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Convert from OpenCV image and write movie with FFmpeg (OpenCV 4.5, FFmpeg 4.4)
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| /* | |
| * Convert from OpenCV image and write movie with FFmpeg | |
| * | |
| * Copyright (c) 2021 yohhoy | |
| */ | |
| #include <iostream> | |
| #include <vector> | |
| // FFmpeg | |
| extern "C" { | |
| #include <libavformat/avformat.h> | |
| #include <libavcodec/avcodec.h> | |
| #include <libavutil/imgutils.h> | |
| #include <libswscale/swscale.h> | |
| } | |
| // OpenCV | |
| #include <opencv2/opencv.hpp> | |
| #include <opencv2/highgui.hpp> | |
| int main(int argc, char* argv[]) | |
| { | |
| if (argc < 2) { | |
| std::cout << "Usage: cv2ff <outfile>" << std::endl; | |
| return 1; | |
| } | |
| const char* outfile = argv[1]; | |
| // av_log_set_level(AV_LOG_DEBUG); | |
| int ret; | |
| const int dst_width = 640; | |
| const int dst_height = 480; | |
| const AVRational dst_fps = {30, 1}; | |
| // initialize OpenCV capture as input frame generator | |
| cv::VideoCapture cvcap(0); | |
| if (!cvcap.isOpened()) { | |
| std::cerr << "fail to open cv::VideoCapture"; | |
| return 2; | |
| } | |
| cvcap.set(cv::CAP_PROP_FRAME_WIDTH, dst_width); | |
| cvcap.set(cv::CAP_PROP_FRAME_HEIGHT, dst_height); | |
| cvcap.set(cv::CAP_PROP_FPS, dst_fps.num); | |
| // some device ignore above parameters for capturing image, | |
| // so we query actual parameters for image rescaler. | |
| const int cv_width = cvcap.get(cv::CAP_PROP_FRAME_WIDTH); | |
| const int cv_height = cvcap.get(cv::CAP_PROP_FRAME_HEIGHT); | |
| const int cv_fps = cvcap.get(cv::CAP_PROP_FPS); | |
| // open output format context | |
| AVFormatContext* outctx = nullptr; | |
| ret = avformat_alloc_output_context2(&outctx, nullptr, nullptr, outfile); | |
| if (ret < 0) { | |
| std::cerr << "fail to avformat_alloc_output_context2(" << outfile << "): ret=" << ret; | |
| return 2; | |
| } | |
| // create new video stream | |
| AVCodec* vcodec = avcodec_find_encoder(outctx->oformat->video_codec); | |
| AVStream* vstrm = avformat_new_stream(outctx, vcodec); | |
| if (!vstrm) { | |
| std::cerr << "fail to avformat_new_stream"; | |
| return 2; | |
| } | |
| // open video encoder | |
| AVCodecContext* cctx = avcodec_alloc_context3(vcodec); | |
| if (!vstrm) { | |
| std::cerr << "fail to avcodec_alloc_context3"; | |
| return 2; | |
| } | |
| cctx->width = dst_width; | |
| cctx->height = dst_height; | |
| cctx->pix_fmt = vcodec->pix_fmts[0]; | |
| cctx->time_base = av_inv_q(dst_fps); | |
| cctx->framerate = dst_fps; | |
| if (outctx->oformat->flags & AVFMT_GLOBALHEADER) | |
| cctx->flags |= AV_CODEC_FLAG_GLOBAL_HEADER; | |
| ret = avcodec_open2(cctx, vcodec, nullptr); | |
| if (ret < 0) { | |
| std::cerr << "fail to avcodec_open2: ret=" << ret; | |
| return 2; | |
| } | |
| avcodec_parameters_from_context(vstrm->codecpar, cctx); | |
| // initialize sample scaler | |
| SwsContext* swsctx = sws_getContext( | |
| cv_width, cv_height, AV_PIX_FMT_BGR24, | |
| dst_width, dst_height, cctx->pix_fmt, | |
| SWS_BILINEAR, nullptr, nullptr, nullptr); | |
