stream.cpp

// Real-time speech recognition of input from a microphone
//
// A very quick-n-dirty implementation serving mainly as a proof of concept.
//

#include "whisper.h"

#include <SDL.h>
#include <SDL_audio.h>

#include <atomic>
#include <cassert>
#include <cstdio>
#include <string>
#include <thread>
#include <vector>
#include <fstream>
#include <mutex>

//  500 -> 00:05.000
// 6000 -> 01:00.000
std::string to_timestamp(int64_t t) {
    int64_t sec = t/100;
    int64_t msec = t - sec*100;
    int64_t min = sec/60;
    sec = sec - min*60;

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

    return std::string(buf);
}

// command-line parameters
struct whisper_params {
    int32_t n_threads  = std::min(4, (int32_t) std::thread::hardware_concurrency());
    int32_t step_ms    = 3000;
    int32_t length_ms  = 10000;
    int32_t keep_ms    = 200;
    int32_t capture_id = -1;
    int32_t max_tokens = 32;
    int32_t audio_ctx  = 0;

    float vad_thold    = 0.6f;
    float freq_thold   = 100.0f;

    bool speed_up      = false;
    bool translate     = false;
    bool print_special = false;
    bool no_context    = true;
    bool no_timestamps = false;

    std::string language  = "en";
    std::string model     = "models/ggml-base.en.bin";
    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 == "-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 == "--step")          { params.step_ms       = std::stoi(argv[++i]); }
        else if (                 arg == "--length")        { params.length_ms     = std::stoi(argv[++i]); }
        else if (                 arg == "--keep")          { params.keep_ms       = std::stoi(argv[++i]); }
        else if (arg == "-c"   || arg == "--capture")       { params.capture_id    = std::stoi(argv[++i]); }
        else if (arg == "-mt"  || arg == "--max-tokens")    { params.max_tokens    = std::stoi(argv[++i]); }
        else if (arg == "-ac"  || arg == "--audio-ctx")     { params.audio_ctx     = std::stoi(argv[++i]); }
        else if (arg == "-vth" || arg == "--vad-thold")     { params.vad_thold     = std::stof(argv[++i]); }
        else if (arg == "-fth" || arg == "--freq-thold")    { params.freq_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 == "-ps"  || arg == "--print-special") { params.print_special = true; }
        else if (arg == "-kc"  || arg == "--keep-context")  { params.no_context    = false; }
        else if (arg == "-l"   || arg == "--language")      { params.language      = argv[++i]; }
        else if (arg == "-m"   || arg == "--model")         { params.model         = argv[++i]; }
        else if (arg == "-f"   || arg == "--file")          { params.fname_out     = 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]\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, "            --step N        [%-7d] audio step size in milliseconds\n",             params.step_ms);
    fprintf(stderr, "            --length N      [%-7d] audio length in milliseconds\n",                params.length_ms);
    fprintf(stderr, "            --keep N        [%-7d] audio to keep from previous step in ms\n",      params.keep_ms);
    fprintf(stderr, "  -c ID,    --capture ID    [%-7d] capture device ID\n",                           params.capture_id);
    fprintf(stderr, "  -mt N,    --max-tokens N  [%-7d] maximum number of tokens per audio chunk\n",    params.max_tokens);
    fprintf(stderr, "  -ac N,    --audio-ctx N   [%-7d] audio context size (0 - all)\n",                params.audio_ctx);
    fprintf(stderr, "  -vth N,   --vad-thold N   [%-7.2f] voice activity detection threshold\n",        params.vad_thold);
    fprintf(stderr, "  -fth N,   --freq-thold N  [%-7.2f] high-pass frequency cutoff\n",                params.freq_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, "  -ps,      --print-special [%-7s] print special tokens\n",                        params.print_special ? "true" : "false");
    fprintf(stderr, "  -kc,      --keep-context  [%-7s] keep context between audio chunks\n",           params.no_context ? "false" : "true");
    fprintf(stderr, "  -l LANG,  --language LANG [%-7s] spoken language\n",                             params.language.c_str());
    fprintf(stderr, "  -m FNAME, --model FNAME   [%-7s] model path\n",                                  params.model.c_str());
    fprintf(stderr, "  -f FNAME, --file FNAME    [%-7s] text output file name\n",                       params.fname_out.c_str());
    fprintf(stderr, "\n");
}

//
// SDL Audio capture
//

class audio_async {
public:
    audio_async(int len_ms);
    ~audio_async();

    bool init(int capture_id, int sample_rate);

