GMSL 介绍

一、GMSL是什么？

GMSL–Gigabit Multimedia Serial Link (中文译为：吉比特多媒体串行链路)， 整个传输线路包含串行器和解串器(SerDes)，GMSL全面支持汽车信息娱乐系统、高级驾驶辅助系统(ADAS)甚至未来无人驾驶 要求的宽带、复杂互连和数据完整性。

从摄像头的超低功耗要求、到传感器数据汇聚的宽带要求，GMSL SerDes能够满足未来系统的所有需求。先进的链路完整性和诊断功能提供可靠的链路性能监测——这对汽车安全系统的设计至关重要。GMSL串行器和解串器支持长达15m的屏蔽双绞线(STP)或同轴电缆传输，满足汽车行业最苛刻的电磁兼容(EMC)要求。

串行器和解串器IC均内置扩频功能，以改善链路的电磁兼容(EMI)性，无需外部扩频时钟。串行器和解串器系列产品的互操作性允许链路两侧使用不同接口。除驱动高分辨率中央/后排显示屏和仪表盘外，GMSL SerDes也能出胜任百万像素级摄像机系统设计。

在现代新型汽车视频互连众多性能的基础上，GMSL技术提供宽带、功能丰富、设计灵活性等优势，支持无人驾驶系统等未来汽车的设计需求。

GMSL 技术芯片厂商：MAXIM美信

二、GMSL可以做是什么？

近来，汽车ADAS高级驾驶辅助系统装车率快速增长，纵览各大厂商，这些技术基本上集中在L2-L3级自动驾驶，而为了实现这些功能，单车感知系统中，摄像头的使用量基本上都在5个以上。比如说特斯拉8个、小鹏P7为14个、威马W6是7个、而背靠阿里与上汽的智己汽车将之增加到15个。

这些摄像头根据不同位置分布实现其不同功能，GMSL摄像头典型应用场景：

1. 前视： 前车防撞预警、车道偏离预警、交通标识识别、行人防撞预警等ADAS应用
2. 环视： 360°全景泊车 Automotive Surround View
3. 后视： 倒车影像（采用广角）
4. 侧视： 视觉盲点监测等
5. 内置： 疲劳提醒、手势识别、情绪识别等

三、如何利用GMSL 来做这些事 ？

举例NVIDIA Jetson Xavier AGX 平台+GMSL信号采集板+8路GMSL相机的应用案例：

硬件：

Jetson Xavier AGX Devkit 开发套件

GMSL2 信号采集板 — 4xMAX9296/4x4Lane CSI

GMSL2 相机 — AR0231RGB + MAX9295A (后置ISP）

软件：

Jetson Xavier AGX JetPack4.4 SDK（可兼容其他版本）

Ubuntu 18.04 — Linux-4.9.140

应用：

Gstreamer 命令查看RAW相机

#查看相机/dev/video0 带帧率显示
gst-launch-1.0 --gst-debug=4 nvarguscamerasrc sensor-id=0 ! 'video/x-raw(memory:NVMM),width=1920,height=1080,framerate=30/1,format=NV12' ! nvvidconv ! fpsdisplaysink video-sink=xvimagesink sync=false

#查看多路相机/dev/video0|1 带帧率显示
gst-launch-1.0 nvarguscamerasrc sensor-id=0 ! 'video/x-raw(memory:NVMM),width=1920,height=1080,framerate=30/1,format=NV12' ! nvvidconv ! fpsdisplaysink video-sink=xvimagesink sync=false \
& gst-launch-1.0 nvarguscamerasrc sensor-id=1 ! 'video/x-raw(memory:NVMM),width=1920,height=1080,framerate=30/1,format=NV12' ! nvvidconv ! fpsdisplaysink video-sink=xvimagesink sync=false

JetPack SDK –>nvidia-l4t-jetson-multimedia-api 打开RAW 相机参考

/usr/src/jetson_multimedia_api/samples/13_multi_camera/

OpenCV 预览多路相机代码参考：

/*
 * Copyright (c) 2019, NVIDIA CORPORATION. All rights reserved.

 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *  * Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.

 *  * Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.

 *  * Neither the name of NVIDIA CORPORATION nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.

 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS  IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

#include
#include
#include
#include
#include
#include
#include
#include

static void help()
{
    std::cout << "\nThis is a sample OpenCV application to demonstrate "
    "CSI-camera capture1 pipeline for NVIDIA accelerated GStreamer.\n\n"
    "./opencv_nvgstcam [--Options]\n\n"
    "OPTIONS:\n"
    "\t-h,--help            Prints this message\n"
    "\t--width              capture1 width [Default = 1280]\n"
    "\t--height             capture1 height [Default = 720]\n"
    "\t--fps                Frames per second [Default = 30]\n"
    "\tq                    Runtime command to stop capture1\n\n"
    << std::endl;

}

static std::string create_capture (int index, int width, int height, int fps)
{
    std::stringstream pipeline_str;
    pipeline_str << "nvarguscamerasrc sensor-id=" <("fps");
    width = cmd_parser.get("width");
    height = cmd_parser.get("height");

    if (!cmd_parser.check())
    {
        cmd_parser.printErrors();
        help();
        return_val = -1;
        goto cleanup;
    }

    capture1.open(create_capture(0, width, height, fps), cv::CAP_GSTREAMER);//Open
    capture2.open(create_capture(1, width, height, fps), cv::CAP_GSTREAMER);
    capture3.open(create_capture(2, width, height, fps), cv::CAP_GSTREAMER);
    capture4.open(create_capture(3, width, height, fps), cv::CAP_GSTREAMER);

    //
    if (!capture1.isOpened())
    {
        std::cerr << "Failed to open VideoCapture" << std::endl;
        return_val = -4;
        goto cleanup;
    }

    //Display window setting
    cv::namedWindow("FPDLINKIII_4xCamera_Demo");
    cv::moveWindow("FPDLINKIII_4xCamera_Demo", 0, 0);

    while (true)
    {
        ticks.start();
        capture1 >> frame1;
    capture2 >> frame2;
        capture3 >> frame3;
        capture4 >> frame4;
    cv::resize(frame1, frame1_dst, cv::Size(640,360));
    cv::resize(frame2, frame2_dst, cv::Size(640,360));
    cv::resize(frame3, frame3_dst, cv::Size(640,360));
    cv::resize(frame4, frame4_dst, cv::Size(640,360));
    #if 1
    cv::hconcat(frame1_dst, frame2_dst, disp_mat1);
    cv::hconcat(frame3_dst, frame4_dst, disp_mat2);
    cv::vconcat(disp_mat1, disp_mat2, disp_vmat);
    cv::imshow("FPDLINKIII_4xCamera_Demo", disp_vmat);
    #else
    cv::imshow("FPDLINKIII_4xCamera_Demo", frame1);
    #endif
        int key = cv::waitKey(1);
        // 'q' for termination
        if (key == 'q' )
        {
            break;
        }
        ticks.stop();
    }

    if (ticks.getCounter() == 0)
    {
        std::cerr << "No frames processed" << std::endl;
        return_val = -10;
        goto cleanup;
    }

    fps_calculated = ticks.getCounter() / ticks.getTimeSec();
    std::cout << "Fps observed " << fps_calculated << std::endl;

cleanup:
    capture1.release();
    capture2.release();
    capture3.release();
    capture4.release();
    return return_val;
}

Original: https://blog.csdn.net/weixin_45227638/article/details/120562769
Author: v流年笑掷未来可期v
Title: GMSL 介绍