\u5728\u672c\u7ae0\u4e2d\uff0c\u6211\u4eec\u5c06\u5982\u4e0b\u642d\u5efa\u4e00\u6761\u7ba1\u7ebf\uff1a<\/p>\n
gst_bin_add_many(GST_BIN(pipeline), source, capsfilter, myele, convert, sink, NULL);<\/code><\/pre>\n\u5728\u8fd9\u6761\u7ba1\u7ebf\u4e2d\uff0c\u6211\u4eec\u5c06\u4ecev4l2src\u4e2d\u83b7\u53d6\u89c6\u9891\u6d41\uff0c\u7ecf\u8fc7\u6211\u4eec\u81ea\u5df1\u7684\u63d2\u4ef6myele<\/code>\u540e\uff0c\u5c06\u6570\u636e\u63a8\u9001\u7ed9waylandsink\u3002<\/p>\n\u4e8c\u3001\u6e90\u7801<\/h2>\n2.1 main<\/h3>\n
\u6211\u4eec\u9996\u5148\u6765\u770b\u4e00\u4e0bmain\u662f\u600e\u4e48\u5199\u7684\u3002\u8fd9\u548c\u666e\u901a\u7684v4l2\u6355\u83b7\u4e00\u6837\uff0c\u53ea\u662f\u6211\u4eec\u5728caps\u4e4b\u540e\u94fe\u63a5\u4e0a\u6211\u4eec\u81ea\u5df1\u7684\u63d2\u4ef6\u3002<\/p>\n
int my_main(int argc, char** argv)\n{\n GstElement *pipeline;\n GstElement *source, *capsfilter, *convert, *sink;\n GstElement *myele;\n GstCaps *caps;\n GstBus *bus;\n GstMessage *msg;\n GstStateChangeReturn ret;\n gboolean terminate = FALSE;\n int retval = 0;\n\n \/* Initialize GStreamer *\/\n gst_init(&argc, &argv);\n\n \/* Create the elements *\/\n source = gst_element_factory_make("v4l2src", "source");\n convert = gst_element_factory_make("videoconvert", "convert");\n sink = gst_element_factory_make("waylandsink", "sink");\n capsfilter = gst_element_factory_make("capsfilter", "capsfilter");\n\/\/debug myele\n myele = gst_element_factory_make("rgb2grey", "rgb2grey");\n\n \/* Create the empty pipeline *\/\n pipeline = gst_pipeline_new("test-pipeline");\n\n \/* Check creation *\/\n if (!pipeline || !source || !convert || !sink || !capsfilter) {\n g_printerr("Not all elements could be created.\\n");\n retval = -1;\n goto out_return;\n }\n\/\/debug myele\n if (!myele) {\n g_printerr("myele not created.\\n");\n retval = -1;\n goto out_return;\n }\n g_object_set(G_OBJECT(myele), "width", 1920, "height", 1080, NULL);\n\n \/* Set caps on source *\/\n g_object_set(G_OBJECT(source), "device", "\/dev\/video0", NULL);\n caps = gst_caps_new_simple(\n "video\/x-raw", \n "format", G_TYPE_STRING, "NV12",\n "width", G_TYPE_INT, 1920, \n "height", G_TYPE_INT, 1080, \n "framerate", GST_TYPE_FRACTION, 30, 1,\n NULL\n );\n g_object_set(G_OBJECT(capsfilter), "caps", caps, NULL);\n gst_caps_unref(caps);\n\n \/* Build the pipeline *\/\n gst_bin_add_many(GST_BIN(pipeline), source, capsfilter, myele, convert, sink, NULL);\n if (!gst_element_link_many(source, capsfilter, myele, convert, sink, NULL))\n {\n g_printerr("Elements could not be linked.\\n");\n retval = -2;\n goto out_unref;\n }\n\n \/* Set the pipeline to "playing" state *\/\n ret = gst_element_set_state(pipeline, GST_STATE_PLAYING);\n if (ret == GST_STATE_CHANGE_FAILURE) {\n g_printerr("Unable to set the pipeline to the playing state.\\n");\n retval = -3;\n goto out_unref;\n }\n\n \/* Wait until error or EOS *\/\n bus = gst_element_get_bus(pipeline);\n do {\n msg = gst_bus_timed_pop_filtered(bus, GST_CLOCK_TIME_NONE, GST_MESSAGE_ERROR | GST_MESSAGE_EOS);\n\n \/* Parse message *\/\n if (msg != NULL) {\n GError *err;\n gchar *debug_info;\n\n switch (GST_MESSAGE_TYPE(msg)) {\n case GST_MESSAGE_ERROR:\n gst_message_parse_error(msg, &err, &debug_info);\n g_printerr("Error received from element %s: %s\\n", GST_OBJECT_NAME(msg->src), err->message);\n g_printerr("Debugging information: %s\\n", debug_info ? debug_info : "none");\n g_clear_error(&err);\n g_free(debug_info);\n terminate = TRUE;\n break;\n case GST_MESSAGE_EOS:\n g_print("End-Of-Stream reached.