diff --git a/dlls/msacm/wineacm.h b/dlls/msacm/wineacm.h
index 819dd59..4356cc6 100644
--- a/dlls/msacm/wineacm.h
+++ b/dlls/msacm/wineacm.h
@@ -1,4 +1,268 @@
 /* -*- tab-width: 8; c-basic-offset: 4 -*- */
+#ifndef __WINE_WINEACM_H
+#define __WINE_WINEACM_H
+
+#include "wine/windef16.h"
+#include "wine/mmsystem16.h"
+
+/***********************************************************************
+ * Win16 definitions
+ */
+typedef BOOL16 CALLBACK (*ACMDRIVERENUMCB16)(
+  HACMDRIVERID16 hadid, DWORD dwInstance, DWORD fdwSupport
+);
+typedef UINT CALLBACK (*ACMFILTERCHOOSEHOOKPROC16)(
+  HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam
+);
+typedef UINT16 CALLBACK (*ACMFORMATCHOOSEHOOKPROC16)(
+  HWND16 hwnd, UINT16 uMsg, WPARAM16 wParam, LPARAM lParam
+);
+
+typedef struct _ACMDRIVERDETAILS16
+{
+  DWORD   cbStruct;
+
+  FOURCC  fccType;
+  FOURCC  fccComp;
+
+  WORD    wMid;
+  WORD    wPid;
+
+  DWORD   vdwACM;
+  DWORD   vdwDriver;
+
+  DWORD   fdwSupport;
+  DWORD   cFormatTags;
+  DWORD   cFilterTags;
+
+  HICON16 hicon;
+
+  CHAR    szShortName[ACMDRIVERDETAILS_SHORTNAME_CHARS];
+  CHAR    szLongName[ACMDRIVERDETAILS_LONGNAME_CHARS];
+  CHAR    szCopyright[ACMDRIVERDETAILS_COPYRIGHT_CHARS];
+  CHAR    szLicensing[ACMDRIVERDETAILS_LICENSING_CHARS];
+  CHAR    szFeatures[ACMDRIVERDETAILS_FEATURES_CHARS];
+} ACMDRIVERDETAILS16, *NPACMDRIVERDETAILS16, *LPACMDRIVERDETAILS16;
+
+typedef struct _ACMFILTERCHOOSE16
+{
+  DWORD          cbStruct;
+  DWORD          fdwStyle;
+
+  HWND16         hwndOwner;
+
+  LPWAVEFILTER   pwfltr;
+  DWORD          cbwfltr;
+
+  LPCSTR         pszTitle;
+
+  char           szFilterTag[ACMFILTERTAGDETAILS_FILTERTAG_CHARS];
+  char           szFilter[ACMFILTERDETAILS_FILTER_CHARS];
+  LPSTR          pszName;
+  DWORD          cchName;
+
+  DWORD          fdwEnum;
+  LPWAVEFILTER   pwfltrEnum;
+    
+  HINSTANCE16    hInstance;
+  LPCSTR         pszTemplateName;
+  LPARAM         lCustData;
+  ACMFILTERCHOOSEHOOKPROC16 pfnHook;
+} ACMFILTERCHOOSE16, *NPACMFILTERCHOOSE16, *LPACMFILTERCHOOSE16;
+
+typedef struct _ACMFILTERDETAILS16
+{
+  DWORD          cbStruct;
+  DWORD          dwFilterIndex;
+  DWORD          dwFilterTag;
+  DWORD          fdwSupport;
+  LPWAVEFILTER   pwfltr;
+  DWORD          cbwfltr;
+  CHAR           szFilter[ACMFILTERDETAILS_FILTER_CHARS];
+} ACMFILTERDETAILS16, *NPACMFILTERDETAILS16, *LPACMFILTERDETAILS16;
+
+typedef struct _ACMFILTERTAGDETAILS16
+{
+  DWORD cbStruct;
+  DWORD dwFilterTagIndex;
+  DWORD dwFilterTag;
+  DWORD cbFilterSize;
+  DWORD fdwSupport;
+  DWORD cStandardFilters;
+  CHAR  szFilterTag[ACMFILTERTAGDETAILS_FILTERTAG_CHARS];
+} ACMFILTERTAGDETAILS16, *NPACMFILTERTAGDETAILS16, *LPACMFILTERTAGDETAILS16;
+
+typedef struct _ACMFORMATCHOOSE16
+{
+  DWORD            cbStruct;
+  DWORD            fdwStyle;
