Wayland-drm pixel formats
This page describes the formats used by the private
implemented by Mesa. This extension has been superseded by the linux-dmabuf
extension, which provides a generic buffer-exchange protocol using the DRM
pixel format descriptors.
The wayland-drm pixel formats follow the scheme:
component-format part specifies the order and sizes of the components.
All the components are listed first, optionally followed by their corresponding sizes
in bits (e.g.,
The wayland-drm formats are a subset of the drm fourcc formats.
There are a few categories of wayland-drm formats:
rgba-component-formatspecifies the order and sizes of the components in a native type on a little-endian system, with the leftmost component stored in the most significant bits, and the rightmost in the least significant bits.
Although the formats are expressed in terms of a native type, the addition of little-endianness specification makes the format endianness-independent.
For formats where components occupy whole bytes, an alternative, and probably more straightforward way to express the expected order, is that the
component-listspecifies the order of the components in memory with the leftmost component at the highest address and the rightmost at the lowest addres.
Always stored as B, G, R, A in memory (B at lowest address, A at highest)
Always stored in memory as:
0 1 M L M L G₂G₁G₀B₄B₃B₂B₁B₀ R₄R₃R₂R₁R₀G₅G₄G₃
yuva-component-formatspecifies the order of the components in a 32-bit native type on a little-endian system, with the leftmost component stored in the least significant bits, and the rightmost in the most significant bits. In this format category each components is always 8 bits long.
An alternative, and probably more straightforward way to interpret the
yuva-component-format, is that it specifies the order of the components in memory with the leftmost component at the lowest address and the rightmost at the highest.
Always stored as Y₀, U, Y₁, V in memory (Y₀ at lowest address, V at the highest)
We won’t describe these in detail in this guide.