whisper.cpp/examples/main/main.cpp

#include "common.h"

#include "whisper.h"

#include <cmath>
#include <fstream>
#include <cstdio>
#include <string>
#include <thread>
#include <vector>
#include <cstring>

// Terminal color map. 10 colors grouped in ranges [0.0, 0.1, ..., 0.9]
// Lowest is red, middle is yellow, highest is green.
const std::vector<std::string> k_colors = {
    "\033[38;5;196m", "\033[38;5;202m", "\033[38;5;208m", "\033[38;5;214m", "\033[38;5;220m",
    "\033[38;5;226m", "\033[38;5;190m", "\033[38;5;154m", "\033[38;5;118m", "\033[38;5;82m",
};

//  500 -> 00:05.000
// 6000 -> 01:00.000
std::string to_timestamp(int64_t t, bool comma = false) {
    int64_t msec = t * 10;
    int64_t hr = msec / (1000 * 60 * 60);
    msec = msec - hr * (1000 * 60 * 60);
    int64_t min = msec / (1000 * 60);
    msec = msec - min * (1000 * 60);
    int64_t sec = msec / 1000;
    msec = msec - sec * 1000;

    char buf[32];
    snprintf(buf, sizeof(buf), "%02d:%02d:%02d%s%03d", (int) hr, (int) min, (int) sec, comma ? "," : ".", (int) msec);

    return std::string(buf);
}

int timestamp_to_sample(int64_t t, int n_samples) {
    return std::max(0, std::min((int) n_samples - 1, (int) ((t*WHISPER_SAMPLE_RATE)/100)));
}

// helper function to replace substrings
void replace_all(std::string & s, const std::string & search, const std::string & replace) {
    for (size_t pos = 0; ; pos += replace.length()) {
        pos = s.find(search, pos);
        if (pos == std::string::npos) break;
        s.erase(pos, search.length());
        s.insert(pos, replace);
    }
}

// command-line parameters
struct whisper_params {
    int32_t n_threads    = std::min(4, (int32_t) std::thread::hardware_concurrency());
    int32_t n_processors =  1;
    int32_t offset_t_ms  =  0;
    int32_t offset_n     =  0;
    int32_t duration_ms  =  0;
    int32_t max_context  = -1;
    int32_t max_len      =  0;
    int32_t best_of      =  5;
    int32_t beam_size    = -1;

    float word_thold    =  0.01f;
    float entropy_thold =  2.40f;
    float logprob_thold = -1.00f;

    bool speed_up       = false;
    bool translate      = false;
    bool diarize        = false;
    bool split_on_word  = false;
    bool no_fallback    = false;
    bool output_txt     = false;
    bool output_vtt     = false;
    bool output_srt     = false;
    bool output_wts     = false;
    bool output_csv     = false;
    bool output_jsn     = false;
    bool output_lrc     = false;
    bool print_special  = false;
    bool print_colors   = false;
    bool print_progress = false;
    bool no_timestamps  = false;

    std::string language = "en";
    std::string prompt;
    std::string font_path = "/System/Library/Fonts/Supplemental/Courier New Bold.ttf";
    std::string model    = "models/ggml-base.en.bin";

    std::vector<std::string> fname_inp = {};
    std::vector<std::string> fname_out = {};
};

void whisper_print_usage(int argc, char ** argv, const whisper_params & params);

bool whisper_params_parse(int argc, char ** argv, whisper_params & params) {
    for (int i = 1; i < argc; i++) {
        std::string arg = argv[i];

        if (arg == "-"){
            params.fname_inp.push_back(arg);
            continue;
        }

        if (arg[0] != '-') {
            params.fname_inp.push_back(arg);
            continue;
        }

