C语言接收rtp包组成h264帧
时间: 2023-12-05 10:06:05 浏览: 244
要接收RTP包并组成H264帧,你需要了解RTP和H264的基本知识,以及C语言的网络编程和字节操作。
首先,你需要使用套接字(Socket)来接收RTP包。在C语言中,你可以使用系统调用socket()和相关函数来创建和操作套接字。你需要指定协议类型为UDP,因为RTP是一个基于UDP的协议。然后,你需要绑定套接字到本地IP地址和端口,以便接收到来自远程主机的RTP数据包。
接下来,你需要解析RTP头部和负载。RTP头部包含了序列号、时间戳、SSRC等信息,而负载则是包含H264码流的NAL单元。你需要使用C语言中的结构体来定义RTP头部,并使用位运算和字节操作来解析和提取其中的字段。对于H264码流,你需要使用NAL单元的起始码来判断每个NAL单元的边界,然后将它们组成完整的H264帧。
最后,你可以将组成的H264帧进行处理和显示,或者将它们写入文件中进行存储。注意,H264帧的处理和显示需要使用相应的编解码库和图形库,比如FFmpeg和SDL等。
总之,实现接收RTP包并组成H264帧需要具备多方面的技能和经验,包括网络编程、字节操作、结构体定义、协议解析和编解码等。
相关问题
c语言编写rtp接收代码并组成h264帧
要编写一个基于C语言的RTP接收代码并组成H.264帧,可以按照以下步骤进行:
1. 创建一个UDP套接字并绑定到一个端口上,以接收RTP包。
```
int socket_fd = socket(AF_INET, SOCK_DGRAM, 0); // 创建UDP套接字
struct sockaddr_in local_addr;
memset(&local_addr, 0, sizeof(local_addr));
local_addr.sin_family = AF_INET;
local_addr.sin_addr.s_addr = htonl(INADDR_ANY); // 接收所有IP地址发送的数据
local_addr.sin_port = htons(rtp_port); // 绑定到RTP端口号
bind(socket_fd, (struct sockaddr*)&local_addr, sizeof(local_addr));
```
2. 接收RTP包并解析其中的头部信息,包括序列号、时间戳等。
```
char rtp_packet[1500];
struct sockaddr_in remote_addr;
unsigned int addr_len = sizeof(remote_addr);
recvfrom(socket_fd, rtp_packet, sizeof(rtp_packet), 0, (struct sockaddr*)&remote_addr, &addr_len);
// 解析RTP头部信息
unsigned char payload_type = rtp_packet[1] & 0x7f; // RTP负载类型
unsigned short sequence_number = ntohs(*(unsigned short*)(rtp_packet + 2)); // RTP序列号
unsigned int timestamp = ntohl(*(unsigned int*)(rtp_packet + 4)); // RTP时间戳
unsigned int ssrc = ntohl(*(unsigned int*)(rtp_packet + 8)); // RTP同步信源标识符
```
3. 解析RTP负载数据,将之前分割的NALU序列组合成一帧H.264码流。
```
unsigned char* payload_data = rtp_packet + 12; // RTP负载数据
unsigned int payload_len = ntohs(*(unsigned short*)(rtp_packet + 2)) - 12; // RTP负载长度
while (payload_len > 0) {
// 解析NALU头部信息
unsigned char nal_unit_type = payload_data[0] & 0x1f;
unsigned char nal_ref_idc = (payload_data[0] >> 5) & 0x03;
// 将NALU序列组合成一帧H.264码流
if (nal_unit_type == 7 || nal_unit_type == 8) {
// SPS或PPS单独组成一帧
if (frame_pos > 0) {
// 发送前面组合的帧
send_h264_frame(h264_frame, frame_pos);
frame_pos = 0;
}
memcpy(h264_frame, start_code, 4);
memcpy(h264_frame + 4, payload_data, payload_len);
frame_pos = 4 + payload_len;
} else {
// 其他类型NALU组成一帧
if (frame_pos + 4 + payload_len > MAX_FRAME_SIZE) {
// 超过最大帧长度,发送当前组合的帧
send_h264_frame(h264_frame, frame_pos);
frame_pos = 0;
}
memcpy(h264_frame + frame_pos, start_code, 4);
memcpy(h264_frame + frame_pos + 4, payload_data, payload_len);
frame_pos += 4 + payload_len;
}
// 跳过当前NALU
payload_data += payload_len;
payload_len = ntohs(*(unsigned short*)payload_data);
payload_data += 2;
}
```
4. 发送组合好的H.264帧。
```
void send_h264_frame(unsigned char* frame_data, unsigned int frame_len) {
// 发送一帧H.264码流
sendto(socket_fd, frame_data, frame_len, 0, (struct sockaddr*)&remote_addr, sizeof(remote_addr));
}
```
c语言编写rtp接收代码并组成h264帧,保存成h264文件
下面是一个简单的示例代码,使用C语言编写了RTP接收程序,并将接收到的数据组成H264帧并保存为H264文件:
```c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <arpa/inet.h>
