示例
#include <iostream>
#include <vector>
#include <libavformat/avformat.h>
#include <libavcodec/avcodec.h>
#include <libavutil/opt.h>
#include <libavutil/time.h>
#include <libavutil/avassert.h>
#include <cstdint>
#include <cstring>
#include <cstdio> // for file input// 错误处理宏
#define CHECK_RET(ret, msg) do { \if (ret < 0) { \std::cerr << msg << ": " << av_err2str(ret) << std::endl; \goto end; \} \
} while (0)// 查找 Annex B start code (00 00 00 01 或 00 00 01)
static int find_start_code(const uint8_t* buf, int size, int* start_code_len) {if (size >= 4 && buf[0] == 0 && buf[1] == 0 && buf[2] == 0 && buf[3] == 1) {*start_code_len = 4;return 0;}if (size >= 3 && buf[0] == 0 && buf[1] == 0 && buf[2] == 1) {*start_code_len = 3;return 0;}return -1;
}// 解析 VPS/SPS/PPS 并存储到 extradata
static int parse_nalu_extradata(AVCodecParserContext* parser, AVCodecContext* codec_ctx,const uint8_t* data, int size,uint8_t** extradata, int* extradata_size) {std::vector<uint8_t> extradata_buf;int offset = 0;while (offset < size) {int start_code_len = 0;if (find_start_code(data + offset, size - offset, &start_code_len) < 0) {offset++;continue;}// 找到下一个 start code 或数据末尾int next_offset = offset + start_code_len;while (next_offset < size) {if (find_start_code(data + next_offset, size - next_offset, &start_code_len) == 0) {break;}next_offset++;}if (next_offset == size) {next_offset = size; // 最后一个 NALU}int nalu_size = next_offset - offset;uint8_t* nalu_data = (uint8_t*)data + offset;int nalu_type = codec_ctx->codec_id == AV_CODEC_ID_H264 ?(nalu_data[start_code_len] & 0x1F) :((nalu_data[start_code_len] >> 1) & 0x3F);// H.264: SPS (7), PPS (8); H.265: VPS (32), SPS (33), PPS (34)bool is_extradata_nalu = false;if (codec_ctx->codec_id == AV_CODEC_ID_H264 &&(nalu_type == 7 || nalu_type == 8)) {is_extradata_nalu = true;} else if (codec_ctx->codec_id == AV_CODEC_ID_HEVC &&(nalu_type == 32 || nalu_type == 33 || nalu_type == 34)) {is_extradata_nalu = true;}if (is_extradata_nalu) {extradata_buf.insert(extradata_buf.end(), nalu_data, nalu_data + nalu_size);}offset = next_offset;}if (extradata_buf.empty()) {return -1; // 未找到 extradata}*extradata_size = extradata_buf.size();*extradata = (uint8_t*)av_malloc(*extradata_size + AV_INPUT_BUFFER_PADDING_SIZE);if (!*extradata) {return AVERROR(ENOMEM);}memcpy(*extradata, extradata_buf.data(), *extradata_size);memset(*extradata + *extradata_size, 0, AV_INPUT_BUFFER_PADDING_SIZE);return 0;
}int main(int argc, char** argv) {if (argc != 4) {std::cerr << "Usage: " << argv[0] << " <input_codec> <input_file> <output_fmp4>\n";std::cerr << "input_codec: h264 or hevc\n";std::cerr << "input_file: path to raw H.264/H.265 stream or 'udp://host:port'\n";return -1;}const char* codec_name = argv[1]; // "h264" or "hevc"const char* input_filename = argv[2];const char* output_filename = argv[3];AVFormatContext* fmt_ctx = nullptr;AVStream* stream = nullptr;AVCodecParserContext* parser = nullptr;AVCodecContext* codec_ctx = nullptr;AVPacket pkt;int ret = 0;AVCodecID codec_id = strcmp(codec_name, "h264") == 0 ? AV_CODEC_ID_H264 : AV_CODEC_ID_HEVC;// 1. 初始化 FFmpegavformat_network_init();// 2. 分配输出上下文 (mp4 muxer)ret = avformat_alloc_output_context2(&fmt_ctx, nullptr, "mp4", output_filename);CHECK_RET(ret, "Failed to allocate output context");// 3. 创建视频流stream = avformat_new_stream(fmt_ctx, nullptr);if (!stream) {std::cerr << "Failed to create stream" << std::endl;ret = AVERROR_UNKNOWN;goto end;}stream->id = fmt_ctx->nb_streams - 1;// 4. 