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gst: libcamerasrc: Implement selection and acquisition

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This adds code to select and acquire a camera. With this, it is now
possible to run a pipeline like:

   gst-launch-1.0 libcamerasrc ! fakesink

Though no buffer will be streamed yet. In this function, we implement the
change_state() virtual method to trigger actions on specific state transitions.
Note that we also return GST_STATE_CHANGE_NO_PREROLL in
GST_STATE_CHANGE_READY_TO_PAUSED and GST_STATE_CHANGE_PLAYING_TO_PAUSED
transitions as this is required for all live sources.

Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
This commit is contained in:
Nicolas Dufresne 2020-01-16 10:31:45 -05:00 • committed by Laurent Pinchart
parent cfa61225a4
commit 58feb69f85
1 changed files with 125 additions and 0 deletions
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125
src/gstreamer/gstlibcamerasrc.cpp
View file

@ -8,16 +8,29 @@
#include "gstlibcamerasrc.h"
#include <libcamera/camera.h>
#include <libcamera/camera_manager.h>
#include "gstlibcamerapad.h"
#include "gstlibcamera-utils.h"
using namespace libcamera;
GST_DEBUG_CATEGORY_STATIC(source_debug);
#define GST_CAT_DEFAULT source_debug
/* Used for C++ object with destructors. */
struct GstLibcameraSrcState {
std::unique_ptr<CameraManager> cm_;
std::shared_ptr<Camera> cam_;
};
struct _GstLibcameraSrc {
GstElement parent;
GstPad *srcpad;
gchar *camera_name;
GstLibcameraSrcState *state;
};
enum {
@ -41,6 +54,83 @@ GstStaticPadTemplate request_src_template = {
"src_%s", GST_PAD_SRC, GST_PAD_REQUEST, TEMPLATE_CAPS
};
static bool
gst_libcamera_src_open(GstLibcameraSrc *self)
{
std::unique_ptr<CameraManager> cm = std::make_unique<CameraManager>();
std::shared_ptr<Camera> cam;
gint ret = 0;
GST_DEBUG_OBJECT(self, "Opening camera device ...");
ret = cm->start();
if (ret) {
GST_ELEMENT_ERROR(self, LIBRARY, INIT,
("Failed listing cameras."),
("libcamera::CameraMananger::start() failed: %s", g_strerror(-ret)));
return false;
}
g_autofree gchar *camera_name = nullptr;
{
GLibLocker lock(GST_OBJECT(self));
if (self->camera_name)
camera_name = g_strdup(self->camera_name);
}
if (camera_name) {
cam = cm->get(self->camera_name);
if (!cam) {
GST_ELEMENT_ERROR(self, RESOURCE, NOT_FOUND,
("Could not find a camera named '%s'.", self->camera_name),
("libcamera::CameraMananger::get() returned nullptr"));
return false;
}
} else {
if (cm->cameras().empty()) {
GST_ELEMENT_ERROR(self, RESOURCE, NOT_FOUND,
("Could not find any supported camera on this system."),
("libcamera::CameraMananger::cameras() is empty"));
return false;
}
cam = cm->cameras()[0];
}
GST_INFO_OBJECT(self, "Using camera named '%s'", cam->name().c_str());
ret = cam->acquire();
if (ret) {
GST_ELEMENT_ERROR(self, RESOURCE, BUSY,
("Camera name '%s' is already in use.", cam->name().c_str()),
("libcamera::Camera::acquire() failed: %s", g_strerror(ret)));
return false;
}
/* No need to lock here, we didn't start our threads yet. */
self->state->cm_ = std::move(cm);
self->state->cam_ = cam;
return true;
}
static void
gst_libcamera_src_close(GstLibcameraSrc *self)
{
GstLibcameraSrcState *state = self->state;
gint ret;
ret = state->cam_->release();
if (ret) {
GST_ELEMENT_WARNING(self, RESOURCE, BUSY,
("Camera name '%s' is still in use.", state->cam_->name().c_str()),
("libcamera::Camera.release() failed: %s", g_strerror(-ret)));
}
state->cam_.reset();
state->cm_->stop();
state->cm_.reset();
}
static void
gst_libcamera_src_set_property(GObject *object, guint prop_id,
const GValue *value, GParamSpec *pspec)
@ -76,6 +166,36 @@ gst_libcamera_src_get_property(GObject *object, guint prop_id, GValue *value,
}
}
static GstStateChangeReturn
gst_libcamera_src_change_state(GstElement *element, GstStateChange transition)
{
GstLibcameraSrc *self = GST_LIBCAMERA_SRC(element);
GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
GstElementClass *klass = GST_ELEMENT_CLASS(gst_libcamera_src_parent_class);
ret = klass->change_state(element, transition);
if (ret == GST_STATE_CHANGE_FAILURE)
return ret;
switch (transition) {
case GST_STATE_CHANGE_NULL_TO_READY:
if (!gst_libcamera_src_open(self))
return GST_STATE_CHANGE_FAILURE;
break;
case GST_STATE_CHANGE_READY_TO_PAUSED:
case GST_STATE_CHANGE_PLAYING_TO_PAUSED:
ret = GST_STATE_CHANGE_NO_PREROLL;
break;
case GST_STATE_CHANGE_READY_TO_NULL:
gst_libcamera_src_close(self);
break;
default:
break;
}
return ret;
}
static void
gst_libcamera_src_finalize(GObject *object)
{
@ -83,6 +203,7 @@ gst_libcamera_src_finalize(GObject *object)
GstLibcameraSrc *self = GST_LIBCAMERA_SRC(object);
g_free(self->camera_name);
delete self->state;
return klass->finalize(object);
}
@ -90,10 +211,12 @@ gst_libcamera_src_finalize(GObject *object)
static void
gst_libcamera_src_init(GstLibcameraSrc *self)
{
GstLibcameraSrcState *state = new GstLibcameraSrcState();
GstPadTemplate *templ = gst_element_get_pad_template(GST_ELEMENT(self), "src");
self->srcpad = gst_pad_new_from_template(templ, "src");
gst_element_add_pad(GST_ELEMENT(self), self->srcpad);
self->state = state;
}
static void
@ -106,6 +229,8 @@ 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->change_state = gst_libcamera_src_change_state;
gst_element_class_set_metadata(element_class,
"libcamera Source", "Source/Video",
"Linux Camera source using libcamera",