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• compile own ffmpeg filter

  20 juin 2023, par lfk

  I'm trying compile my own ffmpeg filter using official tutorial. My filter uses C++ code. I made header file and adapted my C++ function definition for C. Now I'm trying compile with command make -j<libavfilter> ffmpeg</libavfilter>, but receiving an error message

  


  


  gcc -Llibavcodec -Llibavdevice -Llibavfilter -Llibavformat
-Llibavresample -Llibavutil -Llibpostproc -Llibswscale -Llibswresample -Wl,—as-needed -Wl,-z,noexecstack -Wl,—warn-common -Wl,-rpath-link=libpostproc:libswresample:libswscale:libavfilter:libavdevice:libavformat:libavcodec:libavutil:libavresample
-o ffmpeg_g fftools/ffmpeg_opt.o fftools/ffmpeg_filter.o fftools/ffmpeg_hw.o fftools/cmdutils.o fftools/ffmpeg.o -lavdevice
-lavfilter -lavformat -lavcodec -lswresample -lswscale -lavutil -lm -pthread -lm -lm -lz -pthread -lm -lz -lm -lm -pthread -lm libavfilter/libavfilter.a(vf_foobar.o) : In function `filter_frame' :
/home/joeyes/ffmpeg_sources/ffmpeg/libavfilter/vf_foobar.c:302 :
undefined reference to MyFunction.c
collect2 : ld returned 1 exit status
*** [ffmpeg_g] Error 1

  


  


  For compilation I added OBJS-$(CONFIG_FOOBAR_FILTER) += vf_foobar.o MyCode.o to /libavfilter/makefile

  


  Also I put MyCode.h & MyCode.cpp to /libavfilter folder

  


• Error while saving a matplotlib animation, missing 'dpi' argument

  27 septembre 2020, par aarcas

  I'm trying to save an animation of matplotlib.animation.AnimationFunc and I get an error saying 'dpi' argument missing. Obviously, I have the dpi set so I don't understand where this error comes from.

  



  I'm running python 3.6 and matplotlib 3.0.3, I also just installed ffmpeg from ubuntu official repositories (Ubuntu 18.04).

  



  This is the part of my code that should affect that, although I think it should be something of the system :

  



  Writer = writers['ffmpeg']
writer = Writer(fps=15, metadata=dict(artist='Me'), bitrate=1800,)
ani = FuncAnimation(fig, anime, interval=time_step *
                    10**3, frames=F, repeat=False,) 
ani.save('standard_map.mp4', writer=Writer, dpi=100)


  



  The errors is :

  



  with writer.saving(self._fig, filename, dpi):
File "/usr/lib/python3.6/contextlib.py", line 159, in helper
    return _GeneratorContextManager(func, args, kwds)
File "/usr/lib/python3.6/contextlib.py", line 60, in __init__
    self.gen = func(*args, **kwds) TypeError: saving() missing 1 required positional argument: 'dpi'


  



  I tried both adding the lines they suggested there and the error stills the same.

  



  plt.rcParams['animation.ffmpeg_path'] = '/usr/bin/ffmpeg'


  



  I also tried changing the writer to 'imagemagick' the one set on Ubuntu by default and the error persists.

  


• What are all the command `options` to execute with ?

  25 janvier 2023, par Phil Lucks

  I'd like to be able to compress the video in a way to help improve upload times.

  


  In reading the docs for FFMpeg Kit, using React Native, there is a basic execute command string of '-i file1.mp4 -c:v mpeg4 file2.mp4'... I can guess at what some of this means, in terms of input & output file names based on the ffMPEG docs, however, some of these options I am not sure of.

  


  Like why is there a -i flag prefix ? Is this "input" ?
Why is there -c:v ? Is this "convert video" ?
What if I want to reduce frame rate, or change size of video ?

  


  The TS def is just a string...

  


  Is there a good place to understand what the official docs options map to the strings ? I think