    // start capturing audio via the provided SDL callback
    // keep last len_ms seconds of audio in a circular buffer
    bool resume();
    bool pause();
    bool clear();

    // callback to be called by SDL
    void callback(uint8_t * stream, int len);

    // get audio data from the circular buffer
    void get(int ms, std::vector<float> & audio);

private:
    SDL_AudioDeviceID m_dev_id_in = 0;

    int m_len_ms = 0;
    int m_sample_rate = 0;

    std::atomic_bool m_running;
    std::mutex       m_mutex;

    std::vector<float> m_audio;
    std::vector<float> m_audio_new;
    size_t             m_audio_pos = 0;
    size_t             m_audio_len = 0;
};

audio_async::audio_async(int len_ms) {
    m_len_ms = len_ms;

    m_running = false;
}

audio_async::~audio_async() {
    if (m_dev_id_in) {
        SDL_CloseAudioDevice(m_dev_id_in);
    }
}

bool audio_async::init(int capture_id, int sample_rate) {
    SDL_LogSetPriority(SDL_LOG_CATEGORY_APPLICATION, SDL_LOG_PRIORITY_INFO);

    if (SDL_Init(SDL_INIT_AUDIO) < 0) {
        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Couldn't initialize SDL: %s\n", SDL_GetError());
        return false;
    }

    SDL_SetHintWithPriority(SDL_HINT_AUDIO_RESAMPLING_MODE, "medium", SDL_HINT_OVERRIDE);

    {
        int nDevices = SDL_GetNumAudioDevices(SDL_TRUE);
        fprintf(stderr, "%s: found %d capture devices:\n", __func__, nDevices);
        for (int i = 0; i < nDevices; i++) {
            fprintf(stderr, "%s:    - Capture device #%d: '%s'\n", __func__, i, SDL_GetAudioDeviceName(i, SDL_TRUE));
        }
    }

    SDL_AudioSpec capture_spec_requested;
    SDL_AudioSpec capture_spec_obtained;

    SDL_zero(capture_spec_requested);
    SDL_zero(capture_spec_obtained);

    capture_spec_requested.freq     = sample_rate;
    capture_spec_requested.format   = AUDIO_F32;
    capture_spec_requested.channels = 1;
    capture_spec_requested.samples  = 1024;
    capture_spec_requested.callback = [](void * userdata, uint8_t * stream, int len) {
        audio_async * audio = (audio_async *) userdata;
        audio->callback(stream, len);
    };
    capture_spec_requested.userdata = this;

    if (capture_id >= 0) {
        fprintf(stderr, "%s: attempt to open capture device %d : '%s' ...\n", __func__, capture_id, SDL_GetAudioDeviceName(capture_id, SDL_TRUE));
        m_dev_id_in = SDL_OpenAudioDevice(SDL_GetAudioDeviceName(capture_id, SDL_TRUE), SDL_TRUE, &capture_spec_requested, &capture_spec_obtained, 0);
    } else {
        fprintf(stderr, "%s: attempt to open default capture device ...\n", __func__);
        m_dev_id_in = SDL_OpenAudioDevice(nullptr, SDL_TRUE, &capture_spec_requested, &capture_spec_obtained, 0);
    }

    if (!m_dev_id_in) {
        fprintf(stderr, "%s: couldn't open an audio device for capture: %s!\n", __func__, SDL_GetError());
        m_dev_id_in = 0;

        return false;
    } else {
        fprintf(stderr, "%s: obtained spec for input device (SDL Id = %d):\n", __func__, m_dev_id_in);
        fprintf(stderr, "%s:     - sample rate:       %d\n",                   __func__, capture_spec_obtained.freq);
        fprintf(stderr, "%s:     - format:            %d (required: %d)\n",    __func__, capture_spec_obtained.format,
                capture_spec_requested.format);
        fprintf(stderr, "%s:     - channels:          %d (required: %d)\n",    __func__, capture_spec_obtained.channels,
                capture_spec_requested.channels);
        fprintf(stderr, "%s:     - samples per frame: %d\n",                   __func__, capture_spec_obtained.samples);
    }

    m_sample_rate = capture_spec_obtained.freq;

    m_audio.resize((m_sample_rate*m_len_ms)/1000);

    return true;
}

bool audio_async::resume() {
    if (!m_dev_id_in) {
        fprintf(stderr, "%s: no audio device to resume!\n", __func__);
        return false;
    }

    if (m_running) {
        fprintf(stderr, "%s: already running!\n", __func__);
        return false;
    }