\\n");\n terminate = TRUE;\n break;\n default:\n \/* Should not be reached *\/\n g_printerr("Unexpected message received.\\n");\n break;\n }\n\n gst_message_unref(msg);\n }\n } while (!terminate);\n\n gst_object_unref(bus);\n gst_element_set_state(pipeline, GST_STATE_NULL);\nout_unref:\n gst_object_unref(pipeline);\nout_return:\n return retval;\n}<\/code><\/pre>\n2.2 plugin.h<\/h3>\n
\u8fd9\u91cc\u53c2\u7167gst\u7c7b\u7684\u6a21\u677f\u5b8c\u6210\uff0c\u9700\u8981\u6ce8\u610f\uff1a\u6210\u5458\u53d8\u91cf\u7684\u679a\u4e3e\uff0c\u6709\u6548\u6570\u5b57\u5e94\u8be5\u4ece1<\/code>\u5f00\u59cb\u3002<\/p>\n#pragma once\n\n#include <gstreamer-1.0\/gst\/gst.h>\n#include <gstreamer-1.0\/gst\/gstcontext.h>\n#include <gstreamer-1.0\/gst\/video\/video-info.h>\n\n#define VERSION "1.0"\n#define PACKAGE "rgb2grey"\n\nG_BEGIN_DECLS\n\nenum{\n PROP_0 = 0,\n PROP_WIDTH,\n PROP_HEIGHT,\n};\n\ntypedef struct _GstRGB2GreyFilter {\n GstElement element;\n GstPad *sinkpad;\n GstPad *srcpad;\n\n guint width;\n guint height;\n}GstRGB2GreyFilter;\n\ntypedef struct _GstRGB2GreyFilterClass {\n GstElementClass parent_class;\n}GstRGB2GreyFilterClass;\n\n\/* declare get_type Func, defined in G_DEFINE_TYPE *\/\nGType gst_rgb2grey_filter_get_type(void);\n\n\/* ===== Standard macros for defining types for this element. ===== *\/\n\n\/\/return GType\n#define GST_TYPE_RGB2GREY_FILTER (gst_rgb2grey_filter_get_type())\n\n\/\/get a GstObtFilter ptr from any ptr #obj ,if obj is GST_TYPE_OBT_FILTER GType , return result , otherwise return null\n#define GST_RGB2GREY_FILTER(obj) \\\n (G_TYPE_CHECK_INSTANCE_CAST((obj), GST_TYPE_RGB2GREY_FILTER, GstRGB2GreyFilter))\n\n\/\/get a GstObtFilterClass ptr from any ptr #obj ,if obj is GST_TYPE_OBT_FILTER GType , return result , otherwise return null\n#define GST_RGB2GREY_FILTER_CLASS(klass) \\\n (G_TYPE_CHECK_CLASS_CAST((klass), GST_TYPE_RGB2GREY_FILTER, GstRGB2GreyFilterClass))\n\n#define GST_IS_RGB2GREY_FILTER(obj) \\\n (G_TYPE_CHECK_INSTANCE_TYPE((obj), GST_TYPE_RGB2GREY_FILTER))\n\n#define GST_IS_RGB2GREY_FILTER_CLASS(klass) \\\n (G_TYPE_CHECK_CLASS_TYPE((klass), GST_TYPE_RGB2GREY_FILTER))\n\nG_END_DECLS<\/code><\/pre>\n2.3 plugin.c<\/h3>\n#include "rgb2grey.h"\n\nstatic GstBuffer* gst_rgb2grey_filter_process_data(GstRGB2GreyFilter* filter, GstBuffer* buf);\nstatic gboolean gst_rgb2grey_filter_stop_processing(GstRGB2GreyFilter* filter);\nstatic gboolean gst_rgb2grey_filter_allocate_memory(GstRGB2GreyFilter* filter);\nstatic gboolean gst_rgb2grey_filter_free_memory(GstRGB2GreyFilter* filter);\n\n\/**\n * ==============================\n * @par boilerplate Funcs [START]\n * ==============================\n *\/\n\nG_DEFINE_TYPE(GstRGB2GreyFilter, gst_rgb2grey_filter, GST_TYPE_ELEMENT);\n\nstatic GstStaticPadTemplate sink_factory = GST_STATIC_PAD_TEMPLATE(\n "sink",\n GST_PAD_SINK,\n GST_PAD_ALWAYS,\n GST_STATIC_CAPS("ANY")\n);\n\nstatic