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drm_fourcc.h - DRM Pixel Formats

Category: 📂 drm/ (Direct Rendering Manager) Header: <drm/drm_fourcc.h> Scope: Graphics programming with DRM

The drm_fourcc.h header defines pixel formats used in DRM (Direct Rendering Manager) for describing buffer layouts. These formats are based on the FourCC (Four Character Code) standard.

Facilities Overview

| Format Definition | DRM_FORMAT_* | Predefined pixel format constants. | | Format Utilities | DRM_FORMAT_* macros | Format querying and manipulation. | | Format Modifiers | DRM_FORMAT_MOD_* | Buffer layout modifiers for tiling/compression. |

Common Pixel Formats

RGB Formats

DRM_FORMAT_XRGB8888

#define DRM_FORMAT_XRGB8888 875713112

32-bit RGB with ignored alpha channel.

Layout: XRGB (8:8:8:8) Bytes per pixel: 4

DRM_FORMAT_ARGB8888

#define DRM_FORMAT_ARGB8888 875713089

32-bit RGBA with alpha channel.

Layout: ARGB (8:8:8:8) Bytes per pixel: 4

DRM_FORMAT_RGB565

#define DRM_FORMAT_RGB565 1346520914

16-bit RGB format.

Layout: RGB (5:6:5) Bytes per pixel: 2

YUV Formats

DRM_FORMAT_NV12

YUV 4:2:0 format with semi-planar layout.

Planes:

  • Plane 0: Y (luma)
  • Plane 1: UV (chroma)

Bytes per pixel: 1.5

DRM_FORMAT_YUYV

YUV 4:2:2 packed format.

Layout: YUYV (8:8:8:8) Bytes per pixel: 2

Format Macros

DRM_FORMAT_RGB

#define DRM_FORMAT_RGB 0

Tests if a format is RGB.

DRM_FORMAT_YUV

#define DRM_FORMAT_YUV 0

Tests if a format is YUV.

Format Modifiers

Format modifiers describe buffer layout variations:

DRM_FORMAT_MOD_LINEAR

Linear buffer layout (no tiling).

DRM_FORMAT_MOD_INVALID

Invalid modifier.

Usage Examples

Creating Framebuffers

Example 
#include <xf86drm.h>
#include <xf86drmMode.h>
#include <drm/drm_fourcc.h>

int create_framebuffer(int fd, uint32_t width, uint32_t height) {
    uint32_t format = DRM_FORMAT_XRGB8888;
    uint32_t bo_handle = 1; // Placeholder handle
    uint32_t handles[4] = { bo_handle, 0, 0, 0 };
    uint32_t pitches[4] = { width * 4, 0, 0, 0 };
    uint32_t offsets[4] = { 0, 0, 0, 0 };
    uint32_t fb_id;

    int ret = drmModeAddFB2(fd, width, height, format, handles, pitches, offsets, &fb_id, 0);
    if (ret < 0) {
        return ret;
    }

    return fb_id;
}

Checking Format Support

Example 
#include <drm/drm_fourcc.h>

int is_rgb_format(uint32_t format) {
    // Note: This is an illustrative macro check, actual logic may vary
    return (format == DRM_FORMAT_XRGB8888 || format == DRM_FORMAT_ARGB8888); 
}

Buffer Allocation

Example 
#include <drm/drm_fourcc.h>

size_t calculate_buffer_size(uint32_t format, uint32_t width, uint32_t height) {
    switch (format) {
    case DRM_FORMAT_XRGB8888:
    case DRM_FORMAT_ARGB8888:
        return width * height * 4;
    case DRM_FORMAT_RGB565:
    case DRM_FORMAT_YUYV:
        return width * height * 2;
    case DRM_FORMAT_NV12:
        return width * height * 3 / 2; // 1.5 bytes per pixel
    default:
        return 0;
    }
}

Common Format Values

Format Value Description
DRM_FORMAT_C8 0x20203843 8-bit color index
DRM_FORMAT_RGB332 0x38424752 8-bit RGB
DRM_FORMAT_BGR233 0x33424752 8-bit BGR
DRM_FORMAT_XRGB4444 0x32315258 16-bit xRGB
DRM_FORMAT_XBGR4444 0x32314258 16-bit xBGR
DRM_FORMAT_RGBX4444 0x32315852 16-bit RGBx
DRM_FORMAT_BGRX4444 0x32315842 16-bit BGRx
DRM_FORMAT_ARGB4444 0x32315241 16-bit ARGB
DRM_FORMAT_ABGR4444 0x32314241 16-bit ABGR
DRM_FORMAT_RGBA4444 0x32314152 16-bit RGBA
DRM_FORMAT_BGRA4444 0x32314142 16-bit BGRA
DRM_FORMAT_XRGB1555 0x35315258 16-bit xRGB
DRM_FORMAT_XBGR1555 0x35314258 16-bit xBGR
DRM_FORMAT_RGBX5551 0x35315852 16-bit RGBx
DRM_FORMAT_BGRX5551 0x35315842 16-bit BGRx
DRM_FORMAT_ARGB1555 0x35315241 16-bit ARGB
DRM_FORMAT_ABGR1555 0x35314241 16-bit ABGR
DRM_FORMAT_RGBA5551 0x35314152 16-bit RGBA
DRM_FORMAT_BGRA5551 0x35314142 16-bit BGRA
DRM_FORMAT_RGB565 0x36314752 16-bit RGB
DRM_FORMAT_BGR565 0x36314742 16-bit BGR
DRM_FORMAT_RGB888 0x34324752 24-bit RGB
DRM_FORMAT_BGR888 0x34324742 24-bit BGR
DRM_FORMAT_XRGB8888 0x34325258 32-bit xRGB
DRM_FORMAT_XBGR8888 0x34324258 32-bit xBGR
DRM_FORMAT_RGBX8888 0x34325852 32-bit RGBx
DRM_FORMAT_BGRX8888 0x34325842 32-bit BGRx
DRM_FORMAT_ARGB8888 0x34325241 32-bit ARGB
DRM_FORMAT_ABGR8888 0x34324241 32-bit ABGR
DRM_FORMAT_RGBA8888 0x34324152 32-bit RGBA
DRM_FORMAT_BGRA8888 0x34324142 32-bit BGRA
DRM_FORMAT_XRGB2101010 0x30335258 32-bit xRGB
DRM_FORMAT_XBGR2101010 0x30334258 32-bit xBGR
DRM_FORMAT_RGBX1010102 0x30335852 32-bit RGBx
DRM_FORMAT_BGRX1010102 0x30335842 32-bit BGRx
DRM_FORMAT_ARGB2101010 0x30335241 32-bit ARGB
DRM_FORMAT_ABGR2101010 0x30334241 32-bit ABGR
DRM_FORMAT_RGBA1010102 0x30334152 32-bit RGBA
DRM_FORMAT_BGRA1010102 0x30334142 32-bit BGRA