MMIOINFO - Win32 Multimedia Programmer's Reference

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MMIOINFO

The MMIOINFO structure contains the current state of a file opened by using the mmioOpen function.

typedef struct {

DWORD dwFlags;

FOURCC fccIOProc;

LPMMIOPROC pIOProc;

UINT wErrorRet;

HTASK hTask;

LONG cchBuffer;

HPSTR pchBuffer;

HPSTR pchNext;

HPSTR pchEndRead;

HPSTR pchEndWrite;

LONG lBufOffset;

LONG lDiskOffset;

DWORD adwInfo[4];

DWORD dwReserved1;

DWORD dwReserved2;

HMMIO hmmio;

} MMIOINFO;

Members
dwFlags

Flags specifying how a file was opened. The following values are defined:

MMIO_ALLOCBUF

File's I/O buffer was allocated by the mmioOpen or mmioSetBuffer function.

MMIO_CREATE

The mmioOpen function was directed to create the file (or truncate it to zero length if it already existed).

MMIO_DIRTY

The I/O buffer has been modified.

MMIO_EXIST

Checks for the existence of the file.

MMIO_GETTEMP

A temporary name was retrieved by the mmioOpen function.

MMIO_PARSE

The new file's path is returned.

The following values may be set when the file is opened in share mode (identified by using the MMIO_SHAREMODE bit mask):

MMIO_COMPAT

File was opened with compatibility mode, allowing any process on a given machine to open the file any number of times.

MMIO_DENYNONE

Other processes are not denied read or write access to the file.

MMIO_DENYREAD

Other processes are denied read access to the file.

MMIO_DENYWRITE

Other processes are denied write access to the file.

MMIO_EXCLUSIVE

Other processes are denied read and write access to the file.

The following values may be set when the file is opened in read/write mode (identified by using the MMIO_RWMODE bit mask):

MMIO_READ

File was opened only for reading.

MMIO_READWRITE

File was opened for reading and writing.

MMIO_WRITE

File was opened only for writing.

fccIOProc

Four-character code identifying the file's I/O procedure. If the I/O procedure is not an installed I/O procedure, this member is NULL.

pIOProc
Address of file's IO procedure.

wErrorRet

Extended error value from the mmioOpen function if it returns NULL. This member is not used to return extended error information from any other functions.

hTask

Handle of a local I/O procedure. Media Control Interface (MCI) devices that perform file I/O in the background and need an I/O procedure can locate a local I/O procedure with this handle.

cchBuffer

Size, in bytes, of the file's I/O buffer. If the file does not have an I/O buffer, this member is zero.

pchBuffer

Address of the file's I/O buffer. If the file is unbuffered, this member is NULL.

pchNext

Address of the next location in the I/O buffer to be read or written. If no more bytes can be read without calling the mmioAdvance or mmioRead function, this member points to the pchEndRead member. If no more bytes can be written without calling the mmioAdvance or mmioWrite function, this member points to the pchEndWrite member.

pchEndRead

Address of the location that is 1 byte past the last location in the buffer that can be read.

pchEndWrite

Address of the location that is 1 byte past the last location in the buffer that can be written.

lBufOffset
Reserved.

lDiskOffset

Current file position, which is an offset, in bytes, from the beginning of the file. I/O procedures are responsible for maintaining this member.

adwInfo

State information maintained by the I/O procedure. I/O procedures can also use these members to transfer information from the application to the I/O procedure when the application opens a file.

dwReserved1
Reserved.

dwReserved2
Reserved.

hmmio

Handle of the open file, as returned by the mmioOpen function. I/O procedures can use this handle when calling other multimedia file I/O functions.

See Also
mmioAdvance, mmioOpen, mmioRead, mmioSetBuffer, mmioWrite

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