        if (arg == "-h" || arg == "--help") {
            whisper_print_usage(argc, argv, params);
            exit(0);
        }
        else if (arg == "-t"    || arg == "--threads")        { params.n_threads      = std::stoi(argv[++i]); }
        else if (arg == "-p"    || arg == "--processors")     { params.n_processors   = std::stoi(argv[++i]); }
        else if (arg == "-ot"   || arg == "--offset-t")       { params.offset_t_ms    = std::stoi(argv[++i]); }
        else if (arg == "-on"   || arg == "--offset-n")       { params.offset_n       = std::stoi(argv[++i]); }
        else if (arg == "-d"    || arg == "--duration")       { params.duration_ms    = std::stoi(argv[++i]); }
        else if (arg == "-mc"   || arg == "--max-context")    { params.max_context    = std::stoi(argv[++i]); }
        else if (arg == "-ml"   || arg == "--max-len")        { params.max_len        = std::stoi(argv[++i]); }
        else if (arg == "-bo"   || arg == "--best-of")        { params.best_of        = std::stoi(argv[++i]); }
        else if (arg == "-bs"   || arg == "--beam-size")      { params.beam_size      = std::stoi(argv[++i]); }
        else if (arg == "-wt"   || arg == "--word-thold")     { params.word_thold     = std::stof(argv[++i]); }
        else if (arg == "-et"   || arg == "--entropy-thold")  { params.entropy_thold  = std::stof(argv[++i]); }
        else if (arg == "-lpt"  || arg == "--logprob-thold")  { params.logprob_thold  = std::stof(argv[++i]); }
        else if (arg == "-su"   || arg == "--speed-up")       { params.speed_up       = true; }
        else if (arg == "-tr"   || arg == "--translate")      { params.translate      = true; }
        else if (arg == "-di"   || arg == "--diarize")        { params.diarize        = true; }
        else if (arg == "-sow"  || arg == "--split-on-word")  { params.split_on_word  = true; }
        else if (arg == "-nf"   || arg == "--no-fallback")    { params.no_fallback    = true; }
        else if (arg == "-otxt" || arg == "--output-txt")     { params.output_txt     = true; }
        else if (arg == "-ovtt" || arg == "--output-vtt")     { params.output_vtt     = true; }
        else if (arg == "-osrt" || arg == "--output-srt")     { params.output_srt     = true; }
        else if (arg == "-owts" || arg == "--output-words")   { params.output_wts     = true; }
        else if (arg == "-olrc" || arg == "--output-lrc")     { params.output_lrc     = true; }
        else if (arg == "-fp"   || arg == "--font-path")      { params.font_path      = argv[++i]; }
        else if (arg == "-ocsv" || arg == "--output-csv")     { params.output_csv     = true; }
        else if (arg == "-oj"   || arg == "--output-json")    { params.output_jsn     = true; }
        else if (arg == "-of"   || arg == "--output-file")    { params.fname_out.emplace_back(argv[++i]); }
        else if (arg == "-ps"   || arg == "--print-special")  { params.print_special  = true; }
        else if (arg == "-pc"   || arg == "--print-colors")   { params.print_colors   = true; }
        else if (arg == "-pp"   || arg == "--print-progress") { params.print_progress = true; }
        else if (arg == "-nt"   || arg == "--no-timestamps")  { params.no_timestamps  = true; }
        else if (arg == "-l"    || arg == "--language")       { params.language       = argv[++i]; }
        else if (                  arg == "--prompt")         { params.prompt         = argv[++i]; }
        else if (arg == "-m"    || arg == "--model")          { params.model          = argv[++i]; }
        else if (arg == "-f"    || arg == "--file")           { params.fname_inp.emplace_back(argv[++i]); }
        else {
            fprintf(stderr, "error: unknown argument: %s\n", arg.c_str());
            whisper_print_usage(argc, argv, params);
            exit(0);
        }
    }

