Once a CODEC procedure is determined, the CODEC DLL is loaded and added to the linked list of CODECs currently loaded for this movie instance. The ioLoadCodecDLL routine shown in the following example first checks to see that the CODEC procedure is not already loaded in the list. If it is not loaded in the list, it sends a DOSLoadModule function to load the DLL and find the entry. Next, it initializes the CODEC procedure in the ffOpenCodec routine shown in the following example.
Note: Refer to the OS/2 Presentation Manager Guide and Reference for more information on the DosLoadModule function.
PCCB ioLoadCodecDLL ( PINSTANCE pinstance,
PCODECINIFILEINFO pcifi,
PULONG phCodec )
{
LONG rc = MMIO_SUCCESS; /* Return code of IOProc's call. */
SZ szLoadError[260]; /* Error returns. */
PCCB pccbNew;
PCCB pccb;
HMODULE hmod = 0L;
PMMIOPROC pmmioproc;
ULONG hCodec = 0L;
/********************************************************************/
/* Search if the CCB entry has been created for the passed in */
/* pszDLLName and pszProcName,if yes, then sets pccb pointer of */
/* ptracki to that node.(different track may share a same CCB) */
/********************************************************************/
for (pccb = pinstance->pccbList; pccb; pccb = pccb->pccbNext) {
if (!stricmp(pcifi->szDLLName,pccb->cifi.szDLLName)) {
hCodec = pccb->hCodec;
if (!stricmp(pcifi->szProcName,pccb->cifi.szProcName)) {
/* Proc entry names match */
return(pccb);
}
}
} /* end loop */
/*******************************************************************/
/* The above searching cannot find the DCIO node; if a same */
/* DLLName was found, query IOProc address directly, else load */
/* module then query I/O address before allocates a new pccb node. */
/*******************************************************************/
if (DosLoadModule(szLoadError,
(ULONG)sizeof(szLoadError),
pcifi->szDLLName,
&hmod)) {
/* Load Error - MMIOERR_INVALID_DLLNAME */
return(NULL);
}
if (DosQueryProcAddr(hmod,
0L,
pcifi->szProcName,
(PFN *)&pmmioproc)) {
/* Query Error - MMIOERR_INVALID_PROCEDURENAME */
return(NULL);
}
/********************************************************************/
/* The above loading and querying was successful; then create a new */
/* node for the DCIO. If HhpAllocMem fails, call DosFreeModule to */
/* free DCIO module before returning error. */
/********************************************************************/
if (ENTERCRIT(rc)) {
return(NULL);
}
pccbNew = (PCCB)HhpAllocMem(hheap,(ULONG)sizeof(CCB));
EXITCRIT;
if(!pccbNew) {
DosFreeModule(hmod);
/* Allocate error - MMIOERR_OUTOFMEMORY */
return(NULL);
}
/*********************************************************************/
/* Assigns the Decompress IOProc information, which is in record map */
/* table, to the new DCIO node. */
/*********************************************************************/
pccbNew->cifi = *pcifi;
pccbNew->hmodule = hmod;
pccbNew->pmmioproc = pmmioproc;
pccbNew->hCodec = 0L;
pccbNew->ulLastSrcBuf = 0L;
pccbNew->ulMisc1 = 0L;
pccbNew->ulMisc2 = 0L;
/******************************************************************/
/* Adds new node to the beginning of ccb list. */
/******************************************************************/
pccbNew->pccbNext = pinstance->pccbList;
pinstance->pccbList = pccbNew;
*phCodec = hCodec;
return(pccbNew);
}
/************************** START OF SPECIFICATIONS *****************/
/* */
/* SUBROUTINE NAME: ioLoadCodec */
/* */
/* DESCRIPTIVE NAME: Load a CODEC IOProc and add it the PCCB list */
/* */
/* FUNCTION: This function loads a CODEC IOProc and adds it to the */
/* linked list of CODECs currently loaded for this movie instance. */
/* */
/* NOTES: */
/* */
/* ENTRY POINT: ioLoadCodec */
/* LINKAGE: CALL FAR (00:32) */
/* */
/* INPUT: */
/* PINSTANCE pinstance - Instant structure */
/* PTRACKI ptracki - Track specific information */
/* PCODECINIFILEINFO pcifi - CODEC INI file information */
/* */
/* EXIT-NORMAL: */
/* pccb */
/* */
/* EXIT-ERROR: */
/* 0L */
/* */
/* SIDE EFFECTS: */
/* */
/*************************** END OF SPECIFICATIONS ******************/
PCCB ioLoadCodec ( PINSTANCE pinstance,
PTRACKI ptracki,
PCODECINIFILEINFO pcifi )
{
LONG rc = MMIO_SUCCESS; /* Return code of IOProc's call.*/
PCCB pccbNew;
ULONG hCodec = 0L;
if (pccbNew = ioLoadCodecDLL(pinstance,pcifi,&hCodec)) {
/*******************************************************************/
/* Open the Codec IOProc and save the hCodec in the pccb structure */
/*******************************************************************/
if (rc = ffOpenCodec(pinstance, pccbNew, hCodec, ptracki)) {
pinstance->pccbList = pccbNew->pccbNext; /* unlink from list */
ioCloseCodec(pccbNew);
pccbNew = NULL; /* return error condition */
}
}
return(pccbNew);
}
/************************** START OF SPECIFICATIONS ****************/
/* */
/* SUBROUTINE NAME: ioFindCodec */
/* */
/* DESCRIPTIVE NAME: */
/* */
/* FUNCTION: This function finds a compression/decompression */
/* control block for this compression type. */
/* */
/* NOTES: None */
/* */
/* ENTRY POINT: ioFindCodec */
/* LINKAGE: CALL FAR (00:32) */
/* */
/* INPUT: */
/* PINSTANCE pinstance - Movie instance structure */
/* ULONG ulCompressType - Compression type */
/* */
/* */
/* EXIT-NORMAL: */
/* pccb */
/* */
/* EXIT-ERROR: */
/* NULL - 0L */
/* */
/* */
/* SIDE EFFECTS: */
/* */
/*************************** END OF SPECIFICATIONS *****************/
PCCB ioFindCodec ( PINSTANCE pinstance,
ULONG ulCompressType )
{
PCCB pccb;
for (pccb = pinstance->pccbList; pccb; pccb = pccb->pccbNext) {
if (pccb->cifi.ulCompressType == ulCompressType)
return(pccb);
}
return(NULL); /* not found */
}
The ffOpenCodec routine shown in the following example opens a CODEC instance for a movie instance and creates file format specific header information (including a source video header and a destination video header). Next, it calls MMIO services to open the CODEC.
