滤镜描述
drawtext
官网链接 =》 FFmpeg Filters Documentation
这个滤镜可以给视频添加上文本，可以给文本加边框、颜色、阴影。注意不是字幕功能，因为这个滤镜不能精准的控制开始和结束的时间。
滤镜使用
参数
fontfile <string> ..FV....... set font file
text <string> ..FV.....T. set text
textfile <string> ..FV....... set text file
fontcolor <color> ..FV.....T. set foreground color (default "black")
fontcolor_expr <string> ..FV....... set foreground color expression (default "")
boxcolor <color> ..FV.....T. set box color (default "white")
bordercolor <color> ..FV.....T. set border color (default "black")
shadowcolor <color> ..FV.....T. set shadow color (default "black")
box <boolean> ..FV.....T. set box (default false)
boxborderw <string> ..FV.....T. set box borders width (default "0")
line_spacing <int> ..FV.....T. set line spacing in pixels (from INT_MIN to INT_MAX) (default 0)
fontsize <string> ..FV.....T. set font size
text_align <flags> ..FV.....T. set text alignment (default 0)
left ..FV.....T.
L ..FV.....T.
right ..FV.....T.
R ..FV.....T.
center ..FV.....T.
C ..FV.....T.
top ..FV.....T.
T ..FV.....T.
bottom ..FV.....T.
B ..FV.....T.
middle ..FV.....T.
M ..FV.....T.
x <string> ..FV.....T. set x expression (default "0")
y <string> ..FV.....T. set y expression (default "0")
boxw <int> ..FV.....T. set box width (from 0 to INT_MAX) (default 0)
boxh <int> ..FV.....T. set box height (from 0 to INT_MAX) (default 0)
shadowx <int> ..FV.....T. set shadow x offset (from INT_MIN to INT_MAX) (default 0)
shadowy <int> ..FV.....T. set shadow y offset (from INT_MIN to INT_MAX) (default 0)
borderw <int> ..FV.....T. set border width (from INT_MIN to INT_MAX) (default 0)
tabsize <int> ..FV.....T. set tab size (from 0 to INT_MAX) (default 4)
basetime <int64> ..FV....... set base time (from I64_MIN to I64_MAX) (default I64_MIN)
font <string> ..FV....... Font name (default "Sans")
expansion <int> ..FV....... set the expansion mode (from 0 to 2) (default normal)
none 0 ..FV....... set no expansion
normal 1 ..FV....... set normal expansion
strftime 2 ..FV....... set strftime expansion (deprecated)
y_align <int> ..FV.....T. set the y alignment (from 0 to 2) (default text)
text 0 ..FV....... y is referred to the top of the first text line
baseline 1 ..FV....... y is referred to the baseline of the first line
font 2 ..FV....... y is referred to the font defined line metrics
timecode <string> ..FV....... set initial timecode
tc24hmax <boolean> ..FV....... set 24 hours max (timecode only) (default false)
timecode_rate <rational> ..FV....... set rate (timecode only) (from 0 to INT_MAX) (default 0/1)
r <rational> ..FV....... set rate (timecode only) (from 0 to INT_MAX) (default 0/1)
rate <rational> ..FV....... set rate (timecode only) (from 0 to INT_MAX) (default 0/1)
reload <int> ..FV....... reload text file at specified frame interval (from 0 to INT_MAX) (default 0)
alpha <string> ..FV.....T. apply alpha while rendering (default "1")
fix_bounds <boolean> ..FV....... check and fix text coords to avoid clipping (default false)
start_number <int> ..FV....... start frame number for n/frame_num variable (from 0 to INT_MAX) (default 0)
text_source <string> ..FV....... the source of text
text_shaping <boolean> ..FV....... attempt to shape text before drawing (default true)
ft_load_flags <flags> ..FV....... set font loading flags for libfreetype (default 0)
default ..FV.......
no_scale ..FV.......
no_hinting ..FV.......
render ..FV.......
no_bitmap ..FV.......
vertical_layout ..FV.......
force_autohint ..FV.......
crop_bitmap ..FV.......
pedantic ..FV.......
ignore_global_advance_width ..FV.......
no_recurse ..FV.......
ignore_transform ..FV.......
monochrome ..FV.......
linear_design ..FV.......
no_autohint ..FV.......