    return true;
}

void whisper_print_usage(int /*argc*/, char ** argv, const whisper_params & params) {
    fprintf(stderr, "\n");
    fprintf(stderr, "usage: %s [options] file0.wav file1.wav ...\n", argv[0]);
    fprintf(stderr, "\n");
    fprintf(stderr, "options:\n");
    fprintf(stderr, "  -h,        --help              [default] show this help message and exit\n");
    fprintf(stderr, "  -t N,      --threads N         [%-7d] number of threads to use during computation\n",    params.n_threads);
    fprintf(stderr, "  -p N,      --processors N      [%-7d] number of processors to use during computation\n", params.n_processors);
    fprintf(stderr, "  -ot N,     --offset-t N        [%-7d] time offset in milliseconds\n",                    params.offset_t_ms);
    fprintf(stderr, "  -on N,     --offset-n N        [%-7d] segment index offset\n",                           params.offset_n);
    fprintf(stderr, "  -d  N,     --duration N        [%-7d] duration of audio to process in milliseconds\n",   params.duration_ms);
    fprintf(stderr, "  -mc N,     --max-context N     [%-7d] maximum number of text context tokens to store\n", params.max_context);
    fprintf(stderr, "  -ml N,     --max-len N         [%-7d] maximum segment length in characters\n",           params.max_len);
    fprintf(stderr, "  -sow,      --split-on-word     [%-7s] split on word rather than on token\n",             params.split_on_word ? "true" : "false");
    fprintf(stderr, "  -bo N,     --best-of N         [%-7d] number of best candidates to keep\n",              params.best_of);
    fprintf(stderr, "  -bs N,     --beam-size N       [%-7d] beam size for beam search\n",                      params.beam_size);
    fprintf(stderr, "  -wt N,     --word-thold N      [%-7.2f] word timestamp probability threshold\n",         params.word_thold);
    fprintf(stderr, "  -et N,     --entropy-thold N   [%-7.2f] entropy threshold for decoder fail\n",           params.entropy_thold);
    fprintf(stderr, "  -lpt N,    --logprob-thold N   [%-7.2f] log probability threshold for decoder fail\n",   params.logprob_thold);
    fprintf(stderr, "  -su,       --speed-up          [%-7s] speed up audio by x2 (reduced accuracy)\n",        params.speed_up ? "true" : "false");
    fprintf(stderr, "  -tr,       --translate         [%-7s] translate from source language to english\n",      params.translate ? "true" : "false");
    fprintf(stderr, "  -di,       --diarize           [%-7s] stereo audio diarization\n",                       params.diarize ? "true" : "false");
    fprintf(stderr, "  -nf,       --no-fallback       [%-7s] do not use temperature fallback while decoding\n", params.no_fallback ? "true" : "false");
    fprintf(stderr, "  -otxt,     --output-txt        [%-7s] output result in a text file\n",                   params.output_txt ? "true" : "false");
    fprintf(stderr, "  -ovtt,     --output-vtt        [%-7s] output result in a vtt file\n",                    params.output_vtt ? "true" : "false");
    fprintf(stderr, "  -osrt,     --output-srt        [%-7s] output result in a srt file\n",                    params.output_srt ? "true" : "false");
    fprintf(stderr, "  -olrc,     --output-lrc        [%-7s] output result in a lrc file\n",                    params.output_lrc ? "true" : "false");
    fprintf(stderr, "  -owts,     --output-words      [%-7s] output script for generating karaoke video\n",     params.output_wts ? "true" : "false");
    fprintf(stderr, "  -fp,       --font-path         [%-7s] path to a monospace font for karaoke video\n",     params.font_path.c_str());
    fprintf(stderr, "  -ocsv,     --output-csv        [%-7s] output result in a CSV file\n",                    params.output_csv ? "true" : "false");
    fprintf(stderr, "  -oj,       --output-json       [%-7s] output result in a JSON file\n",                   params.output_jsn ? "true" : "false");
    fprintf(stderr, "  -of FNAME, --output-file FNAME [%-7s] output file path (without file extension)\n",      "");
    fprintf(stderr, "  -ps,       --print-special     [%-7s] print special tokens\n",                           params.print_special ? "true" : "false");
    fprintf(stderr, "  -pc,       --print-colors      [%-7s] print colors\n",                                   params.print_colors ? "true" : "false");
    fprintf(stderr, "  -pp,       --print-progress    [%-7s] print progress\n",                                 params.print_progress ? "true" : "false");
    fprintf(stderr, "  -nt,       --no-timestamps     [%-7s] do not print timestamps\n",                        params.no_timestamps ? "false" : "true");
    fprintf(stderr, "  -l LANG,   --language LANG     [%-7s] spoken language ('auto' for auto-detect)\n",       params.language.c_str());
    fprintf(stderr, "             --prompt PROMPT     [%-7s] initial prompt\n",                                 params.prompt.c_str());
    fprintf(stderr, "  -m FNAME,  --model FNAME       [%-7s] model path\n",                                     params.model.c_str());
    fprintf(stderr, "  -f FNAME,  --file FNAME        [%-7s] input WAV file path\n",                            "");
    fprintf(stderr, "\n");
}

struct whisper_print_user_data {
    const whisper_params * params;

    const std::vector<std::vector<float>> * pcmf32s;
};

void whisper_print_segment_callback(struct whisper_context * ctx, struct whisper_state * /*state*/, int n_new, void * user_data) {
    const auto & params  = *((whisper_print_user_data *) user_data)->params;
    const auto & pcmf32s = *((whisper_print_user_data *) user_data)->pcmf32s;

    const int n_segments = whisper_full_n_segments(ctx);

    std::string speaker = "";

    int64_t t0 = 0;
    int64_t t1 = 0;

