[libcamera-devel] [RFC PATCH v5] gstreamer: Added virtual functions needed to support request pads
Nicolas Dufresne
nicolas at ndufresne.ca
Fri Jun 18 19:40:15 CEST 2021
Le samedi 12 juin 2021 à 13:52 +0530, Vedant Paranjape a écrit :
> Using request pads needs virtual functions to create new request pads and
> release the allocated pads. Added way to generate unique stream_id in
> gst_libcamera_src_task_enter(). It failed to execute when more than one
> pad was added.
>
> This patch defines the functions gst_libcamera_src_request_new_pad() and
> gst_libcamera_src_release_pad() which handle, creating and releasing
> request pads. Also assigns these functions to their callback
> handlers in GstLibcameraSrcClass.
>
> gst_pad_create_stream_id() failed as this gstreamer element has more than 2
> source pads, and a nullptr was passed to it's stream_id argument.
> This function fails to auto generate a stream id for scenario of more
> than one source pad present.
>
> Used a gint which increments everytime new stream_id is requested and
> group_id to generate an unique stream_id by appending them togther as
> %i%i.
>
> This doesn't enable request pad support in gstreamer element. This is
> one of the series of changes needed to make it work.
I would suggest to rework the commit message, and focus on what feature this
adds and how to use it.
>
> Signed-off-by: Vedant Paranjape <vedantparanjape160201 at gmail.com>
The code looks fine, I'll let you send the final one before adding by R-b. Note
that when importing this patch:
.git/rebase-apply/patch:58: trailing whitespace.
return NULL;
.git/rebase-apply/patch:60: trailing whitespace.
.git/rebase-apply/patch:68: trailing whitespace.
.git/rebase-apply/patch:85: trailing whitespace.
}
And also, running checkstyle.py shows some more issues:
----------------------------------------------------------------------------------------------------------
0e4fbbad9ffaed512593848212facffed0f4620f gstreamer: Added virtual functions needed to support request pads
----------------------------------------------------------------------------------------------------------
--- src/gstreamer/gstlibcamerasrc.cpp
+++ src/gstreamer/gstlibcamerasrc.cpp
@@ -642,9 +641,9 @@
self->state = state;
}
-static GstPad*
+static GstPad *
gst_libcamera_src_request_new_pad(GstElement *element, GstPadTemplate *templ,
- const gchar *name, [[maybe_unused]] const GstCaps *caps)
+ const gchar *name, [[maybe_unused]] const GstCaps *caps)
{
GstLibcameraSrc *self = GST_LIBCAMERA_SRC(element);
g_autoptr(GstPad) pad = NULL;
@@ -654,44 +653,40 @@
pad = gst_pad_new_from_template(templ, name);
g_object_ref_sink(pad);
- if (gst_element_add_pad(element, pad))
+ if (gst_element_add_pad(element, pad)) {
+ GLibLocker lock(GST_OBJECT(self));
+ self->state->srcpads_.push_back(reinterpret_cast<GstPad *>(g_object_ref(pad)));
+ } else {
+ GST_ELEMENT_ERROR(element, STREAM, FAILED,
+ ("Internal data stream error."),
+ ("Could not add pad to element"));
+ return NULL;
+ }
+
+ return reinterpret_cast<GstPad *>(g_steal_pointer(&pad));
+}
+
+static void
+gst_libcamera_src_release_pad(GstElement *element, GstPad *pad)
+{
+ GstLibcameraSrc *self = GST_LIBCAMERA_SRC(element);
+
+ GST_DEBUG_OBJECT(self, "Pad %" GST_PTR_FORMAT " being released", pad);
+
{
GLibLocker lock(GST_OBJECT(self));
- self->state->srcpads_.push_back(reinterpret_cast<GstPad*>(g_object_ref(pad)));
- }
- else
- {
- GST_ELEMENT_ERROR (element, STREAM, FAILED,
- ("Internal data stream error."),
- ("Could not add pad to element"));
- return NULL;
- }
-
- return reinterpret_cast<GstPad*>(g_steal_pointer(&pad));
-}
-
-static void
-gst_libcamera_src_release_pad(GstElement *element, GstPad *pad)
-{
- GstLibcameraSrc *self = GST_LIBCAMERA_SRC(element);
-
- GST_DEBUG_OBJECT (self, "Pad %" GST_PTR_FORMAT " being released", pad);
-
- {
- GLibLocker lock(GST_OBJECT(self));
- std::vector<GstPad*> &pads = self->state->srcpads_;
+ std::vector<GstPad *> &pads = self->state->srcpads_;
auto begin_iterator = pads.begin();
auto end_iterator = pads.end();
auto pad_iterator = std::find(begin_iterator, end_iterator, pad);
- if (pad_iterator != end_iterator)
- {
+ if (pad_iterator != end_iterator) {
g_object_unref(*pad_iterator);
pads.erase(pad_iterator);
}
}
gst_element_remove_pad(element, pad);
-}
+}
static void
gst_libcamera_src_class_init(GstLibcameraSrcClass *klass)
---
2 potential issues detected, please review
> ---
> In _request_new_pad and _release_pad, a GLibLock is taken on
> self->state. But since self->state is a C++ object,
> GST_OBJECT(self->state) fails and returns null, so GLibLocker throws a
> warning "invalid cast from '(null)' to 'GstObject'. This means that it
> actually fails to get lock the resource that needs to be protected,
> i.e., the srcpads_ vector.
