set mixer volume

stepmania/src/arch/Sound/DSoundHelpers.cpp

@@ -7,6 +7,8 @@
 #include <mmsystem.h>
 #include <dsound.h>
 
+#include <math.h>
+
 #pragma comment(lib, "dsound.lib")
 #pragma comment(lib, "dxguid.lib")
 
@@ -44,8 +46,12 @@ bool DSound::IsEmulated() const
 }
 
 DSoundBuf::DSoundBuf(DSound &ds, DSoundBuf::hw hardware,
-			int channels_, int samplerate_, int samplebits_, int writeahead_)
+			int channels_, int samplerate_, int samplebits_, int writeahead_,
+			float vol)
 {
+	ASSERT(vol >= 0);
+	ASSERT(vol <= 1);
+
 	channels = channels_;
 	samplerate = samplerate_;
 	samplebits = samplebits_;
@@ -80,6 +86,8 @@ DSoundBuf::DSoundBuf(DSound &ds, DSoundBuf::hw hardware,
 		format.dwFlags |= DSBCAPS_LOCSOFTWARE;
 	if(hardware == HW_DONT_CARE)
 		format.dwFlags |= DSBCAPS_STATIC;
+	if(vol != 1)
+		format.dwFlags |= DSBCAPS_CTRLVOLUME;
 	format.dwBufferBytes = buffersize;
 	format.dwReserved = 0;
 	format.lpwfxFormat = &waveformat;
@@ -94,8 +102,15 @@ DSoundBuf::DSoundBuf(DSound &ds, DSoundBuf::hw hardware,
 	if(buf == NULL)
 		RageException::ThrowNonfatal("foo"); // XXX
 
+	float vl2 = log10f(vol) / log10f(2); /* vol log 2 */
+
+	/* Volume is in percent; SetVolume wants attenuation in thousands of a
+	 * decibel. */
+	if(vol != 1)
+		buf->SetVolume(max(int(1000 * vl2), DSBVOLUME_MIN));
 }
 
+
 DSoundBuf::~DSoundBuf()
 {
 	buf->Release();

stepmania/src/arch/Sound/DSoundHelpers.h

@@ -40,7 +40,8 @@ class DSoundBuf
 public:
 	enum hw { HW_HARDWARE, HW_SOFTWARE, HW_DONT_CARE };
 	DSoundBuf(DSound &ds, hw hardware, 
-		int channels, int samplerate, int samplebits, int writeahead);
+		int channels, int samplerate, int samplebits, int writeahead,
+		float vol=1);
 
 	bool get_output_buf(char **buffer, unsigned *bufsiz, int *play_pos, int chunksize);
 	void release_output_buf(char *buffer, unsigned bufsiz);

stepmania/src/arch/Sound/RageSoundDriver_DSound.cpp

@@ -161,7 +161,8 @@ RageSound_DSound::RageSound_DSound()
 		try {
 			newbuf = new DSoundBuf(ds, 
 				DSoundBuf::HW_HARDWARE,
-				channels, samplerate, 16, buffersize);
+				channels, samplerate, 16, buffersize,
+				0.50f);
 		} catch(const RageException &e) {
 			/* If we didn't get at least 8, fail. */
 			if(i >= 8) break; /* OK */