+    
+  HWND16           hwndOwner;
+
+  LPWAVEFORMATEX   pwfx;
+  DWORD            cbwfx;
+  LPCSTR           pszTitle;
+    
+  CHAR             szFormatTag[ACMFORMATTAGDETAILS_FORMATTAG_CHARS];
+  CHAR             szFormat[ACMFORMATDETAILS_FORMAT_CHARS];    
+
+  LPSTR            pszName;
+  DWORD            cchName;
+
+  DWORD            fdwEnum;
+  LPWAVEFORMATEX   pwfxEnum;
+    
+  HINSTANCE16      hInstance;
+  LPCSTR           pszTemplateName;
+  LPARAM           lCustData;
+  ACMFORMATCHOOSEHOOKPROC16 pfnHook;
+} ACMFORMATCHOOSE16, *NPACMFORMATCHOOSE16, *LPACMFORMATCHOOSE16;
+
+typedef struct _ACMFORMATDETAILS16
+{
+    DWORD            cbStruct;
+    DWORD            dwFormatIndex;
+    DWORD            dwFormatTag;
+    DWORD            fdwSupport;
+    LPWAVEFORMATEX   pwfx;
+    DWORD            cbwfx;
+    CHAR             szFormat[ACMFORMATDETAILS_FORMAT_CHARS];
+} ACMFORMATDETAILS16, *NPACMFORMATDETAILS16, *LPACMFORMATDETAILS16;
+
+typedef struct _ACMFORMATTAGDETAILS16
+{
+  DWORD cbStruct;
+  DWORD dwFormatTagIndex;
+  DWORD dwFormatTag;
+  DWORD cbFormatSize;
+  DWORD fdwSupport;
+  DWORD cStandardFormats;
+  CHAR  szFormatTag[ACMFORMATTAGDETAILS_FORMATTAG_CHARS];
+} ACMFORMATTAGDETAILS16, *NPACMFORMATTAGDETAILS16, *LPACMFORMATTAGDETAILS16;
+
+typedef ACMSTREAMHEADER ACMSTREAMHEADER16, *NPACMSTREAMHEADER16, *LPACMSTREAMHEADER16;
+
+typedef BOOL16 CALLBACK (*ACMFILTERENUMCB16)(
+ HACMDRIVERID16 hadid, LPACMFILTERDETAILS16 pafd,
+ DWORD dwInstance, DWORD fdwSupport
+);
+
+typedef BOOL16 CALLBACK (*ACMFILTERTAGENUMCB16)(
+  HACMDRIVERID16 hadid, LPACMFILTERTAGDETAILS16 paftd,
+  DWORD dwInstance, DWORD fdwSupport
+);
+
+typedef BOOL16 CALLBACK (*ACMFORMATENUMCB16)(
+  HACMDRIVERID16 hadid, LPACMFORMATDETAILS16 pafd,
+  DWORD dwInstance, DWORD fdwSupport
+);
+
+typedef BOOL16 CALLBACK (*ACMFORMATTAGENUMCB16)(
+  HACMDRIVERID16 hadid, LPACMFORMATTAGDETAILS16 paftd,
+  DWORD dwInstance, DWORD fdwSupport
+);
+
+/***********************************************************************
+ * Functions - Win16
+ */
+
+DWORD WINAPI acmGetVersion16(
+);
+MMRESULT16 WINAPI acmMetrics16(
+  HACMOBJ16 hao, UINT16 uMetric, LPVOID pMetric
+);
+MMRESULT16 WINAPI acmDriverEnum16(
+  ACMDRIVERENUMCB16 fnCallback, DWORD dwInstance, DWORD fdwEnum
+);
+MMRESULT16 WINAPI acmDriverDetails16(
+  HACMDRIVERID16 hadid, LPACMDRIVERDETAILS16 padd, DWORD fdwDetails
+);
+MMRESULT16 WINAPI acmDriverAdd16(
+  LPHACMDRIVERID16 phadid, HINSTANCE16 hinstModule,
+  LPARAM lParam, DWORD dwPriority, DWORD fdwAdd
+);
+MMRESULT16 WINAPI acmDriverRemove16(
+  HACMDRIVERID16 hadid, DWORD fdwRemove
+);
+MMRESULT16 WINAPI acmDriverOpen16(
+  LPHACMDRIVER16 phad, HACMDRIVERID16 hadid, DWORD fdwOpen
+);
+MMRESULT16 WINAPI acmDriverClose16(
+  HACMDRIVER16 had, DWORD fdwClose
