textoverlay and overlapping subtitles

[Jérôme Laheurte]

It looks like textoverlay can only display one text buffer « at a time »; when several subtitle strings should be displayed it just keeps displaying the first it received, until it’s no longer valid (gstbasetextoverlay.c:2575). I have several videos in which people are talking while a sign is displayed and I often miss half the dialogue because of this. Is there an existing fix/workaround? If not I can try my hand at this. I can see two ways of doing it:

1. Change textoverlay to hold a liked list of currently valid text buffers instead of just the latest one, and compose them before rendering.
2. Create a new « subtitlecompose » element that receives text buffers, does the composition, and outputs text buffers containing all currently valid strings.

The obvious advantage of 2 is that it will work with any combination of text overlay / source elements. May be a bit tricky to use in a playbin though; I guess I could use the text-sink property for that. The problem is that is will rely on textoverlay doing the opposite of what it’s doing right now and discard the existing buffer as soon as it receives a new one. Thoughts?

Best regards
Jérome Laheurte

-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 842 bytes
Desc: Message signed with OpenPGP using GPGMail
URL: <https://lists.freedesktop.org/archives/gstreamer-devel/attachments/20161127/d4e53d7b/attachment.sig>