avconv.c

    { "atag", HAS_ARG | OPT_EXPERT | OPT_AUDIO | OPT_FUNC2, {(void*)opt_audio_tag}, "force audio tag/fourcc", "fourcc/tag" },
    { "vol", OPT_INT | HAS_ARG | OPT_AUDIO, {(void*)&audio_volume}, "change audio volume (256=normal)" , "volume" }, //
    { "sample_fmt", HAS_ARG | OPT_EXPERT | OPT_AUDIO | OPT_SPEC | OPT_STRING, {.off = OFFSET(sample_fmts)}, "set sample format", "format" },

    /* subtitle options */
    { "sn", OPT_BOOL | OPT_SUBTITLE | OPT_OFFSET, {.off = OFFSET(subtitle_disable)}, "disable subtitle" },
    { "scodec", HAS_ARG | OPT_SUBTITLE | OPT_FUNC2, {(void*)opt_subtitle_codec}, "force subtitle codec ('copy' to copy stream)", "codec" },
    { "stag", HAS_ARG | OPT_EXPERT | OPT_SUBTITLE | OPT_FUNC2, {(void*)opt_subtitle_tag}, "force subtitle tag/fourcc", "fourcc/tag" },

    /* grab options */
    { "isync", OPT_BOOL | OPT_EXPERT | OPT_GRAB, {(void*)&input_sync}, "sync read on input", "" },

    /* muxer options */
    { "muxdelay", OPT_FLOAT | HAS_ARG | OPT_EXPERT   | OPT_OFFSET, {.off = OFFSET(mux_max_delay)}, "set the maximum demux-decode delay", "seconds" },
    { "muxpreload", OPT_FLOAT | HAS_ARG | OPT_EXPERT | OPT_OFFSET, {.off = OFFSET(mux_preload)},   "set the initial demux-decode delay", "seconds" },

    { "bsf", HAS_ARG | OPT_STRING | OPT_SPEC, {.off = OFFSET(bitstream_filters)}, "A comma-separated list of bitstream filters", "bitstream_filters" },

    /* data codec support */
    { "dcodec", HAS_ARG | OPT_DATA | OPT_FUNC2, {(void*)opt_data_codec}, "force data codec ('copy' to copy stream)", "codec" },

    { "default", HAS_ARG | OPT_AUDIO | OPT_VIDEO | OPT_EXPERT, {(void*)opt_default}, "generic catch all option", "" },
    { NULL, },
};

int main(int argc, char **argv)
{
    OptionsContext o = { 0 };
    int64_t ti;

    reset_options(&o);

    av_log_set_flags(AV_LOG_SKIP_REPEATED);

    avcodec_register_all();
#if CONFIG_AVDEVICE
    avdevice_register_all();
#endif
#if CONFIG_AVFILTER
    avfilter_register_all();
#endif
    av_register_all();

    avio_set_interrupt_cb(decode_interrupt_cb);

    show_banner();

    /* parse options */
    parse_options(&o, argc, argv, options, opt_output_file);

    if(nb_output_files <= 0 && nb_input_files == 0) {
        show_usage();
        fprintf(stderr, "Use -h to get full help or, even better, run 'man %s'\n", program_name);
        exit_program(1);
    }

    /* file converter / grab */
    if (nb_output_files <= 0) {
        fprintf(stderr, "At least one output file must be specified\n");
        exit_program(1);
    }

    if (nb_input_files == 0) {
        fprintf(stderr, "At least one input file must be specified\n");
        exit_program(1);
    }

    ti = getutime();
    if (transcode(output_files, nb_output_files, input_files, nb_input_files) < 0)
        exit_program(1);
    ti = getutime() - ti;
    if (do_benchmark) {
        int maxrss = getmaxrss() / 1024;
        printf("bench: utime=%0.3fs maxrss=%ikB\n", ti / 1000000.0, maxrss);
    }

    exit_program(0);
    return 0;
}