[RFC PATCH v2 1/2] media: docs-rst: Append HEVC specific term

[Sebastian Fricke]

Describe the coding tree unit as replacement for the macroblock in the
HEVC codec. Highlight a key difference of the HEVC codec to predecessors
like AVC(H.264) to give a better overview of the differences between the
coding standards.

Signed-off-by: Sebastian Fricke <sebastian.fricke at collabora.com>
---
 Documentation/userspace-api/media/v4l/dev-decoder.rst | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/Documentation/userspace-api/media/v4l/dev-decoder.rst b/Documentation/userspace-api/media/v4l/dev-decoder.rst
index 3cf2b496f2d0..eb5b1b1e3a51 100644
--- a/Documentation/userspace-api/media/v4l/dev-decoder.rst
+++ b/Documentation/userspace-api/media/v4l/dev-decoder.rst
@@ -72,6 +72,11 @@ coded resolution
 coded width
    width for given coded resolution.
 
+coding tree unit
+   processing unit of the HEVC codec (≘ macroblock units in H.264, VP8, VP9);
+   can use block structures of up to 64×64 pixels;
+   Good at sub-partitioning the picture into variable sized structures.
+
 decode order
    the order in which frames are decoded; may differ from display order if the
    coded format includes a feature of frame reordering; for decoders,
@@ -104,7 +109,8 @@ keyframe
 macroblock
    a processing unit in image and video compression formats based on linear
    block transforms (e.g. H.264, VP8, VP9); codec-specific, but for most of
-   popular codecs the size is 16x16 samples (pixels).
+   popular codecs the size is 16x16 samples (pixels). The HEVC codec uses a
+   slightly more flexible processing unit called coding tree unit (CTU).
 
 OUTPUT
    the source buffer queue; for decoders, the queue of buffers containing
-- 
2.25.1