gitadora: (arena model) simulate Realtek device, fix asio redirect hooks (#732)

## Link to GitHub Issue or related Pull Request, if one exists #730, #718 ## Description of change Part 1) When ASIO is in use, the game also looks for a Realtek device so that it can open a WASAPI Exclusive mode stream for headphones. Add an option to fake that, in case the user doesn't have a Realtek device. Part 2) `-gdaasio` wasn't workign properly - fix the logic. ## Testing Seems to work with FlexASIO, and Xonar with no real Realtek device.
2026-08-01 22:30:42 -07:00 · 2026-06-05 00:08:52 -07:00
parent 85058c2156
commit 2dae86a6f2
15 changed files with 504 additions and 8 deletions
@@ -0,0 +1,141 @@
+#include "null_discard_backend.h"
+
+#include <algorithm>
+#include <chrono>
+
+#include "hooks/audio/util.h"
+#include "util/logging.h"
+#include "util/precise_timer.h"
+
+NullDiscardBackend::~NullDiscardBackend() {
+    this->running = false;
+    if (this->pacing_thread.joinable()) {
+        this->pacing_thread.join();
+    }
+}
+
+const WAVEFORMATEXTENSIBLE &NullDiscardBackend::format() const noexcept {
+    return this->format_;
+}
+
+HRESULT NullDiscardBackend::on_initialize(
+    AUDCLNT_SHAREMODE *,
+    DWORD *,
+    REFERENCE_TIME *hnsBufferDuration,
+    REFERENCE_TIME *,
+    const WAVEFORMATEX *pFormat,
+    LPCGUID)
+{
+    copy_wave_format(&this->format_, pFormat);
+
+    // honor the game's requested buffer duration, falling back to 10 ms
+    constexpr REFERENCE_TIME DEFAULT_REFTIME = 100000; // 10 ms in 100-ns units
+    this->period_reftime = (hnsBufferDuration && *hnsBufferDuration > 0)
+            ? *hnsBufferDuration
+            : DEFAULT_REFTIME;
+
+    this->buffer_frames = std::max<uint32_t>(1, static_cast<uint32_t>(
+            static_cast<double>(this->format_.Format.nSamplesPerSec)
+                    * this->period_reftime / 10000000.0 + 0.5));
+
+    log_info("audio::null", "initializing null render device with {} channels, {} Hz, {}-bit",
+             this->format_.Format.nChannels,
+             this->format_.Format.nSamplesPerSec,
+             this->format_.Format.wBitsPerSample);
+
+    return S_OK;
+}
+
+HRESULT NullDiscardBackend::on_get_buffer_size(uint32_t *buffer_frames) {
+    *buffer_frames = this->buffer_frames;
+    return S_OK;
+}
+
+HRESULT NullDiscardBackend::on_get_stream_latency(REFERENCE_TIME *latency) {
+    *latency = this->period_reftime;
+    return S_OK;
+}
+
+HRESULT NullDiscardBackend::on_get_current_padding(std::optional<uint32_t> &padding_frames) {
+    // discarded immediately, so the buffer always reads as fully drained
+    padding_frames = 0;
+    return S_OK;
+}
+
+HRESULT NullDiscardBackend::on_is_format_supported(
+    AUDCLNT_SHAREMODE *,
+    const WAVEFORMATEX *,
+    WAVEFORMATEX **ppClosestMatch)
+{
+    if (ppClosestMatch) {
+        *ppClosestMatch = nullptr;
+    }
+    return S_OK;
+}
+
+HRESULT NullDiscardBackend::on_get_mix_format(WAVEFORMATEX **) {
+    return E_NOTIMPL;
+}
+
+HRESULT NullDiscardBackend::on_get_device_period(
+    REFERENCE_TIME *default_device_period,
+    REFERENCE_TIME *minimum_device_period)
+{
+    if (default_device_period) {
+        *default_device_period = this->period_reftime;
+    }
+    if (minimum_device_period) {
+        *minimum_device_period = this->period_reftime;
+    }
+    return S_OK;
+}
+
+HRESULT NullDiscardBackend::on_start() {
+    if (!this->running.exchange(true)) {
+        this->pacing_thread = std::thread(&NullDiscardBackend::pace_loop, this);
+    }
+    return S_OK;
+}
+
+HRESULT NullDiscardBackend::on_stop() {
+    return S_OK;
+}
+
+HRESULT NullDiscardBackend::on_set_event_handle(HANDLE *event_handle) {
+    // keep the game's event so pace_loop() can wake it; there is no real device behind it
+    this->relay_handle = *event_handle;
+    return S_OK;
+}
+
+HRESULT NullDiscardBackend::on_get_buffer(uint32_t num_frames_requested, BYTE **ppData) {
+    const size_t buffer_size =
+            static_cast<size_t>(this->format_.Format.nBlockAlign) * num_frames_requested;
+    if (this->scratch.size() < buffer_size) {
+        this->scratch.resize(buffer_size);
+    }
+    *ppData = this->scratch.data();
+    return S_OK;
+}
+
+HRESULT NullDiscardBackend::on_release_buffer(uint32_t, DWORD) {
+    // discard the audio entirely
+    return S_OK;
+}
+
+void NullDiscardBackend::pace_loop() {
+    using namespace std::chrono;
+
+    timeutils::PreciseSleepTimer timer;
+
+    // audio is discarded, so timing precision and drift do not matter; just wake the
+    // game once per buffer period to keep its render thread from blocking on the event.
+    const auto period = duration_cast<steady_clock::duration>(
+            duration<double>(this->period_reftime / 10000000.0));
+
+    while (this->running.load()) {
+        if (this->relay_handle) {
+            SetEvent(this->relay_handle);
+        }
+        timer.sleep(period);
+    }
+}