deepstresam的插件配置说明，通过配置osd，设置字体的背景为透明

插件说明：
https://docs.nvidia.com/metropolis/deepstream/dev-guide/text/DS_plugin_gst-nvdsosd.html

python开发中插件参数：
https://docs.nvidia.com/metropolis/deepstream/python-api/index.html
举例说明：
osd插件中text-bg-color的参数含义：

red – float, Holds red component of color. Value must be in the range 0-1.

green – float, Holds green component of color. Value must be in the range 0-1.

blue – float, Holds blue component of color. Value must be in the range 0-1.

alpha – float, Holds alpha component of color. Value must be in the range 0-1.

透明化设置：

[osd]
enable=1
gpu-id=0
border-width=1
text-size=15
text-color=1;0;0;1;
text-bg-color=0.3;0.3;0.3;0
font=Serif
show-clock=0
clock-x-offset=800
clock-y-offset=820
clock-text-size=12
clock-color=1;0;0;0
nvbuf-memory-type=0