whisper.cpp/examples/stream.wasm/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>
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;
void stream_set_status(const std::string & status) {
std::lock_guard<std::mutex> lock(g_mutex);
g_status = status;
}
void stream_main(size_t index) {
stream_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
// disable temperature fallback
wparams.temperature_inc = -1.0f;
wparams.language = "en";
printf("stream: using %d threads\n", wparams.n_threads);
std::vector<float> pcmf32;
// whisper context
auto & ctx = g_contexts[index];
// 5 seconds interval
const int64_t window_samples = 5*WHISPER_SAMPLE_RATE;
while (g_running) {
stream_set_status("waiting for audio ...");
{
std::unique_lock<std::mutex> lock(g_mutex);
if (g_pcmf32.size() < 1024) {
lock.unlock();
std::this_thread::sleep_for(std::chrono::milliseconds(10));
continue;
}
pcmf32 = std::vector<float>(g_pcmf32.end() - std::min((int64_t) g_pcmf32.size(), window_samples), g_pcmf32.end());
g_pcmf32.clear();
}
{
const auto t_start = std::chrono::high_resolution_clock::now();
stream_set_status("running whisper ...");
int ret = whisper_full(ctx, wparams, pcmf32.data(), pcmf32.size());
if (ret != 0) {
printf("whisper_full() failed: %d\n", ret);
break;
}
const auto t_end = std::chrono::high_resolution_clock::now();
printf("stream: whisper_full() returned %d in %f seconds\n", ret, std::chrono::duration<double>(t_end - t_start).count());
}
{
std::string text_heard;
{
const int n_segments = whisper_full_n_segments(ctx);
for (int i = n_segments - 1; 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);
printf("transcribed: %s\n", text);
text_heard += text;
}
}
{
std::lock_guard<std::mutex> lock(g_mutex);
g_transcribed = text_heard;
}
}
}
if (index < g_contexts.size()) {
whisper_free(g_contexts[index]);
g_contexts[index] = nullptr;
}
}
EMSCRIPTEN_BINDINGS(stream) {
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]() {
stream_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;
}
}));
}