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====== 工业相机 ======
  * Industrial camera
  * 度申 do3think

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### GenICam 标准
- 下载：https://www.emva.org/standards-technology/genicam/genicam-downloads/

### GigE Vision 协议

- https://en.wikipedia.org/wiki/GigE_Vision
- https://www.automate.org/vision/vision-standards/vision-standards-gige-vision
- 设备发现机制：GVCP Device Discovery
  - 使用UDP广播，不能跨路由，所以只限定同一局域网  a “limited broadcast” by RFC1122
  - Definitions of broadcast types are provided in section 3.3.6 of RFC1122
  - In GigE Vision 1.x, GVCP is only defined to listen on UDP port **3956**.
  - GigE Vision version 2.0 defines how devices can advertise and discover each other using a combination of multicast DNS and DNS-SD, called **Zeroconf Discovery**
- A GigE Vision device MUST have an XML device description file with the syntax 
described in the GenApi module of the GenICam standard
  - The filename of the XML device description file MUST be different when the file 
content changes.

#### GVCP
 - GVCP是一种基于UDP传输层协议的应用层协议，此控制协议不包括GigE视觉流媒体协议（GVSP）。
 - 控制设备的连接是唯一的，读取的连接可以多个
 - GVCP 的 IP头固定为20字节，不使用 IP 头可选项（linux socket 就是默认不使用）
 - The first GVCP port of the device MUST use UDP port 3956.This standard GVCP port has been registered with IANA (http://www.iana.org/assignments/port-numbers).
 - GVCP, 命令（command）和确认（ack）消息包含在同一个包中，这样能确保包不用碎片化分割，同理，GVCP的包大小不能超过 576 字节，因为可避免IP碎片化的最大传输单元（MTU）为576字节
- 一个GVCP包的结构大小：
	| Layer |  Size(in bytes) |
	| -------- |--------------------|
	| IP header (options not allowed) | 20 |
	| UDP header | 8 |
	| GVCP header | 8 |
	| Max. GVCP payload | 540 |
	| Total | 576 |
- **GVCP 包必须32位对齐，header已满足条件，即要求有效载荷payload部分必须4字节对齐**
- 应用获取设备确认消息超时后，必须重发命令消息，重发命令消息时  req_id 保持不变
- 重传消息默认是 200 ms  超时，次数3，这两个值都应可设置
- req_id 初始值不能为0，由应用端按命令消息递增
- 设备端的 ack_id 返回与命令消息一一对应，即重复的命令也会重复返回（但可能不会重复执行），应用端需处理收到多次同一 ack_id 消息的情况
- 应用端必须忽略 ack_id 不匹配的消息，应用端必须收到前一条命令的ack确认消息后才能发送下一条命令（除了 DISCOVERY_CMD, PACKETRESEND_CMD）
- 应用端要确保心跳连接。设备提供一个**Heartbeat Timeout**启动寄存器。建议应用端在该设备心跳超时时间内发送三次心跳消息，避免连接被设备端自动关闭
- GVCP header 头结构： 第一字节值固定 0x42
- 命令头结构 Command Messaeg Header ![gvcp_1.png](:public:it:gvcp_1.png)

	| **COMMAND MESSAGE HEADER** |||
	| - |
	| 0x42 | 8 bits | Hard-coded key code value used for message validation.|
	| flag | 8 bits | Upper 4 bits (msb, bit 0 to bit 3) are specific to each GVCP commands. |
	|^^|^^| Lower 4 bits (lsb, bit 4 to bit 7) are common to all GVCP commands. |
	|^^|^^| All unused bits must be set to 0. |
	|^^|^^| bit 0 to 3 – Specific to each command. Set to 0 if the command does not use them. |
	|^^|^^| bit 4 – Reserved, set to 0 on transmission, ignore on reception. |
	|^^|^^| bit 5 – Reserved, set to 0 on transmission, ignore on reception. | |
	|^^|^^| bit 6 – Reserved, set to 0 on transmission, ignore on reception. |
	|^^|^^| bit 7 – ACKNOWLEDGE:  |
	|^^|^^|  SET = 要求接收者必须发送 ack 确认消息.  |
	|^^|^^|  CLEAR = 接收者不应发送 ack 确认消息.  |
	|^^|^^|  ACKNOWLEDGE 的优先级比命令本身是否需要回复的优先级要高 |
	| command | 16 bits |  Command message value (see dictionary section). | 
	|^^|^^| Commands from 0 to 32765 are reserved for GigE Vision. Others are available for customization (device-specific).| 
	| length | 16 bits | 负载 payload  的字节数，不包括头长度 | 
	| req_id | 16 bits | 递增的 req_id, 非0，应用端提供，设备端回复 ack_id 时拷贝相同值 | 
	
