MMIOM_CODEC_OPEN

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**.

lParam1 (LONG) - input

Pointer to an CODECOPEN structure.

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.