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emscripten.cpp
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emscripten.cpp
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#include "ggml.h"
#include "whisper.h"
#include <emscripten.h>
#include <emscripten/bind.h>
#include <atomic>
#include <cmath>
#include <mutex>
#include <string>
#include <thread>
#include <vector>
#include <regex>
constexpr int N_THREAD = 8;
std::vector<struct whisper_context *> g_contexts(4, nullptr);
std::mutex g_mutex;
std::thread g_worker;
std::atomic<bool> g_running(false);
std::string g_status = "";
std::string g_status_forced = "";
std::string g_transcribed = "";
std::vector<float> g_pcmf32;
static std::string trim(const std::string & s) {
std::regex e("^\\s+|\\s+$");
return std::regex_replace(s, e, "");
}
static 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;
}
}
// compute similarity between two strings using Levenshtein distance
static float similarity(const std::string & s0, const std::string & s1) {
const size_t len0 = s0.size() + 1;
const size_t len1 = s1.size() + 1;
std::vector<int> col(len1, 0);
std::vector<int> prevCol(len1, 0);
for (size_t i = 0; i < len1; i++) {
prevCol[i] = i;
}
for (size_t i = 0; i < len0; i++) {
col[0] = i;
for (size_t j = 1; j < len1; j++) {
col[j] = std::min(std::min(1 + col[j - 1], 1 + prevCol[j]), prevCol[j - 1] + (s0[i - 1] == s1[j - 1] ? 0 : 1));
}
col.swap(prevCol);
}
const float dist = prevCol[len1 - 1];
return 1.0f - (dist / std::max(s0.size(), s1.size()));
}
void command_set_status(const std::string & status) {
std::lock_guard<std::mutex> lock(g_mutex);
g_status = status;
}
bool command_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 (size_t 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;
}
std::string command_transcribe(whisper_context * ctx, const whisper_full_params & wparams, const std::vector<float> & pcmf32, float & prob, int64_t & t_ms) {
const auto t_start = std::chrono::high_resolution_clock::now();
prob = 0.0f;
t_ms = 0;
if (whisper_full(ctx, wparams, pcmf32.data(), pcmf32.size()) != 0) {
return "";
}
int prob_n = 0;
std::string result;
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);
result += text;
const int n_tokens = whisper_full_n_tokens(ctx, i);
for (int j = 0; j < n_tokens; ++j) {
const auto token = whisper_full_get_token_data(ctx, i, j);
prob += token.p;
++prob_n;
}
}
if (prob_n > 0) {
prob /= prob_n;
}
const auto t_end = std::chrono::high_resolution_clock::now();
t_ms = std::chrono::duration_cast<std::chrono::milliseconds>(t_end - t_start).count();
return result;
}
void command_get_audio(int ms, int sample_rate, std::vector<float> & audio) {
const int64_t n_samples = (ms * sample_rate) / 1000;
int64_t n_take = 0;
if (g_pcmf32.size() < n_samples) {
n_take = g_pcmf32.size();
} else {
n_take = n_samples;
}
audio.resize(n_take);
std::copy(g_pcmf32.end() - n_take, g_pcmf32.end(), audio.begin());
}
void command_main(size_t index) {
command_set_status("loading data ...");
struct whisper_full_params wparams = whisper_full_default_params(whisper_sampling_strategy::WHISPER_SAMPLING_GREEDY);
wparams.n_threads = std::min(N_THREAD, (int) std::thread::hardware_concurrency());
wparams.offset_ms = 0;
wparams.translate = false;
wparams.no_context = true;
wparams.single_segment = true;
wparams.print_realtime = false;
wparams.print_progress = false;
wparams.print_timestamps = true;
wparams.print_special = false;
wparams.max_tokens = 32;
wparams.audio_ctx = 768; // partial encoder context for better performance
wparams.language = "en";
printf("command: using %d threads\n", wparams.n_threads);
bool is_running = true;
bool have_prompt = false;
bool ask_prompt = true;
bool print_energy = false;
float prob0 = 0.0f;
float prob = 0.0f;
std::vector<float> pcmf32_cur;
std::vector<float> pcmf32_prompt;
const std::string k_prompt = "Ok Whisper, start listening for commands.";
// whisper context
auto & ctx = g_contexts[index];
const int32_t vad_ms = 2000;
const int32_t prompt_ms = 5000;
const int32_t command_ms = 4000;
const float vad_thold = 0.1f;
const float freq_thold = -1.0f;
while (g_running) {
// delay
std::this_thread::sleep_for(std::chrono::milliseconds(100));
if (ask_prompt) {
fprintf(stdout, "\n");
fprintf(stdout, "%s: Say the following phrase: '%s%s%s'\n", __func__, "\033[1m", k_prompt.c_str(), "\033[0m");
fprintf(stdout, "\n");
{
char txt[1024];
