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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 ...

  


• FFmpeg - add an animated gif (cropped by mask) to the video

  11 mars 2021, par zeromodule

  I have 3 inputs :

  


  

  1. Video file : https://file.io/6jtUlnZ7TGmT

  


  2. Animated GIF with transparent background https://i.imgur.com/Vo3KHZm.gif

  


  3. Mask file (BW) the same resolution as the video https://i.imgur.com/YJXUUrZ.png

  


  


  I want to put the image on the video, but throw out all GIF pixels that are transparent in the mask (replace them with transparent ones).

  


  
  

  

  


  


  My current command, without masking (it works fine) :

  


  ffmpeg -i input.mp4 -ignore_loop 0 -i animation.gif \
-filter_complex "[1]scale=700x700[scaled_gif];\
[0][scaled_gif]overlay=50:30:shortest=1" \
-codec:a copy output.mp4


  


  UPDATE #1

  


  I managed to get closer to my goal with this command :

  


  ffmpeg -y -i input.mp4 -loop 1 -i mask.png \ 
-filter_complex "[1:v]alphaextract[mask]; \
movie=animation.gif,scale=1920x1080[scaled_gif]; \
[scaled_gif][mask]alphamerge[masked]; \
[0:v][masked]overlay=0:0" \
-c:a copy output_masked.mp4


  


  but it has 2 problems :

  


  

  1. GIF loses it's transparency. Transparent pixels become white.

  


  2. GIF plays only once (i.e. no loop)

  


  


  Output : https://file.re/2021/03/11/outputmasked/

  


• ffmpeg need perfect pixels for LED processing (h264, mpeg 1, 2)

  24 avril 2018, par Shawn Faherty

  
  We have .mov with Animation codec and the pixels look great. But the LED media players are looking for h264, mpeg-1 or mpeg2. Is this even possible to get high pixel accuracy ? I read a lot of the comments and tried the h264 lossless to no avail. Thanks for your help !