Ffmpeg --- image processing

explain ： In the following test command image_source Is the input file to be processed ,out_source It is the output file after processing

1. Picture compression ：ffmpeg It can perfectly compress pictures to generate new pictures , And you can set the compression level

ffmpeg -i image_source -q compress_level out_source
#compress_level： The compression level is a positive integer , The higher the value, the higher the compression level 

2. Constrain proportional compression

ffmpeg You can compress the picture to a specified size

ffmpeg -i image_source -vf scale=width:height out_source
#width Is the width of the compressed picture 
#height Is the height of the compressed picture 
# When width or height One of the values is -1 It will keep the original image size ratio compressed 

3. Image clipping

ffmpeg You can specify the cropping position and size of the image

ffmpeg -i image_source -vf crop=width:height:from_x:from_y out_source
#width Is the width of the image to be cropped 
#height Is the height of the image to be cropped 
#from_x It is the beginning of cutting X Position of the shaft 
#from_y It is the beginning of cutting Y Position of the shaft 
# If you don't specify from_x and from_y Means to crop from the center of the original picture 

4. Add watermark image

ffmpeg You can add watermarks to pictures , You can set the size of the watermark image 、 Location and transparency

ffmpeg -i image_source -vf movie=logo_source,scale=logo_width:logo_height,lut=a=val*opacity_num[watermask];[in][watermask] overlay=from_x:from_y[out] -y  out_source
#logo_source Is the watermark image address 
#logo_width Is the width of the watermark image 
#logo_height Is the height of the watermark image 
#opacity_num For the transparency of watermark image 
#from_x Is the beginning of the watermark X Position of the shaft 
#from_y Is the beginning of the watermark Y Position of the shaft 

5. Add text watermark  

ffmpeg You can add text watermarks to pictures , You can set the font 、 Color 、 Size 、 Written content 、 Text location

ffmpeg -i image_source -vf drawtext=fontfile=font_ttf_path:fontcolor=font_color:fontsize=font_size:text=message_info:x=from_x:y=from_y  out_source
#font_ttf_path Is the font path , This item must be set, otherwise there will be an error that the font cannot be found ;
# Set the absolute path for the font path and pay attention to the escape of the positive and negative slashes of the path ( for example C\\:/Windows/Fonts/simhei.ttf)
#font_color For the color of the font 
#font_size Is the size of the font 
#message_info Watermark text content 
#from_x Is the beginning of the watermark X Position of the shaft 
#from_y Is the beginning of the watermark Y Position of the shaft 
# If the watermark content is Chinese, you need to set the Chinese font, otherwise the text will display garbled 

6. Rotate the picture by the specified angle

ffmpeg You can rotate the picture according to the specified angle to generate a new picture

ffmpeg -i image_source -vf rotate=route_num*PI/180 -y  out_source
#route_num Is the angle to rotate 
# When route_num Greater than 0 Rotate clockwise when , When route_num Less than 0 Rotate counterclockwise when 

7. Image rotation special simple command

The above command can theoretically complete all image rotation operations , but ffmpeg There is still a special simple rotating life

ffmpeg -i image_source -vf transpose=route_number -y out_source
#route_number=0 Clockwise rotation 90 Degrees mirror left and right again 
#route_number=1 Clockwise rotation 90 degree 
#route_number=2 Counter clockwise rotation 90 degree 
#route_number=3 Counter clockwise rotation 90 Degrees mirror left and right again 

8. The picture is mirrored left and right

ffmpeg -i image_source -vf hflip out_source

9. Mirror the picture up and down

ffmpeg -i image_source -vf vflip out_source