#define RTP_HEADER_SIZE 12
#define NALU_HEADER_SIZE 1
typedef struct rtp_header {
uint8_t version:2;
uint8_t padding:1;
uint8_t extension:1;
uint8_t csrc_count:4;
uint8_t marker:1;
uint8_t payload_type:7;
uint16_t sequence_number;
uint32_t timestamp;
uint32_t ssrc;
} rtp_header_t;
int main(int argc, char *argv[]) {
if (argc != 3) {
printf("Usage: %s <rtp_port> <output_file>\n", argv[0]);
return 1;
}
uint16_t port = atoi(argv[1]);
char *output_file = argv[2];
FILE *fp = fopen(output_file, "wb");
if (fp == NULL) {
printf("Failed to open output file!\n");
return 1;
}
int sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
if (sock < 0) {
printf("Failed to create socket!\n");
return 1;
}
struct sockaddr_in server;
memset(&server, 0, sizeof(server));
server.sin_family = AF_INET;
server.sin_addr.s_addr = INADDR_ANY;
server.sin_port = htons(port);
if (bind(sock, (struct sockaddr *)&server, sizeof(server)) < 0) {
printf("Failed to bind socket!\n");
return 1;
}
uint8_t buffer[65536];
rtp_header_t *rtp_header;
uint8_t *nalu_buffer = NULL;
int nalu_size = 0;
int nalu_type;
int last_nalu_end = 0;
while (1) {
ssize_t bytes_received = recvfrom(sock, buffer, sizeof(buffer), 0, NULL, NULL);
if (bytes_received < RTP_HEADER_SIZE + NALU_HEADER_SIZE) {
printf("Invalid RTP packet!\n");
continue;
}
rtp_header = (rtp_header_t *)buffer;
uint8_t *payload = buffer + RTP_HEADER_SIZE;
int payload_size = bytes_received - RTP_HEADER_SIZE;
if (nalu_buffer == NULL) {
// Look for the start of an H.264 NAL unit
for (int i = 0; i < payload_size - 4; i++) {
if ((payload[i] == 0x00) && (payload[i+1] == 0x00) &&
(payload[i+2] == 0x00) && (payload[i+3] == 0x01)) {
// Found the start of a NAL unit
nalu_buffer = payload + i + 4;
nalu_size = payload_size - i - 4;
nalu_type = nalu_buffer[0] & 0x1F;
break;
}
}
} else {
// Look for the end of the current NAL unit
int new_nalu_end = 0;
for (int i = 0; i < payload_size - 4; i++) {
if ((payload[i] == 0x00) && (payload[i+1] == 0x00) &&
(payload[i+2] == 0x00) && (payload[i+3] == 0x01)) {
// Found the start of a new NAL unit
new_nalu_end = i;
break;
}
}
if (new_nalu_end > 0) {
// This packet contains the end of the current NAL unit
fwrite(nalu_buffer, nalu_size, 1, fp);
// Start assembling the next NAL unit
nalu_buffer = payload + new_nalu_end + 4;
nalu_size = payload_size - new_nalu_end - 4;
nalu_type = nalu_buffer[0] & 0x1F;
// Update the last NAL unit end position
last_nalu_end = new_nalu_end;
} else {
// This packet contains part of the current NAL unit
fwrite(nalu_buffer, RTP_HEADER_SIZE + NALU_HEADER_SIZE,
1, fp);
fwrite(payload, payload_size, 1, fp);
nalu_size += payload_size;
}
}
}
fclose(fp);
return 0;
}
```
该程序将从指定的RTP端口接收数据,并将接收到的数据组成H264帧并保存到指定的文件中。程序使用了一个简单的技巧来查找H264的NAL单元边界,也就是4个0字节后紧跟着一个1字节。程序的核心是一个无限循环,该循环将不断接收RTP数据包并处理它们。
请注意,这只是一个非常简单的示例程序,可能无法处理所有情况。在实际应用中,您需要考虑更多的细节和错误情况,并进行适当的错误处理和恢复。
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