[libcamera-devel] [PATCH] gstreamer: Implement EOS handling
nicolas at ndufresne.ca
nicolas at ndufresne.ca
Thu Nov 9 16:23:12 CET 2023
Le jeudi 09 novembre 2023 à 13:40 +0000, Kieran Bingham via libcamera-
devel a écrit :
> Quoting Jaslo Ziska via libcamera-devel (2023-11-09 12:51:15)
> > Hi,
> >
> > Umang Jain <umang.jain at ideasonboard.com> writes:
> > > Hi Jalso
> > >
> > > On 11/6/23 10:22 PM, Jaslo Ziska via libcamera-devel wrote:
> > > > ---
> > > > Hi,
> > > >
> > > > I recently implemented basic EOS handling for the libcamerasrc
> > > > gstreamer element.
> > >
> > > Ah thanks, I remember we do track a bug report here:
> > > https://bugs.libcamera.org/show_bug.cgi?id=91
> >
> > Ah yes, I remember that I stumbled upon this when I was first
> > investigating this, I will update the bug report.
> >
> > > >
> > > > I basically looked at how GstBaseSrc does it and tried to do it
> > > > similarly.
> > > >
> > > > I have no idea whether the locking is correct or if this is
> > > > thread safe but so far it worked without any issues for my
> > > > purposes.
> > > >
> > > > You can also now run the following command and receive a
> > > > working video file:
> > > >
> > > > gst-launch-1.0 -e libcamerasrc ! videoconvert ! x264enc !
> > > > h264parse ! mp4mux ! filesink location=test.mp4
> > >
> > > Good to see that the diff is tested :-D
> >
> > Speaking of testing, I just ran the test suite and, except for the
> > multi_stream_test (which was skipped) the other tests succeeded.
> >
> > > >
> > > > Looking forward for feedback!
> > >
> > > It looks logical and on the right track to me atleast. But there
> > > might be other implications regarding the threading and
> > > locking mechanisms.
> >
> > Thanks! That is what I worry about too, maybe someone can review
> > this.
> >
> > > > Cheers,
> > > >
> > > > Jaslo
> > > >
> > > > src/gstreamer/gstlibcamerasrc.cpp | 47
> > > > +++++++++++++++++++++++++++++++
> > > > 1 file changed, 47 insertions(+)
> > > >
> > > > diff --git a/src/gstreamer/gstlibcamerasrc.cpp
> > > > b/src/gstreamer/gstlibcamerasrc.cpp
> > > > index 63d99571..a4681e1e 100644
> > > > --- a/src/gstreamer/gstlibcamerasrc.cpp
> > > > +++ b/src/gstreamer/gstlibcamerasrc.cpp
> > > > @@ -144,6 +144,9 @@ struct _GstLibcameraSrc {
> > > > gchar *camera_name;
> > > > controls::AfModeEnum auto_focus_mode =
> > > > controls::AfModeManual;
> > > >
> > > > + GstEvent *pending_eos;
> > > > + int has_pending_eos;
> > > > +
> > > > GstLibcameraSrcState *state;
> > > > GstLibcameraAllocator *allocator;
> > > > GstFlowCombiner *flow_combiner;
> > > > @@ -397,6 +400,21 @@ gst_libcamera_src_task_run(gpointer
> > > > user_data)
> > > >
> > > > bool doResume = false;
> > > >
> > > > + if (g_atomic_int_get(&self->has_pending_eos)) {
> > > > + g_atomic_int_set(&self->has_pending_eos, FALSE);
> > > > +
> > > > + GST_OBJECT_LOCK(self);
> > > > + GstEvent *event = self->pending_eos;
> > > > + self->pending_eos = NULL;
> > > > + GST_OBJECT_UNLOCK(self);
> > > > +
> > > > + for (GstPad *srcpad : state->srcpads_)
> > > > + gst_pad_push_event(srcpad, gst_event_ref(event));
> > > > + gst_event_unref(event);
> > > > +
> > > > + return;
> > > > + }
> > > > +
> > > > /*
> > > > * Create and queue one request. If no buffers are
> > > > available the
> > > > * function returns -ENOBUFS, which we ignore here as
