最近在使用ffmpeg取鱼眼相机的视频流做全景播放时遇到需要cv::Mat转AVFrame的转换，看到了这篇文章，记录一下
1.OpenCV cv::Mat转换为FFmpeg AVFrame
下面是两种方法
void CvMatToAVFrame(const cv::Mat& input_mat, AVFrame* out_avframe)
{int image_width = input_mat.cols;int image_height = input_mat.rows;int cvLinesizes[1];cvLinesizes[0] = input_mat.step1();SwsContext* openCVBGRToAVFrameSwsContext = sws_getContext(image_width,image_height,AVPixelFormat::AV_PIX_FMT_BGR24,image_width,image_height,AVPixelFormat::AV_PIX_FMT_YUV420P,SWS_FAST_BILINEAR,nullptr, nullptr, nullptr);sws_scale(openCVBGRToAVFrameSwsContext,&input_mat.data,cvLinesizes,0,image_height,out_avframe->data,out_avframe->linesize);if (openCVBGRToAVFrameSwsContext != nullptr){sws_freeContext(openCVBGRToAVFrameSwsContext);openCVBGRToAVFrameSwsContext = nullptr;}
}
#include <opencv2/opencv.hpp>extern "C" {
#include <libavcodec/avcodec.h>
#include <libavutil/frame.h>
#include <libavutil/imgutils.h>
}void convertMatToAVPicture(const cv::Mat& mat, AVFrame* frame)
{int width = mat.cols;int height = mat.rows;int channels = mat.channels();int ret;frame->width = width;frame->height = height;frame->format = AV_PIX_FMT_BGR24;enum AVPixelFormat pix_fmt = AV_PIX_FMT_BGR24;// 为AVFrame分配内存ret = av_image_alloc(frame->data, frame->linesize, width, height, pix_fmt , 32);if (ret < 0){return;}// 将opencv的Mat转换成AVFrameint step = width * channels;for (int row = 0; row < height; row++) {memcpy(frame->data[0] + row * frame->linesize[0], mat.data + row * step, step);}
}
2.FFmpeg AVFrame转换为OpenCV cv::Mat
cv::Mat AVFrameToCvMat(AVFrame* input_avframe)
{int image_width = input_avframe->width;int image_height = input_avframe->height;cv::Mat resMat(image_height, image_width, CV_8UC3);int cvLinesizes[1];cvLinesizes[0] = resMat.step1();SwsContext* avFrameToOpenCVBGRSwsContext = sws_getContext(image_width,image_height,AVPixelFormat::AV_PIX_FMT_YUV420P,image_width,image_height,AVPixelFormat::AV_PIX_FMT_BGR24,SWS_FAST_BILINEAR,nullptr, nullptr, nullptr);sws_scale(avFrameToOpenCVBGRSwsContext,input_avframe->data,input_avframe->linesize,0,image_height,&resMat.data,cvLinesizes);if (avFrameToOpenCVBGRSwsContext != nullptr){sws_freeContext(avFrameToOpenCVBGRSwsContext);avFrameToOpenCVBGRSwsContext = nullptr;}return resMat;
}
3.使用示例
#include <iostream>// ffmpeg
extern "C" {
#include "libavcodec/avcodec.h"
#include "libavformat/avformat.h"
#include "libavutil/avutil.h"
#include "libswscale/swscale.h"
#include <libavutil/imgutils.h>
}// opencv
#include "opencv/cv.h"
#include "opencv2/opencv.hpp"void CvMatToAVFrame(const cv::Mat& input_mat, AVFrame* out_avframe)
{int image_width = input_mat.cols;int image_height = input_mat.rows;int cvLinesizes[1];cvLinesizes[0] = input_mat.step1();SwsContext* openCVBGRToAVFrameSwsContext = sws_getContext(image_width,image_height,AVPixelFormat::AV_PIX_FMT_BGR24,image_width,image_height,AVPixelFormat::AV_PIX_FMT_YUV420P,SWS_FAST_BILINEAR,nullptr, nullptr, nullptr);sws_scale(openCVBGRToAVFrameSwsContext,&input_mat.data,cvLinesizes,0,image_height,out_avframe->data,out_avframe->linesize);if (openCVBGRToAVFrameSwsContext != nullptr){sws_freeContext(openCVBGRToAVFrameSwsContext);openCVBGRToAVFrameSwsContext = nullptr;}
}cv::Mat AVFrameToCvMat(AVFrame* input_avframe)
{int image_width = input_avframe->width;int image_height = input_avframe->height;cv::Mat resMat(image_height, image_width, CV_8UC3);int cvLinesizes[1];cvLinesizes[0] = resMat.step1();SwsContext* avFrameToOpenCVBGRSwsContext = sws_getContext(image_width,image_height,AVPixelFormat::AV_PIX_FMT_YUV420P,image_width,image_height,AVPixelFormat::AV_PIX_FMT_BGR24,SWS_FAST_BILINEAR,nullptr, nullptr, nullptr);sws_scale(avFrameToOpenCVBGRSwsContext,input_avframe->data,input_avframe->linesize,0,image_height,&resMat.data,cvLinesizes);if (avFrameToOpenCVBGRSwsContext != nullptr){sws_freeContext(avFrameToOpenCVBGRSwsContext);avFrameToOpenCVBGRSwsContext = nullptr;}return resMat;
}int main()
{cv::Mat input_image = cv::imread("C:/Users/Administrator/Desktop/example.jpg");AVFrame* avFrame = av_frame_alloc();avFrame->format = AVPixelFormat::AV_PIX_FMT_YUV420P;avFrame->width = input_image.cols;avFrame->height = input_image.rows;// 为需要创建的YUV Frame分配内存if (av_frame_get_buffer(avFrame, 0) < 0){av_frame_free(&avFrame);avFrame = nullptr;return -1;}cv::imshow("解码前", input_image);// OpenCV cv::Mat转换成AVFrameCvMatToAVFrame(input_image,avFrame);// 将AVFrame转换成OpenCV cv::Matcv::Mat out_avFrameToMat = AVFrameToCvMat(avFrame);cv::imshow("解码后", out_avFrameToMat);cv::waitKey(0);cv::destroyAllWindows();// free memoryif (avFrame != nullptr){av_frame_free(&avFrame);avFrame = nullptr;}return 0;
}
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