>
> The following changes were tested using the following test code: https://pastebin.com/gNDF1cyG
>
> src/gstreamer/gstlibcamerasrc.cpp | 57 ++++++++++++++++++++++++++++++-
> 1 file changed, 56 insertions(+), 1 deletion(-)
>
> diff --git a/src/gstreamer/gstlibcamerasrc.cpp b/src/gstreamer/gstlibcamerasrc.cpp
> index ccc61590..1614971d 100644
> --- a/src/gstreamer/gstlibcamerasrc.cpp
> +++ b/src/gstreamer/gstlibcamerasrc.cpp
> @@ -361,10 +361,12 @@ 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();
> + gint stream_id_num = 0;
> StreamRoles roles;
> 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);
> + g_autofree gchar *stream_id_intermediate = g_strdup_printf("%i%i", 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_pad_push_event(srcpad, event);
> @@ -640,6 +642,57 @@ gst_libcamera_src_init(GstLibcameraSrc *self)
> self->state = state;
> }
>
> +static GstPad*
> +gst_libcamera_src_request_new_pad(GstElement *element, GstPadTemplate *templ,
> + const gchar *name, [[maybe_unused]] const GstCaps *caps)
> +{
> + GstLibcameraSrc *self = GST_LIBCAMERA_SRC(element);
> + g_autoptr(GstPad) pad = NULL;
> +
> + GST_DEBUG_OBJECT(self, "new request pad created");
> +
> + pad = gst_pad_new_from_template(templ, name);
> + g_object_ref_sink(pad);
> +
> + if (gst_element_add_pad(element, pad))
> + {
> + GLibLocker lock(GST_OBJECT(self));
> + self->state->srcpads_.push_back(reinterpret_cast<GstPad*>(g_object_ref(pad)));
> + }
> + else
> + {
> + GST_ELEMENT_ERROR (element, STREAM, FAILED,
> + ("Internal data stream error."),
> + ("Could not add pad to element"));
> + return NULL;
> + }
> +
> + return reinterpret_cast<GstPad*>(g_steal_pointer(&pad));
> +}
> +
> +static void
> +gst_libcamera_src_release_pad(GstElement *element, GstPad *pad)
> +{
> + GstLibcameraSrc *self = GST_LIBCAMERA_SRC(element);
> +
> + GST_DEBUG_OBJECT (self, "Pad %" GST_PTR_FORMAT " being released", pad);
> +
> + {
> + GLibLocker lock(GST_OBJECT(self));
> + std::vector<GstPad*> &pads = self->state->srcpads_;
> + auto begin_iterator = pads.begin();
> + auto end_iterator = pads.end();
> + auto pad_iterator = std::find(begin_iterator, end_iterator, pad);
> +
> + if (pad_iterator != end_iterator)
> + {
> + g_object_unref(*pad_iterator);
> + pads.erase(pad_iterator);
> + }
> + }
> + gst_element_remove_pad(element, pad);
> +}
> +
> static void
> gst_libcamera_src_class_init(GstLibcameraSrcClass *klass)
> {
> @@ -650,6 +703,8 @@ gst_libcamera_src_class_init(GstLibcameraSrcClass *klass)
> object_class->get_property = gst_libcamera_src_get_property;
> object_class->finalize = gst_libcamera_src_finalize;
>
> + 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;
>
> gst_element_class_set_metadata(element_class,
More information about the libcamera-devel
mailing list