Video and Image Functions
[The feature associated with this page, DirectShow, is a legacy feature. It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation. Those features have been optimized for Windows 10 and Windows 11. Microsoft strongly recommends that new code use MediaPlayer, IMFMediaEngine and Audio/Video Capture in Media Foundation instead of DirectShow, when possible. Microsoft suggests that existing code that uses the legacy APIs be rewritten to use the new APIs if possible.]
These functions and macros manipulate the DirectShow video format structures.
| Function | Description |
|---|---|
| BIT_MASKS_MATCH | Compares the color masks for two VIDEOINFO structures. |
| BITMASKS | Retrieves the color masks from a VIDEOINFO structure |
| CheckVideoInfoType | Checks a media type that contains a VIDEOINFOHEADER format structure for errors that can cause buffer overruns or integer overflows. |
| CheckVideoInfo2Type | Checks a media type that contains a VIDEOINFOHEADER2 format structure for errors that can cause buffer overruns or integer overflows. |
| COLORS | Retrieves the palette entries from a VIDEOINFO structure |
| ContainsPalette | Determines whether a specified VIDEOINFOHEADER structure contains a palette. |
| ConvertVideoInfoToVideoInfo2 | Converts a media type that uses VIDEOINFOHEADER to one that uses VIDEOINFOHEADER2 |
| DIBSIZE | Calculates the number of bytes required by a device-independent bitmap (DIB). |
| GetBitCount | Returns the number of bits per pixel used by a specified video subtype. |
| GetBitmapFormatSize | Calculates the size needed for a VIDEOINFO structure that can hold a specified BITMAPINFOHEADER structure. |
| GetBitmapPalette | Returns the first palette entry in a VIDEOINFOHEADER structure. |
| GetBitmapSize | Calculates the number of bytes required by a device-independent bitmap (DIB). |
| GetBitmapSubtype | Returns the media subtype GUID for the specified bitmap. |
| GetSubtypeName | Retrieves the human-readable name of a video subtype. |
| GetTrueColorType | Returns the media subtype GUID for a 16-bit uncompressed RGB bitmap. |
| HEADER | Returns the address of the BITMAPINFOHEADER within a VIDEOINFOHEADER. |
| MPEG1_SEQUENCE_INFO | Returns the address of the sequence header inside an MPEG1VIDEOINFO structure. |
| PALETTISED | Checks whether a bitmap has a color depth of 8 bits or less. |
| PALETTE_ENTRIES | Retrieves the maximum number of colors in the palette of a specified bitmap. |
| RESET_MASKS | Fills the color mask fields in a VIDEOINFO structure with zeroes. |
| RESET_HEADER | Fills a VIDEOINFOHEADER with zeroes. |
| RESET_PALETTE | Fills the palette entries in a VIDEOINFO structure with zeroes. |
| SIZE_EGA_PALETTE | Calculates the size needed for the palette entries in a 4-bit RGB bitmap. |
| SIZE_MASKS | Calculates the size of the color masks in a VIDEOINFO structure. |
| SIZE_MPEG1VIDEOINFO | Calculates the size of an MPEG1VIDEOINFO structure, including the sequence header. |
| SIZE_PALETTE | calculates the size of the palette entries in a VIDEOINFO structure. |
| SIZE_PREHEADER | Calculates the byte offset of the bmiHeader field within a VIDEOINFOHEADER structure. |
| SIZE_VIDEOHEADER | Calculates the size of the VIDEOINFOHEADER structure. |
| TRUECOLOR | Returns the TRUECOLORINFO structure from a VIDEOINFO structure. |
| ValidateBitmapInfoHeader | Checks a BITMAPINFOHEADER structure for errors that can cause buffer overruns or integer overflows. |
Remarks
Most of the macros and functions described in the section are designed for manipulating VIDEOINFOHEADER and VIDEOINFO structures for RGB bitmaps. Use these macros with care: Most of them assume that the specified structure has been initialized properly. Many of them also assume that the BITMAPINFOHEADER structure is the standard size; that is, biSize == sizeof(BITMAPINFOHEADER).
The DirectShow base class library also provide the following global constants, which define the standard color masks for true-color bitmaps.
| Global Data | Description |
|---|---|
| bits555 | Array of color masks for a 16-bit RGB bitmap in 5-5-5 format. |
| bits565 | Array of color masks for a 16-bit RGB bitmap in 5-6-5 format. |
| bits888 | Array of color masks for a 24-bit RGB bitmap. |
Each of these constants in an array of three DWORDs, containing the red, green, and blue masks, in that order.