM_3
};
}
}

Table 2 - Video codec params description. Some params not supported by particular VCodecLibav library.

Parameter	Access	Description
LOG_LEVEL	read / write	Logging mode. Values: 0 - Disable. 1 - Only file. 2 - Only terminal (console). 3 - File and terminal.
BITRATE_KBPS	read / write	Bitrate, kbps. Default 5000 kbps. For H264 and H265(HEVC) encoding. According to this value, FPS and GOP size video codec calculate parameter for H264 or H265(HEVC) encoding. - Sets special settings for noisy video if bitrate is 0 for hardware encoding. - For software JPEG encoding bitrate incising gives higher quality.
MIN_BITRATE_KBPS	read / write	Minimum bitrate, kbps. Only for H264 and H265(HEVC) codecs. Default 2000 kbps. For variable bitrate mode. For H264 and H265(HEVC) encoding.
MAX_BITRATE_KBPS	read / write	Maximum bitrate, kbps. Only for H264 and H265(HEVC) codecs. Default 8000 kbps. For variable bitrate mode. For H264 and H265(HEVC) encoding.
BITRATE_MODE	read / write	Only for H264 and H265(HEVC) codecs. Bitrate mode: 0 - constant bitrate (default), 1 - variable bitrate. In variable bitrate mode for software encoder
QUALITY	read / write	Quality 0(low quality)-100%(maximum quality). Only for hardware JPEG encoding. Not supported by JPEG SW encoding.
FPS	read / write	FPS. For H264 and H265(HEVC) encoding only. According to this value, FPS and GOP size video codec calculate parameter for H264 and H265(HEVC) encoding.
GOP	read / write	GOP size (Period of key frames) for H264 and H265(HEVC) encoding. Value: 1 - each output frame is key frame, 20 - each 20th frame is key frame etc.
H264_PROFILE	read / write	H264 profile for H264 encoding: 0 - Baseline. 1 - Main. 2 - High. For hardware encoding only.
TYPE	read / write	Type of encoder/decoder: 0 - hardware (default). 1 - software.
CUSTOM_1	read / write	Number of thread for software encoder/decoder. Thread’s count for software encoder\decoder H264 / HEVC(H265) (not for JPEG): 1 - 32, default value 1. Note: in case one thread software encoder produces only one slice per frame. In case multiple threads frame can have multiple slices which can effect on RTSP servers.
CUSTOM_2	read / write	Not supported by VCodecLibav library.
CUSTOM_3	read / write	Not supported by VCodecLibav library.

getParam method

The getParam(…) method designed to obtain video codec parameter value. Method declaration:

float getParam(VCodecParam id) override;

Parameter	Description
id	Video codec parameter ID according to VCodecParam enum (see Table 2).

Returns: parameter value or -1 of the parameters doesn’t exist in particular video codec class.

executeCommand method

The executeCommand(…) method designed to execute video codec command. Version 2.0.2 doesn’t support commands. Method will return FALSE. Method declaration:

bool executeCommand(VCodecCommand id) override;

Parameter	Description
id	Video codec command ID according to VCodecCommand enum.

Returns: method returns FALSE in any case.

VCodec.h file of VCodec library defines IDs for parameters (VCodecParam enum) and IDs for commands (VCodecCommand enum). VCodecCommand declaration:

enum class VCodecCommand
{
    /// Reset.
    RESET = 1,
    /// Generate key frame. For H264 and H265 codecs.
    MAKE_KEY_FRAME
};

Table 3 - Video codec commands description. Some commands maybe unsupported by particular video codec class.

Command	Description
RESET	Not supported by VCodecJetPack library.
MAKE_KEY_FRAME	Not supported by VCodecJetPack library.

Build and connect to your project

Before build install necessary libraries. In general, when installing JetPack on your Jetson platform via Nvidia SDK Manager, there should be a jetson_multimedia_api folder in the /usr/src directory. If it is missing, you need to copy the jetson_multimedia_api folder from the /_static/jetson_multimedia_api.zip to the /usr/src directory on your Jetson. Typical commands to build VCodecJetPack library:

cd VCodecJetPack
git submodule update --init --recursive
mkdir build
cd build
cmake ..
make

If you want connect VCodecJetPack library to your CMake project as source code you can make follow. For example, if your repository has structure:

CMakeLists.txt
src
    CMakeList.txt
    yourLib.h
    yourLib.cpp

Create folder 3rdparty in your repository. Copy repository folder VCodecJetPack to 3rdparty folder. New structure of your repository:

CMakeLists.txt
src
    CMakeList.txt
    yourLib.h
    yourLib.cpp
3rdparty
    VCodecJetPack

Create CMakeLists.txt file in 3rdparty folder. CMakeLists.txt should contain:

cmake_minimum_required(VERSION 3.13)

################################################################################
## 3RD-PARTY
## dependencies for the project
################################################################################
project(3rdparty LANGUAGES CXX)

################################################################################
## SETTINGS
## basic 3rd-party settings before use
################################################################################
# To inherit the top-level architecture when the project is used as a submodule.
SET(PARENT ${PARENT}_YOUR_PROJECT_3RDPARTY)
# Disable self-overwriting of parameters inside included subdirectories.
SET(${PARENT}_SUBMODULE_CACHE_OVERWRITE OFF CACHE BOOL "" FORCE)