    // print the last n_new segments
    const int s0 = n_segments - n_new;

    if (s0 == 0) {
        printf("\n");
    }

    for (int i = s0; i < n_segments; i++) {
        if (!params.no_timestamps || params.diarize) {
            t0 = whisper_full_get_segment_t0(ctx, i);
            t1 = whisper_full_get_segment_t1(ctx, i);
        }

        if (!params.no_timestamps) {
            printf("[%s --> %s]  ", to_timestamp(t0).c_str(), to_timestamp(t1).c_str());
        }

        if (params.diarize && pcmf32s.size() == 2) {
            const int64_t n_samples = pcmf32s[0].size();

            const int64_t is0 = timestamp_to_sample(t0, n_samples);
            const int64_t is1 = timestamp_to_sample(t1, n_samples);

            double energy0 = 0.0f;
            double energy1 = 0.0f;

            for (int64_t j = is0; j < is1; j++) {
                energy0 += fabs(pcmf32s[0][j]);
                energy1 += fabs(pcmf32s[1][j]);
            }

            if (energy0 > 1.1*energy1) {
                speaker = "(speaker 0)";
            } else if (energy1 > 1.1*energy0) {
                speaker = "(speaker 1)";
            } else {
                speaker = "(speaker ?)";
            }

            //printf("is0 = %lld, is1 = %lld, energy0 = %f, energy1 = %f, %s\n", is0, is1, energy0, energy1, speaker.c_str());
        }

        if (params.print_colors) {
            for (int j = 0; j < whisper_full_n_tokens(ctx, i); ++j) {
                if (params.print_special == false) {
                    const whisper_token id = whisper_full_get_token_id(ctx, i, j);
                    if (id >= whisper_token_eot(ctx)) {
                        continue;
                    }
                }

                const char * text = whisper_full_get_token_text(ctx, i, j);
                const float  p    = whisper_full_get_token_p   (ctx, i, j);

                const int col = std::max(0, std::min((int) k_colors.size() - 1, (int) (std::pow(p, 3)*float(k_colors.size()))));

                printf("%s%s%s%s", speaker.c_str(), k_colors[col].c_str(), text, "\033[0m");
            }
        } else {
            const char * text = whisper_full_get_segment_text(ctx, i);

            printf("%s%s", speaker.c_str(), text);
        }

        // with timestamps or speakers: each segment on new line
        if (!params.no_timestamps || params.diarize) {
            printf("\n");
        }

        fflush(stdout);
    }
}

bool output_txt(struct whisper_context * ctx, const char * fname) {
    std::ofstream fout(fname);
    if (!fout.is_open()) {
        fprintf(stderr, "%s: failed to open '%s' for writing\n", __func__, fname);
        return false;
    }

    fprintf(stderr, "%s: saving output to '%s'\n", __func__, fname);

    const int n_segments = whisper_full_n_segments(ctx);
    for (int i = 0; i < n_segments; ++i) {
        const char * text = whisper_full_get_segment_text(ctx, i);
        fout << text << "\n";
    }

    return true;
}

bool output_vtt(struct whisper_context * ctx, const char * fname) {
    std::ofstream fout(fname);
    if (!fout.is_open()) {
        fprintf(stderr, "%s: failed to open '%s' for writing\n", __func__, fname);
        return false;
    }

    fprintf(stderr, "%s: saving output to '%s'\n", __func__, fname);

    fout << "WEBVTT\n\n";

    const int n_segments = whisper_full_n_segments(ctx);
    for (int i = 0; i < n_segments; ++i) {
        const char * text = whisper_full_get_segment_text(ctx, i);
        const int64_t t0 = whisper_full_get_segment_t0(ctx, i);
        const int64_t t1 = whisper_full_get_segment_t1(ctx, i);

        fout << to_timestamp(t0) << " --> " << to_timestamp(t1) << "\n";
        fout << text << "\n\n";
    }

    return true;
}

bool output_srt(struct whisper_context * ctx, const char * fname, const whisper_params & params) {
    std::ofstream fout(fname);
    if (!fout.is_open()) {
        fprintf(stderr, "%s: failed to open '%s' for writing\n", __func__, fname);
        return false;
    }

    fprintf(stderr, "%s: saving output to '%s'\n", __func__, fname);

    const int n_segments = whisper_full_n_segments(ctx);
    for (int i = 0; i < n_segments; ++i) {
        const char * text = whisper_full_get_segment_text(ctx, i);
        const int64_t t0 = whisper_full_get_segment_t0(ctx, i);
        const int64_t t1 = whisper_full_get_segment_t1(ctx, i);

        fout << i + 1 + params.offset_n << "\n";
        fout << to_timestamp(t0, true) << " --> " << to_timestamp(t1, true) << "\n";
        fout << text << "\n\n";
    }

