how to override the subtitleoverlay bin in playbin2

[Mart Raudsepp]

Hello,

On T, 2011-10-04 at 10:38 +0800, bcxa sz wrote:
> Hi Developers,
> 
> I have developed own text overlay element to match my embedded system.
> And also due to some reason (S/W and H/W architecture), I can not
> insert the ffmpegcolorspace (pre-colorspace) after my video decoder
> element.
> 
> And I found that the gstreamer native subtitleoverlay bin is hard
> coded to use gstreamer native text overlay element and insert
> pre-colorspace converter. And playsink bin in playbin2 is also hard
> coded to use gstreamer native subtitleoverlay bin.
> 
> So I WANT TO KNOW whether it is possible to override the gstreamer
> native subtitleoverlay bin in playbin2 with my own developed
> subtitleoverlay bin which can use my own textoverlay element.

You could try setting the playbin2 text-sink property to your custom
subtitling element.

The native-video flag on playbin2 (flags property) can be used to signal
it that the video is assumed to be in the native format, and therefore
no colorspace converter is to be plugged after the video decoder or
elsewhere. This would also prevent the builtin textoverlay to be used,
as it includes colorspace converting elements.


We have some vague plans to redesign subtitle handling to be more
efficient and more fitting, including being more straightforward to
handle for such use cases as yours. The discussions for more concrete
plans are yet to take place as far as I know, but hey, maybe this is a
start :)
So writing down your experiences with all this with your use case and
hardware requirements in mind might be quite useful here.


Best,
Mart Raudsepp