Structure of Selected Movie File Data Chunks

This section describes some of the movie-file data chunks listed in the previous section. It does not describe all the structures; instead, it describes those likely to be useful to a movie player application.

CFTC Table of Contents Entries

The “cftc” chunk identifies the contents and location of the other data chunks in the movie file. The CFTC chunk can be defined as follows (using RIFF notation):

<CFTC-ck> <189>         cftc( <CFTC entry> . . .  )

<CFTC entry> <189> struct {
                                    FOURCC ckID;
                                    DWORD  dwSize;
                                    DWORD  dwResID;
                                    DWORD  dwOffset;
                            }

The <CFTC entry> fields are described in the following table:

All integer values in the CFTC chunk are in Intel format.

Windows Bitmap (DIB) Chunk

The “dib” chunk contains a Windows bitmap, minus the palette. The data portion of this chunk begins with a Windows BITMAPINFOHEADER structure, followed immediately by the bitmap data. When appropriate, the bitmap data is run-length encoded into Windows RLE format.

The following RIFF notation shows the format of the DIB chunk:

<DIB-ck> <189> dib(         <dwResID:DWORD>                                                                                <ResourceName:BSTR>                                                                                <dibHeader:BITMAPINFOHEADER>
                                        <BitmapData:BYTE> . . .  )

All integer data in the “dib” chunk is in Intel format. The fields in the “dib” chunk are described in the following table:

Label-List (VWLB) Chunk

The “vwlb” chunk contains the label list for the movie file. A label is a textual string assigned to a frame. The Movie Player provides two functions, mmpGetInfo and mmpSetInfo, that allow you to get and set the label-list information. See Chapter 3, “Function Directory,” for descriptions of these functions.

The following RIFF notation show the format of the “vwlb” chunk:

<VWLB-ck> <189> vwlb (        <dwResID:DWORD>
                                    <ResourceName:BSTR>
                                    <LabelCount:WORD>
                                    <LabelRecord:LREC> . . . 
                                    <LabelText:CHAR> . . .  )

<LREC> <189>         struct {
                                WORD  wFrameNumber;
                                WORD  wTextOffset;
                        }

The fields of the “vwlb” chunk are described in the following. All integers, with the exception of the SeqID field, are in Motorola format.

The fields of the LREC structure are described in the following. All integers are in Motorola format.

Action-Code (VWAC) Chunk

The “vwac” chunk contains the script-channel text (action entries) for the movie. The Movie Player provides two functions, mmpGetInfo and mmpSetInfo, that allow you to get and set the label-list information. See Chapter 3, “Function Directory,” for descriptions of these functions.

The following RIFF notation shows the format of the “vwac” chunk:

<VWLB-ck> <189> vwac (        <dwResID:DWORD>
                                    <ResourceName:BSTR>
                                    <ActionCount:WORD>
                                    <ActionRecord:ACREC> . . . 
                                    <ActionText:CHAR> . . .     )

<ACREC> <189>         struct {
                            BYTE   chMenuItem;
                            BYTE   wActionCode;
                            WORD   wTextOffset;
                        }

The fields of the “vwac” chunk are described in the following. All integers, with the exception of the SeqID field, are in Motorola format.

The fields of the ACREC structure are described in the following. Integers are in Motorola format.