    // 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.
        It attempts to read audio from a microphone if available, and saves the audio to wav.
    */

    #include <iostream>
    #include <chrono>
    #include <dlib/media.h>
    #include <dlib/cmd_line_parser.h>

    using namespace std;
    using namespace std::chrono;
    using namespace std::chrono_literals;
    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 audio file", 1);
        parser.add_option("o",      "output audio device (speaker). E.g. hw:0,0", 1);
        parser.add_option("codec",  "audio codec. E.g. pcm_s16le", 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", "o", "codec"};
        parser.check_one_time_options(one_time_opts);

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

        const std::string filename  = get_option(parser, "i",       "");
        const std::string device    = get_option(parser, "o",       "hw:0,0");
        const std::string codec     = get_option(parser, "codec",   "");

        if (device.empty())
        {
            cout << "Didn't find a speaker. Exiting.\n";
            return EXIT_FAILURE;
        }

        // Open file
        demuxer cap({filename, video_disabled, audio_enabled});

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

        // Create writer to speaker
        muxer writer([&] {
            muxer::args args;
            args.filepath                   = device;
            args.output_format              = "alsa";
            args.enable_image               = false;
            args.args_audio.codec_name      = codec;
            args.args_audio.sample_rate     = 44100;
            args.args_audio.channel_layout  = AV_CH_LAYOUT_STEREO;
            args.args_audio.fmt             = cap.sample_fmt();
            return args;
        }());

        if (!writer.is_open())
        {
            cout << "Failed to open wav file" << endl;
            return EXIT_FAILURE;
        }

        // Pull and push
        frame f;
        while (cap.read(f))
            writer.push(std::move(f));

        return EXIT_SUCCESS;
    }
    catch (const std::exception& e)
    {
        printf("%s\n", e.what());
        return EXIT_FAILURE;
    }