Several MMIO functions use the MMFORMATINFO data structure for media conversions. The mmioOpen function includes MMIO_TRANSLATEHEADER and MMIO_TRANSLATEDATA flags which are defined in the ulTranslate field of the MMIOINFO structure. All subsequent read and write operations of multimedia files return data based on these flags. Translation is currently defined only for image and audio. The MMIOOS2.H header file defines the MMFORMATINFO structure as shown in the following example.

typedef struct _MMFORMATINFO {         /* mmformatinfo                 */
                                                                       */
   ULONG    ulStructLen;               /* Length of this structure     */
   FOURCC   fccIOProc;                 /* IOProc identifier            */
   ULONG    ulIOProcType;              /* Type of IOProc               */
   ULONG    ulMediaType;               /* Media type                   */
   ULONG    ulFlags;                   /* IOProc capability flags      */
   CHAR     szDefaultFormatExt[sizeof(FOURCC) + 1];  */
                                       /* Default extension 4 + null   */
   ULONG    ulCodePage;                /* Code page                    */
   ULONG    ulLanguage;                /* Language                     */
   LONG     lNameLength;               /* Length of identifier string  */
   } MMFORMATINFO;