docs: interlaced video: small additions for alternate interlacing

Clarify that width/height in caps is still the frame height/width,
not field height width, just like framerate is frame rate not
field rate.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/1465>
This commit is contained in:
Tim-Philipp Müller 2021-12-23 01:52:04 +00:00
parent 85d2118a53
commit 2452f0bbcf
2 changed files with 9 additions and 2 deletions

View file

@ -119,5 +119,9 @@ Caps for this interlace mode must also carry a `format:Interlaced` caps feature
(`GST_CAPS_FEATURE_FORMAT_INTERLACED`) to ensure backwards compatibility for (`GST_CAPS_FEATURE_FORMAT_INTERLACED`) to ensure backwards compatibility for
the new mode. the new mode.
The frame rate in the caps still signals the frame rate, so the notional field 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`). rate will be twice the frame rate from the caps (see `GST_VIDEO_INFO_FIELD_RATE_N`).
In the same vein the width and height in the caps will indicate *frame*
dimensions not field dimensions, meaning the height of the video data inside
the buffers (1 field) will be half of the height in the caps.

View file

@ -43,7 +43,10 @@
bottom field (`GST_VIDEO_BUFFER_FLAG_BOTTOM_FIELD`). Top and bottom fields 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 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`) also carry a `format:Interlaced` caps feature (`GST_CAPS_FEATURE_FORMAT_INTERLACED`)
to ensure backwards compatibility for the new mode (Since: 1.16) to ensure backwards compatibility for the new mode. `width` and `height`
fields in caps indicate **frame** dimensions not field dimensions, meaning
the height of the video data inside the buffers will be half of the height
in the caps. (Since: 1.16)
- **chroma-site**, `G_TYPE_STRING`: Default `GST_VIDEO_CHROMA_SITE_UNKNOWN`. - **chroma-site**, `G_TYPE_STRING`: Default `GST_VIDEO_CHROMA_SITE_UNKNOWN`.
The chroma siting of the video frames. The chroma siting of the video frames.