Use ffmpeg to rotate, flip up and down, and flip horizontally

brief introduction ： In the use of ffmpeg do .h264 After coding, you may use vlc When playing, the image is vertically reversed . Probable cause ：RGB There are two ways to store images ： One is to scan from top to bottom ; The other is scanning from bottom to top .OpenCV Scanning from top to bottom ,ffmpeg It may also be a top-down storage method , and OpenGL/Unity The frame buffer data in may be scanned from bottom to top , This leads to the problem of vertical flipping of the image .

Vertical rotation ：

ffmpeg -i  Original video .mp4 -vf vflip -y  Flip left and right .mp4

Flip left and right horizontally ：

ffmpeg -i  Original video .mp4 -vf hflip -y  Flip left and right .mp4

The picture rotates clockwise 90 degree ：

ffmpeg -i  Original video .mp4 -vf transpose=1  along 90 degree .mp4

The picture rotates counterclockwise 90°：

ffmpeg -i  Original video .mp4 -vf transpose=2  The inverse 90 degree .mp4

The processing method of pictures is consistent with that of videos , Switch the corresponding type to picture .

ffmpeg -i  Original picture .png -vf vflip -y   Flip up and down .png
ffmpeg -i  Original picture .png -vf hflip -y   Flip left and right .png
ffmpeg -i  Original picture .png -vf transpose=1  along 90 degree .png
ffmpeg -i  Original picture .png -vf transpose=2  The inverse 90 degree .png

Final execution result ：

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Welcome to your attention , Common progress , thank you ！