diff --git a/markdown/design/interlaced-video.md b/markdown/design/interlaced-video.md
index 578e5ca558..bc0886d72f 100644
--- a/markdown/design/interlaced-video.md
+++ b/markdown/design/interlaced-video.md
@@ -100,3 +100,24 @@ For example in the following sequence, the third buffer would be mixed
 (yes, it is a strange pattern, but it can happen):
 
     AtAb AtBb BtCb CtDb DtDb
+
+### Alternate fields
+
+Since: 1.16
+
+If the video info interlace mode is **"alternate"**, then each buffer
+carries a single field of interlaced video.
+
+`GST_VIDEO_BUFFER_FLAG_TOP_FIELD` and `GST_VIDEO_BUFFER_FLAG_BOTTOM_FIELD`
+indicate whether the buffer carries a top or bottom field. The order of
+buffers/fields in the stream and the timestamps on the buffers indicate the
+temporal order of the fields.
+
+Top and bottom fields are expected to alternate in this mode.
+
+Caps for this interlace mode must also carry a `format:Interlaced` caps feature
+(`GST_CAPS_FEATURE_FORMAT_INTERLACED`) to ensure backwards compatibility for
+the new mode.
+
+The frame rate in the caps still signals the frame rate, so the notional field
+rate will be twice the frame rate from the caps (see `GST_VIDEO_INFO_FIELD_RATE_N`).
diff --git a/markdown/design/mediatype-video-raw.md b/markdown/design/mediatype-video-raw.md
index 59d6bf4829..8c59bde2e8 100644
--- a/markdown/design/mediatype-video-raw.md
+++ b/markdown/design/mediatype-video-raw.md
@@ -18,7 +18,8 @@
    view. use the frame id to get access to the different views.
 
  - **interlace-mode**, `G_TYPE_STRING`: Default progressive. The interlace
-   mode. The following values are possible:
+   mode (also see the [interlaced video design docs](design/interlaced-video.md)).
+   The following values are possible:
 
    - *"progressive"*: all frames are progressive
 
@@ -37,6 +38,13 @@
      must be prepared for this. This mode requires multiple
      GstVideoMeta metadata to describe the fields.
 
+   - *"alternate"*: one field per buffer, with buffer flags indicating
+     whether the field is the top field (`GST_VIDEO_BUFFER_FLAG_TOP_FIELD`) or
+     bottom field (`GST_VIDEO_BUFFER_FLAG_BOTTOM_FIELD`). Top and bottom fields
+     are expected to alternate in this mode. Caps for this interlace mode must
+     also carry a `format:Interlaced` caps feature (`GST_CAPS_FEATURE_FORMAT_INTERLACED`)
+     to ensure backwards compatibility for the new mode (Since: 1.16)
+
  - **chroma-site**, `G_TYPE_STRING`: Default `GST_VIDEO_CHROMA_SITE_UNKNOWN`.
    The chroma siting of the video frames.