gsttextoverlay deadlock or something

[Mailing List SVR]

Il 15/10/2017 17:32, Jérôme Laheurte ha scritto:
>
>> Le 15 oct. 2017 à 17:03, Mailing List SVR <lists at svrinformatica.it 
>> <mailto: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>  a écrit :
>>>>
>>>> So two week-ends later I kind of have a working dev environment and started working onhttps://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
>>> * 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.

adding the queue and replacing vtdec with avdec_h264 works for me on 
linux, so the problem seems related to vtdec, I don't have a mac 
available to test with vtdec now,

Nicola
>
> Jérôme Laheurte
>
>
>
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