GStreamer multi pipeline time sync

Wed Dec 2 00:05:05 UTC 2020

Le mar. 1 déc. 2020 16 h 45, Peter Biro <pettair at gmail.com> a écrit :

> Thanks! That can work!
>
>  Is there a way how I can 'send silence' from an audio source (or anything
> in the middle)?
>

audiotestsrc wave=silence ! ...
... ! volume volume=0.0 ! ...


> Currently this is my audio pipeline:
> alsasrc ! queue ! audioconvert ! appsink name=app_sink
>
> Also  I tried to play around with the 'max-size-time' property on a queue,
> but I cut that solution since I had issues with disabling only the filesink
> output. The way I tried it is to redirect the filesink output to the
> /dev/null and reconfigure it to a proper place when a recording event
> arrives but for that I had to set the file sink state to GST_STATE_NULL (or
> GST_STATE_READY it was a while ago) which caused issues with the other
> parts of he pipeline. But it would be great if this part could also be
> covered by plain pipeline on the gst side.
>
> On 2020. Dec 1., at 11:38, Thornton, Keith <keith.thornton at zeiss.com>
> wrote:
>
> Hi,
> the buffering can be done with a standard gstreamer queue by dynamically
> manipulating the threshold and queue size parameters. Have you considered
> the possibility of recording silence when no audio is present.
> Gruesse
>
> *Von:* gstreamer-devel <gstreamer-devel-bounces at lists.freedesktop.org> *Im
> Auftrag von *Peter Biro
> *Gesendet:* Dienstag, 1. Dezember 2020 10:21
> *An:* Discussion of the development of and with GStreamer <
> gstreamer-devel at lists.freedesktop.org>
> *Betreff:* Re: GStreamer multi pipeline time sync
>
> Sure, I can describe it more in detail.
>
> You are right about that the streaming / displaying is mandatory and the
> recording is optional (it can be triggered).
>
> Unfortunately the actual use case is a bit more complex: when the user
> hits record the recording also should include the video(and maybe audio
> too) for the previous 30 seconds(actual time is also configurable) as well.
> So there should be a live stream and this 'buffered' recording. Also I
> cannot 'pre-mux' the audio with the video since audio is
> completely optional and it could be configured to be recorded only when the
> recording is started (so there would be video for like 30 seconds from the
> buffer and then audio would join in later). The hard requirement is this
> (to have X seconds of video before the user hits the record and optional
> audio attached to it) but I wanted to implement it in a general way so the
> other part of the application should not be aware if the 'buffered' data is
> audio or video.
>
> This is why I started with separate pipelines and transferring the data
> between them with appsinks and appsrcs, and do the buffering and other
> logic on the application side, I guess this is a naive way of implementing
> it so if there is any suggestion it is more than welcomed :D
>
> Thanks!
>
>
> On 2020. Dec 1., at 5:06, gotsring <gotsring at live.com> wrote:
>
> Can you describe what you are trying to achieve? It sounds like you want to
> grab video and audio (e.g. webcam and mic), combine/mux those streams, then
> be able to view the stream it and optionally record it. Something like:
>
> View/Record pipeline (gst-launch-1.0)
> videotestsrc ! timeoverlay ! tee name=videotee ! queue ! autovideosink \
> audiotestsrc wave=8 ! tee name=audiotee ! queue ! autoaudiosink \
> videotee. ! queue ! x264enc ! matroskamux name=muxer ! filesink
> location=save_location.mkv async=false \
> audiotee. ! queue ! muxer.
>
>
> Playback (just to test)
> gst-play-1.0 save_location.mkv
>
> This should probably not be used exactly, but that's the gist. You can just
> google how to mux streams using GStreamer. I also think that queue has a
> property that allows you to effectively add a delay to a stream
> (min-threshold-time), is this what you wanted?
>
>
>
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