    SDL_PauseAudioDevice(m_dev_id_in, 0);

    m_running = true;

    return true;
}

bool audio_async::pause() {
    if (!m_dev_id_in) {
        fprintf(stderr, "%s: no audio device to pause!\n", __func__);
        return false;
    }

    if (!m_running) {
        fprintf(stderr, "%s: already paused!\n", __func__);
        return false;
    }

    SDL_PauseAudioDevice(m_dev_id_in, 1);

    m_running = false;

    return true;
}

bool audio_async::clear() {
    if (!m_dev_id_in) {
        fprintf(stderr, "%s: no audio device to clear!\n", __func__);
        return false;
    }

    if (!m_running) {
        fprintf(stderr, "%s: not running!\n", __func__);
        return false;
    }

    {
        std::lock_guard<std::mutex> lock(m_mutex);

        m_audio_pos = 0;
        m_audio_len = 0;
    }

    return true;
}

// callback to be called by SDL
void audio_async::callback(uint8_t * stream, int len) {
    if (!m_running) {
        return;
    }

    const size_t n_samples = len / sizeof(float);

    m_audio_new.resize(n_samples);
    memcpy(m_audio_new.data(), stream, n_samples * sizeof(float));

    //fprintf(stderr, "%s: %zu samples, pos %zu, len %zu\n", __func__, n_samples, m_audio_pos, m_audio_len);

    {
        std::lock_guard<std::mutex> lock(m_mutex);

        if (m_audio_pos + n_samples > m_audio.size()) {
            const size_t n0 = m_audio.size() - m_audio_pos;

            memcpy(&m_audio[m_audio_pos], stream, n0 * sizeof(float));
            memcpy(&m_audio[0], &stream[n0], (n_samples - n0) * sizeof(float));

            m_audio_pos = (m_audio_pos + n_samples) % m_audio.size();
            m_audio_len = m_audio.size();
        } else {
            memcpy(&m_audio[m_audio_pos], stream, n_samples * sizeof(float));

            m_audio_pos = (m_audio_pos + n_samples) % m_audio.size();
            m_audio_len = std::min(m_audio_len + n_samples, m_audio.size());
        }
    }
}

void audio_async::get(int ms, std::vector<float> & result) {
    if (!m_dev_id_in) {
        fprintf(stderr, "%s: no audio device to get audio from!\n", __func__);
        return;
    }

    if (!m_running) {
        fprintf(stderr, "%s: not running!\n", __func__);
        return;
    }

    result.clear();

    {
        std::lock_guard<std::mutex> lock(m_mutex);

        if (ms <= 0) {
            ms = m_len_ms;
        }

        size_t n_samples = (m_sample_rate * ms) / 1000;
        if (n_samples > m_audio_len) {
            n_samples = m_audio_len;
        }

        result.resize(n_samples);

        int s0 = m_audio_pos - n_samples;
        if (s0 < 0) {
            s0 += m_audio.size();
        }

        if (s0 + n_samples > m_audio.size()) {
            const size_t n0 = m_audio.size() - s0;

            memcpy(result.data(), &m_audio[s0], n0 * sizeof(float));
            memcpy(&result[n0], &m_audio[0], (n_samples - n0) * sizeof(float));
        } else {
            memcpy(result.data(), &m_audio[s0], n_samples * sizeof(float));
        }
    }
}

///////////////////////////

void high_pass_filter(std::vector<float> & data, float cutoff, float sample_rate) {
    const float rc = 1.0f / (2.0f * M_PI * cutoff);
    const float dt = 1.0f / sample_rate;
    const float alpha = dt / (rc + dt);

    float y = data[0];

    for (size_t i = 1; i < data.size(); i++) {
        y = alpha * (y + data[i] - data[i - 1]);
        data[i] = y;
    }
}

bool vad_simple(std::vector<float> & pcmf32, int sample_rate, int last_ms, float vad_thold, float freq_thold, bool verbose) {
    const int n_samples      = pcmf32.size();
    const int n_samples_last = (sample_rate * last_ms) / 1000;

    if (n_samples_last >= n_samples) {
        // not enough samples - assume no speech
        return false;
    }

    if (freq_thold > 0.0f) {
        high_pass_filter(pcmf32, freq_thold, sample_rate);
    }

    float energy_all  = 0.0f;
    float energy_last = 0.0f;

    for (int i = 0; i < n_samples; i++) {
        energy_all += fabsf(pcmf32[i]);

        if (i >= n_samples - n_samples_last) {
            energy_last += fabsf(pcmf32[i]);
        }
    }

