[libcamera-devel] [PATCH v1 13/23] gst: libcamerasrc: Send stream start event

[Kieran Bingham]

Hi Nicolas,

On 29/01/2020 03:32, Nicolas Dufresne wrote:
> From: Nicolas Dufresne <nicolas.dufresne at collabora.com>
> 
> Prior to sending caps, we need to send a stream-start event. This requires
> generating a stream and a group id. The stream id is random for live sources and
> the group id is shared across all pads.

Interestingly, I can compile against gstreamer1.0 1.14 up until this
patch, but then I hit another dependency.

The target I'm building on has glib-2.0 version 2.59, and
GRecMutexLocker was introduced in 2.60 :S


Perhaps this patch might also need to add something like the (untested)
following:

diff --git a/src/gstreamer/meson.build b/src/gstreamer/meson.build
index 9d273437..58cf0009 100644
--- a/src/gstreamer/meson.build
+++ b/src/gstreamer/meson.build
@@ -11,6 +11,9 @@ libcamera_gst_c_args = [
     '-DPACKAGE="@0@"'.format(meson.project_name()),
 ]

+glib_dep = dependency('glib-2.0', version : '>=2.60',
+    required : get_option('gstreamer'))
+
 gst_dep = dependency('gstreamer-video-1.0', version : '>=1.14',
     required : get_option('gstreamer'))


> Signed-off-by: Nicolas Dufresne <nicolas.dufresne at collabora.com>
> ---
>  src/gstreamer/gstlibcamerasrc.cpp | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> diff --git a/src/gstreamer/gstlibcamerasrc.cpp b/src/gstreamer/gstlibcamerasrc.cpp
> index be32a11..b1a21dc 100644
> --- a/src/gstreamer/gstlibcamerasrc.cpp
> +++ b/src/gstreamer/gstlibcamerasrc.cpp
> @@ -18,6 +18,8 @@ using namespace libcamera;
>  GST_DEBUG_CATEGORY_STATIC(source_debug);
>  #define GST_CAT_DEFAULT source_debug
>  
> +#define STREAM_LOCKER(obj) g_autoptr(GRecMutexLocker) stream_locker = g_rec_mutex_locker_new(&GST_LIBCAMERA_SRC(obj)->stream_lock)
> +
>  /* Used for C++ object with destructors */
>  struct GstLibcameraSrcState {
>  	std::shared_ptr<CameraManager> cm;
> @@ -127,9 +129,20 @@ gst_libcamera_src_task_run(gpointer user_data)
>  static void
>  gst_libcamera_src_task_enter(GstTask *task, GThread *thread, gpointer user_data)
>  {
> +	STREAM_LOCKER(user_data);
>  	GstLibcameraSrc *self = GST_LIBCAMERA_SRC(user_data);
> +	GstLibcameraSrcState *state = self->state;
>  
>  	GST_DEBUG_OBJECT(self, "Streaming thread has started");
> +
> +	guint group_id = gst_util_group_id_next();
> +	for (GstPad *srcpad : state->srcpads) {
> +		/* Create stream-id and push stream-start */
> +		g_autofree gchar *stream_id = gst_pad_create_stream_id(srcpad, GST_ELEMENT(self), nullptr);
> +		GstEvent *event = gst_event_new_stream_start(stream_id);
> +		gst_event_set_group_id(event, group_id);
> +		gst_pad_push_event(srcpad, event);
> +	}
>  }
>  
>  static void
> 

-- 
Regards
--
Kieran