Gstreamer学习笔记（6）：如何创建gstreamer插件？

 

    gstreamer的功能强大是毋庸置疑的，它采用C语言编程，但是通过gObject，将各插件封装成面向对象编程的工具。那么如何创建gstreamer呢，当然，可以自己手动写，但是，gstreamer有提供一个叫make_element的工具，我们为什么不直接使用这个工具帮助我们生成所需要的插件呢。

 

1.获取创建插件的模板 gst-template

    首先要确定你的PC安装了git，然后执行以下命令即可在当前目录下获取gst-template源码。

git clone git://anongit.freedesktop.org/gstreamer/gst-template.git

2.创建插件模板

    进入gst-template/gst-plugin/src目录，执行以下操作

user# cd gst-template/gst-plugin/src/
user# ../tools/make_element template

    执行完上面两步之后，在src目录下将会有gsttemplate.c 、gsttemplate.h这两个文件，他们就是生成的插件模板。

3.修改Makefile.am

    在src目录下的Makefile.am文件，内容如下：

# Note: plugindir is set in configure
 
##############################################################################
# TODO: change libgstplugin.la to something else, e.g. libmysomething.la     #
##############################################################################
plugin_LTLIBRARIES = libgstplugin.la libgstaudiofilterexample.la
 
##############################################################################
# TODO: for the next set of variables, name the prefix if you named the .la, #
#  e.g. libmysomething.la => libmysomething_la_SOURCES                       #
#                            libmysomething_la_CFLAGS                        #
#                            libmysomething_la_LIBADD                        #
#                            libmysomething_la_LDFLAGS                       #
##############################################################################
 
## Plugin 1
 
# sources used to compile this plug-in
libgstplugin_la_SOURCES = gstplugin.c gstplugin.h
 
# compiler and linker flags used to compile this plugin, set in configure.ac
libgstplugin_la_CFLAGS = $(GST_CFLAGS)
libgstplugin_la_LIBADD = $(GST_LIBS)
libgstplugin_la_LDFLAGS = $(GST_PLUGIN_LDFLAGS)
libgstplugin_la_LIBTOOLFLAGS = --tag=disable-static
 
## Plugin 2 (audio filter example)
 
# sources used to compile this plug-in
libgstaudiofilterexample_la_SOURCES = gstaudiofilter.c
 
# compiler and linker flags used to compile this plugin, set in configure.ac
libgstaudiofilterexample_la_CFLAGS = $(GST_CFLAGS)
libgstaudiofilterexample_la_LIBADD = $(GST_LIBS)
libgstaudiofilterexample_la_LDFLAGS = $(GST_PLUGIN_LDFLAGS)
libgstaudiofilterexample_la_LIBTOOLFLAGS = --tag=disable-static
 
# headers we need but don't want installed
noinst_HEADERS = gstplugin.h

    从内容可以知道，添加新的插件之后，直接在该Makefile.am添加该插件的内容即可，添加之后的内容如下：

# Note: plugindir is set in configure
 
##############################################################################
# TODO: change libgstplugin.la to something else, e.g. libmysomething.la     #
##############################################################################
plugin_LTLIBRARIES = libgstplugin.la libgstaudiofilterexample.la libgstexample.la
 
##############################################################################
# TODO: for the next set of variables, name the prefix if you named the .la, #
#  e.g. libmysomething.la => libmysomething_la_SOURCES                       #
#                            libmysomething_la_CFLAGS                        #
#                            libmysomething_la_LIBADD                        #
#                            libmysomething_la_LDFLAGS                       #
##############################################################################
 
## Plugin 1
 
# sources used to compile this plug-in
libgstplugin_la_SOURCES = gstplugin.c gstplugin.h
 
# compiler and linker flags used to compile this plugin, set in configure.ac
libgstplugin_la_CFLAGS = $(GST_CFLAGS)
libgstplugin_la_LIBADD = $(GST_LIBS)
libgstplugin_la_LDFLAGS = $(GST_PLUGIN_LDFLAGS)
libgstplugin_la_LIBTOOLFLAGS = --tag=disable-static
 
## Plugin 2 (audio filter example)
 
# sources used to compile this plug-in
libgstaudiofilterexample_la_SOURCES = gstaudiofilter.c
 
# compiler and linker flags used to compile this plugin, set in configure.ac
libgstaudiofilterexample_la_CFLAGS = $(GST_CFLAGS)
libgstaudiofilterexample_la_LIBADD = $(GST_LIBS)
libgstaudiofilterexample_la_LDFLAGS = $(GST_PLUGIN_LDFLAGS)
libgstaudiofilterexample_la_LIBTOOLFLAGS = --tag=disable-static
 
## Plugin 3 (test example)
 
# sources used to compile this plug-in
libgstexample_la_SOURCES = gsttemplate.c
 
# compiler and linker flags used to compile this plugin, set in configure.ac
libgstexample_la_CFLAGS = $(GST_CFLAGS)
libgstexample_la_LIBADD = $(GST_LIBS)
libgstexample_la_LDFLAGS = $(GST_PLUGIN_LDFLAGS)
libgstexample_la_LIBTOOLFLAGS = --tag=disable-static
 
# headers we need but don't want installed
noinst_HEADERS = gstplugin.h

# Note: plugindir is set in configure
 
##############################################################################
# TODO: change libgstplugin.la to something else, e.g. libmysomething.la     #
##############################################################################
plugin_LTLIBRARIES = libgstplugin.la libgstaudiofilterexample.la libgstexample.la
 
##############################################################################
# TODO: for the next set of variables, name the prefix if you named the .la, #
#  e.g. libmysomething.la => libmysomething_la_SOURCES                       #
#                            libmysomething_la_CFLAGS                        #
#                            libmysomething_la_LIBADD                        #
#                            libmysomething_la_LDFLAGS                       #
##############################################################################
 
## Plugin 1
 
# sources used to compile this plug-in
libgstplugin_la_SOURCES = gstplugin.c gstplugin.h
 
# compiler and linker flags used to compile this plugin, set in configure.ac
libgstplugin_la_CFLAGS = $(GST_CFLAGS)
libgstplugin_la_LIBADD = $(GST_LIBS)
libgstplugin_la_LDFLAGS = $(GST_PLUGIN_LDFLAGS)
libgstplugin_la_LIBTOOLFLAGS = --tag=disable-static
 
## Plugin 2 (audio filter example)
 
# sources used to compile this plug-in
libgstaudiofilterexample_la_SOURCES = gstaudiofilter.c
 
# compiler and linker flags used to compile this plugin, set in configure.ac
libgstaudiofilterexample_la_CFLAGS = $(GST_CFLAGS)
libgstaudiofilterexample_la_LIBADD = $(GST_LIBS)
libgstaudiofilterexample_la_LDFLAGS = $(GST_PLUGIN_LDFLAGS)
libgstaudiofilterexample_la_LIBTOOLFLAGS = --tag=disable-static
 
## Plugin 3 (test example)
 
# sources used to compile this plug-in
libgstexample_la_SOURCES = gsttemplate.c
 
# compiler and linker flags used to compile this plugin, set in configure.ac
libgstexample_la_CFLAGS = $(GST_CFLAGS)
libgstexample_la_LIBADD = $(GST_LIBS)
libgstexample_la_LDFLAGS = $(GST_PLUGIN_LDFLAGS)
libgstexample_la_LIBTOOLFLAGS = --tag=disable-static
 
# headers we need but don't want installed
noinst_HEADERS = gstplugin.h

至此，创建gstreamer插件完毕。