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• Controlling ffmpeg at runtime with zmq

  3 avril 2023, par Gavin

  I want to dynamically change the rectilinear view (eg its yaw) of a 360 video as it plays.

  


  basic command

  


  To take a 360 video and show a flat/normal view at a yaw perspective of 60 degrees

  


  ffmpeg -i input360.mp4 -vf "v360=input=e:rectilinear:yaw=60,scale=iw/4:-1" out60.mp4
This works fine.

  


  Changing the yaw during playback

  


  I understand ffmpeg has two methods to change filter params at runtime ; sendcmd (file based) and zmq (message based)

  


  I got sendcmd method working, but am struggling to understand zmq syntax and use. ffmpeg's zmq docs are pretty sparse.
I am using a local Windows 10 PC

  


  sendcmd

  


  ffplay -i input360.mp4 -vf "sendcmd=f=cmd.txt,v360=input=e:rectilinear:reset_rot=1,scale=iw/4:-1"

  


  with a cmd.txt file

  


  0-5 [expr] v360 yaw 'lerp(0,90,TI)';
5-10 [expr] v360 yaw 'lerp(90,0,TI)';


  


  result : yaw changes from 0 to 90 degrees from t=0-5s and then 90 to 0 degrees from t=5-10s. Perfect

  


  zmq

  


  ffplay -i input360.mp4 -vf "v360=input=e:rectilinear:reset_rot=1,zmq,scale=iw/4:-1"

  


  I got zmqsend from ffmpeg-tools.zip and added to my ffmpeg bin directory

  


  


  1. execute above ffplay command from terminal window #1 - and see video playing

     


  


  2. Open terminal window #2 and execute : echo v360 yaw 90 > zmqsend

     


  


  


  result : no change to video yaw. No errors either

  


  What am I doing wrong ? Im not sure if my ffmpeg command is wrong, or if my zmq message does not reach ffmpeg (or both). I checked my ffmpeg v2022-10-10 config has —enable-libzmq

  


• ffmpeg setpts filter not applied to output

  29 avril 2019, par joe5

  Learning to speed up and slow down video using the ffmpeg setpts filter, but I am struggling to get a simple expression to work.

  ffmpeg -i .\F5-ff.mp4 -filter:v "setpts=0.25*PTS" ff-test3.mp4

  I get the output file, but it is not any faster than the original.

  I’m sorry if this has already been addressed. Most related post I’ve found were trouble shooting more complex operations past this step. Im working in a powershell terminal fyi.

• OpenCV3.1 compilation error 'ffmpeg/avformat.h' file not found

  15 décembre 2016, par aquagremlin

  On MacOS 10.9.5 Mavericks. I used homebrew to install Python, cmake, ffmpeg.
  Entering ffmpeg in terminal shows it is installed.
  I downloaded Opencv3 and opencv_contrib

  Then cmake with this :

  cmake -D CMAKE_BUILD_TYPE=RELEASE \
  
      -D WITH_CUDA=OFF -D CMAKE_INSTALL_PREFIX=/Users/stefan/Downloads/opencv-3.1.0dl/build \
  
      -D PYTHON2_LIBRARIES=/usr/local/Cellar/python/2.7.10/Frameworks/Python.framework/Versions/2.7/bin \
  
      -D PYTHON2_PACKAGES_PATH=~/.virtualenvs/cv/lib/python2.7/site-packages \
  
      -D PYTHON2_NUMPY_INCLUDE_DIRS=~/.virtualenvs/cv/lib/python2.7/site-packages/numpy/core/include \
  
      -D PYTHON2_INCLUDE_DIR=/usr/local/Frameworks/Python.framework/Headers \
  
      -D INSTALL_PYTHON_EXAMPLES=ON -D WITH_TBB=ON  -D INSTALL_C_EXAMPLES=ON \
  
      -D FFMPEG_INCLUDE_DIR=/usr/local/Cellar/ffmpeg/3.0.2/include \
  
      -D FFMPEG_LIB_DIR=/usr/local/Cellar/ffmpeg/3.0.2/lib \
  
      -D BUILD_EXAMPLES=ON \
  
      -D OPENCV_EXTRA_MODULES_PATH=~/Downloads/opencv_contrib-3.0.0/modules ..

  Terminal output included this :

  --   Video I/O:
  
  --     DC1394 1.x:                  NO
  
  --     DC1394 2.x:                  NO
  
  --     FFMPEG:                      YES
  
  --       codec:                     YES (ver 57.24.102)
  
  --       format:                    YES (ver 57.25.100)
  
  --       util:                      YES (ver 55.17.103)
  
  --       swscale:                   YES (ver 4.0.100)
  
  --       resample:                  YES (ver 3.0.0)
  
  --       gentoo-style:              YES

  But CMakeError.log had this as its only error :

  ffmpeg/avformat.h file not found

  The file does exist at

  /usr/local/Cellar/ffmpeg/3.0.2/include/libavformat/avformat.h

  I do not understand why I am getting this error if I properly specified the FFMPEG include directories in the cmake command. Also the variables FMPEG_INCLUDE_DIR and FFMPEG_LIB_DIR do not exist in the file, CMakeLists.txt.
  Does that make my use of those variables in the cake command useless ?