GstStaticPadTemplate src_factory = GST_STATIC_PAD_TEMPLATE(\n "src",\n GST_PAD_SRC,\n GST_PAD_ALWAYS,\n GST_STATIC_CAPS("ANY")\n);\n\n\/**\n * @brief \n * \n * @param pad pad reveive buffer\n * @param parent \n * @param buf to be precessed\n * @return GstFlowReturn \n *\/\nstatic GstFlowReturn gst_rgb2grey_filter_chain(GstPad* pad, GstObject *parent, GstBuffer *buf)\n{\n \/\/ g_print("gst_rgb2grey_filter_chain\\n");\n GstRGB2GreyFilter *filter = GST_RGB2GREY_FILTER(parent);\n\n \/* Get input Buffer *\/\n GstMapInfo in_map;\n gst_buffer_map(buf, &in_map, GST_MAP_READ | GST_MAP_WRITE);\n guint in_width = filter->width;\n guint in_height = filter->height;\n guint in_pixel_size = in_width * in_height;\n guint in_full_size = in_pixel_size * 1.5;\n gsize in_size = in_map.size;\n\n \/* TODO: set UV to 0 *\/\n \/\/ input format is NV12\n\n for (int i = in_pixel_size; i < in_full_size; ++i)\n {\n in_map.data[i] = (guint8)(0);\n }\n\n \/\/ g_print("in_size = %d\\n", in_size);\n\n gst_buffer_unmap(buf, &in_map);\n\n return gst_pad_push(filter->srcpad, buf);\n}\n\n\/**\n * @brief \n * \n * @param pad pad reveive event\n * @param parent \n * @param event to be preocessed\n * @return gboolean \n *\/\nstatic gboolean gst_rgb2grey_filter_event(GstPad* pad, GstObject *parent, GstEvent *event)\n{\n gboolean ret;\n GstRGB2GreyFilter *filter = GST_RGB2GREY_FILTER(parent);\n\n g_print("event : %s \\n",GST_EVENT_TYPE_NAME(event));\n\n switch (GST_EVENT_TYPE(event)) {\n case GST_EVENT_CAPS:\n ret = gst_pad_push_event(filter->srcpad, event); \/* push the event downstream *\/\n break;\n case GST_EVENT_EOS:\n gst_rgb2grey_filter_stop_processing(filter);\n ret = gst_pad_event_default(pad, parent, event); \/\/default deal transaction\n break;\n default:\n ret = gst_pad_event_default(pad, parent, event);\n break;\n }\n\n return ret;\n}\n\nstatic gboolean gst_rgb2grey_filter_src_query(GstPad* pad, GstObject* parent, GstQuery* query)\n{\n gboolean ret;\n GstRGB2GreyFilter *filter = GST_RGB2GREY_FILTER(parent);\n\n switch (GST_QUERY_TYPE(query)) {\n case GST_QUERY_POSITION:\n \/* we should report the current position *\/\n break;\n case GST_QUERY_DURATION:\n \/* we should report the duration here *\/\n break;\n case GST_QUERY_CAPS:\n \/* we should report the supported caps here *\/\n break;\n default:\n \/* just call the default handler *\/\n ret = gst_pad_query_default(pad, parent, query);\n break;\n }\n return ret;\n}\n\nstatic GstStateChangeReturn gst_rgb2grey_filter_change_state(GstElement *element, GstStateChange transition)\n{\n GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;\n GstRGB2GreyFilter *filter = GST_RGB2GREY_FILTER(element);\n\n \/\/process upwards state change\n switch (transition) {\n case GST_STATE_CHANGE_NULL_TO_READY:\n if (!gst_rgb2grey_filter_allocate_memory(filter)) \/\/require for resource, memory \/ libs \/ ... are included\n return GST_STATE_CHANGE_FAILURE;\n break;\n case GST_STATE_CHANGE_READY_TO_PAUSED:\n \/\/dosomething\n break;\n case GST_STATE_CHANGE_PAUSED_TO_PLAYING:\n \/\/dosomething\n break;\n default:\n break;\n }\n\n \/\/call state changed Func of parent class.