MMIOM CODEC OPEN: Difference between revisions
Created page with "{{DISPLAYTITLE:MMIOM_CODEC_OPEN}} This message requests a CODEC procedure instance be opened. On completion, it returns a CODEC handle in ''phCODEC''. ==Syntax== <PRE> param1 PHCODEC phCODEC; →Pointer to CODEC handle.: param2 USHORT usMsg; →Set to MMIOM_CODEC_OPEN.: param3 LONG lParam1; →Pointer to an CODECOPEN structure.: param4 LONG lParam2; →This parameter is not used.: </PRE> ==Parameters== ;''phCODEC'' (PHCODEC) - input :Pointer to CODEC han..." |
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Revision as of 02:00, 26 November 2025
This message requests a CODEC procedure instance be opened. On completion, it returns a CODEC handle in phCODEC.
Syntax
param1 PHCODEC phCODEC; /* Pointer to CODEC handle. */ param2 USHORT usMsg; /* Set to MMIOM_CODEC_OPEN. */ param3 LONG lParam1; /* Pointer to an CODECOPEN structure. */ param4 LONG lParam2; /* This parameter is not used. */
Parameters
- phCODEC (PHCODEC) - input
- Pointer to CODEC handle.
- usMsg (USHORT) - input
- Set to **MMIOM_CODEC_OPEN**.
- lParam2 (LONG) - input
- This parameter is not used.
Returns
- rc (ULONG) - returns
- Return codes indicating success or failure:
- MMIO_SUCCESS The specified instance is opened successfully.
- MMIO_ERROR An error code is returned.
Remarks
Typically the phCODEC parameter is set to **NULL**. If multiple CODEC algorithms are all installed in one DLL with separate entry points, subsequent open calls can have the phCODEC set to the first returned handle. This allows the CODEC procedure to share the same movie data structure among the different algorithms.