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dsdstudio/ff2cv.cpp

Forked from yohhoy/ff2cv.cpp
Created Feb 23, 2019
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Read video frame with FFmpeg and convert to OpenCV image
/*
* Read video frame with FFmpeg and convert to OpenCV image
*
* Copyright (c) 2016 yohhoy
*/
#include <iostream>
#include <vector>
// FFmpeg
extern "C" {
#include <libavformat/avformat.h>
#include <libavcodec/avcodec.h>
#include <libavutil/avutil.h>
#include <libavutil/pixdesc.h>
#include <libswscale/swscale.h>
}
// OpenCV
#include <opencv2/core.hpp>
#include <opencv2/highgui.hpp>
int main(int argc, char* argv[])
{
if (argc < 2) {
std::cout << "Usage: ff2cv <infile>" << std::endl;
return 1;
}
const char* infile = argv[1];
// initialize FFmpeg library
av_register_all();
// av_log_set_level(AV_LOG_DEBUG);
int ret;
// open input file context
AVFormatContext* inctx = nullptr;
ret = avformat_open_input(&inctx, infile, nullptr, nullptr);
if (ret < 0) {
std::cerr << "fail to avforamt_open_input(\"" << infile << "\"): ret=" << ret;
return 2;
}
// retrive input stream information
ret = avformat_find_stream_info(inctx, nullptr);
if (ret < 0) {
std::cerr << "fail to avformat_find_stream_info: ret=" << ret;
return 2;
}
// find primary video stream
AVCodec* vcodec = nullptr;
ret = av_find_best_stream(inctx, AVMEDIA_TYPE_VIDEO, -1, -1, &vcodec, 0);
if (ret < 0) {
std::cerr << "fail to av_find_best_stream: ret=" << ret;
return 2;
}
const int vstrm_idx = ret;
AVStream* vstrm = inctx->streams[vstrm_idx];
// open video decoder context
ret = avcodec_open2(vstrm->codec, vcodec, nullptr);
if (ret < 0) {
std::cerr << "fail to avcodec_open2: ret=" << ret;
return 2;
}
// print input video stream informataion
std::cout
<< "infile: " << infile << "\n"
<< "format: " << inctx->iformat->name << "\n"
<< "vcodec: " << vcodec->name << "\n"
<< "size: " << vstrm->codec->width << 'x' << vstrm->codec->height << "\n"
<< "fps: " << av_q2d(vstrm->codec->framerate) << " [fps]\n"
<< "length: " << av_rescale_q(vstrm->duration, vstrm->time_base, {1,1000}) / 1000. << " [sec]\n"
<< "pixfmt: " << av_get_pix_fmt_name(vstrm->codec->pix_fmt) << "\n"
<< "frame: " << vstrm->nb_frames << "\n"
<< std::flush;
// initialize sample scaler
const int dst_width = vstrm->codec->width;
const int dst_height = vstrm->codec->height;
const AVPixelFormat dst_pix_fmt = AV_PIX_FMT_BGR24;
SwsContext* swsctx = sws_getCachedContext(
nullptr, vstrm->codec->width, vstrm->codec->height, vstrm->codec->pix_fmt,
dst_width, dst_height, dst_pix_fmt, SWS_BICUBIC, nullptr, nullptr, nullptr);
if (!swsctx) {
std::cerr << "fail to sws_getCachedContext";
return 2;
}
std::cout << "output: " << dst_width << 'x' << dst_height << ',' << av_get_pix_fmt_name(dst_pix_fmt) << std::endl;
// allocate frame buffer for output
AVFrame* frame = av_frame_alloc();
std::vector<uint8_t> framebuf(avpicture_get_size(dst_pix_fmt, dst_width, dst_height));
avpicture_fill(reinterpret_cast<AVPicture*>(frame), framebuf.data(), dst_pix_fmt, dst_width, dst_height);
// decoding loop
AVFrame* decframe = av_frame_alloc();
unsigned nb_frames = 0;
bool end_of_stream = false;
int got_pic = 0;
AVPacket pkt;
do {
if (!end_of_stream) {
// read packet from input file
ret = av_read_frame(inctx, &pkt);
if (ret < 0 && ret != AVERROR_EOF) {
std::cerr << "fail to av_read_frame: ret=" << ret;
return 2;
}
if (ret == 0 && pkt.stream_index != vstrm_idx)
goto next_packet;
end_of_stream = (ret == AVERROR_EOF);
}
if (end_of_stream) {
// null packet for bumping process
av_init_packet(&pkt);
pkt.data = nullptr;
pkt.size = 0;
}
// decode video frame
avcodec_decode_video2(vstrm->codec, decframe, &got_pic, &pkt);
if (!got_pic)
goto next_packet;
// convert frame to OpenCV matrix
sws_scale(swsctx, decframe->data, decframe->linesize, 0, decframe->height, frame->data, frame->linesize);
{
cv::Mat image(dst_height, dst_width, CV_8UC3, framebuf.data(), frame->linesize[0]);
cv::imshow("press ESC to exit", image);
if (cv::waitKey(1) == 0x1b)
break;
}
std::cout << nb_frames << '\r' << std::flush; // dump progress
++nb_frames;
next_packet:
av_free_packet(&pkt);
} while (!end_of_stream || got_pic);
std::cout << nb_frames << " frames decoded" << std::endl;
av_frame_free(&decframe);
av_frame_free(&frame);
avcodec_close(vstrm->codec);
avformat_close_input(&inctx);
return 0;
}
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