> > > > that's not a
> > > > @@ -747,6 +765,32 @@ gst_libcamera_src_change_state(GstElement
> > > > *element, GstStateChange transition)
> > > > return ret;
> > > > }
> > > >
> > > > +static gboolean
> > > > +gst_libcamera_src_send_event(GstElement *element, GstEvent
> > > > *event)
> > > > +{
> > > > + GstLibcameraSrc *self = GST_LIBCAMERA_SRC(element);
> > > > + gboolean ret = FALSE;
> > > > +
> > > > + switch (GST_EVENT_TYPE(event)) {
> > > > + case GST_EVENT_EOS: {
> > > > + GST_OBJECT_LOCK(self);
> > > > + g_atomic_int_set(&self->has_pending_eos, TRUE);
> > > > + if (self->pending_eos)
> > > > + gst_event_unref(self->pending_eos);
> > > > + self->pending_eos = event;
> > > > + GST_OBJECT_UNLOCK(self);
> > > > +
> > > > + ret = TRUE;
> > > > + break;
> > > > + }
> > > > + default:
> > > > + gst_event_unref(event);
> > > > + break;
> > > > + }
> > > > +
> > > > + return ret;
> > > > +}
> > > > +
> > > > static void
> > > > gst_libcamera_src_finalize(GObject *object)
> > > > {
> > > > @@ -779,6 +823,8 @@ gst_libcamera_src_init(GstLibcameraSrc
> > > > *self)
> > > > state->srcpads_.push_back(gst_pad_new_from_template(templ,
> > > > "src"));
> > > > gst_element_add_pad(GST_ELEMENT(self),
> > > > state->srcpads_.back());
> > > >
> > > > + GST_OBJECT_FLAG_SET(self, GST_ELEMENT_FLAG_SOURCE);
> > > > +
> > >
> > > I always thought libcamerasrc was inheriting from GstBaseSrc,
> > > but in fact it's not.
> > > So, setting the GST_ELEMENT_FLAG_SOURCE makes sense here.
> >
> > This flag is actually required to receive the eos signal when it
> > is send to the pipeline bin and not the element directly. Took me
> > a while to figure out.
> >
> > > Apart from a missing commit mesasge, the patch looks good to me.
> > > I'll put this on my radar soon for testing it
> > > rigorously.
> >
> > Oh yeah, a commit message would indeed be nice, completely forgot
> > that, thanks :)
>
> Can you also add/clarify /how/ the EOS event is being sent in the commit
> message please?
>
> Is this issue occuring when you run the pipeline and press ctrl-c for
> instance? or is there some other detail?
This patch covers cases where the application decides to stop the
pipeline by sending it an EOS. To CTRL+C combined with -e option of
gst-launch-1.0 is a good example.
This patch does not cover (and this can be done later/seperatly):
libcamerasrc ! identity eos-after=10 ! fakesink
Which is the case when downstream decides to stop. This case is a
little more complex for multi-pad elements and is actually nice to
tackle separately (its also more niche).
Nicolas
>
> --
> Kieran
>
>
> >
> > > > /* C-style friend. */
> > > > state->src_ = self;
> > > > self->state = state;
> > > > @@ -844,6 +890,7 @@
> > > > gst_libcamera_src_class_init(GstLibcameraSrcClass *klass)
> > > > element_class->request_new_pad =
> > > > gst_libcamera_src_request_new_pad;
> > > > element_class->release_pad =
> > > > gst_libcamera_src_release_pad;
> > > > element_class->change_state =
> > > > gst_libcamera_src_change_state;
> > > > + element_class->send_event = gst_libcamera_src_send_event;
> > > >
> > > > gst_element_class_set_metadata(element_class,
> > > > "libcamera Source", "Source/Video",
> > > > --
> > > > 2.42.1
> >
> > Regards,
> >
> > Jaslo
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