Dynamic pipeline: record frames before mux/filesink is linked

[Marianna Smidth Buschle]

Hi

You can try installing a buffer probe on the queue and checking the 
levels to figure out what is going on.
And listening to the overrun signal.

You might also try taking a look at the `min-threshold-` properties.

Best regards

Marianna

On 22.01.2023 13.00, gstreamer-devel-request at lists.freedesktop.org wrote:
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>     1. Dynamic pipeline: record frames before mux/filesink is linked
>        (Sylvain Garrigues)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Sat, 21 Jan 2023 19:16:16 +0100
> From: Sylvain Garrigues<sylgar at gmail.com>
> To:gstreamer-devel at lists.freedesktop.org
> Subject: Dynamic pipeline: record frames before mux/filesink is linked
> 	
> Message-ID:<3196DBB7-8007-4825-BD43-AA70AF1213FD at gmail.com>
> Content-Type: text/plain;	charset=utf-8
>
> Hello,
>
> I?m trying to setup a pipeline which can record parts of the currently displayed stream on demand (I have a ctrl-c handler installed which start/stop the recording), INCLUDING 5 seconds before the signal is emitted. It works perfectly except the recording doesn?t start 5 seconds before the signal but 2/3 seconds after.
>
> I have this pipeline:
> filesrc location="longvideo.mp4" -> qtdemux -> tee -> queue -> h264parse -> ? -> autovideosink
> On the other branch of the tee i.e. the recording one I have: tee -> queue (named queue_recording)
>
> I have set the recording queue to act like a 10 seconds ring buffer:
> queue_recording.set_property_from_str("max-size-time", "10000000000");
> queue_recording.set_property_from_str("max-size-buffers", "0");
> queue_recording.set_property_from_str("max-size-bytes", "0");
> queue_recording.set_property_from_str("leaky", "2");
>
> (This is Rust code).
>
> I have the pipeline playing and start watching the video.
>
> When I hit ctrl-C and my program detects it, it add matroskamux -> filesink location="record.mkv" to the pipeline and link the video_0 sink pad of the matroskamux to queue_recording which was already there.
>
> Since I hit ctrl-c more than 10 seconds after the video is playing, I expected the resulting record.mpv to display frames from 10 seconds before the crtl-c signal since the queue_recording has stored those frame on the sink side and there was no consumer on the src side before the matrosmamux was linked.
>
>
> Can anybody explain me why I don?t get what I expect (the recording starting 10 seconds before the signal), and how you would solve my problem?
>
>
> I already manage, when hitting ctrl-c another time to stop the recording, to block the src_1 pad of the tee win a probe and send an EOS to the queue and unlink it, and when the pipeline bus gets the eos message from filesink (via message forward), I can remove the queue / matroskamux / filesink pair - just waiting for another signal to start another recording. I can share the source code if needed.
>
> Best
>
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> End of gstreamer-devel Digest, Vol 144, Issue 28
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-- 
Best regards / Med venlig hilsen
“Marianna Smidth Buschle”
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