dsdstudio · February 23, 2019 15:12 · Feb 18, 2016 · Feb 14, 2016
diff --git a/ff2cv.cpp b/ff2cv.cpp
@@ -28,6 +28,7 @@ int main(int argc, char* argv[])
 
     // initialize FFmpeg library
     av_register_all();
+//  av_log_set_level(AV_LOG_DEBUG);
     int ret;
 
     // open input file context

diff --git a/ff2cv.cpp b/ff2cv.cpp
@@ -0,0 +1,142 @@
+/*
+ * 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();
+    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;
+}