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• Installing gifify on Windows

  12 octobre 2017, par Robert Wojciechowski

  So gifify is a pretty awesome script that converts videos to gifs via command line : https://github.com/vvo/gifify

  I’m keen to get this working on my Windows 10 machine. I’m pretty new to windows and relatively new to coding, but I was able to get a few things working, but ran into a problem.

  Here is what I did :

  1. Installed node.js + npm
  2. Installed FFmpeg using npm
  3. Installed ImageMagick using npm (i think i did this wrong, might have only installed the wrapper).
  4. Downloaded giflossy. It needed to be built (?)
  5. Installed Visual Studio 2015, tried to build it using nmake and got this error :

  NMAKE : fatal error U1073: don't know how to make 'win32cfg.h'

  The command I used was :

  PS C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\bin> .\nmake -f "C:\Users\Robert's Workstation\.npm-global\node_modules\giflossy-lossy-1.82.1\src\Makefile.w32"

  Would really appreciate some help with this :D

• Using ffmpeg to split videos into frames doesn't work

  28 décembre 2018, par אבנר יעקב

  In my code i’m trying to split video to frames using ffmpeg.

  for this I’m using this code

  experiments = ['iguazu.mp4', 'boat.mp4']
  
  
  
  for experiment in experiments:
  
      exp_no_ext = experiment.split('.')[0]
  
      os.system('mkdir dump')
  
      os.system('mkdir dump\%s' % exp_no_ext)
  
      os.system("ffmpeg -i videos\%s dump\%s\%s%%03d.jpg" % (experiment, 
  
  exp_no_ext, exp_no_ext))

  So in visual studio code it’s working perfect but in visual studio community the line "os.system("ffmpeg -i videos\%s dump\%s\%s%%03d.jpg" % (experiment,
  exp_no_ext, exp_no_ext))" showing error "ffmpeg is not recognized as an internal or external command".

• How to save ffmpeg segmets to disk immediately with sub-second intervals ?

  20 octobre 2023, par amfast

  I'm trying to record video on a raspberry and have it save as much as possible (sub-second resolution) in case of a power cutoff.

  


  I use -f segment to save the encoded stream in 100ms segments with the hope that all but the interrupted (by power cutoff) segment will be saved in memory. Unfortunately, when cutting off power, all the destination files (output_0001.mp4, output_0002.mp4, ...) are created, but empty.

  


  To save the files to disk immediately, I added the -strftime 1 option that allows formatting the output filename as time. It seems weird that this is the (only ?) way to trigger immediate saving of files, but it works - untill I try to have segments smaller than 1 second. The problem seems to be that the format string %d, that previously added a sequence number in my output filenames, now represents "day" (i.e. date) and the smallest resolution time format string is %S for second. I saw %f suggested somewhere for smaller resolutions, but it only prints "%f".

  


  The result is that the segmentation part of ffmpeg does create 100ms segments and save them to disk immediately, but the strftime feature gives the output files names that only change every second, so all the interim files are overwritten.

  


  Example of the failing command below. Without the -strftime option this creates nice segments, but does not save them to disk immediately.

  


  libcamera-vid --flush \
    --framerate ${FRAMERATE} \
    --width ${WIDTH} \
    --height ${HEIGHT} \
    -n \
    -t ${TIMEOUT} \
    --codec yuv420 \
    -o - | 
ffmpeg \
    -fflags nobuffer \
    -strict experimental \
    -loglevel debug \
    -flags low_delay \
    -f rawvideo \
    -pix_fmt yuv420p \
    -s:v ${WIDTH}x${HEIGHT} \
    -r ${FRAMERATE} \
    -i - \
    -c:v h264_v4l2m2m \
    -f segment \
    -segment_time 0.1 \
    -segment_format mp4 \
    -reset_timestamps 1 \
    -strftime 1 \
    -b:v ${ENCODING_BITRATE} \
    -g 1 \
    "output_%04d.mp4"


  


  Question :
  
Is there another way besides -strftime to trigger immediate saving ? Or is there a mechanism to feed finer resolution format strings to the output filename ?