    return true;
}

bool output_csv(struct whisper_context * ctx, const char * fname) {
    std::ofstream fout(fname);
    if (!fout.is_open()) {
        fprintf(stderr, "%s: failed to open '%s' for writing\n", __func__, fname);
        return false;
    }

    fprintf(stderr, "%s: saving output to '%s'\n", __func__, fname);

    const int n_segments = whisper_full_n_segments(ctx);
    fout << "start,end,text\n";
    for (int i = 0; i < n_segments; ++i) {
        const char * text = whisper_full_get_segment_text(ctx, i);
        const int64_t t0 = whisper_full_get_segment_t0(ctx, i);
        const int64_t t1 = whisper_full_get_segment_t1(ctx, i);

        //need to multiply times returned from whisper_full_get_segment_t{0,1}() by 10 to get milliseconds.
        fout << 10 * t0 << "," << 10 * t1 << ",\"" << text    << "\"\n";
    }

    return true;
}

char *escape_double_quotes(const char *str) {
    if (str == NULL) {
        return NULL;
    }

    size_t escaped_length = strlen(str) + 1;

    for (size_t i = 0; str[i] != '\0'; i++) {
        if (str[i] == '"') {
            escaped_length++;
        }
    }

    char *escaped = (char *)calloc(escaped_length, 1); // pre-zeroed
    if (escaped == NULL) {
        return NULL;
    }

    size_t pos = 0;
    for (size_t i = 0; str[i] != '\0'; i++) {
        if (str[i] == '"') {
            escaped[pos++] = '\\';
            escaped[pos++] = '"';
        } else {
            escaped[pos++] = str[i];
        }
    }

    // no need to set zero due to calloc() being used prior

    return escaped;
}

bool output_json(struct whisper_context * ctx, const char * fname, const whisper_params & params) {
    std::ofstream fout(fname);
    int indent = 0;

    auto doindent = [&]() {
        for (int i = 0; i < indent; i++) fout << "\t";
    };

    auto start_arr = [&](const char *name) {
        doindent();
        fout << "\"" << name << "\": [\n";
        indent++;
    };

    auto end_arr = [&](bool end = false) {
        indent--;
        doindent();
        fout << (end ? "]\n" : "},\n");
    };

    auto start_obj = [&](const char *name = nullptr) {
        doindent();
        if (name) {
            fout << "\"" << name << "\": {\n";
        } else {
            fout << "{\n";
        }
        indent++;
    };

    auto end_obj = [&](bool end = false) {
        indent--;
        doindent();
        fout << (end ? "}\n" : "},\n");
    };

    auto start_value = [&](const char *name) {
        doindent();
        fout << "\"" << name << "\": ";
    };

    auto value_s = [&](const char *name, const char *val, bool end = false) {
        start_value(name);
        char * val_escaped = escape_double_quotes(val);
        fout << "\"" << val_escaped << (end ? "\"\n" : "\",\n");
        free(val_escaped);
    };

    auto end_value = [&](bool end = false) {
        fout << (end ? "\n" : ",\n");
    };

    auto value_i = [&](const char *name, const int64_t val, bool end = false) {
        start_value(name);
        fout << val;
        end_value(end);
    };

    auto value_b = [&](const char *name, const bool val, bool end = false) {
        start_value(name);
        fout << (val ? "true" : "false");
        end_value(end);
    };

    if (!fout.is_open()) {
        fprintf(stderr, "%s: failed to open '%s' for writing\n", __func__, fname);
        return false;
    }

    fprintf(stderr, "%s: saving output to '%s'\n", __func__, fname);
    start_obj();
        value_s("systeminfo", whisper_print_system_info());
        start_obj("model");
            value_s("type", whisper_model_type_readable(ctx));
            value_b("multilingual", whisper_is_multilingual(ctx));
            value_i("vocab", whisper_model_n_vocab(ctx));
            start_obj("audio");
                value_i("ctx", whisper_model_n_audio_ctx(ctx));
                value_i("state", whisper_model_n_audio_state(ctx));
                value_i("head", whisper_model_n_audio_head(ctx));
                value_i("layer", whisper_model_n_audio_layer(ctx), true);
            end_obj();
            start_obj("text");
                value_i("ctx", whisper_model_n_text_ctx(ctx));
                value_i("state", whisper_model_n_text_state(ctx));
                value_i("head", whisper_model_n_text_head(ctx));
                value_i("layer", whisper_model_n_text_layer(ctx), true);
            end_obj();
            value_i("mels", whisper_model_n_mels(ctx));
            value_i("f16", whisper_model_f16(ctx), true);
        end_obj();
        start_obj("params");
            value_s("model", params.model.c_str());
            value_s("language", params.language.c_str());
            value_b("translate", params.translate, true);
        end_obj();
        start_obj("result");
            value_s("language", whisper_lang_str(whisper_full_lang_id(ctx)), true);
        end_obj();
        start_arr("transcription");

