GESEffect seems incompatible with videorate

[Thibault Saunier]

Hello,

Have you tried using `videorate rate=0.0` outside GES? I am not sure it has
been tested at all I have to say.

Also you should modify effects properties through the
`ges_timeline_element_set_child_property` and friends API, `g_object_set`
is not going to work the way you are using it here, and it explains why it
didn't work.

Also, time effects is a complex matter in GES and we are almost ready to
merge its support:
https://gitlab.freedesktop.org/gstreamer/gst-editing-services/-/merge_requests/177!
I have been reviewing the branch and playing with it lately and it is
almost ready to get merged, it will be in for 1.18 in any case, `videorate`
with a `rate` set is going to work well in that branch.

Regards,

- Thibault

On Tue, May 19, 2020 at 8:41 PM David Ing <ding at panopto.com> wrote:

> Using gstreamer 1.16.1
>
> My goal is to create a GESTimeline that contains a video clip which
> freezes on a single frame, or which plays back at a modified rate of speed.
>
> So I make a GESEffect and attached it to my GESClip as follows.
>
>
> GESEffect* gesRateEffect = ges_effect_new("videorate");
>
> gobject::setDouble(reinterpret_cast<GObject*>(gesRateEffect), "max-rate",
> 0.0);
> gobject::setDouble(reinterpret_cast<GObject*>(gesRateEffect), "rate", 0.0
> );
> gobject::setBool(reinterpret_cast<GObject*>(gesRateEffect), "skip-to-first",
> true);
>
> ges_container_add(
>     reinterpret_cast<GESContainer*>(gesUriClip),
>     reinterpret_cast<GESTimelineElement*>(gesRateEffect)
> );
>
> I build out the rest of my timeline and then I call
> `ges_timeline_save_to_uri`, and the clip gets serialized with an effect
> having different values.
>
> <effect asset-id='videorate' clip-id='0' type-name='GESEffect'
> track-type='4' track-id='1' properties='properties, active=(boolean)true,
> track-type=(int)4;' metadatas='metadatas;' children-properties='properties,
> GstVideoRate::average-period=(guint64)0,
> GstVideoRate::drop-only=(boolean)false,
> GstVideoRate::max-duplication-time=(guint64)0, GstVideoRate::
> max-rate=(int)2147483647, GstVideoRate::new-pref=(double)1,
> GstBaseTransform::qos=(boolean)false, GstVideoRate::rate=(double)1,
> GstVideoRate::silent=(boolean)true, GstVideoRate::
> skip-to-first=(boolean)false;'>
> </effect>
>
>
> Even stranger, when I look at the *.dot files in my
> GST_DEBUG_DUMP_DOT_DIR, I don't see any evidence that this effect is being
> applied (not that I know what to look for).
>
> Why is GES modifying my GESEffect?  Can I prevent it from doing this?
>
> Is there a better way to achieve my goal?
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