初始化 codec 参数和解析器const AVCodec* codec = avcodec_find_decoder(codec_id);if (!codec) {std::cerr << "Decoder not found for " << codec_name << std::endl;ret = AVERROR_DEMUXER_NOT_FOUND;goto end;}parser = av_parser_init(codec_id);if (!parser) {std::cerr << "Failed to init parser" << std::endl;ret = AVERROR_UNKNOWN;goto end;}codec_ctx = avcodec_alloc_context3(codec);if (!codec_ctx) {std::cerr << "Failed to allocate codec context" << std::endl;ret = AVERROR(ENOMEM);goto end;}// 设置 codecpar（稍后填充 extradata）AVCodecParameters* codecpar = stream->codecpar;codecpar->codec_type = AVMEDIA_TYPE_VIDEO;codecpar->codec_id = codec_id;codecpar->format = AV_PIX_FMT_YUV420P; // 假设codecpar->width = 1920; // 示例；可从 SPS 解析codecpar->height = 1080;codecpar->bit_rate = 5000000;// 设置时间基stream->time_base = {1, 30}; // 30fpscodec_ctx->time_base = stream->time_base;// 5. 打开输入（文件或 UDP）FILE* input_file = nullptr;if (strncmp(input_filename, "udp://", 6) != 0) {input_file = fopen(input_filename, "rb");if (!input_file) {std::cerr << "Failed to open input file: " << input_filename << std::endl;ret = AVERROR(EIO);goto end;}} else {// UDP 示例：替换为 avformat_open_input/*AVFormatContext* input_ctx = nullptr;ret = avformat_open_input(&input_ctx, input_filename, nullptr, nullptr);CHECK_RET(ret, "Failed to open UDP input");// 读取逻辑替换 fread*/}// 6. 解析 extradata（VPS/SPS/PPS）uint8_t buffer[1024 * 1024]; // 1MB 缓冲size_t bytes_read = fread(buffer, 1, sizeof(buffer), input_file);if (bytes_read == 0) {std::cerr << "Failed to read input stream" << std::endl;ret = AVERROR(EIO);goto end;}uint8_t* extradata = nullptr;int extradata_size = 0;ret = parse_nalu_extradata(parser, codec_ctx, buffer, bytes_read, &extradata, &extradata_size);CHECK_RET(ret, "Failed to parse extradata");codecpar->extradata = extradata;codecpar->extradata_size = extradata_size;// 7. 打开输出文件if (!(fmt_ctx->oformat->flags & AVFMT_NOFILE)) {ret = avio_open(&fmt_ctx->pb, output_filename, AVIO_FLAG_WRITE);CHECK_RET(ret, "Failed to open output file");}// 8. fMP4 选项AVDictionary* opt = nullptr;av_dict_set(&opt, "movflags", "frag_keyframe+empty_moov+default_base_moof", 0);av_dict_set(&opt, "fragment_duration", "4000", 0); // 4s 片段av_dict_set(&opt, "flush_packets", "1", 0);av_dict_set(&opt, "use_editlist", "0", 0); // 避免 edit list// 9. 写头ret = avformat_write_header(fmt_ctx, &opt);av_dict_free(&opt);CHECK_RET(ret, "Failed to write header");// 10. 实时循环：读取裸流，封装 AVPacketav_init_packet(&pkt);int64_t frame_count = 0;int64_t start_time = av_gettime();fseek(input_file, 0, SEEK_SET); // 重置文件指针while ((bytes_read = fread(buffer, 1, sizeof(buffer), input_file)) > 0) {int offset = 0;while (offset < bytes_read) {int start_code_len = 0;if (find_start_code(buffer + offset, bytes_read - offset, &start_code_len) < 0) {offset++;continue;}int next_offset = offset + start_code_len;while (next_offset < bytes_read) {if (find_start_code(buffer + next_offset, bytes_read - next_offset, &start_code_len) == 0) {break;}next_offset++;}if (next_offset == bytes_read) {next_offset = bytes_read;}// 封装 AVPacketpkt.data = buffer + offset;pkt.size = next_offset - offset;pkt.stream_index = stream->id;// 时间戳：基于实时时间int64_t current_time = av_gettime();int64_t time_diff = (current_time - start_time) / 1000000.0 * 30; // 30fpspkt.pts = time_diff;pkt.dts = pkt.pts; // 假设无 B 帧pkt.duration = 1;// 检查关键帧 (H.264: IDR=5; H.265: IDR=19-21)int nalu_type = codec_id == AV_CODEC_ID_H264 ?(buffer[offset + start_code_len] & 0x1F) :((buffer[offset + start_code_len] >> 1) & 0x3F);if ((codec_id == AV_CODEC_ID_H264 && nalu_type == 5) ||(codec_id == AV_CODEC_ID_HEVC && (nalu_type >= 19 && nalu_type <= 21))) {pkt.flags |= AV_PKT_FLAG_KEY;}// 写包ret = av_interleaved_write_frame(fmt_ctx, &pkt);if (ret < 0) {std::cerr << "Failed to write frame: " << av_err2str(ret) << std::endl;break;}offset = next_offset;frame_count++;if (frame_count % 30 == 0) {std::cout << "Muxed " << frame_count << " frames" << std::endl;}}}// 11. 写尾av_write_trailer(fmt_ctx);end:if (extradata) av_freep(&extradata);if (input_file) fclose(input_file);if (parser) av_parser_close(parser);if (codec_ctx) avcodec_free_context(&codec_ctx);if (fmt_ctx && !(fmt_ctx->oformat->flags & AVFMT_NOFILE)) {avio_closep(&fmt_ctx->pb);}avformat_free_context(fmt_ctx);return ret < 0 ? ret : 0;
}