            const int n_segments = whisper_full_n_segments(ctx);
            for (int i = 0; i < n_segments; ++i) {
                const char * text = whisper_full_get_segment_text(ctx, i);
                const int64_t t0 = whisper_full_get_segment_t0(ctx, i);
                const int64_t t1 = whisper_full_get_segment_t1(ctx, i);

                start_obj();
                    start_obj("timestamps");
                        value_s("from", to_timestamp(t0, true).c_str());
                        value_s("to", to_timestamp(t1, true).c_str(), true);
                    end_obj();
                    start_obj("offsets");
                        value_i("from", t0 * 10);
                        value_i("to", t1 * 10, true);
                    end_obj();
                    value_s("text", text, true);
                end_obj(i == (n_segments - 1));
            }

        end_arr(true);
    end_obj(true);
    return true;
}

// karaoke video generation
// outputs a bash script that uses ffmpeg to generate a video with the subtitles
// TODO: font parameter adjustments
bool output_wts(struct whisper_context * ctx, const char * fname, const char * fname_inp, const whisper_params & params, float t_sec) {
    std::ofstream fout(fname);

    fprintf(stderr, "%s: saving output to '%s'\n", __func__, fname);

    static const char * font = params.font_path.c_str();

    std::ifstream fin(font);
    if (!fin.is_open()) {
        fprintf(stderr, "%s: font not found at '%s', please specify a monospace font with -fp\n", __func__, font);
        return false;
    }

    fout << "#!/bin/bash" << "\n";
    fout << "\n";

    fout << "ffmpeg -i " << fname_inp << " -f lavfi -i color=size=1200x120:duration=" << t_sec << ":rate=25:color=black -vf \"";

    for (int i = 0; i < whisper_full_n_segments(ctx); i++) {
        const int64_t t0 = whisper_full_get_segment_t0(ctx, i);
        const int64_t t1 = whisper_full_get_segment_t1(ctx, i);

        const int n = whisper_full_n_tokens(ctx, i);

        std::vector<whisper_token_data> tokens(n);
        for (int j = 0; j < n; ++j) {
            tokens[j] = whisper_full_get_token_data(ctx, i, j);
        }

        if (i > 0) {
            fout << ",";
        }

        // background text
        fout << "drawtext=fontfile='" << font << "':fontsize=24:fontcolor=gray:x=(w-text_w)/2:y=h/2:text='':enable='between(t," << t0/100.0 << "," << t0/100.0 << ")'";

        bool is_first = true;

        for (int j = 0; j < n; ++j) {
            const auto & token = tokens[j];

            if (tokens[j].id >= whisper_token_eot(ctx)) {
                continue;
            }

            std::string txt_bg;
            std::string txt_fg; // highlight token
            std::string txt_ul; // underline

            txt_bg = "> ";
            txt_fg = "> ";
            txt_ul = "\\ \\ ";

            {
                for (int k = 0; k < n; ++k) {
                    const auto & token2 = tokens[k];

                    if (tokens[k].id >= whisper_token_eot(ctx)) {
                        continue;
                    }

                    const std::string txt = whisper_token_to_str(ctx, token2.id);

                    txt_bg += txt;

                    if (k == j) {
                        for (int l = 0; l < (int) txt.size(); ++l) {
                            txt_fg += txt[l];
                            txt_ul += "_";
                        }
                        txt_fg += "|";
                    } else {
                        for (int l = 0; l < (int) txt.size(); ++l) {
                            txt_fg += "\\ ";
                            txt_ul += "\\ ";
                        }
                    }
                }

                ::replace_all(txt_bg, "'", "\u2019");
                ::replace_all(txt_bg, "\"", "\\\"");
                ::replace_all(txt_fg, "'", "\u2019");
                ::replace_all(txt_fg, "\"", "\\\"");
            }

            if (is_first) {
                // background text
                fout << ",drawtext=fontfile='" << font << "':fontsize=24:fontcolor=gray:x=(w-text_w)/2:y=h/2:text='" << txt_bg << "':enable='between(t," << t0/100.0 << "," << t1/100.0 << ")'";
                is_first = false;
            }

