FFMPEG rotation metadata sometimes goes clockwise and sometimes goes counterclockwise - ffmpeg

Question

I have two different machines with two different versions of ffmpeg installed. I'm trying to set the display matrix of a video to have a rotation value by using the -metadata:s:v:0 rotate=$theta filter.
On machine #1
FFMPEG version:
$ ffmpeg -version
ffmpeg version 4.2.1 Copyright (c) 2000-2019 the FFmpeg developers
built with Apple clang version 11.0.0 (clang-1100.0.33.8)
configuration: --prefix=/usr/local/Cellar/ffmpeg/4.2.1_2 --enable-shared --enable-pthreads --enable-version3 --enable-avresample --cc=clang --host-cflags='-I/Library/Java/JavaVirtualMachines/adoptopenjdk-13.jdk/Contents/Home/include -I/Library/Java/JavaVirtualMachines/adoptopenjdk-13.jdk/Contents/Home/include/darwin -fno-stack-check' --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libbluray --enable-libmp3lame --enable-libopus --enable-librubberband --enable-libsnappy --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librtmp --enable-libspeex --enable-libsoxr --enable-videotoolbox --disable-libjack --disable-indev=jack
libavutil 56. 31.100 / 56. 31.100
libavcodec 58. 54.100 / 58. 54.100
libavformat 58. 29.100 / 58. 29.100
libavdevice 58. 8.100 / 58. 8.100
libavfilter 7. 57.100 / 7. 57.100
libavresample 4. 0. 0 / 4. 0. 0
libswscale 5. 5.100 / 5. 5.100
libswresample 3. 5.100 / 3. 5.100
libpostproc 55. 5.100 / 55. 5.100
Command:
$ ffmpeg -i 0_degree_rotation.mp4 -vcodec copy -metadata:s:v:0 rotate=90 /tmp/out.mp4
Metadata on output video:
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/tmp/out.mp4':
Metadata:
major_brand : isom
minor_version : 512
compatible_brands: isomiso2avc1mp41
title : "Camio"
encoder : Lavf58.29.100
Duration: 00:00:10.71, start: 0.000000, bitrate: 2241 kb/s
Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], 2239 kb/s, 14.94 fps, 14.94 tbr, 14941 tbn, 29.88 tbc (default)
Metadata:
rotate : 270
handler_name : VideoHandler
Side data:
displaymatrix: rotation of 90.00 degrees
On Machine #2
FFMPEG Version:
ffmpeg version 2.8.15-0ubuntu0.16.04.1 Copyright (c) 2000-2018 the FFmpeg developers
built with gcc 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.10) 20160609
configuration: --prefix=/usr --extra-version=0ubuntu0.16.04.1 --build-suffix=-ffmpeg --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --cc=cc --cxx=g++ --enable-gpl --enable-shared --disable-stripping --disable-decoder=libopenjpeg --disable-decoder=libschroedinger --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librtmp --enable-libschroedinger --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxvid --enable-libzvbi --enable-openal --enable-opengl --enable-x11grab --enable-libdc1394 --enable-libiec61883 --enable-libzmq --enable-frei0r --enable-libx264 --enable-libopencv
libavutil 54. 31.100 / 54. 31.100
libavcodec 56. 60.100 / 56. 60.100
libavformat 56. 40.101 / 56. 40.101
libavdevice 56. 4.100 / 56. 4.100
libavfilter 5. 40.101 / 5. 40.101
libavresample 2. 1. 0 / 2. 1. 0
libswscale 3. 1.101 / 3. 1.101
libswresample 1. 2.101 / 1. 2.101
libpostproc 53. 3.100 / 53. 3.100
Command:
$ ffmpeg -i /tmp/0_degree_rotation.mp4 -vcodec copy -metadata:s:v:0 rotate=90 /tmp/out.mp4
Metadata on output video
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/tmp/out.mp4':
Metadata:
major_brand : isom
minor_version : 512
compatible_brands: isomiso2avc1mp41
title : "Camio"
encoder : Lavf56.40.101
Duration: 00:00:10.71, start: 0.000000, bitrate: 2241 kb/s
Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], 2239 kb/s, 14.94 fps, 14.94 tbr, 14941 tbn, 29.88 tbc (default)
Metadata:
rotate : 90
handler_name : VideoHandler
Side data:
displaymatrix: rotation of -90.00 degrees
Why does the same command produce a rotation of +90 degrees in one version of ffmpeg and -90 degrees on a different version?

Answer 1

The rotate API was changed in version 3.3. The new API internally uses a different data structure to represent and store the rotation (and flipping) values, and its orientation is opposite to the old API. In general, 2.8 is a very old version, and you should upgrade all machines to 4.2.