Move AdjustVolume to AudioDecoderBase as this is needed for WildMidi.

Also convert datatypes from double to float, is a bit faster and good enough here.

src/audio_decoder.cpp

@@ -34,16 +34,6 @@
 
 using namespace std::chrono_literals;
 
-namespace {
-	static double AdjustVolume(double volume) {
-		// Adjust to RPG_RT (Direct Sound) volume scale
-		if (volume > 0) {
-			return 100 * std::pow(10, (-100 + volume) / 60.0);
-		}
-		return 0.0;
-	}
-}
-
 class WMAUnsupportedFormatDecoder : public AudioDecoder {
 public:
 	WMAUnsupportedFormatDecoder() {
@@ -182,8 +172,8 @@ void AudioDecoder::Update(std::chrono::microseconds delta) {
 
 	fade_time -= delta;
 
-	volume += static_cast<double>(std::chrono::duration_cast<std::chrono::microseconds>(delta).count()) * delta_volume_step;
-	volume = Utils::Clamp<double>(static_cast<double>(volume), 0.0, 100.0);
+	volume += static_cast<float>(std::chrono::duration_cast<std::chrono::microseconds>(delta).count()) * delta_volume_step;
+	volume = Utils::Clamp(static_cast<float>(volume), 0.0f, 100.0f);
 	log_volume = AdjustVolume(volume);
 }
 
@@ -192,7 +182,7 @@ int AudioDecoder::GetVolume() const {
 }
 
 void AudioDecoder::SetVolume(int new_volume) {
-	volume = Utils::Clamp<double>(static_cast<double>(new_volume), 0.0, 100.0);
+	volume = Utils::Clamp(static_cast<float>(new_volume), 0.0f, 100.0f);
 	log_volume = AdjustVolume(volume);
 }
 
@@ -206,7 +196,7 @@ void AudioDecoder::SetFade(int end, std::chrono::milliseconds duration) {
 
 	fade_volume_end = end;
 	fade_time = duration;
-	delta_volume_step = (static_cast<double>(fade_volume_end) - volume) / fade_time.count();
+	delta_volume_step = (static_cast<float>(fade_volume_end) - volume) / fade_time.count();
 }
 
 int AudioDecoder::GetSamplesizeForFormat(AudioDecoderBase::Format format) {

src/audio_decoder.h

@@ -102,12 +102,12 @@ class AudioDecoder : public AudioDecoderBase {
 	void Update(std::chrono::microseconds delta) final override;
 private:
 	bool paused = false;
-	double volume = 0.0;
-	double log_volume = 0.0; // as used by RPG_RT
+	float volume = 0.0f;
+	float log_volume = 0.0f; // as used by RPG_RT
 
 	int fade_volume_end = 0;
 	std::chrono::microseconds fade_time = std::chrono::microseconds(0);
-	double delta_volume_step = 0.0;
+	float delta_volume_step = 0.0f;
 };
 
 #endif

src/audio_decoder_base.cpp

@@ -23,6 +23,14 @@
 #include "system.h"
 #include "utils.h"
 
+float AudioDecoderBase::AdjustVolume(float volume) {
+	// Adjust to RPG_RT (Direct Sound) volume scale
+	if (volume > 0) {
+		return 100.0f * std::pow<float>(10, (-100 + volume) / 60.0f);
+	}
+	return 0.0f;
+}
+
 int AudioDecoderBase::Decode(uint8_t* buffer, int length) {
 	return Decode(buffer, length, 0);
 }

src/audio_decoder_base.h

@@ -35,6 +35,16 @@
  */
 class AudioDecoderBase {
 public:
+	/**
+	 * Takes a linear volume and converts it to a logarithmic used by
+	 * RPG_RT (Direct Sound).
+	 * Do not use this for Midi, is already logarithmic by design.
+	 *
+	 * @param volume linear volume
+	 * @return logarithmic volume
+	 */
+	static float AdjustVolume(float volume);
+
 	virtual ~AudioDecoderBase() = default;
 
 	/** Sample format */

src/audio_decoder_midi.cpp

@@ -148,13 +148,10 @@ void AudioDecoderMidi::Resume() {
 }
 
 int AudioDecoderMidi::GetVolume() const {
-	// When handled by Midi messages fake a 100 otherwise it is double-silenced
+	// When handled by Midi messages fake a 100 otherwise the volume is adjusted twice
 
 	if (!mididec->SupportsMidiMessages()) {
-		if (fade_steps > 0) {
-			return static_cast<int>(fade_volume_end * 100);
-		}
-		return 100;
+		return static_cast<int>(log_volume);
 	}
 
 	return 100;
@@ -164,11 +161,15 @@ void AudioDecoderMidi::SetVolume(int new_volume) {
 	// cancel any pending fades
 	fade_steps = 0;
 
-	volume = new_volume / 100.0f;
+	volume = static_cast<float>(new_volume) / 100.0f;
 	for (int i = 0; i < 16; i++) {
 		uint32_t msg = midimsg_volume(i, static_cast<uint8_t>(channel_volumes[i] * volume));
 		mididec->SendMidiMessage(msg);
 	}
+
+	if (!mididec->SupportsMidiMessages()) {
+		log_volume = AdjustVolume(volume * 100.0f);
+	}
 }
 
 void AudioDecoderMidi::SetFade(int end, std::chrono::milliseconds duration) {
@@ -181,7 +182,7 @@ void AudioDecoderMidi::SetFade(int end, std::chrono::milliseconds duration) {
 	}
 
 	fade_volume_end = end / 100.0f;
-	fade_steps = duration.count() / 100;
+	fade_steps = duration.count() / 100.0;
 	delta_volume_step = (fade_volume_end - volume) / fade_steps;
 }
 
@@ -220,6 +221,9 @@ void AudioDecoderMidi::Update(std::chrono::microseconds delta) {
 	}
 	if (fade_steps >= 0 && mtime - last_fade_mtime > 0.1s) {
 		volume = Utils::Clamp<float>(volume + delta_volume_step, 0.0f, 1.0f);
+		if (!mididec->SupportsMidiMessages()) {
+			log_volume = AdjustVolume(volume * 100.0f);
+		}
 		for (int i = 0; i < 16; i++) {
 			uint32_t msg = midimsg_volume(i, static_cast<uint8_t>(channel_volumes[i] * volume));
 			mididec->SendMidiMessage(msg);

src/audio_decoder_midi.h

@@ -170,12 +170,13 @@ class AudioDecoderMidi final : public AudioDecoderBase, public midisequencer::ou
 	std::chrono::microseconds mtime = std::chrono::microseconds(0);
 	float pitch = 1.0f;
 	bool paused = false;
-	float volume = 0;
+	float volume = 0.0f;
+	float log_volume = 0.0f; // as used by RPG_RT, for Midi decoder without event support
 	bool loops_to_end = false;
 
 	int fade_steps = 0;
-	double fade_volume_end = 0;
-	double delta_volume_step = 0;
+	float fade_volume_end = 0;
+	float delta_volume_step = 0;
 	std::chrono::microseconds last_fade_mtime = std::chrono::microseconds(0);
 
 	int frequency = EP_MIDI_FREQ;