Pixel Formats and Buffer Sizes

Size Notation

For image width W and height H, define:

• P = W * H
• CW = (W + 1) / 2
• CH = (H + 1) / 2

The rounded chroma dimensions allow odd W and H. Applications must perform checked multiplication before allocating buffers from untrusted dimensions.

RGB Layouts

FourCC	Exact byte or plane order	Bytes
SGL_FOURCC_RGBA	packed R, G, B, A	4P
SGL_FOURCC_ARGB	packed A, R, G, B	4P
SGL_FOURCC_BGRA	packed B, G, R, A	4P
SGL_FOURCC_ABGR	packed A, B, G, R	4P
SGL_FOURCC_RGB	packed R, G, B	3P
SGL_FOURCC_BGR	packed B, G, R	3P
SGL_FOURCC_RGBA_PLANAR	planes R, G, B, A	4P
SGL_FOURCC_ARGB_PLANAR	planes A, R, G, B	4P
SGL_FOURCC_BGRA_PLANAR	planes B, G, R, A	4P
SGL_FOURCC_ABGR_PLANAR	planes A, B, G, R	4P
SGL_FOURCC_RGB_PLANAR	planes R, G, B	3P
SGL_FOURCC_BGR_PLANAR	planes B, G, R	3P

The planar RGB identifiers are SGL extensions because DRM/V4L2 do not define equivalent RGB-only planar FourCC values.

YUV Layouts

FourCC	Exact byte or plane order	Bytes
SGL_FOURCC_YUV444_PACKED	packed Y, Cb, Cr	3P
SGL_FOURCC_YUV444_PLANAR	planes Y, Cb, Cr	3P
SGL_FOURCC_YUYV	groups Y0, Cb0, Y1, Cr0	4 * CW * H
SGL_FOURCC_YVYU	groups Y0, Cr0, Y1, Cb0	4 * CW * H
SGL_FOURCC_UYVY	groups Cb0, Y0, Cr0, Y1	4 * CW * H
SGL_FOURCC_VYUY	groups Cr0, Y0, Cb0, Y1	4 * CW * H
SGL_FOURCC_YUV422_PLANAR	Y plane, then Cb, Cr at half width	P + 2 * CW * H
SGL_FOURCC_YUV420_PLANAR	Y plane, then Cb, Cr at half width/height	P + 2 * CW * CH
SGL_FOURCC_NV12	Y plane, then interleaved Cb, Cr	P + 2 * CW * CH
SGL_FOURCC_NV21	Y plane, then interleaved Cr, Cb	P + 2 * CW * CH

Viewing Raw Output

Use ffplay's rawvideo demuxer with matching dimensions and pixel format. For example:

ffplay -f rawvideo -pixel_format rgba -video_size 1280x720 frame.raw
ffplay -f rawvideo -pixel_format nv12 -video_size 1280x720 frame.raw
ffplay -f rawvideo -pixel_format yuyv422 -video_size 1280x720 frame.raw

ffplay does not expose names for every SGL planar RGB layout. Convert such a file to a viewer-supported packed layout before display.