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• Using `grab_frame` with `FFMpegFileWriter` Yields Error in the Figure Argument to Subprocess

  7 juillet 2024, par GPU Programmer

  I want to generate an MP4 file using frames produced by a rather complicated simulation. If I have to watch the movie as a side affect of generating it I will not complain too much, but would rather not "show" anything on the screen. The overhead of making the movie is trivial compared to the simulations, so I care much more about clean simple code than about performance.

  


  It seemed natural to use grab_frame with FFMpegFileWriter. The following code seemed right.

  


  fig, ax = plot.subplots(figsize=(6.5, 6.5))

assert(animation.FFMpegFileWriter().isAvailable())
writer = animation.FFMpegFileWriter(fig)
writer.setup(fig, "test1.mp4",224)

with writer.saving(fig,"test1.mp4", dpi=224):
    for i in range(len(frameSeg)):
        PlotFrame(i)
        writer.grab_frame()

# writer.finish()

print("done")


  


  It runs, but yeilds the following error

  


  


  [image2 demuxer @ 0000021fab8c1000] Unable to parse option value "Figure(650x650)" as video rate
[image2 demuxer @ 0000021fab8c1000] Error setting option framerate to value Figure(650x650).
[in#0 @ 0000021fab8c1e00] Error opening input : Invalid argument
Error opening input file ... AppData\Local\Temp\tmpe19ci2wz\tmp%07d.png.
Error opening input files : Invalid argument

  


  


  


  subprocess.CalledProcessError : Command '['ffmpeg', '-framerate', 'Figure(650x650)', '-i', 'F :\Users\Kenne.DESKTOP-BT6VROU\AppData\Local\Temp\tmpe19ci2wz\tmp%07d.png', '-loglevel', 'error', '-vcodec', 'h264', '-pix_fmt', 'yuv420p', '-y', 'test1.mp4']' returned non-zero exit status 4294967274.

  


  


  Did I miss something in setup, is it an installation problem, or is it a bug ?

  


  By the way using FFMpegWRiter with FuncAnimation works ...

  


• Where is my ffmpeg stream getting saved to ?

  20 mars 2019, par Chris

  I’m just starting to explore ffmpeg (ultimately for use with openCV), and I’m running this command :

  root@beaglebone:/# ffmpeg -f video4linux2 -r 25 -s 640x480 -i /dev/video0 /out.avi

  At which point the camera indicator light turns on and it appears to be capturing. However when I end it with CTRL+C, the file is nowhere to be found.

  Any thoughts ?

  Full output :

  root@beaglebone:/# ffmpeg -f video4linux2 -r 25 -s 640x480 -i /dev/video0 /out.avi
  
  ffmpeg version v0.7.4, Copyright (c) 2000-2011 the Libav developers
  
    built on Oct  9 2012 10:50:57 with gcc 4.5.4 20120305 (prerelease)
  
    configuration: --enable-shared --enable-pthreads --enable-gpl --enable-postproc --enable-avfilter --cross-prefix=arm-angstrom-linux-gnueabi- --prefix=/usr --enable-ffserver --enable-ffplay --enable-x11grab --enable-libtheora --enable-libvorbis --arch=arm --target-os=linux --enable-cross-compile --extra-cflags=' -fexpensive-optimizations -fomit-frame-pointer -O4 -ffast-math -march=armv7-a -fno-tree-vectorize -mthumb-interwork -mfloat-abi=softfp -mfpu=neon -mtune=cortex-a8 --sysroot=/home/koen/setup-scripts/build/tmp-angstrom_v2012_05-eglibc/sysroots/beaglebone' --extra-ldflags='-Wl,-O1 -Wl,--hash-style=gnu -Wl,--as-needed' --sysroot=/home/koen/setup-scripts/build/tmp-angstrom_v2012_05-eglibc/sysroots/beaglebone --enable-hardcoded-tables --cpu=cortex-a8
  
    libavutil    51.  7. 0 / 51.  7. 0
  
    libavcodec   53.  6. 0 / 53.  6. 0
  
    libavformat  53.  3. 0 / 53.  3. 0
  
    libavdevice  53.  0. 0 / 53.  0. 0
  
    libavfilter   2.  4. 0 /  2.  4. 0
  
    libswscale    2.  0. 0 /  2.  0. 0
  
    libpostproc  52.  0. 0 / 52.  0. 0
  
  ^C
  
  root@beaglebone:/# ls
  
  bin   dev  home  lost+found  mnt  proc  sbin  tmp  var
  
  boot  etc  lib   media       opt  run   sys   usr
  
  root@beaglebone:/#

• Where is my ffmpeg stream getting saved to ?

  14 mars 2013, par Chris

  I'm just starting to explore ffmpeg (ultimately for use with openCV), and I'm running this command :

  root@beaglebone:/# ffmpeg -f video4linux2 -r 25 -s 640x480 -i /dev/video0 /out.avi

  At which point the camera indicator light turns on and it appears to be capturing. However when I end it with CTRL+C, the file is nowhere to be found.

  Any thoughts ?

  Full output :

  root@beaglebone:/# ffmpeg -f video4linux2 -r 25 -s 640x480 -i /dev/video0 /out.avi
  
  ffmpeg version v0.7.4, Copyright (c) 2000-2011 the Libav developers
  
    built on Oct  9 2012 10:50:57 with gcc 4.5.4 20120305 (prerelease)
  
    configuration: --enable-shared --enable-pthreads --enable-gpl --enable-postproc --enable-avfilter --cross-prefix=arm-angstrom-linux-gnueabi- --prefix=/usr --enable-ffserver --enable-ffplay --enable-x11grab --enable-libtheora --enable-libvorbis --arch=arm --target-os=linux --enable-cross-compile --extra-cflags=' -fexpensive-optimizations -fomit-frame-pointer -O4 -ffast-math -march=armv7-a -fno-tree-vectorize -mthumb-interwork -mfloat-abi=softfp -mfpu=neon -mtune=cortex-a8 --sysroot=/home/koen/setup-scripts/build/tmp-angstrom_v2012_05-eglibc/sysroots/beaglebone' --extra-ldflags='-Wl,-O1 -Wl,--hash-style=gnu -Wl,--as-needed' --sysroot=/home/koen/setup-scripts/build/tmp-angstrom_v2012_05-eglibc/sysroots/beaglebone --enable-hardcoded-tables --cpu=cortex-a8
  
    libavutil    51.  7. 0 / 51.  7. 0
  
    libavcodec   53.  6. 0 / 53.  6. 0
  
    libavformat  53.  3. 0 / 53.  3. 0
  
    libavdevice  53.  0. 0 / 53.  0. 0
  
    libavfilter   2.  4. 0 /  2.  4. 0
  
    libswscale    2.  0. 0 /  2.  0. 0
  
    libpostproc  52.  0. 0 / 52.  0. 0
  
  ^C
  
  root@beaglebone:/# ls
  
  bin   dev  home  lost+found  mnt  proc  sbin  tmp  var
  
  boot  etc  lib   media       opt  run   sys   usr
  
  root@beaglebone:/#