| if (!swsctx) { | |
| std::cerr << "fail to sws_getContext"; | |
| return 2; | |
| } | |
| // allocate frame buffer for encoding | |
| AVFrame* frame = av_frame_alloc(); | |
| frame->width = dst_width; | |
| frame->height = dst_height; | |
| frame->format = static_cast<int>(cctx->pix_fmt); | |
| ret = av_frame_get_buffer(frame, 32); | |
| if (ret < 0) { | |
| std::cerr << "fail to av_frame_get_buffer: ret=" << ret; | |
| return 2; | |
| } | |
| // allocate packet to retrive encoded frame | |
| AVPacket* pkt = av_packet_alloc(); | |
| // open output IO context | |
| ret = avio_open2(&outctx->pb, outfile, AVIO_FLAG_WRITE, nullptr, nullptr); | |
| if (ret < 0) { | |
| std::cerr << "fail to avio_open2: ret=" << ret; | |
| return 2; | |
| } | |
| std::cout | |
| << "camera: " << cv_width << 'x' << cv_height << '@' << cv_fps << "\n" | |
| << "outfile: " << outfile << "\n" | |
| << "format: " << outctx->oformat->name << "\n" | |
| << "vcodec: " << vcodec->name << "\n" | |
| << "size: " << dst_width << 'x' << dst_height << "\n" | |
| << "fps: " << av_q2d(cctx->framerate) << "\n" | |
| << "pixfmt: " << av_get_pix_fmt_name(cctx->pix_fmt) << "\n" | |
| << std::flush; | |
| // write media container header (if any) | |
| ret = avformat_write_header(outctx, nullptr); | |
| if (ret < 0) { | |
| std::cerr << "fail to avformat_write_header: ret=" << ret; | |
| return 2; | |
| } | |
| cv::Mat image; | |
| // encoding loop | |
| int64_t frame_pts = 0; | |
| unsigned nb_frames = 0; | |
| bool end_of_stream = false; | |
| for (;;) { | |
| if (!end_of_stream) { | |
| // retrieve source image | |
| cvcap >> image; | |
| cv::imshow("press ESC to exit", image); | |
| if (cv::waitKey(33) == 0x1b) { | |
| // flush encoder | |
| avcodec_send_frame(cctx, nullptr); | |
| end_of_stream = true; | |
| } | |
| } | |
| if (!end_of_stream) { | |
| // convert cv::Mat(OpenCV) to AVFrame(FFmpeg) | |
| const int stride[4] = { static_cast<int>(image.step[0]) }; | |
| sws_scale(swsctx, &image.data, stride, 0, image.rows, frame->data, frame->linesize); | |
| frame->pts = frame_pts++; | |
| // encode video frame | |
| ret = avcodec_send_frame(cctx, frame); | |
| if (ret < 0) { | |
| std::cerr << "fail to avcodec_send_frame: ret=" << ret << "\n"; | |
| break; | |
| } | |
| } | |
| while ((ret = avcodec_receive_packet(cctx, pkt)) >= 0) { | |
| // rescale packet timestamp | |
| pkt->duration = 1; | |
| av_packet_rescale_ts(pkt, cctx->time_base, vstrm->time_base); | |
| // write encoded packet | |
| av_write_frame(outctx, pkt); | |
| av_packet_unref(pkt); | |
| std::cout << nb_frames << '\r' << std::flush; // dump progress | |
| ++nb_frames; | |
| } | |
| if (ret == AVERROR_EOF) | |
| break; | |
| }; | |
| std::cout << nb_frames << " frames encoded" << std::endl; | |
| // write trailer and close file | |
| av_write_trailer(outctx); | |
| avio_close(outctx->pb); | |
| av_packet_free(&pkt); | |
| av_frame_free(&frame); | |
| sws_freeContext(swsctx); | |
| avcodec_free_context(&cctx); | |
| avformat_free_context(outctx); | |
| return 0; | |
| } |
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