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-rw-r--r--Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst18
1 files changed, 18 insertions, 0 deletions
diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst b/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
index 188aef8e40d0..6af3774fbb75 100644
--- a/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
+++ b/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
@@ -3427,3 +3427,21 @@ enum v4l2_mpeg_video_hevc_size_of_length_field -
so this has to come from client.
This is applicable to H264 and valid Range is from 0 to 63.
Source Rec. ITU-T H.264 (06/2019); G.7.4.1.1, G.8.8.1.
+
+``V4L2_CID_MPEG_VIDEO_LTR_COUNT (integer)``
+ Specifies the maximum number of Long Term Reference (LTR) frames at any
+ given time that the encoder can keep.
+ This is applicable to the H264 and HEVC encoders.
+
+``V4L2_CID_MPEG_VIDEO_FRAME_LTR_INDEX (integer)``
+ After setting this control the frame that will be queued next
+ will be marked as a Long Term Reference (LTR) frame
+ and given this LTR index which ranges from 0 to LTR_COUNT-1.
+ This is applicable to the H264 and HEVC encoders.
+ Source Rec. ITU-T H.264 (06/2019); Table 7.9
+
+``V4L2_CID_MPEG_VIDEO_USE_LTR_FRAMES (bitmask)``
+ Specifies the Long Term Reference (LTR) frame(s) to be used for
+ encoding the next frame queued after setting this control.
+ This provides a bitmask which consists of bits [0, LTR_COUNT-1].
+ This is applicable to the H264 and HEVC encoders.