    energy_all  /= n_samples;
    energy_last /= n_samples_last;

    if (verbose) {
        fprintf(stderr, "%s: energy_all: %f, energy_last: %f, vad_thold: %f, freq_thold: %f\n", __func__, energy_all, energy_last, vad_thold, freq_thold);
    }

    if (energy_last > vad_thold*energy_all) {
        return false;
    }

    return true;
}

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

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

    params.keep_ms   = std::min(params.keep_ms,   params.step_ms);
    params.length_ms = std::max(params.length_ms, params.step_ms);

    const int n_samples_step = (params.step_ms  *1e-3)*WHISPER_SAMPLE_RATE;
    const int n_samples_len  = (params.length_ms*1e-3)*WHISPER_SAMPLE_RATE;
    const int n_samples_keep = (params.keep_ms  *1e-3)*WHISPER_SAMPLE_RATE;
    const int n_samples_30s  = (30000           *1e-3)*WHISPER_SAMPLE_RATE;

    const bool use_vad = n_samples_step <= 0; // sliding window mode uses VAD

    const int n_new_line = !use_vad ? std::max(1, params.length_ms / params.step_ms - 1) : 1; // number of steps to print new line

    params.no_timestamps  = !use_vad;
    params.no_context    |= use_vad;
    params.max_tokens     = 0;

    // init audio

    audio_async audio(params.length_ms);
    if (!audio.init(params.capture_id, WHISPER_SAMPLE_RATE)) {
        fprintf(stderr, "%s: audio.init() failed!\n", __func__);
        return 1;
    }

    audio.resume();

    // whisper init

    if (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);
    }

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

    std::vector<float> pcmf32    (n_samples_30s, 0.0f);
    std::vector<float> pcmf32_old;
    std::vector<float> pcmf32_new(n_samples_30s, 0.0f);

    std::vector<whisper_token> prompt_tokens;

    // 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 %d samples (step = %.1f sec / len = %.1f sec / keep = %.1f sec), %d threads, lang = %s, task = %s, timestamps = %d ...\n",
                __func__,
                n_samples_step,
                float(n_samples_step)/WHISPER_SAMPLE_RATE,
                float(n_samples_len )/WHISPER_SAMPLE_RATE,
                float(n_samples_keep)/WHISPER_SAMPLE_RATE,
                params.n_threads,
                params.language.c_str(),
                params.translate ? "translate" : "transcribe",
                params.no_timestamps ? 0 : 1);

        if (!use_vad) {
            fprintf(stderr, "%s: n_new_line = %d, no_context = %d\n", __func__, n_new_line, params.no_context);
        } else {
            fprintf(stderr, "%s: using VAD, will transcribe on speech activity\n", __func__);
        }

        fprintf(stderr, "\n");
    }

    int n_iter = 0;

    bool is_running = true;

    std::ofstream fout;
    if (params.fname_out.length() > 0) {
        fout.open(params.fname_out);
        if (!fout.is_open()) {
            fprintf(stderr, "%s: failed to open output file '%s'!\n", __func__, params.fname_out.c_str());
            return 1;
        }
    }

    printf("[Start speaking]");
    fflush(stdout);

          auto t_last  = std::chrono::high_resolution_clock::now();
    const auto t_start = t_last;

    // main audio loop
    while (is_running) {
        // handle Ctrl + C
        {
            SDL_Event event;
            while (SDL_PollEvent(&event)) {
                switch (event.type) {
                    case SDL_QUIT:
                        {
                            is_running = false;
                        } break;
                    default:
                        break;
                }
            }

            if (!is_running) {
                break;
            }
        }

        if (!is_running) {
            break;
        }

        // process new audio

        if (!use_vad) {
            while (true) {
                audio.get(params.step_ms, pcmf32_new);

                if ((int) pcmf32_new.size() > 2*n_samples_step) {
                    fprintf(stderr, "\n\n%s: WARNING: cannot process audio fast enough, dropping audio ...\n\n", __func__);
                    audio.clear();
                    continue;
                }

                if ((int) pcmf32_new.size() >= n_samples_step) {
                    audio.clear();
                    break;
                }

                SDL_Delay(1);
            }

            const int n_samples_new = pcmf32_new.size();

            // take up to params.length_ms audio from previous iteration
            const int n_samples_take = std::min((int) pcmf32_old.size(), std::max(0, n_samples_keep + n_samples_len - n_samples_new));