\n ret = GST_ELEMENT_CLASS (gst_rgb2grey_filter_parent_class)->change_state (element, transition);\n if (ret == GST_STATE_CHANGE_FAILURE) return ret;\n\n \/\/process downwards state change\n switch (transition) {\n case GST_STATE_CHANGE_PLAYING_TO_PAUSED:\n \/\/dosomething\n break;\n case GST_STATE_CHANGE_PAUSED_TO_READY:\n \/\/dosomething\n break;\n case GST_STATE_CHANGE_READY_TO_NULL:\n gst_rgb2grey_filter_free_memory(filter);\n break;\n default:\n break;\n }\n\n return ret;\n}\n\nstatic void gst_rgb2grey_filter_set_property(GObject* object, guint prop_id, const GValue * value, GParamSpec *pspec)\n{\n GstRGB2GreyFilter* filter = GST_RGB2GREY_FILTER(object);\n\n switch (prop_id) {\n case PROP_WIDTH:\n filter->width = g_value_get_uint(value);\n break;\n case PROP_HEIGHT:\n filter->height = g_value_get_uint(value);\n break;\n default:\n G_OBJECT_WARN_INVALID_PROPERTY_ID(object, prop_id, pspec);\n break;\n }\n}\n\nstatic void gst_rgb2grey_filter_get_property(GObject* object, guint prop_id, GValue * value, GParamSpec *pspec)\n{\n GstRGB2GreyFilter *filter = GST_RGB2GREY_FILTER(object);\n\n switch (prop_id) {\n \/\/ do sth\n default:\n G_OBJECT_WARN_INVALID_PROPERTY_ID(object, prop_id, pspec);\n break;\n }\n}\n\nstatic void gst_rgb2grey_filter_class_init(GstRGB2GreyFilterClass *klass)\n{\n g_print("gst_rgb2grey_filter_class_init\\n");\n GstElementClass *element_class = GST_ELEMENT_CLASS(klass); \/\/ for others\n GObjectClass *object_class = G_OBJECT_CLASS(klass); \/\/ for property setter and getter\n\n \/\/ meta data\n gst_element_class_set_static_metadata(element_class,\n "[meta data]Filter Demo of rgb2grey Plugin",\n "[meta data]rgb2grey\/Filter Demo",\n "[meta data]Shows the basic structure of a plugin",\n "[meta data]xjt");\n\n \/\/ register state change funcution\n element_class->change_state = gst_rgb2grey_filter_change_state;\n\n \/\/ register property setter and getter\n object_class->set_property = gst_rgb2grey_filter_set_property;\n object_class->get_property = gst_rgb2grey_filter_get_property;\n\n \/\/ register pads\n gst_element_class_add_pad_template(element_class,\n gst_static_pad_template_get(&src_factory));\n gst_element_class_add_pad_template(element_class,\n gst_static_pad_template_get(&sink_factory));\n\n \/\/ width and height\n GParamSpec *param_spec;\n param_spec = g_param_spec_uint(\n "width", "Width", "The width of the input video", \n 0, G_MAXUINT, 0, \n G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS\n );\n g_object_class_install_property(object_class, PROP_WIDTH, param_spec);\n\n param_spec = g_param_spec_uint(\n "height", "Height", \n "The height of the input video", \n 0, G_MAXUINT, 0, \n G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS\n );\n g_object_class_install_property(object_class, PROP_HEIGHT, param_spec);\n}\n\nstatic void gst_rgb2grey_filter_init(GstRGB2GreyFilter *filter)\n{\n g_print("gst_rgb2grey_filter_init\\n");\n \/\/instantiates and assigns pads\n filter->srcpad = gst_pad_new_from_static_template(&src_factory, "src");\n filter->sinkpad = gst_pad_new_from_static_template(&sink_factory, "sink");\n\n \/\/add pads to element\n gst_element_add_pad(GST_ELEMENT(filter), filter->srcpad);\n gst_element_add_pad(GST_ELEMENT(filter), filter->sinkpad);\n\n \/\/set chain