LONG ffOpenCodec ( PINSTANCE pinstance,
PCCB pccb,
ULONG hCodec,
PTRACKI ptracki)
{
LONG rc = MMIO_SUCCESS;/* Return code of IOProc's call. */
PMMVIDEOHEADER pmmVideoHdr; /* Video header node. */
PCODECVIDEOHEADER pcodecvidhdr;
/****************************************************************/
/* Fill in necessary information for DC IOProc. */
/****************************************************************/
/* Get standard track header */
pmmVideoHdr = (PMMVIDEOHEADER)ptracki->pTrackHeader;
pccb->codecopen.pControlHdr = NULL;
// FOR AVI, fill in from CODEC SPECIFIC DATA SECTION OF HEADER!
pccb->codecopen.pOtherInfo = NULL;
ENTERCRITX;
/********************************************/
/* Create Source Video Header */
/********************************************/
if (pcodecvidhdr = (PCODECVIDEOHEADER)HhpAllocMem(hheap,(ULONG)
sizeof(CODECVIDEOHEADER))) {
pccb->codecopen.pSrcHdr = (PVOID)pcodecvidhdr;
pcodecvidhdr->ulStructLen = sizeof(CODECVIDEOHEADER);
pcodecvidhdr->cx = pmmVideoHdr->ulWidth;
pcodecvidhdr->cy = pmmVideoHdr->ulHeight;
pcodecvidhdr->cPlanes = 1; /* Hardcoded */
pcodecvidhdr->cBitCount = 16; /* Hardcoded */
pcodecvidhdr->ulColorEncoding = MMIO_COMPRESSED; /* Hardcoded */
/********************************************/
/* Create Destination Video Header */
/********************************************/
if (pcodecvidhdr = (PCODECVIDEOHEADER)HhpAllocMem(hheap,(ULONG)
sizeof(CODECVIDEOHEADER))) {
pccb->codecopen.pDstHdr = (PVOID)pcodecvidhdr;
pcodecvidhdr->ulStructLen = sizeof(CODECVIDEOHEADER);
pcodecvidhdr->cx = pmmVideoHdr->ulWidth;
pcodecvidhdr->cy = pmmVideoHdr->ulHeight;
pcodecvidhdr->cPlanes = 1; // Hardcoded
/********************************************/
/* Initialize the Flags and color encoding */
/********************************************/
pccb->codecopen.ulFlags = pccb->cifi.ulCapsFlags &
(VALID_CODECOPEN_INPUTFLAGS);
/* Set the color depth for the CODEC we want */
if (ulNumColors == 16) {
pccb->codecopen.ulFlags |= CODEC_4_BIT_COLOR;
pcodecvidhdr->cBitCount = 16;
pcodecvidhdr->ulColorEncoding = MMIO_PALETTIZED;
}
else if (ulNumColors > 256) {
pccb->codecopen.ulFlags |= CODEC_16_BIT_COLOR;
pcodecvidhdr->cBitCount = 256;
pcodecvidhdr->ulColorEncoding = MMIO_RGB_5_6_5;
}
else { /* 256 and anything else */
pccb->codecopen.ulFlags |= CODEC_8_BIT_COLOR;
pcodecvidhdr->cBitCount = 8;
pcodecvidhdr->ulColorEncoding = MMIO_PALETTIZED;
}
/*****************/
/* Open the CODEC
/*****************/
rc = pccb->pmmioproc(&hCodec,
MMIOM_CODEC_OPEN,
(LONG)&pccb->codecopen,
0L);
if (!rc) {
pccb->hCodec = hCodec;
}
}
}
EXITCRIT;
return(rc);
}
LONG ffAssociateCodec ( PINSTANCE pinstance,
PMMEXTENDINFO pmmextendinfo )
{
LONG rc = MMIO_SUCCESS;
return(rc);
}