            // foreground text
            fout << ",drawtext=fontfile='" << font << "':fontsize=24:fontcolor=lightgreen:x=(w-text_w)/2+8:y=h/2:text='" << txt_fg << "':enable='between(t," << token.t0/100.0 << "," << token.t1/100.0 << ")'";

            // underline
            fout << ",drawtext=fontfile='" << font << "':fontsize=24:fontcolor=lightgreen:x=(w-text_w)/2+8:y=h/2+16:text='" << txt_ul << "':enable='between(t," << token.t0/100.0 << "," << token.t1/100.0 << ")'";
        }
    }

    fout << "\" -c:v libx264 -pix_fmt yuv420p -y " << fname_inp << ".mp4" << "\n";

    fout << "\n\n";
    fout << "echo \"Your video has been saved to " << fname_inp << ".mp4\"" << "\n";
    fout << "\n";
    fout << "echo \"  ffplay " << fname_inp << ".mp4\"\n";
    fout << "\n";

    fout.close();

    fprintf(stderr, "%s: run 'source %s' to generate karaoke video\n", __func__, fname);

    return true;
}

bool output_lrc(struct whisper_context * ctx, const char * fname) {

    std::ofstream fout(fname);
    if (!fout.is_open()) {
        fprintf(stderr, "%s: failed to open '%s' for writing\n", __func__, fname);
        return false;
    }

    fprintf(stderr, "%s: saving output to '%s'\n", __func__, fname);

    fout << "[by:whisper.cpp]\n";

    const int n_segments = whisper_full_n_segments(ctx);
    for (int i = 0; i < n_segments; ++i) {
        const char * text = whisper_full_get_segment_text(ctx, i);
        const int64_t t = whisper_full_get_segment_t0(ctx, i);

        int64_t msec = t * 10;
        int64_t min = msec / (1000 * 60);
        msec = msec - min * (1000 * 60);
        int64_t sec = msec / 1000;
        msec = msec - sec * 1000;

        char buf[16];
        snprintf(buf, sizeof(buf), "%02d:%02d.%02d", (int) min, (int) sec, (int) ( msec / 10));
        std::string timestamp_lrc = std::string(buf);

        fout <<  '[' << timestamp_lrc << ']' << text << "\n";
    }

    return true;
}

int main(int argc, char ** argv) {
    whisper_params params;

    if (whisper_params_parse(argc, argv, params) == false) {
        return 1;
    }

    if (params.fname_inp.empty()) {
        fprintf(stderr, "error: no input files specified\n");
        whisper_print_usage(argc, argv, params);
        return 2;
    }

    if (params.language != "auto" && whisper_lang_id(params.language.c_str()) == -1) {
        fprintf(stderr, "error: unknown language '%s'\n", params.language.c_str());
        whisper_print_usage(argc, argv, params);
        exit(0);
    }

    // whisper init

    struct whisper_context * ctx = whisper_init_from_file(params.model.c_str());

    if (ctx == nullptr) {
        fprintf(stderr, "error: failed to initialize whisper context\n");
        return 3;
    }

    for (int f = 0; f < (int) params.fname_inp.size(); ++f) {
        const auto fname_inp = params.fname_inp[f];
		const auto fname_out = f < (int) params.fname_out.size() && !params.fname_out[f].empty() ? params.fname_out[f] : params.fname_inp[f];

        std::vector<float> pcmf32;               // mono-channel F32 PCM
        std::vector<std::vector<float>> pcmf32s; // stereo-channel F32 PCM

        if (!::read_wav(fname_inp, pcmf32, pcmf32s, params.diarize)) {
            fprintf(stderr, "error: failed to read WAV file '%s'\n", fname_inp.c_str());
            continue;
        }

        // print system information
        {
            fprintf(stderr, "\n");
            fprintf(stderr, "system_info: n_threads = %d / %d | %s\n",
                    params.n_threads*params.n_processors, std::thread::hardware_concurrency(), whisper_print_system_info());
        }