            //printf("processing: take = %d, new = %d, old = %d\n", n_samples_take, n_samples_new, (int) pcmf32_old.size());

            pcmf32.resize(n_samples_new + n_samples_take);

            for (int i = 0; i < n_samples_take; i++) {
                pcmf32[i] = pcmf32_old[pcmf32_old.size() - n_samples_take + i];
            }

            memcpy(pcmf32.data() + n_samples_take, pcmf32_new.data(), n_samples_new*sizeof(float));

            pcmf32_old = pcmf32;
        } else {
            const auto t_now  = std::chrono::high_resolution_clock::now();
            const auto t_diff = std::chrono::duration_cast<std::chrono::milliseconds>(t_now - t_last).count();

            if (t_diff < 2000) {
                std::this_thread::sleep_for(std::chrono::milliseconds(100));

                continue;
            }

            audio.get(2000, pcmf32_new);

            if (vad_simple(pcmf32_new, WHISPER_SAMPLE_RATE, 1000, params.vad_thold, params.freq_thold, false)) {
                audio.get(params.length_ms, pcmf32);
            } else {
                std::this_thread::sleep_for(std::chrono::milliseconds(100));

                continue;
            }

            t_last = t_now;
        }

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

            wparams.print_progress   = false;
            wparams.print_special    = params.print_special;
            wparams.print_realtime   = false;
            wparams.print_timestamps = !params.no_timestamps;
            wparams.translate        = params.translate;
            wparams.no_context       = true;
            wparams.single_segment   = !use_vad;
            wparams.max_tokens       = params.max_tokens;
            wparams.language         = params.language.c_str();
            wparams.n_threads        = params.n_threads;

            wparams.audio_ctx        = params.audio_ctx;
            wparams.speed_up         = params.speed_up;

            // disable temperature fallback
            wparams.temperature_inc  = -1.0f;

            wparams.prompt_tokens    = params.no_context ? nullptr : prompt_tokens.data();
            wparams.prompt_n_tokens  = params.no_context ? 0       : prompt_tokens.size();

            if (whisper_full(ctx, wparams, pcmf32.data(), pcmf32.size()) != 0) {
                fprintf(stderr, "%s: failed to process audio\n", argv[0]);
                return 6;
            }

            // print result;
            {
                if (!use_vad) {
                    printf("\33[2K\r");

                    // print long empty line to clear the previous line
                    printf("%s", std::string(100, ' ').c_str());

                    printf("\33[2K\r");
                } else {
                    const int64_t t1 = (t_last - t_start).count()/1000000;
                    const int64_t t0 = std::max(0.0, t1 - pcmf32.size()*1000.0/WHISPER_SAMPLE_RATE);

                    printf("\n");
                    printf("### Transcription %d START | t0 = %d ms | t1 = %d ms\n", n_iter, (int) t0, (int) t1);
                    printf("\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);

                    if (params.no_timestamps) {
                        printf("%s", text);
                        fflush(stdout);

                        if (params.fname_out.length() > 0) {
                            fout << text;
                        }
                    } else {
                        const int64_t t0 = whisper_full_get_segment_t0(ctx, i);
                        const int64_t t1 = whisper_full_get_segment_t1(ctx, i);

                        printf ("[%s --> %s]  %s\n", to_timestamp(t0).c_str(), to_timestamp(t1).c_str(), text);

                        if (params.fname_out.length() > 0) {
                            fout << "[" << to_timestamp(t0) << " --> " << to_timestamp(t1) << "]  " << text << std::endl;
                        }
                    }
                }

                if (params.fname_out.length() > 0) {
                    fout << std::endl;
                }

                if (use_vad){
                    printf("\n");
                    printf("### Transcription %d END\n", n_iter);
                }
            }

            ++n_iter;

            if (!use_vad && (n_iter % n_new_line) == 0) {
                printf("\n");

                // keep part of the audio for next iteration to try to mitigate word boundary issues
                pcmf32_old = std::vector<float>(pcmf32.end() - n_samples_keep, pcmf32.end());

                // Add tokens of the last full length segment as the prompt
                if (!params.no_context) {
                    prompt_tokens.clear();

                    const int n_segments = whisper_full_n_segments(ctx);
                    for (int i = 0; i < n_segments; ++i) {
                        const int token_count = whisper_full_n_tokens(ctx, i);
                        for (int j = 0; j < token_count; ++j) {
                            prompt_tokens.push_back(whisper_full_get_token_id(ctx, i, j));
                        }
                    }
                }
            }
        }
    }

    audio.pause();

    whisper_print_timings(ctx);
    whisper_free(ctx);

    return 0;
}