gsttextoverlay deadlock or something

[Jérôme Laheurte]

> Le 15 oct. 2017 à 17:03, Mailing List SVR <lists at svrinformatica.it> a écrit :
> 
> Il 15/10/2017 14:50, Jérôme Laheurte ha scritto:
>>> Le 15 oct. 2017 à 14:45, Jérôme Laheurte <jerome at jeromelaheurte.net> <mailto:jerome at jeromelaheurte.net> a écrit :
>>> 
>>> So two week-ends later I kind of have a working dev environment and started working on https://bugzilla.gnome.org/show_bug.cgi?id=540131 <https://bugzilla.gnome.org/show_bug.cgi?id=540131>. Unfortunately in the process I noticed that the use case (subtitle buffer arriving while another one hasn’t expired) now result in a kind of deadlock, and I’m not familiar enough with gstreamer to fully understand what is happening here. Some observations:
>>> 
>>> 1. The text_chain method is blocked waiting for the previous buffer to get popped (at gstbasetextoverlay.c:2713)
>>> 2. But the video_chain method doesn’t get called any more. Since it’s the one popping old text buffers, everything stops.
>>> 3. There is nothing of interest in the debug output
>>> 
>>> This didn’t happen last time I tested a video with multiple concurrent subtitles, but that was a long time ago. It kind of looks like the text_chain and video_chain functions are now called by the same thread. Does anybody have any light to share on this ?
>> More information, sorry:
>> 
>> * Video file: https://jeromelaheurte.net/owncloud/s/21E1m14sFOxfAmy <https://jeromelaheurte.net/owncloud/s/21E1m14sFOxfAmy>
>> * Pipeline: gst-launch-1.0 -v filesrc location=sub.mkv ! matroskademux name=demux ! queue ! vtdec ! subtitleoverlay name=overlay ! autovideosink demux. ! ssaparse ! overlay.
> 
> try to add a queue before ssaparse,

Nope, still deadlocking. Same place. If I’m not mistaken the queue ensures that the text_chain function is called in the queue’s thread, am I wrong ? So the problem is not as simple as I supposed.

Jérôme Laheurte

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