| box | 是不是给文字添加背景 | 1 (enable) 0(disable). |
| boxborderw | 设置上下边框的宽度，举个例子 boxborderw=10|20|30|40，分别是上边框|右边框|底边框|左边框 | |
| boxcolor | 背景的颜色，可以输入颜色名字（ffmpeg -colors），也可以输入颜色值（比如#afeeee） | |
| y_align | 想象一下画面就是一个二维坐标系，当把文字放到坐标系的时候，文字的那一部分与坐标点对齐。 | text-最高处与坐标对齐 baseline-文字的中间与坐标对齐 |
| borderw | 文字的描边的宽度 | |
| bordercolor | 文字描边的颜色 | |
| expansion | 文本扩展功能，现在就是normal和none两个值了，默认是normal,意思是你可以在text中使用函数 | normal支持的函数参考toc-Text-expansion |
| fix_bounds | 当你的文本要超出视频的左边的时候，这个值打开的时候，会修复超出边界问题，一直保持着不超出视频的左边 | |
| fontcolor | 字体的颜色 | |
| fontcolor_expr | 颜色的表达式，可以实现动态颜色 | |
| font | 字体名字 | |
| fontfile | 字体文件的路径 | |
| fontsize | 字体大小 | |
| shadowcolor | 阴影的颜色 | |
| shadowx、shadowy | 阴影的位置 | |
| start_number | 设置变量的n的开始数字 | |
| text | 要写的文字 | |
| textfile | 文字可以保存在文件中，这里写文件的路径 | |
| reload | 经过多少帧重新加载一次textfile |
我测试了一下boxh boxw line_spacing text_align，感觉他们没有起作用，不知道啥原因（有清楚的大神请给留个言）
案例
原图
ffmpeg -y -i ffm_media/wonder_girls.jpg -filter_complex "drawtext=textfile='ffm_media/drawtext.txt':fontsize=80:x=(w-text_w)/2:y=h-text_h+5:fontcolor=white" result/drawtext/drawtext_test_002.jpg设置了字体，文本保存在了文件中了
ffmpeg -y -i ffm_media/wonder_girls.jpg -filter_complex "drawtext=text='hello wonder girls':fontsize=80:x=(w-text_w)/2:y=h-text_h:fontcolor=white:borderw=5:bordercolor=pink" result/drawtext/drawtext_test_005.jpg设置了字体的描边
ffmpeg -y -i ffm_media/wonder_girls.jpg -filter_complex "drawtext=text='hello wonder girls':fontsize=80:x=(w-text_w)/2:y=h-text_h:fontcolor=white:borderw=5:shadowcolor=green:shadowx=5:shadowy=7" result/drawtext/drawtext_test_007.jpg设置了字体的阴影
ffmpeg -y -i ffm_media/wonder_girls.jpg -filter_complex "drawtext=text='hello wonder girls':fontsize=80:x=(w-text_w)/2:y=h-text_h-50:fontcolor=white:box=1:boxborderw=10|20|30|40:boxcolor=blue" result/drawtext/drawtext_test_009.jpg设置了背景
ffmpeg -y -i ffm_media/short_dancer.mp4 -ss 3 -filter_complex "drawtext=text='%{localtime} frame %{n}':fontsize=40:x=(w-text_w)/2:y=h-text_h-n:fontcolor=white:box=1:boxborderw=10|20|30|40:boxcolor=blue:y_align=baseline" result/drawtext/drawtext_dancer_005.mp4设置动态移动的文字，这里主要是纵向移动，是因为在y变量中应用了 n（当前的帧数） 这个变量
ffmpeg -y -i ffm_media/short_dancer.mp4 -filter_complex "drawtext=text='%{localtime} frame %{n}':fontsize=40:x=(w-text_w)/2:y=h-text_h-n:fontcolor_expr='%{eif\\:if(between(t\, 0\, 3)\, 0xFFFFFF\, 0xFFB6C1) \\: x}':box=1:boxborderw=10|20|30|40:boxcolor=blue" result/drawtext/drawtext_dancer_006.mp4动态改变颜色的，这个是根据时间判断的，3秒前是一个颜色，3秒以后是另一个颜色。
## 祝你好运
hope("大神多多指点")
topic("有问题可以交流呀")
concat("球球QUN", "61480", "9646")