Still capture implementation in source plugin

[caoxi]

I wonder if Gstreamer plugin can do still capture while doing preview at the same time? Or even like smart phones to do preview, video recording and snapshot at the same time?

[Nicolas Dufresne-5]

Le 16 avr. 2017 10:52 PM, "caoxi" <[hidden email]> a écrit :

I wonder if Gstreamer plugin can do still capture while doing preview at the
same time? Or even like smart phones to do preview, video recording and
snapshot at the same time?

I have written an experiment with that, and it worked. I added a streaming mode property to the pad, in still mode, you have to call a snapshot action signal to get a frame. That also make per frame settings really easy. We also added burst with start-burt and stop-burst action signal.

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[caoxi]

Thanks, can you help to explain how to trigger the action you mentioned to do snapshot? by calling Gstreamer APIs

[Yi-Lung Tsai]

I have done similar feature before.

My method is to get “last-sample” from videosink and then create another pipeline to save that sample to image file.

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Yi-Lung (Bruce) Tsai

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On Apr 18, 2017, at 10:36 AM, caoxi <[hidden email]> wrote:

Thanks, can you help to explain how to trigger the action you mentioned to do
snapshot? by calling Gstreamer APIs



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[caoxi]

Hi, do you have any examples? I haven't used last-sample before, thanks!

[Nicolas Dufresne-5]

Le lundi 17 avril 2017 à 19:36 -0700, caoxi a écrit :
> Thanks, can you help to explain how to trigger the action you
> mentioned to do
> snapshot? by calling Gstreamer APIs

The action signal works like GObject signal, but instead of the object
emiting to the outisde, it's outside that emits the signal to the
object. You can find multiple examples of that kind of signal in
GStreamer code base, here's just one:

https://cgit.freedesktop.org/gstreamer/gst-plugins-bad/tree/gst-libs/gs
t/insertbin/gstinsertbin.c#n145

Calling an API could look like:

  g_signal_emit_by_name (G_OBJECT (self), "trigger-capture", NULL);

regards,
Nicolas
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[Yi-Lung Tsai]

I use “last-sample” as follows:

GstSample *last = NULL;

g_object_get(my_sink, “last-sample”, &last, NULL);

Then push last sample to “appsrc” with following pipeline.

appsrc ! videoconvert ! capsfilter ! jpegenc ! filesink 

You could emit a signal to push sample to “appsrc” as follows:

GstFlowReturn ret;

g_signal_emit_by_name(appsrc, “push-sample”, last, &ret);

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On Apr 25, 2017, at 10:10 AM, caoxi <[hidden email]> wrote:

Hi, do you have any examples? I haven't used last-sample before, thanks!



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