        // print some info about the processing
        {
            fprintf(stderr, "\n");
            if (!whisper_is_multilingual(ctx)) {
                if (params.language != "en" || params.translate) {
                    params.language = "en";
                    params.translate = false;
                    fprintf(stderr, "%s: WARNING: model is not multilingual, ignoring language and translation options\n", __func__);
                }
            }
            fprintf(stderr, "%s: processing '%s' (%d samples, %.1f sec), %d threads, %d processors, lang = %s, task = %s, timestamps = %d ...\n",
                    __func__, fname_inp.c_str(), int(pcmf32.size()), float(pcmf32.size())/WHISPER_SAMPLE_RATE,
                    params.n_threads, params.n_processors,
                    params.language.c_str(),
                    params.translate ? "translate" : "transcribe",
                    params.no_timestamps ? 0 : 1);

            fprintf(stderr, "\n");
        }

        // run the inference
        {
            whisper_full_params wparams = whisper_full_default_params(WHISPER_SAMPLING_GREEDY);

            wparams.strategy = params.beam_size > 1 ? WHISPER_SAMPLING_BEAM_SEARCH : WHISPER_SAMPLING_GREEDY;

            wparams.print_realtime   = false;
            wparams.print_progress   = params.print_progress;
            wparams.print_timestamps = !params.no_timestamps;
            wparams.print_special    = params.print_special;
            wparams.translate        = params.translate;
            wparams.language         = params.language.c_str();
            wparams.n_threads        = params.n_threads;
            wparams.n_max_text_ctx   = params.max_context >= 0 ? params.max_context : wparams.n_max_text_ctx;
            wparams.offset_ms        = params.offset_t_ms;
            wparams.duration_ms      = params.duration_ms;

            wparams.token_timestamps = params.output_wts || params.max_len > 0;
            wparams.thold_pt         = params.word_thold;
            wparams.max_len          = params.output_wts && params.max_len == 0 ? 60 : params.max_len;
            wparams.split_on_word    = params.split_on_word;

            wparams.speed_up         = params.speed_up;

            wparams.initial_prompt   = params.prompt.c_str();

            wparams.greedy.best_of        = params.best_of;
            wparams.beam_search.beam_size = params.beam_size;

            wparams.temperature_inc  = params.no_fallback ? 0.0f : wparams.temperature_inc;
            wparams.entropy_thold    = params.entropy_thold;
            wparams.logprob_thold    = params.logprob_thold;

            whisper_print_user_data user_data = { &params, &pcmf32s };

            // this callback is called on each new segment
            if (!wparams.print_realtime) {
                wparams.new_segment_callback           = whisper_print_segment_callback;
                wparams.new_segment_callback_user_data = &user_data;
            }

            // example for abort mechanism
            // in this example, we do not abort the processing, but we could if the flag is set to true
            // the callback is called before every encoder run - if it returns false, the processing is aborted
            {
                static bool is_aborted = false; // NOTE: this should be atomic to avoid data race

                wparams.encoder_begin_callback = [](struct whisper_context * /*ctx*/, struct whisper_state * /*state*/, void * user_data) {
                    bool is_aborted = *(bool*)user_data;
                    return !is_aborted;
                };
                wparams.encoder_begin_callback_user_data = &is_aborted;
            }

            if (whisper_full_parallel(ctx, wparams, pcmf32.data(), pcmf32.size(), params.n_processors) != 0) {
                fprintf(stderr, "%s: failed to process audio\n", argv[0]);
                return 10;
            }
        }

        // output stuff
        {
            printf("\n");

            // output to text file
            if (params.output_txt) {
                const auto fname_txt = fname_out + ".txt";
                output_txt(ctx, fname_txt.c_str());
            }

            // output to VTT file
            if (params.output_vtt) {
                const auto fname_vtt = fname_out + ".vtt";
                output_vtt(ctx, fname_vtt.c_str());
            }

            // output to SRT file
            if (params.output_srt) {
                const auto fname_srt = fname_out + ".srt";
                output_srt(ctx, fname_srt.c_str(), params);
            }

            // output to WTS file
            if (params.output_wts) {
                const auto fname_wts = fname_out + ".wts";
                output_wts(ctx, fname_wts.c_str(), fname_inp.c_str(), params, float(pcmf32.size() + 1000)/WHISPER_SAMPLE_RATE);
            }

            // output to CSV file
            if (params.output_csv) {
                const auto fname_csv = fname_out + ".csv";
                output_csv(ctx, fname_csv.c_str());
            }

            // output to JSON file
            if (params.output_jsn) {
                const auto fname_jsn = fname_out + ".json";
                output_json(ctx, fname_jsn.c_str(), params);
            }

            // output to LRC file
            if (params.output_lrc) {
                const auto fname_lrc = fname_out + ".lrc";
                output_lrc(ctx, fname_lrc.c_str());
            }
        }
    }

    whisper_print_timings(ctx);
    whisper_free(ctx);

    return 0;
}