function for sink pad\n gst_pad_set_chain_function(filter->sinkpad, gst_rgb2grey_filter_chain);\n\n \/\/set event function\n gst_pad_set_event_function(filter->sinkpad, gst_rgb2grey_filter_event);\n\n \/\/set query function\n gst_pad_set_query_function(filter->srcpad, gst_rgb2grey_filter_src_query);\n}\n\nstatic gboolean plugin_init(GstPlugin* plugin)\n{\n g_print("rgb2grey_plugin_init\\n");\n gboolean ret;\n\n \/\/register plugin feature\n \/\/[todo]\n\n \/\/register element into plugin\n ret = gst_element_register(plugin, "rgb2grey", GST_RANK_MARGINAL, GST_TYPE_RGB2GREY_FILTER);\n\n return ret;\n}\n\nGST_PLUGIN_DEFINE(\n GST_VERSION_MAJOR,\n GST_VERSION_MINOR,\n rgb2grey,\n "rgb2grey filter plugin",\n plugin_init,\n VERSION,\n "LGPL",\n "LocalPlugin",\n "n\/a"\n)\n\n\/**\n * ========================\n * @par Local Funcs [START]\n * ========================\n *\/\n\nstatic GstBuffer* gst_rgb2grey_filter_process_data(GstRGB2GreyFilter* filter, GstBuffer* buf)\n{\n return buf;\n}\n\nstatic gboolean gst_rgb2grey_filter_stop_processing(GstRGB2GreyFilter* filter)\n{\n return TRUE;\n}\n\nstatic gboolean gst_rgb2grey_filter_allocate_memory(GstRGB2GreyFilter* filter)\n{\n return TRUE;\n}\n\nstatic gboolean gst_rgb2grey_filter_free_memory(GstRGB2GreyFilter* filter)\n{\n return TRUE;\n}<\/code><\/pre>\n\u4e09\u3001\u4f7f\u7528<\/h3>\n
\u8fd9\u91cc\u6211\u7684\u63d2\u4ef6\u540d\u79f0\u4e3argb2grey\uff0c\u901a\u8fc7cmake\u521b\u5efa\u4e00\u4e2a\u52a8\u6001\u5e93\u3002<\/p>\n
ADD_LIBRARY(rgb2grey SHARED rgb2grey.c rgb2grey.h)<\/code><\/pre>\n\u7f16\u8bd1\u597d\u4e4b\u540e\u6211\u4eec\u5c06\u6587\u4ef6\u4f20\u5165\/lib\/<\/code>\u6216\u8005usr\/lib\/gstreamer-1.0\/<\/code>\u4e2d\uff0c\u4e4b\u540e\u5c31\u53ef\u4ee5\u5728\u4e3b\u7a0b\u5e8f\u4e2d\u8c03\u7528gst_element_factory_make<\/code>\u6765\u521b\u5efa\u5143\u7d20\u4e86\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"\u4e00\u3001\u7b80\u8ff0 \u5728\u672c\u7ae0\u4e2d\uff0c\u6211\u4eec\u5c06\u5982\u4e0b\u642d\u5efa\u4e00\u6761\u7ba1\u7ebf\uff1a gst_bin_add_many(GST_BIN(pipel …<\/p>","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[54],"tags":[239],"amp_enabled":true,"_links":{"self":[{"href":"https:\/\/swordofmorning.com\/index.php\/wp-json\/wp\/v2\/posts\/938"}],"collection":[{"href":"https:\/\/swordofmorning.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/swordofmorning.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/swordofmorning.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/swordofmorning.com\/index.php\/wp-json\/wp\/v2\/comments?post=938"}],"version-history":[{"count":3,"href":"https:\/\/swordofmorning.com\/index.php\/wp-json\/wp\/v2\/posts\/938\/revisions"}],"predecessor-version":[{"id":941,"href":"https:\/\/swordofmorning.com\/index.php\/wp-json\/wp\/v2\/posts\/938\/revisions\/941"}],"wp:attachment":[{"href":"https:\/\/swordofmorning.com\/index.php\/wp-json\/wp\/v2\/media?parent=938"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/swordofmorning.com\/index.php\/wp-json\/wp\/v2\/categories?post=938"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/swordofmorning.com\/index.php\/wp-json\/wp\/v2\/tags?post=938"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}