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C/C++ H264文件解析

news 2025/6/29 15:11:28

C++实现H264文件以及一段H264码流解析，源码如下：

h264Parse.h:

#ifndef _H264PARSE_H_
#define _H264PARSE_H_#include <fstream>class H264Parse
{
public:int open_file(const std::string &filename);/*** @brief 从文件中读取一个nalu，包含起始码* @param buf 存放nalu的缓冲区* @param size 缓冲区大小* @param len nalu的长度* @param n 每次读取多少个字节* @return  -1 失败    0 已到文件末尾     1 成功获取到一个nalu*/int read_nalu(uint8_t *buf, uint32_t size, uint32_t &len, uint32_t n);void close_file();// 获取起始码长度static int get_startCode_len(const uint8_t *ptr);static const uint8_t *find_startCode_pos(const uint8_t *pbuf, uint32_t len);/*** @brief 从一段h264码流中分割nalu，包含起始码* @param stream h264码流* @param streamLen 码流大小* @param nalu Pointer to the extracted nalu* @param naluLen nalu的长度* @param record Pointer用于记录状态，第一次分割时把 *record 赋值为NULL* @return  -1 失败    0 已分割完     1 成功获取到一个nalu*/static int nalu_tok(const uint8_t *stream, uint32_t streamLen, const uint8_t **nalu,uint32_t &naluLen, const uint8_t **record);private:std::fstream h264File;int read_start_code(uint8_t *buf);int adjust_filePointer_pos(uint32_t totalRead, uint32_t naluLen);
};#endif // _H264PARSE_H_

h264Parse.cpp:

#include "h264Parse.h"
#include <iostream>
#include <cstring>int H264Parse::open_file(const std::string &filename)
{h264File.open(filename, std::ios::in | std::ios::binary);if (!h264File.is_open()){std::cout << "Failed to open the H.264 file." << std::endl;return -1;}return 0;
}int H264Parse::get_startCode_len(const uint8_t *ptr)
{if (ptr[0] == 0x00 && ptr[1] == 0x00){if (ptr[2] == 0x01)return 3;else if (ptr[2] == 0x00 && ptr[3] == 0x01)return 4;}return -1; // 无效的起始码
}// 读取起始码，并返回其长度
int H264Parse::read_start_code(uint8_t *buf)
{// 读取前4个字节来判断起始码长度h264File.read(reinterpret_cast<char *>(buf), 4);if (h264File.gcount() < 4){return -1;}return get_startCode_len(buf);
}// 寻找NALU的起始码位置
const uint8_t *H264Parse::find_startCode_pos(const uint8_t *pbuf, uint32_t len)
{const uint8_t *p = pbuf;if (len < 3)return NULL;for (uint32_t i = 0; i < len - 3; ++i){if ((p[0] == 0x00 && p[1] == 0x00 && p[2] == 0x01) ||(p[0] == 0x00 && p[1] == 0x00 && p[2] == 0x00 && p[3] == 0x01)){return p;}p++;}// 检查最后3字节是不是起始码if (p[0] == 0x00 && p[1] == 0x00 && p[2] == 0x01)return p;return NULL;
}// 调整文件指针位置
int H264Parse::adjust_filePointer_pos(uint32_t totalRead, uint32_t naluLen)
{int offset = -(totalRead - naluLen);if (!h264File.eof()){h264File.seekg(offset, std::ios::cur);}else{h264File.clear(); // 达到文件末尾了要先清除 eof 标志h264File.seekg(offset, std::ios::end);}if (h264File.fail()){std::cout << "seekg failed!" << std::endl;return -1;}return 0;
}int H264Parse::read_nalu(uint8_t *buf, uint32_t size, uint32_t &len, uint32_t n)
{uint32_t totalRead = 0;int startCodeLength = read_start_code(buf);if (startCodeLength == -1){printf("read_start_code failed.\n");return -1;}totalRead += 4; // 已经读取了4字节的长度while (true){if (size < totalRead + n){std::cout << "Buffer size is too small: size=" << size<< ", needed=" << totalRead + n << std::endl;return -1;}h264File.read(reinterpret_cast<char *>(buf + totalRead), n);std::streamsize bytesRead = h264File.gcount();if (bytesRead <= 0){std::cout << "Failed to read from file!" << std::endl;return -1;}uint32_t searchStart = (totalRead > 4) ? totalRead - 3 : startCodeLength;const uint8_t *naluEnd = find_startCode_pos(buf + searchStart,bytesRead + (totalRead > 4 ? 3 : 0));totalRead += bytesRead;if (naluEnd != nullptr){len = naluEnd - buf;if (adjust_filePointer_pos(totalRead, len) < 0)return -1;break;}// 是否读取到文件末尾if (h264File.peek() == std::char_traits<char>::eof()){len = totalRead;return 0; // NALU完整读取}}memset(buf + len, 0, size - len); // 清空剩余部分return 1;                         // 成功读取
}void H264Parse::close_file()
{h264File.close();
}int H264Parse::nalu_tok(const uint8_t *stream, uint32_t streamLen, const uint8_t **nalu,uint32_t &naluLen, const uint8_t **record)
{const uint8_t *current = (record && *record) ? *record : stream;uint32_t offset = static_cast<uint32_t>(current - stream);if (offset >= streamLen){return -1; // 当前记录位置超出缓冲区}int scLen = get_startCode_len(current);if (scLen == -1 || (current + scLen) > (stream + streamLen)){return -1; // 无效的起始码或起始码长度超出缓冲区}// 查找下一个起始码的位置const uint8_t *next_start = find_startCode_pos(current + scLen, streamLen - offset - scLen);if (next_start){*nalu = current;naluLen = static_cast<uint32_t>(next_start - current);*record = next_start;return 1; // 成功获取到一个 NALU}else{// 最后一个 NALU*nalu = current;naluLen = streamLen - offset;*record = NULL; // 重置记录指针return 0;       // 分割完毕}
}