- ACK 消息头结构：

![gvcp_2.png](:public:it:gvcp_2.png)

|ACKNOWLEDGE MESSAGE HEADER|||
|-|
| status | 16 bits | Status of the requested operation (see status code section)| 
| acknowledge | 16 bits | Acknowledge message value (see dictionary section). | 
| length | 16 bits | 头之后的负载的字节数 | 
| ack_id | 16 bits | 值与所响应的命令消息的req_id 相同 | 
  
- GVCP必须使用网络字节顺序，即大端序 big-endian

#### DISCOVERY
- DISCOVERY_CMD 值 0x0002
- 命令消息头 **flag** 的 bit3 指示设备是否广播 DISCOVER_ACK 消息
- 命令消息头 **flag** 的 bit7 必定设置为1，即设备端必须回复 ack 消息
- DISCOVERY_ACK 值 0x0003 , 回复消息的头与负载结构(每行4字节，除了标明长度的）：

	| 0 | 1 | 2 | 3 |
	|:---:|:---:|:---:|:---:|
	| status || answer = DISCOVERY_ACK ||
	| length || ack_id ||
	| spec_version_major || spec_version_minor ||
	| device_mode ||||
	| reserved || device_MAC_address (high) ||
	| device_MAC_address (low) ||||
	| IP_config_options ||||
	| IP_config_current ||||
	| reserved ||||
	| reserved ||||
	| reserved ||||
	| current_IP ||||
	| reserved ||||
	| reserved ||||
	| reserved ||||
	| current_subnet_mask ||||
	| reserved ||||
	| reserved ||||
	| reserved ||||
	| default_gateway ||||
	| manufacturer_name [32 bytes] ||||
	| model_name [32 bytes] ||||
	| device_version [32 bytes] ||||
	| manufacturer_specific_information [48 bytes] ||||
	| serial_number [16 bytes] ||||
	| user_defined_name [16 bytes] ||||

- 测试代码：
	
	```c
	#include <iostream>
	#include <cstring>
	#include <sys/socket.h>
	#include <netinet/in.h>
	#include <arpa/inet.h>
	#include <unistd.h>
	
	#include <iomanip>
	
	#define BROADCAST_PORT 3956 // GigE Vision discovery port
	#define BUFFER_SIZE 1024
	
	int main() {
	    int sock;
	    struct sockaddr_in broadcastAddr;
	    char broadcastBuffer[BUFFER_SIZE];
	    int broadcastPermission;
	    unsigned int sendLen;
	
	    // 创建UDP套接字
	    sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
	    if (sock < 0) {
	        std::cerr << "Socket creation failed." << std::endl;
	        return -1;
	    }
	
	    // 设置广播权限
	    broadcastPermission = 1;
	    if (setsockopt(sock, SOL_SOCKET, SO_BROADCAST, (void *) &broadcastPermission, sizeof(broadcastPermission)) < 0) {
	        std::cerr << "Setting socket option to SO_BROADCAST failed." << std::endl;
	        close(sock);
	        return -1;
	    }
	
	    // 设置广播地址
	    memset(&broadcastAddr, 0, sizeof(broadcastAddr));
	    broadcastAddr.sin_family = AF_INET;
	    broadcastAddr.sin_addr.s_addr = inet_addr("255.255.255.255"); // 广播地址
	    broadcastAddr.sin_port = htons(BROADCAST_PORT);
	
	    // 构造广播消息（这里简化了，实际应该按照GigE Vision协议构造）
	    uint8_t discovery_msg[8] = {0};
	    discovery_msg[0] = 0x42;
	    discovery_msg[1] = 0x80;
	    discovery_msg[2] = 0;
	    discovery_msg[3] = 0x02; // DISCOVERY_CMD: 0x0002
	    discovery_msg[4] = 0;
	    discovery_msg[5] = 0;    // length 0
	    discovery_msg[6] = 0;
	    discovery_msg[7] = 1;    // req_id 1
	
	    const size_t send_len = 8;
	    // 发送广播消息
	    if (sendto(sock, discovery_msg, send_len, 0, (struct sockaddr *) &broadcastAddr, sizeof(broadcastAddr)) != send_len) {
	        std::cerr << "Broadcast sendto() failed." << std::endl;
	        close(sock);
	        return -1;
	    }
	
	    std::cout << "Broadcast message sent. Waiting for responses..." << std::endl;
	
	    // 接收响应（这里简化了，实际应该处理多个响应，并解析GigE Vision协议数据）
	    struct sockaddr_in recvAddr;
	    socklen_t addrLen = sizeof(recvAddr);
	    int recvLen = recvfrom(sock, broadcastBuffer, BUFFER_SIZE, 0, (struct sockaddr *) &recvAddr, &addrLen);
	
	    if (recvLen > 0) {
	        broadcastBuffer[recvLen] = '\0';
	        std::cout << "Received a response from: " << inet_ntoa(recvAddr.sin_addr) << std::endl;
	        std::cout << "Size: " << recvLen << std::endl;
	
	        std::cout << "Response: " << std::hex << std::setfill('0') << std::setw(2) << std::showbase;
	
	        for (int i = 0; i < recvLen; ++i) {
	            if (i >= 80 && broadcastBuffer[i] > 32 && broadcastBuffer[i] < 127) {
	                std::cout << broadcastBuffer[i] << " ";
	            } else {
	                std::cout << (int)(broadcastBuffer[i]) << " ";
	            }
	
	            if (i > 0 && ((i+1) % 16 == 0)) {
	                std::cout << std::endl;
	            }
	        }
	
	        std::cout << std::endl;
	
	        char mac[7] = {0};
	        memcpy(mac, broadcastBuffer + 18, 6);
	
	        char ip[4] = {0};
	        memcpy(ip, broadcastBuffer + 44, 4);
	
	        char manufacturer_name[33] = {0};
	        memcpy(manufacturer_name, broadcastBuffer + 80, 32);
	        char model_name[33] = {0};
	        memcpy(model_name, broadcastBuffer + 80 + 32, 32);
	        char device_version[33] = {0};
	        memcpy(device_version, broadcastBuffer + 80 + 64, 32);
	        char manufacturer_spec_info[49] = {0};
	        memcpy(manufacturer_spec_info, broadcastBuffer + 80 + 96, 48);
	        char serial_number[17] = {0};
	        memcpy(serial_number, broadcastBuffer + 80 + 96 + 48, 16);
	        char user_defined_name[17] = {0};
	        memcpy(user_defined_name, broadcastBuffer + 80 + 96 + 48 + 16, 16);
	
	        std::cout << std::noshowbase << "mac: "
	            << (int)(mac[0]) << ":"
	            << (int)(mac[1]) << ":"
	            << (int)(mac[2]) << ":"
	            << (int)(mac[3]) << ":"
	            << (int)(mac[4]) << ":"
	            << (int)(mac[5]) << std::endl;
	        std::cout << std::dec << std::setw(0) <<  "ip: "
	            << (int)(ip[0]) << "."
	            << (int)(ip[1]) << "."
	            << (int)(ip[2]) << "."
	            << (int)(ip[3]) << std::endl;
	        std::cout << "manufacturer_name : " << manufacturer_name << std::endl;
	        std::cout << "model_name : " << model_name << std::endl;
	        std::cout << "device_version : " << device_version << std::endl;
	        std::cout << "manufacturer_spec_info : " << manufacturer_spec_info << std::endl;
	        std::cout << "serial_number : " << serial_number << std::endl;
	        std::cout << "user_defined_name : " << user_defined_name << std::endl;
	
	    } else {
	        std::cerr << "No response received, or recvfrom() failed." << std::endl;
	    }
	    // 关闭套接字
	    close(sock);
	    return 0;
	}
	