################################################################################
## CONFIGURATION
## 3rd-party submodules configuration
################################################################################
SET(${PARENT}_SUBMODULE_VCODEC_JET_PACK                 ON  CACHE BOOL "" FORCE)
if (${PARENT}_SUBMODULE_VCODEC_JET_PACK )
    SET(${PARENT}_VCODEC_JET_PACK                       ON  CACHE BOOL "" FORCE)
    SET(${PARENT}_VCODEC_JET_PACK_TEST                  OFF CACHE BOOL "" FORCE)
    SET(${PARENT}_VCODEC_JET_PACK_EXAMPLE               OFF CACHE BOOL "" FORCE)
endif()

################################################################################
## INCLUDING SUBDIRECTORIES
## Adding subdirectories according to the 3rd-party configuration
################################################################################
if (${PARENT}_SUBMODULE_VCODEC_JET_PACK )
    add_subdirectory(VCodecJetPack)
endif()

File 3rdparty/CMakeLists.txt adds folder VCodecJetPack to your project and will exclude test application from compiling. Your repository new structure will be:

CMakeLists.txt
src
    CMakeList.txt
    yourLib.h
    yourLib.cpp
3rdparty
    CMakeLists.txt
    VCodecJetPack

Next you need include folder 3rdparty in main CMakeLists.txt file of your repository. Add string at the end of your main CMakeLists.txt:

add_subdirectory(3rdparty)

Next you have to include VCodecJetPack library in your src/CMakeLists.txt file:

target_link_libraries(${PROJECT_NAME} VCodecJetPack)

Done!

Simple example

Example application generates image color pattern with moving rectangle and writes compressed data to binary file “out.hevc”. Example shows how to create codec objects and how to encode video frames:

#include <iostream>
#include "VCodecJetPack.h"

int main(void)
{
    // Create codec.
    cr::video::VCodec* videoCodec = new cr::video::VCodecJetPack();

    // Set codec parameters.
    videoCodec->setParam(cr::video::VCodecParam::BITRATE_KBPS, 7500);
    videoCodec->setParam(cr::video::VCodecParam::GOP, 30);
    videoCodec->setParam(cr::video::VCodecParam::FPS, 30);

    // Create NV12 frame.
    const int width = 1280;
    const int height = 720;
    cr::video::Frame frameNv12(width, height, cr::video::Fourcc::NV12);

    // Fill NV12 frame by random values.
    for (uint32_t i = 0; i < frameNv12.size; ++i)
        frameNv12.data[i] = (uint8_t)i;

    // Create output HEVC frame.
    cr::video::Frame frameHEVC(width, height, cr::video::Fourcc::HEVC);

    // Create output file.
    FILE *outputFile = fopen("out.hevc", "w+b");

    // Params for moving object.
    int objectWidth = 128;
    int objectHeight = 128;
    int directionX = 1;
    int directionY = 1;
    int objectX = width / 4;
    int objectY = height / 2;

    // Encode and record 200 frames.
    for (uint32_t n = 0; n < 200; ++n)
    {
        // Draw moving object.
        memset(frameNv12.data, 128, width * height);
        for (int y = objectY; y < objectY + objectHeight; ++y)
            for (int x = objectX; x < objectX + objectHeight; ++x)
                frameNv12.data[y * width + x] = 255;
        objectX += directionX;
        objectY += directionY;
        if (objectX >= width - objectWidth - 5 || objectX <= objectWidth + 5)
            directionX = -directionX;
        if (objectY >= height - objectHeight - 5 || objectY <= objectHeight + 5)
            directionY = -directionY;

        // Encode.
        if (!videoCodec->transcode(frameNv12, frameHEVC))
        {
            std::cout << "Can't encode frame" << std::endl;
            continue;
        }

        // Write to file.
        fwrite(frameHEVC.data, frameHEVC.size, 1, outputFile);  
    }

    // Close file.
    fclose(outputFile);

    return 1;
}

Test application

Test application for VCodecJetPack C++ library shows how library works on Jetson platform. Test application generates artificial video, compresses it according to user’s parameters (codec type, bitrate , GOP size and H264 profile), writes results to binary file “out.h264” or “out.hevc” . The application shows encoding time for each video frame. To run application perform commands on Linux:

cd <application folder>
sudo chmod +x VCodecJetPackTest
./VCodecJetPackTest

After start you will see output:

====================================
VCodecJetPack v2.0.2 test
====================================

Enter Encoder type (1 - H264, 2 - HEVC) :

Chose codec type (1 - H264 , 2 - HEVC):

====================================
VCodecJetPack v2.0.2 test
====================================

Enter Encoder type (1 - H264, 2 - HEVC) : 1
Default params:
Bitrate, kbps 6000
FPS: 30
GOP size: 30
Video width 1920
Video height 1080
H264 Profile: 0
Use default params (0 - no, 1 - yes) : 1
Set number frames: 200

When params chosen test application will create out.h264 or out.hevc file and will start writing encoded frames until stop. User can set custom parameters (video resolution, bitrate, GOP size and H264 profile). When params chosen test application will start writing encoded frames until stop (if user set number of frames). During encoding the application shows encoded data size and encoding time:

Opening in BLOCKING MODE
NvMMLiteOpen : Block : BlockType = 4
===== NVMEDIA: NVENC =====
NvMMLiteBlockCreate : Block : BlockType = 4
875967048
842091854
H264: Profile = 66, Level = 40
NVMEDIA: Need to set EMC bandwidth : 846000
NVMEDIA_ENC: bBlitMode is set to TRUE
Data size 3110400 / 13404   encoding time  290755 us
Data size 3110400 / 1691   encoding time  12924 us
Data size 3110400 / 3460   encoding time  13089 us
Data size 3110400 / 17007   encoding time  12335 us
Data size 3110400 / 390   encoding time  8417 us
Data size 3110400 / 178   encoding time  8613 us
Data size 3110400 / 176   encoding time  8648 us