[libcamera-devel] [PATCH v2] gstreamer: Store group_id in GstLibcameraSrcState

[Nicolas Dufresne]

Le dimanche 18 juillet 2021 à 00:32 +0530, Vedant Paranjape a écrit :
> This patch adds group_id in GstLibcameraSrcState, since group_id is
> something which should be same for all the pads, it can be reused
> later.
> 
> Signed-off-by: Vedant Paranjape <vedantparanjape160201 at gmail.com>
> ---
>  src/gstreamer/gstlibcamerasrc.cpp | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/src/gstreamer/gstlibcamerasrc.cpp b/src/gstreamer/gstlibcamerasrc.cpp
> index ea53c2b5..79b0d867 100644
> --- a/src/gstreamer/gstlibcamerasrc.cpp
> +++ b/src/gstreamer/gstlibcamerasrc.cpp
> @@ -113,6 +113,7 @@ struct GstLibcameraSrcState {
>  	std::unique_ptr<CameraConfiguration> config_;
>  	std::vector<GstPad *> srcpads_;
>  	std::queue<std::unique_ptr<RequestWrap>> requests_;
> +	guint group_id_;
>  
>  	void requestCompleted(Request *request);
>  };
> @@ -360,15 +361,17 @@ gst_libcamera_src_task_enter(GstTask *task, [[maybe_unused]] GThread *thread,
>  
>  	GST_DEBUG_OBJECT(self, "Streaming thread has started");
>  
> -	guint group_id = gst_util_group_id_next();
> +	if (state->group_id_ == 0) {
> +		state->group_id_ = gst_util_group_id_next();
> +	}

As you never reset this group ID, why don't you pick an ID directly in the
constructor ? (libcamera_src_init() function). Or perhaps we need to read again
the semantic of that group ID, and then grab a new one everything we cycle
through READ state ?

>  	gint stream_id_num = 0;
>  	StreamRoles roles;
>  	for (GstPad *srcpad : state->srcpads_) {
>  		/* Create stream-id and push stream-start. */
> -		g_autofree gchar *stream_id_intermediate = g_strdup_printf("%i%i", group_id, stream_id_num++);
> +		g_autofree gchar *stream_id_intermediate = g_strdup_printf("%i%i", state->group_id_, stream_id_num++);
>  		g_autofree gchar *stream_id = gst_pad_create_stream_id(srcpad, GST_ELEMENT(self), stream_id_intermediate);
>  		GstEvent *event = gst_event_new_stream_start(stream_id);
> -		gst_event_set_group_id(event, group_id);
> +		gst_event_set_group_id(event, state->group_id_);
>  		gst_pad_push_event(srcpad, event);
>  
>  		/* Collect the streams roles for the next iteration. */
> @@ -636,6 +639,7 @@ 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_[0]);
> +	state->group_id_ = 0;

nit: Optional, GObject are initialized to 0.

>  
>  	/* C-style friend. */
>  	state->src_ = self;