AudioServer: Add software volume control

userspace/programs/AudioServer/AudioServer.cpp

@@ -111,17 +111,18 @@ bool AudioServer::on_client_packet(int fd, LibAudio::Packet packet)
 		{
 			// NOTE: maybe we should map [0->100%] -> [min, 0] instead?
 
+			double hw_percent = 1.0;
+
 			const auto& volume = device().volume;
-			if (volume.min_mdB == volume.max_mdB)
-				response = 1000;
-			else
+			if (volume.min_mdB != volume.max_mdB)
 			{
-				const double min_dB = volume.min_mdB / 1000.0;
-				const double max_dB = volume.max_mdB / 1000.0;
-				const double dB = volume.mdB / 1000.0;
-				const double percent = (BAN::Math::pow(10.0, (dB - min_dB) / (max_dB - min_dB)) - 1.0) / 9.0;
-				response = BAN::Math::round(percent * 1000.0);
+				const double min_mdB = volume.min_mdB;
+				const double max_mdB = volume.max_mdB;
+				hw_percent = (BAN::Math::pow(10.0, (device().volume.mdB - min_mdB) / (max_mdB - min_mdB)) - 1.0) / 9.0;
 			}
+
+			response = BAN::Math::round(device().volume_mult * hw_percent * 1000.0);
+
 			break;
 		}
 		case LibAudio::Packet::SetVolume:
@@ -129,16 +130,24 @@ bool AudioServer::on_client_packet(int fd, LibAudio::Packet packet)
 			// NOTE: maybe we should map [0->100%] -> [min, 0] instead?
 
 			const auto& volume = device().volume;
-			const double min_dB = volume.min_mdB / 1000.0;
-			const double max_dB = volume.max_mdB / 1000.0;
+			const double min_mdB = volume.min_mdB;
+			const double max_mdB = volume.max_mdB;
 			const double percent = packet.parameter / 1000.0;
-			const double dB = min_dB + (max_dB - min_dB) * BAN::Math::log10(1.0 + 9.0 * percent);
+			const int32_t mdB = BAN::Math::round(min_mdB + (max_mdB - min_mdB) * BAN::Math::log10(1.0 + 9.0 * percent));
 
-			const int32_t mdB = BAN::Math::round(dB * 1000.0);
 			if (ioctl(device().fd, SND_SET_VOLUME_MDB, &mdB) != 0)
-				dwarnln("Failed to set volume: {}", strerror(errno));
-			else if (ioctl(device().fd, SND_GET_VOLUME_INFO, &device().volume) != 0)
-				dwarnln("Failed to query new volume: {}", strerror(errno));
+				dwarnln("Failed to set hardware volume: {}", strerror(errno));
+
+			if (ioctl(device().fd, SND_GET_VOLUME_INFO, &device().volume) != 0)
+			{
+				dwarnln("Failed to query new hardware volume: {}", strerror(errno));
+				device().volume_mult = 1.0;
+			}
+			else
+			{
+				const double hw_percent = (BAN::Math::pow(10.0, (device().volume.mdB - min_mdB) / (max_mdB - min_mdB)) - 1.0) / 9.0;
+				device().volume_mult = percent / hw_percent;
+			}
 
 			break;
 		}
@@ -313,11 +322,13 @@ void AudioServer::send_samples()
 		auto buffer = BAN::ByteSpan(static_cast<uint8_t*>(alloca(samples_to_send * sizeof(kernel_sample_t))), samples_to_send * sizeof(kernel_sample_t));
 
 		{
+			const double sample_mult = device().volume_mult * BAN::numeric_limits<kernel_sample_t>::max();
+
 			auto sample_buffer = buffer.as_span<kernel_sample_t>();
 			for (size_t i = 0; i < samples_to_send; i++)
 			{
 				sample_buffer[i] = BAN::Math::clamp<sample_t>(
-					m_samples[m_samples_sent + i] * BAN::numeric_limits<kernel_sample_t>::max(),
+					sample_mult * m_samples[m_samples_sent + i],
 					BAN::numeric_limits<kernel_sample_t>::min(),
 					BAN::numeric_limits<kernel_sample_t>::max()
 				);

userspace/programs/AudioServer/AudioServer.h

@@ -17,6 +17,7 @@ struct AudioDevice
 	uint32_t sample_rate;
 	uint32_t total_pins;
 	uint32_t current_pin;
+	double volume_mult;
 	snd_volume_info volume;
 };
 

userspace/programs/AudioServer/main.cpp

@@ -60,6 +60,7 @@ static BAN::Optional<AudioDevice> initialize_audio_device(int fd)
 {
 	AudioDevice result {};
 	result.fd = fd;
+	result.volume_mult = 1.0;
 	if (ioctl(fd, SND_GET_CHANNELS, &result.channels) != 0)
 		return {};
 	if (ioctl(fd, SND_GET_SAMPLE_RATE, &result.sample_rate) != 0)