On 2 Aug 2020 22:22:56 GMT, ray carter wrote:

I simply use 'ffmpeg' - one simple command line. And it's multithreaded
so maxes out all foyr cores on my desktop.

Ah, yes, FFMEPG!
o https://ffmpeg.org/download.html
o https://sourceforge.net/projects/ffmpeg/

Thanks for that suggestion to use FFMPEG freeware, which also came up on
the Android newsgroups when discussing how to run the conversion on the
smartphone:
o *Android ad free gsf free freeware to rotate a cellphone video by 90 degrees*
https://groups.google.com/forum/#!topic/comp.mobile.android/ef_YFoctoLA

Given the US & European patents finally expired, FFMPEG should be
packagable in other apps nowadays, without us having to download it
separately, e.g., for Audacity https://audacityguide.com/ffmpeg-audacity.

Looking up the FFMPEG command to rotate 90 degrees, I find it he
o *How To Rotate Videos Using FFMpeg From Commandline*
https://ostechnix.com/how-to-rotate-videos-using-ffmpeg-from-commandline/
o $ ffmpeg -i input.mp4 -vf "transpose=clock" output.mp4
Or...
o $ ffmpeg -i input.mp4 -vf "transpose=1" output.mp4
Where...
o 0 - Rotate by 90 degrees counter-clockwise and flip vertically
o 1 - Rotate by 90 degrees clockwise.
o 2 - Rotate by 90 degrees counter-clockwise.
o 3 - Rotate by 90 degrees clockwise and flip vertically.

Where flipping vertically & horizontally is also scripted:
o *Rotate/flip video with ffmpeg*
https://duxyng.wordpress.com/2013/04/07/rotateflip-video-with-ffmpeg/
For example... To Flip video vertically:
o ffmpeg -i INPUT -vf vflip -c:a copy OUTPUT

To Flip video horizontally:
o ffmpeg -i INPUT -vf hflip -c:a copy OUTPUT

To Rotate 90 degrees clockwise:
o ffmpeg -i INPUT -vf transpose=1 -c:a copy OUTPUT

To Rotate 90 degrees counterclockwise:
o ffmpeg -i INPUT -vf transpose=2 -c:a copy OUTPUT

Where there's a snippet of FFMPEG batch commands he
https://gist.github.com/cmlewis/f950d876171a11703f89
o ffmpeg_rotate_90_or_180_degrees.bat
rem For the transpose parameter you can pass:
rem
rem 0 = 90CounterCLockwise and Vertical Flip (default)
rem 1 = 90Clockwise
rem 2 = 90CounterClockwise
rem 3 = 90Clockwise and Vertical Flip
rem
rem To rotate 180 degrees, instead use "transpose=2,transpose=2"
rem
rem Using -codec:a copy will simply copy the audio instead of reencoding
rem
ffmpeg -i in.mp4 -vf "transpose=1" -codec:a copy out.mp4
--
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