snprintf(txt, sizeof(txt), "Say the following phrase: '%s'", k_prompt.c_str());
command_set_status(txt);
}
ask_prompt = false;
}
int64_t t_ms = 0;
{
command_get_audio(vad_ms, WHISPER_SAMPLE_RATE, pcmf32_cur);
if (command_vad_simple(pcmf32_cur, WHISPER_SAMPLE_RATE, 1000, vad_thold, freq_thold, print_energy)) {
fprintf(stdout, "%s: Speech detected! Processing ...\n", __func__);
command_set_status("Speech detected! Processing ...");
if (!have_prompt) {
command_get_audio(prompt_ms, WHISPER_SAMPLE_RATE, pcmf32_cur);
const auto txt = ::trim(::command_transcribe(ctx, wparams, pcmf32_cur, prob0, t_ms));
fprintf(stdout, "%s: Heard '%s%s%s', (t = %d ms)\n", __func__, "\033[1m", txt.c_str(), "\033[0m", (int) t_ms);
const float sim = similarity(txt, k_prompt);
if (txt.length() < 0.8*k_prompt.length() || txt.length() > 1.2*k_prompt.length() || sim < 0.8f) {
fprintf(stdout, "%s: WARNING: prompt not recognized, try again\n", __func__);
ask_prompt = true;
} else {
fprintf(stdout, "\n");
fprintf(stdout, "%s: The prompt has been recognized!\n", __func__);
fprintf(stdout, "%s: Waiting for voice commands ...\n", __func__);
fprintf(stdout, "\n");
{
char txt[1024];
snprintf(txt, sizeof(txt), "Success! Waiting for voice commands ...");
command_set_status(txt);
}
// save the audio for the prompt
pcmf32_prompt = pcmf32_cur;
have_prompt = true;
}
} else {
command_get_audio(command_ms, WHISPER_SAMPLE_RATE, pcmf32_cur);
// prepend the prompt audio
pcmf32_cur.insert(pcmf32_cur.begin(), pcmf32_prompt.begin(), pcmf32_prompt.end());
const auto txt = ::trim(::command_transcribe(ctx, wparams, pcmf32_cur, prob, t_ms));
prob = 100.0f*(prob - prob0);
fprintf(stdout, "%s: heard '%s'\n", __func__, txt.c_str());
// find the prompt in the text
float best_sim = 0.0f;
size_t best_len = 0;
for (int n = 0.8*k_prompt.size(); n <= 1.2*k_prompt.size(); ++n) {
const auto prompt = txt.substr(0, n);
const float sim = similarity(prompt, k_prompt);
//fprintf(stderr, "%s: prompt = '%s', sim = %f\n", __func__, prompt.c_str(), sim);
if (sim > best_sim) {
best_sim = sim;
best_len = n;
}
}
const std::string command = ::trim(txt.substr(best_len));
fprintf(stdout, "%s: Command '%s%s%s', (t = %d ms)\n", __func__, "\033[1m", command.c_str(), "\033[0m", (int) t_ms);
fprintf(stdout, "\n");
{
char txt[1024];
snprintf(txt, sizeof(txt), "Command '%s', (t = %d ms)", command.c_str(), (int) t_ms);
command_set_status(txt);
}
{
std::lock_guard<std::mutex> lock(g_mutex);
g_transcribed = command;
}
}
g_pcmf32.clear();
}
}
}
if (index < g_contexts.size()) {
whisper_free(g_contexts[index]);
g_contexts[index] = nullptr;
}
}
EMSCRIPTEN_BINDINGS(command) {
emscripten::function("init", emscripten::optional_override([](const std::string & path_model) {
for (size_t i = 0; i < g_contexts.size(); ++i) {
if (g_contexts[i] == nullptr) {
g_contexts[i] = whisper_init_from_file(path_model.c_str());
if (g_contexts[i] != nullptr) {
g_running = true;
if (g_worker.joinable()) {
g_worker.join();
}
g_worker = std::thread([i]() {
command_main(i);
});
return i + 1;
} else {
return (size_t) 0;
}
}
}
return (size_t) 0;
}));
emscripten::function("free", emscripten::optional_override([](size_t index) {
if (g_running) {
g_running = false;
}
}));
emscripten::function("set_audio", emscripten::optional_override([](size_t index, const emscripten::val & audio) {
--index;
if (index >= g_contexts.size()) {
return -1;
}
if (g_contexts[index] == nullptr) {
return -2;
}
{
std::lock_guard<std::mutex> lock(g_mutex);
const int n = audio["length"].as<int>();
emscripten::val heap = emscripten::val::module_property("HEAPU8");
emscripten::val memory = heap["buffer"];
g_pcmf32.resize(n);
emscripten::val memoryView = audio["constructor"].new_(memory, reinterpret_cast<uintptr_t>(g_pcmf32.data()), n);
memoryView.call<void>("set", audio);
}
return 0;
}));
emscripten::function("get_transcribed", emscripten::optional_override([]() {
std::string transcribed;
{
std::lock_guard<std::mutex> lock(g_mutex);
transcribed = std::move(g_transcribed);
}
return transcribed;
}));
emscripten::function("get_status", emscripten::optional_override([]() {
std::string status;
{
std::lock_guard<std::mutex> lock(g_mutex);
status = g_status_forced.empty() ? g_status : g_status_forced;
}
return status;
}));
emscripten::function("set_status", emscripten::optional_override([](const std::string & status) {
{
std::lock_guard<std::mutex> lock(g_mutex);
g_status_forced = status;
}
}));
}