+);
+LRESULT WINAPI acmDriverMessage16(
+  HACMDRIVER16 had, UINT16 uMsg, LPARAM lParam1, LPARAM lParam2
+);
+MMRESULT16 WINAPI acmDriverID16(
+  HACMOBJ16 hao, LPHACMDRIVERID16 phadid, DWORD fdwDriverID
+);
+MMRESULT16 WINAPI acmDriverPriority16(
+ HACMDRIVERID16 hadid, DWORD dwPriority, DWORD fdwPriority
+);
+MMRESULT16 WINAPI acmFormatTagDetails16(
+  HACMDRIVER16 had, LPACMFORMATTAGDETAILS16 paftd, DWORD fdwDetails
+);
+MMRESULT16 WINAPI acmFormatTagEnum16(
+  HACMDRIVER16 had, LPACMFORMATTAGDETAILS16 paftd,
+  ACMFORMATTAGENUMCB16 fnCallback, DWORD dwInstance, DWORD fdwEnum
+);
+MMRESULT16 WINAPI acmFormatChoose16(
+  LPACMFORMATCHOOSE16 pafmtc
+);
+MMRESULT16 WINAPI acmFormatDetails16(
+  HACMDRIVER16 had, LPACMFORMATDETAILS16 pafd, DWORD fdwDetails
+);
+MMRESULT16 WINAPI acmFormatEnum16(
+  HACMDRIVER16 had, LPACMFORMATDETAILS16 pafd,
+  ACMFORMATENUMCB16 fnCallback, DWORD dwInstance, DWORD fdwEnum
+);
+MMRESULT16 WINAPI acmFormatSuggest16(
+  HACMDRIVER16 had, LPWAVEFORMATEX pwfxSrc, 
+  LPWAVEFORMATEX pwfxDst, DWORD cbwfxDst, DWORD fdwSuggest
+);
+MMRESULT16 WINAPI acmFilterTagDetails16(
+  HACMDRIVER16 had, LPACMFILTERTAGDETAILS16 paftd, DWORD fdwDetails
+);
+MMRESULT16 WINAPI acmFilterTagEnum16(
+  HACMDRIVER16 had, LPACMFILTERTAGDETAILS16 paftd,
+  ACMFILTERTAGENUMCB16 fnCallback, DWORD dwInstance, DWORD fdwEnum
+);
+MMRESULT16 WINAPI acmFilterChoose16(
+  LPACMFILTERCHOOSE16 pafltrc
+);
+MMRESULT16 WINAPI acmFilterDetails16(
+  HACMDRIVER16 had, LPACMFILTERDETAILS16 pafd, DWORD fdwDetails
+);
+MMRESULT16 WINAPI acmFilterEnum16(
+  HACMDRIVER16 had, LPACMFILTERDETAILS16 pafd,
+  ACMFILTERENUMCB16 fnCallback, DWORD dwInstance, DWORD fdwEnum
+);
+MMRESULT16 WINAPI acmStreamOpen16(
+  LPHACMSTREAM16 phas, HACMDRIVER16 had,
+  LPWAVEFORMATEX pwfxSrc, LPWAVEFORMATEX pwfxDst,
+  LPWAVEFILTER pwfltr, DWORD dwCallback,
+  DWORD dwInstance, DWORD fdwOpen
+);
+MMRESULT16 WINAPI acmStreamClose16(
+  HACMSTREAM16 has, DWORD fdwClose
+);
+MMRESULT16 WINAPI acmStreamSize16(
+  HACMSTREAM16 has, DWORD cbInput, 
+  LPDWORD pdwOutputBytes, DWORD fdwSize
+);
+MMRESULT16 WINAPI acmStreamConvert16(
+  HACMSTREAM16 has, LPACMSTREAMHEADER16 pash, DWORD fdwConvert
+);
+MMRESULT16 WINAPI acmStreamReset16(
+  HACMSTREAM16 has, DWORD fdwReset
+);
+MMRESULT16 WINAPI acmStreamPrepareHeader16(
+  HACMSTREAM16 has, LPACMSTREAMHEADER16 pash, DWORD fdwPrepare
+);
+MMRESULT16 WINAPI acmStreamUnprepareHeader16(
+  HACMSTREAM16 has, LPACMSTREAMHEADER16 pash, DWORD fdwUnprepare
+);
+
 
 /***********************************************************************
  * Wine specific - Win32
@@ -80,3 +344,5 @@
 #define IDD_ACMFILTERCHOOSE_CMB_FILTER      102
 #define IDD_ACMFILTERCHOOSE_BTN_SETNAME     103
 #define IDD_ACMFILTERCHOOSE_BTN_DELNAME     104
+
+#endif /* __WINE_WINEACM_H */