From 669b5fbced14434f8c08a20273fa1ea9787a8fc9 Mon Sep 17 00:00:00 2001
From: Raphael Coeffic <raphaelcoeffic@users.noreply.github.com>
Date: Wed, 22 Apr 2026 04:45:48 +0200
Subject: [PATCH] fix(sim): simulator volume (#7302)

---
 .../src/simulation/wasmsimulatorinterface.cpp | 21 +++++++++++++++----
 .../src/simulation/wasmsimulatorinterface.h   |  2 +-
 radio/src/targets/simu/audio_driver.cpp       | 12 +++++++++++
 radio/src/targets/simu/simuaudio.cpp          |  7 +------
 4 files changed, 31 insertions(+), 11 deletions(-)

diff --git a/companion/src/simulation/wasmsimulatorinterface.cpp b/companion/src/simulation/wasmsimulatorinterface.cpp
index 8e6f4309b..97657d665 100644
--- a/companion/src/simulation/wasmsimulatorinterface.cpp
+++ b/companion/src/simulation/wasmsimulatorinterface.cpp
@@ -532,7 +532,8 @@ void WasmSimulatorInterface::setSdPath(const QString & sdPath,
 
 void WasmSimulatorInterface::setVolumeGain(const int value)
 {
-  m_volumeGain = qBound(0, value * SDL_MIX_MAXVOLUME / 100, SDL_MIX_MAXVOLUME);
+  // Stored as user-facing gain (0.5x..3.0x) multiplied by 10.
+  m_volumeGain = value;
 }
 
 void WasmSimulatorInterface::setAnalogValue(uint8_t index, int16_t value)
@@ -834,10 +835,22 @@ void WasmSimulatorInterface::queueAudio(const uint8_t * buf, uint32_t len)
   if (m_audioDevice == 0 || len == 0)
     return;
 
-  // Apply companion volume gain (m_volumeGain is 0..SDL_MIX_MAXVOLUME)
+  // Apply companion volume gain (m_volumeGain = user gain * 10).
+  // SDL_MixAudioFormat cannot amplify above unity, so scale manually
+  // with saturation to support the UI's 0.5..3.0x range.
+  if (m_volumeGain == 10) {
+    SDL_QueueAudio(m_audioDevice, buf, len);
+    return;
+  }
+
   QByteArray scaled(len, 0);
-  SDL_MixAudioFormat((uint8_t *)scaled.data(), buf, AUDIO_S16SYS, len,
-                     m_volumeGain);
+  auto * src = reinterpret_cast<const int16_t *>(buf);
+  auto * dst = reinterpret_cast<int16_t *>(scaled.data());
+  uint32_t n = len / sizeof(int16_t);
+  for (uint32_t i = 0; i < n; ++i) {
+    int32_t s = ((int32_t)src[i] * m_volumeGain) / 10;
+    dst[i] = (int16_t)qBound<int32_t>(INT16_MIN, s, INT16_MAX);
+  }
   SDL_QueueAudio(m_audioDevice, scaled.constData(), len);
 }
 
diff --git a/companion/src/simulation/wasmsimulatorinterface.h b/companion/src/simulation/wasmsimulatorinterface.h
index c45ea9b7f..dd9670ffe 100644
--- a/companion/src/simulation/wasmsimulatorinterface.h
+++ b/companion/src/simulation/wasmsimulatorinterface.h
@@ -112,7 +112,7 @@ class WasmSimulatorInterface : public SimulatorInterface
 
     // Audio
     SDL_AudioDeviceID m_audioDevice = 0;
-    int m_volumeGain = SDL_MIX_MAXVOLUME;
+    int m_volumeGain = 10;  // unity gain (user gain * 10)
 
     // Host-side analog values (polled by WASM via simuGetAnalog)
     static constexpr int MAX_ANALOGS = 32;
diff --git a/radio/src/targets/simu/audio_driver.cpp b/radio/src/targets/simu/audio_driver.cpp
index 58d901d55..c7f487966 100644
--- a/radio/src/targets/simu/audio_driver.cpp
+++ b/radio/src/targets/simu/audio_driver.cpp
@@ -58,6 +58,18 @@ void audioConsumeCurrentBuffer()
     auto nextBuffer = fifo.getNextFilledBuffer();
     if (!nextBuffer) return;
 
+#if !defined(SOFTWARE_VOLUME)
+    // Simulate the hardware volume chip: scale samples in place.
+    int volume = simuAudioGetVolume();
+    if (volume < VOLUME_LEVEL_MAX) {
+      auto* buf = const_cast<AudioBuffer*>(nextBuffer);
+      for (uint16_t i = 0; i < buf->size; ++i) {
+        buf->data[i] = (audio_data_t)(
+            ((int32_t)buf->data[i] * volume) / VOLUME_LEVEL_MAX);
+      }
+    }
+#endif
+
     auto data = (const uint8_t*)nextBuffer->data;
     uint32_t len = nextBuffer->size * sizeof(audio_data_t);
     simuQueueAudio(data, len);
diff --git a/radio/src/targets/simu/simuaudio.cpp b/radio/src/targets/simu/simuaudio.cpp
index 6e4c84e93..42b328fda 100644
--- a/radio/src/targets/simu/simuaudio.cpp
+++ b/radio/src/targets/simu/simuaudio.cpp
@@ -19,7 +19,7 @@
  * GNU General Public License for more details.
  */
 
-#include "audio.h"
+#include "hal/audio_driver.h"
 #include "simuaudio.h"
 #include "simulib.h"
 
@@ -32,11 +32,6 @@ static SDL_AudioDeviceID _sdl_audio_device = 0;
 
 void simuQueueAudio(const uint8_t* data, uint32_t len)
 {
-#if !defined(SOFTWARE_VOLUME)
-  int volume = (simuAudioGetVolume() * SDL_MIX_MAXVOLUME ) / VOLUME_LEVEL_MAX;
-  SDL_MixAudioFormat((uint8_t*)data, data, AUDIO_FMT, len, volume);
-#endif
-
   SDL_QueueAudio(_sdl_audio_device, data, len);
 }