测试：

#include <iostream>
#include <vector>
#include "h264Parse.h"void test1()
{int ret;int number = 0;H264Parse h264;uint8_t buf[1024 * 1024];uint32_t len = 0;h264.open_file("/home/tl/work/app/res/output.h264");while ((ret = h264.read_nalu(buf, sizeof(buf), len, 1024 * 2)) != -1){printf("number: %d nalu len: %u\n", number, len - h264.get_startCode_len(buf));number++;if (ret == 0)break;}if (ret == -1){std::cout << "read_nalu failed." << std::endl;}h264.close_file();
}// 辅助函数：打印 NALU 信息
void print_nalu(const uint8_t *nalu, uint32_t len, int index)
{std::cout << "NALU " << index << ": Length = " << len << " bytes, Data = ";for (uint32_t i = 0; i < len; ++i){printf("%02X ", nalu[i]);}std::cout << std::endl;
}void test2()
{// 构造一个模拟的 H.264 码流缓冲区，包含多个 NALU// 起始码格式：0x000001 (3 字节) 和 0x00000001 (4 字节)// NALU 内容：随机填充的字节数据std::vector<uint8_t> buffer;// NALU 1: 3 字节起始码 + 5 字节数据std::vector<uint8_t> nalu1 = {0x00, 0x00, 0x01, 0x65, 0x88, 0x84, 0x21, 0xA0};buffer.insert(buffer.end(), nalu1.begin(), nalu1.end());// NALU 2: 4 字节起始码 + 6 字节数据std::vector<uint8_t> nalu2 = {0x00, 0x00, 0x00, 0x01, 0x41, 0x9A, 0x5C, 0xD4, 0x00, 0x11};buffer.insert(buffer.end(), nalu2.begin(), nalu2.end());// NALU 3: 3 字节起始码 + 4 字节数据std::vector<uint8_t> nalu3 = {0x00, 0x00, 0x01, 0x06, 0x05, 0xFF, 0xEE};buffer.insert(buffer.end(), nalu3.begin(), nalu3.end());// NALU 4: 3 字节起始码 + 3 字节数据 (测试末尾)std::vector<uint8_t> nalu4 = {0x00, 0x00, 0x01, 0x07, 0xAD, 0xBE};buffer.insert(buffer.end(), nalu4.begin(), nalu4.end());// 输出构建的缓冲区（可选）std::cout << "Constructed H.264 Buffer: ";for (size_t i = 0; i < buffer.size(); ++i){printf("%02X ", buffer[i]);}std::cout << "\n\n";const uint8_t *pnalu = nullptr;uint32_t nale_len = 0;const uint8_t *pRecord = NULL; // 初始时为 NULLint ret;int nalu_index = 1;// 循环分割并打印每个 NALUwhile ((ret = H264Parse::nalu_tok(buffer.data(), buffer.size(), &pnalu, nale_len, &pRecord)) != -1){print_nalu(pnalu, nale_len, nalu_index);nalu_index++;if (ret == 0)break;}if (ret == -1){std::cout << "Error occurred during NALU tokenization." << std::endl;}
}// 主函数
int main()
{test1();// test2();return 0;
}

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