diff --git a/dlls/dmusic/buffer.c b/dlls/dmusic/buffer.c
index f4ea22cec15..ca53db3a2c2 100644
--- a/dlls/dmusic/buffer.c
+++ b/dlls/dmusic/buffer.c
@@ -115,9 +115,12 @@ static HRESULT WINAPI IDirectMusicBufferImpl_PackStructured(LPDIRECTMUSICBUFFER
         return DMUS_E_INVALID_EVENT;
     }
 
+    if (!This->write_pos)
+        This->start_time = ref_time;
+
     header.cbEvent = sizeof(channel_message);
     header.dwChannelGroup = channel_group;
-    header.rtDelta = ref_time;
+    header.rtDelta = ref_time - This->start_time;
     header.dwFlags = DMUS_EVENT_STRUCTURED;
 
     memcpy(This->data + This->write_pos, &header, sizeof(header));
@@ -168,11 +171,18 @@ static HRESULT WINAPI IDirectMusicBufferImpl_GetRawBufferPtr(LPDIRECTMUSICBUFFER
     return S_OK;
 }
 
-static HRESULT WINAPI IDirectMusicBufferImpl_GetStartTime(LPDIRECTMUSICBUFFER iface, LPREFERENCE_TIME prt)
+static HRESULT WINAPI IDirectMusicBufferImpl_GetStartTime(LPDIRECTMUSICBUFFER iface, LPREFERENCE_TIME ref_time)
 {
     IDirectMusicBufferImpl *This = impl_from_IDirectMusicBuffer(iface);
 
-    FIXME("(%p, %p): stub\n", This, prt);
+    TRACE("(%p)->(%p)\n", iface, ref_time);
+
+    if (!ref_time)
+        return E_POINTER;
+    if (!This->write_pos)
+        return DMUS_E_BUFFER_EMPTY;
+
+    *ref_time = This->start_time;
 
     return S_OK;
 }
@@ -218,11 +228,13 @@ static HRESULT WINAPI IDirectMusicBufferImpl_GetBufferFormat(LPDIRECTMUSICBUFFER
     return S_OK;
 }
 
-static HRESULT WINAPI IDirectMusicBufferImpl_SetStartTime(LPDIRECTMUSICBUFFER iface, REFERENCE_TIME rt)
+static HRESULT WINAPI IDirectMusicBufferImpl_SetStartTime(LPDIRECTMUSICBUFFER iface, REFERENCE_TIME ref_time)
 {
     IDirectMusicBufferImpl *This = impl_from_IDirectMusicBuffer(iface);
 
-    FIXME("(%p, 0x%s): stub\n", This, wine_dbgstr_longlong(rt));
+    TRACE("(%p)->(0x%s)\n", This, wine_dbgstr_longlong(ref_time));
+
+    This->start_time = ref_time;
 
     return S_OK;
 }
diff --git a/dlls/dmusic/dmusic_private.h b/dlls/dmusic/dmusic_private.h
index f4897ace9ab..23d010d3896 100644
--- a/dlls/dmusic/dmusic_private.h
+++ b/dlls/dmusic/dmusic_private.h
@@ -114,6 +114,7 @@ struct IDirectMusicBufferImpl {
     DWORD size;
     LPBYTE data;
     DWORD write_pos;
+    REFERENCE_TIME start_time;
 };
 
 /*****************************************************************************
diff --git a/dlls/dmusic/tests/dmusic.c b/dlls/dmusic/tests/dmusic.c
index 71e89fd82b0..a05afcca9f3 100644
--- a/dlls/dmusic/tests/dmusic.c
+++ b/dlls/dmusic/tests/dmusic.c
@@ -113,6 +113,7 @@ static void test_dmbuffer(void)
     GUID format;
     DWORD size;
     DWORD bytes;
+    REFERENCE_TIME time;
 
     hr = CoCreateInstance(&CLSID_DirectMusic, NULL, CLSCTX_INPROC_SERVER, &IID_IDirectMusic, (LPVOID*)&dmusic);
     if (hr != S_OK)
@@ -136,14 +137,30 @@ static void test_dmbuffer(void)
     ok(hr == S_OK, "IDirectMusicBuffer_GetMaxBytes returned %x\n", hr);
     ok(size == 1024, "Buffer size is %u instead of 1024\n", size);
 
-    hr = IDirectMusicBuffer_PackStructured(dmbuffer, 10, 0, 0);
+    hr = IDirectMusicBuffer_GetStartTime(dmbuffer, &time);
+    ok(hr == DMUS_E_BUFFER_EMPTY, "IDirectMusicBuffer_GetStartTime returned %x\n", hr);
+    hr = IDirectMusicBuffer_SetStartTime(dmbuffer, 10);
+    ok(hr == S_OK, "IDirectMusicBuffer_GetStartTime returned %x\n", hr);
+    hr = IDirectMusicBuffer_GetStartTime(dmbuffer, &time);
+    ok(hr == DMUS_E_BUFFER_EMPTY, "IDirectMusicBuffer_GetStartTime returned %x\n", hr);
+
+    hr = IDirectMusicBuffer_PackStructured(dmbuffer, 20, 0, 0);
     ok(hr == DMUS_E_INVALID_EVENT, "IDirectMusicBuffer_PackStructured returned %x\n", hr);
-    hr = IDirectMusicBuffer_PackStructured(dmbuffer, 10, 0, 0x000090); /* note on : chan 0, note 0 & vel 0 */
+    hr = IDirectMusicBuffer_PackStructured(dmbuffer, 20, 0, 0x000090); /* note on : chan 0, note 0 & vel 0 */
     ok(hr == S_OK, "IDirectMusicBuffer_PackStructured returned %x\n", hr);
     hr = IDirectMusicBuffer_GetUsedBytes(dmbuffer, &bytes);
     ok(hr == S_OK, "IDirectMusicBuffer_GetUsedBytes returned %x\n", hr);
     ok(bytes == 24, "Buffer size is %u instead of 0\n", bytes);
 
+    hr = IDirectMusicBuffer_GetStartTime(dmbuffer, &time);
+    ok(hr == S_OK, "IDirectMusicBuffer_GetStartTime returned %x\n", hr);
+    ok(time == 20, "Buffer start time is wrong\n");
+    hr = IDirectMusicBuffer_SetStartTime(dmbuffer, 30);
+    ok(hr == S_OK, "IDirectMusicBuffer_GetStartTime returned %x\n", hr);
+    hr = IDirectMusicBuffer_GetStartTime(dmbuffer, &time);
+    ok(hr == S_OK, "IDirectMusicBuffer_GetStartTime returned %x\n", hr);
+    ok(time == 30, "Buffer start time is wrong\n");
+
     if (dmbuffer)
         IDirectMusicBuffer_Release(dmbuffer);
     IDirectMusic_Release(dmusic);