	````



#### FORCEIP
- FORCEIP_CMD （0x0004）可以强制修改静态IP，
  - 前提1：知道相机的MAC地址
  - 前提2：相机当前没有控制应用端连接

#### channel 概念
- 通道(channel)概念：A channel is a virtual link used to transfer information between GigE Vision entities. GigE Vision supports three types of channels:
	1. Control channel (there is always 1 control channel for the primary application)
	2. Stream channel (from 0 to 512 stream channels)
	3. Message channel (0 or 1 message channel)
- 除了 3965 用于控制通道端口，其它通道可用任何端口
- GVCP 定义了4级权限
  - **Exclusive access**: 独占权限，当应用程序具有独占访问权限时，设备不能允许第二个应用创建控制通道
  - **Control access**：控制权限，当应用程序具有控制权限时，设备可以允许第二个应用端具有读取权限
  - **Control access with switchover enabled**：可切换的控制权限，设备允许第二个具有正确凭据的应用端拥有控制权限
  - **Monitor access**： 监视权限，如果设备当前没有独占权限的应用端连接就可以使用
  - 一个设备只支持独占访问是完全合法的
  - 备忘：14.4节 讲述怎么让额外的应用端控制设备
  - 应用可在不关闭控制通道的情况下切换权限
- **PENDING_ACK**：重置等待 ack 超时时间 

![gvcp_3.png](:public:it:gvcp_3.png)

  
#### GVSP
- A stream channel enables data transfer from a GVSP transmitter to a GVSP receiver. This transfer uses the GigE Vision Streaming Protocol (GVSP).
- 允许 1-512 个连接
- 也是基于 UDP IPv4， IP头也是固定20字节不使用IP头可选项
- GVSP 的包大小不要求32位对齐，包大小取决于链路之间的MTU大小
  -SCPSx  只决定数据负载（data payload）的包的大小,  数据头包（data leader）与尾包(data trailer)还是限定576字节大小的包。
- 标准传输模式（Standard Transmission mode），把数据分为 data leader, data payload, data trailer 三部分package
- 全入传输模式（All-in Transmission Mode），一个package全包含  data leader, payload, trailer.  可选，不一定支持

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