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Code Issues 1 Projects Releases Wiki Activity

design: subtitle-overlays: add missing markup

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Reynaldo H. Verdejo Pinochet 2016-12-30 00:40:41 -08:00
parent 8cc223c9bc
commit e7ba83d049
1 changed files with 13 additions and 7 deletions
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markdown/design/subtitle-overlays.md
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@ -106,7 +106,7 @@ Multiple possible solutions come to mind:
accommodate all the different cases and formats one would end up
with quite convoluted/tricky API.
(Of course there could also be a GstFancyVideoBuffer that provides
(Of course there could also be a `GstFancyVideoBuffer` that provides
an abstraction for such video accelerated objects and that could
provide an API to add overlays to it in a generic way, but in the
end this is just a less generic variant of (c), and it is not clear
@ -221,7 +221,7 @@ overlay in the middle of the pipeline has other advantages:
We need to pass the overlay pixels from the overlay element to the
sink somehow. Whatever the exact mechanism, let's assume we pass a
refcounted GstVideoOverlayComposition struct or object.
refcounted `GstVideoOverlayComposition` struct or object.
A composition is made up of one or more overlays/rectangles.
@ -234,7 +234,8 @@ overlay in the middle of the pipeline has other advantages:
cases such as e.g. logo overlays or so. It is not designed for
full-fledged video stream mixing
though.
```
// Note: don't mind the exact implementation details, they'll be hidden
// FIXME: might be confusing in 0.11 though since GstXOverlay was
@ -353,6 +354,7 @@ overlay in the middle of the pipeline has other advantages:
} else {
video_buffer_attach_composition (logoverlay->cached_composition);
}
```
FIXME: also add some API to modify render position/dimensions of a
rectangle (probably requires creation of new rectangle, unless we
@ -375,8 +377,9 @@ overlay in the middle of the pipeline has other advantages:
if e.g. a screnshotter gets the last buffer via the last-buffer
property of basesink, it would get an image without the subtitles on
top. This could probably be fixed by re-implementing the property in
GstVideoSink though. Playbin2 could handle this internally as well).
`GstVideoSink` though. Playbin2 could handle this internally as well).
```
void
gst_video_overlay_composition_blend (GstVideoOverlayComposition * comp
GstBuffer * video_buf)
@ -411,6 +414,7 @@ overlay in the middle of the pipeline has other advantages:
gst_buffer_unref (pixels);
}
}
```
3) Flatten all rectangles in a composition
@ -427,8 +431,8 @@ overlay in the middle of the pipeline has other advantages:
4) query support for the new video composition mechanism
This is handled via GstMeta and an ALLOCATION query - we can simply
query whether downstream supports the GstVideoOverlayComposition meta.
This is handled via `GstMeta` and an ALLOCATION query - we can simply
query whether downstream supports the `GstVideoOverlayComposition` meta.
There appears to be no issue with downstream possibly not being
linked yet at the time when an overlay would want to do such a
@ -518,6 +522,7 @@ our new API for non-raw video.
TEST: should these look (roughly) alike (note text distortion) - needs
fixing in textoverlay
```
gst-launch-1.0 \
videotestsrc ! video/x-raw,width=640,height=480,pixel-aspect-ratio=1/1 \
! textoverlay text=Hello font-desc=72 ! xvimagesink \
@ -525,3 +530,4 @@ fixing in textoverlay
! textoverlay text=Hello font-desc=72 ! xvimagesink \
videotestsrc ! video/x-raw,width=640,height=240,pixel-aspect-ratio=1/2 \
! textoverlay text=Hello font-desc=72 ! xvimagesink
```