dlib C++ Library - ffmpeg_video_encoding_ex.cpp

    // The contents of this file are in the public domain. See LICENSE_FOR_EXAMPLE_PROGRAMS.txt
    /*

        This is an example illustrating the use of the ffmpeg wrappers, in this case the encding API.

        This is a pretty simple example. It loads a video file, extracts the images and
        re-encodes them into a raw buffer using a user-specified codec.

        Please see the following examples on how to decode, demux, and get information on your installation of ffmpeg:
            - ffmpeg_info_ex.cpp
            - ffmpeg_video_decoding_ex.cpp
            - ffmpeg_video_decoding2_ex.cpp
            - ffmpeg_video_demuxing_ex.cpp
            - ffmpeg_video_demuxing2_ex.cpp
    */

    #include <cstdio>
    #include <dlib/media.h>
    #include <dlib/cmd_line_parser.h>

    using namespace std;
    using namespace dlib;
    using namespace dlib::ffmpeg;

    int main(const int argc, const char** argv)
    try
    {
        command_line_parser parser;
        parser.add_option("i",      "input video", 1);
        parser.add_option("codec",  "codec name. e.g. h264. Defaults to mpeg4", 1);
        parser.add_option("height", "height of encoded stream. Defaults to whatever is in the video file", 1);
        parser.add_option("width",  "width of encoded stream. Defaults to whatever is in the video file", 1);

        parser.set_group_name("Help Options");
        parser.add_option("h",      "alias of --help");
        parser.add_option("help",   "display this message and exit");

        parser.parse(argc, argv);
        const char* one_time_opts[] = {"i", "codec", "height", "width"};
        parser.check_one_time_options(one_time_opts);

        if (parser.option("h") || parser.option("help"))
        {
            parser.print_options();
            return 0;
        }

        const std::string filepath = parser.option("i").argument();

        // Load input video.
        // Note, this uses a convenient constructor which (dis)enables audio and/or video.
        demuxer cap({filepath, video_enabled, audio_disabled});

        if (!cap.is_open() || !cap.video_enabled())
        {
            cout << "Failed to open " << filepath << endl;
            return EXIT_FAILURE;
        }

        // This is a small functor that creates an encoder using the command line arguments
        // and different types of output buffers using the convenient sink() overload.
        const auto make_encoder = [&]
        {
            return encoder([&] {
                encoder::args args;
                args.args_codec.codec_name  = get_option(parser, "codec", "mpeg4");
                args.args_image.h           = get_option(parser, "height", cap.height());
                args.args_image.w           = get_option(parser, "width",  cap.width());
                args.args_image.fmt         = cap.pixel_fmt();
                args.args_image.framerate   = cap.fps();
                return args;
            }());
        };

        // Encode to multiple different types of buffers.
        std::vector<char>       buf1;
        std::vector<int8_t>     buf2;
        std::vector<uint8_t>    buf3;
        std::ostringstream      buf4;
        std::ofstream           buf5("encoded.dat", std::ios::binary);

        // Different encoders for different buffers
        auto enc1 = make_encoder();
        auto enc2 = make_encoder();
        auto enc3 = make_encoder();
        auto enc4 = make_encoder();
        auto enc5 = make_encoder();

        frame f;
        while (cap.read(f))
        {
            enc1.push(f, sink(buf1));
            enc2.push(f, sink(buf2));
            enc3.push(f, sink(buf3));
            enc4.push(f, sink(buf4));
            enc5.push(f, sink(buf5));
        }

        enc1.flush(sink(buf1));
        enc2.flush(sink(buf2));
        enc3.flush(sink(buf3));
        enc4.flush(sink(buf4));
        enc5.flush(sink(buf5));

        cout << "vector<char>       size " << buf1.size() << endl;
        cout << "vector<int8_t>     size " << buf2.size() << endl;
        cout << "vector<uint8_t>    size " << buf3.size() << endl;
        cout << "ostringstream      size " << buf4.tellp() << endl;
        cout << "ofstream           size " << buf5.tellp() << endl;

        return EXIT_SUCCESS;
    }
    catch (const std::exception& e)
    {
        cout << e.what() << endl;
        return EXIT_FAILURE;
    }