背景
最近整理视频编解码的代码，早前在jetson上封装了jetson multimedia作为视频编解码的类，供其他同事和其他组使用，但该解码接口有一个问题，无法首先获取视频宽高信息，更无法直接获取视频的帧率、比特率等信息。
解决方法
- 使用ffmpeg库，命令行参数不适合代码集成
- 使用ffmpeg的API接口进行封装
源码实现
// ffmpeg_videoinfo.h#ifndef FFMPEG_VIDEOINFO_H
#define FFMPEG_VIDEOINFO_H#include <iostream>
#include <memory>struct VideoAsset {float width; float height;float fps;float bitrate; /** bit per second */float duration; /** seconds */
};#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */int GetVideoInfo(const char *in_file, std::shared_ptr<VideoAsset> &info);#ifdef __cplusplus
};
#endif#endif // FFMPEG_VIDEOINFO_H
// ffmpeg_videoinfo.cpp#include "ffmpeg_videoinfo.h"#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */#include <libavformat/avformat.h>
#include <libavcodec/avcodec.h>
#include <libavutil/avutil.h>int GetVideoInfo(const char *in_file, std::shared_ptr<VideoAsset> &info){// 注册所有格式和编解码器av_register_all();// 创建一个格式上下文（Format Context）AVFormatContext* formatContext = nullptr;if (avformat_open_input(&formatContext, in_file, nullptr, nullptr) != 0) {fprintf(stderr, "Could not open input file '%s'", in_file);return -1;}// 获取流信息if (avformat_find_stream_info(formatContext, nullptr) < 0) {fprintf(stderr, "Could not find stream information '%s'", in_file);return -1;}// 查找视频流int videoStreamIndex = -1;for (unsigned i = 0; i < formatContext->nb_streams; i++) {if (formatContext->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {videoStreamIndex = i;break;}}if (videoStreamIndex == -1) {fprintf(stderr, "Could not find video stream '%s'", in_file);return -1;}// 获取视频流的编码参数AVCodecParameters* codecParameters = formatContext->streams[videoStreamIndex]->codecpar;AVStream* videoStream = formatContext->streams[videoStreamIndex];info->fps = av_q2d(videoStream->avg_frame_rate);info->width = codecParameters->width;info->height = codecParameters->height;int64_t totalSize = 0;int64_t totalDuration = 0;AVPacket packet;while (av_read_frame(formatContext, &packet) >= 0) {if (packet.stream_index == 0) {totalSize += packet.size;totalDuration += packet.duration;}av_packet_unref(&packet);}AVRational timeBase = videoStream->time_base; /** 时间基 */info->duration = (float)totalDuration * av_q2d(timeBase);info->bitrate = (totalDuration > 0) ? (totalSize * 8.0 / info->duration) : 0.0;// 清理avformat_close_input(&formatContext);return 0;
}
#ifdef __cplusplus
};
#endif
// 测试脚本 test_single_videoinfo.cpp#include "ffmpeg_videoinfo.h"int main(int argc, char **argv) {if(argc<2){return 1;}const std::string &input_h264=argv[1];std::shared_ptr<VideoAsset> video_info_ptr = std::make_shared<VideoAsset>();// VideoAsset video_info;int status_code = GetVideoInfo(input_h264.c_str(), video_info_ptr);if (status_code < 0) {printf("GetVideoInfo failed\n");return -1;}printf("bitrate:%f, duration:%f, fps:%f, height:%f, width:%f\n",video_info_ptr->bitrate, video_info_ptr->duration, video_info_ptr->fps, video_info_ptr->height, video_info_ptr->width);return 1;
}# CMakelist.txt核心add_executable(test_video_info test_single_videoinfo.cpp ffmpeg_videoinfo.h ffmpeg_videoinfo.cpp)
target_compile_features(test_video_info PRIVATE cxx_std_14)
target_link_libraries(test_video_info avcodec avutil avformat)# 测试./test_video_info /data/videos/l4t.h264# 输出信息示例
[h264 @ 0xaaaac14b16a0] Stream #0: not enough frames to estimate rate; consider increasing probesize
bitrate:30681866.000000, duration:164.490005, fps:20.000000, height:2160.000000, width:3840.000000后记
本人对ffmpeg接口并不熟悉，以上根据文档及搜索结果进行的实现，不敢保证没有bug，如果各位遇到问题，可以留言交流