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• FFMPEG command runs forever even on using timelimit

  21 décembre 2017, par t6nand

  Mostly I use a java code to run FFMPEG bash commands for watermarking a logo on video. I am using the following FFmpeg command to overlay an image on video. I have observed that at times for some random videos, the process keeps on running even after the timelimit assigned to it expires. At times it’s more than a day or couple of days until not directly killed using kill -9 pid :

  ffmpeg -timelimit 900 -y -i
  input_video
  -i logoImage -filter_complex "[0:v]scale=trunc(iw/2)*2:trunc(ih/2)*2[even] ;[1:v][even]scale2ref=iw*0.25 :(iw*0.25)*(0.46446702)[2nd][ref] ;[ref][2nd]overlay=(main_w-overlay_w) :(main_h-overlay_h)"
  -c:v libx264 -b:v 300K -crf 28 -preset slow outputVideo

  But this command never completes even on using -timelimit flag at times for some videos.

  I have observed that for such processes output from ps aux|grep ffmpeg yeilds in something like :

  ubuntu 16620 0.6 6.7 1595044 515392 ? Sl Dec20 12:05
  ffmpeg -timelimit 900 -y -i
  input_video
  -i logoImage -filter_complex "[0:v]scale=trunc(iw/2)*2:trunc(ih/2)*2[even] ;[1:v][even]scale2ref=iw*0.25 :(iw*0.25)*(0.46446702)[2nd][ref] ;[ref][2nd]overlay=(main_w-overlay_w) :(main_h-overlay_h)"
  -c:v libx264 -b:v 300K -crf 28 -preset slow outputVideo

  It indicates that this process is in interruptible sleep state i.e. waiting for an event to complete. On using sudo strace -p 16620 to trace which system call is this process hung up on it results in something like :

  Process 16620 attached write(2, "frame= 4121 fps= 10 q=33.0 size="...,
  99

  i.e. it’s stuck writing to a file.

  What could be the reason for this problem ?
  And is there any other way to kill FFMPEG process which overshoots desired time limit ?

• How do I connect two GIFs to play one after another in Python ?

  9 novembre 2022, par Andrew

  If I have two GIFs, GIF 1 being 10 seconds long and GIF 2 being 5 seconds long, is there a way to connect them so the final GIF is a total of 15 seconds long ?

  


  Would I have to loop through each frame of both the GIFs with imageio.mimread() and output, once all the frames are read in memory ?

  


  Or is there another way by knowing the start and end times and shifting it ?

  


  Edit :
The solution presented by FirefoxMetzger is extremely Pythonic, ideal if you do not wish to install other software / packages like gifsicle.

  


  import imageio.v3 as iio
import numpy as np

frames = np.vstack([
    iio.imread("imageio1.gif"),
    iio.imread("imageio2.gif"),
])

# get duration each frame is displayed
iio.imwrite("imageio_combined.gif", frames)


  


  This completes in 15.6 seconds for two GIFs, each containing 100 frames.

  


  However, if runtime is important, I recommend gifsicle :

  


  gifsicle(
    sources=["imageio1.gif", "imageio2.gif"], # or just omit it and will use the first source provided.
    destination="imageio3.gif",
    options=["--optimize=2", "--threads=2", "--no-conserve-memory"]
)


  


  This completes in 4.8 seconds, which is three times as fast.

  


• Run ffmpeg once but get multiple screenshots

  9 novembre 2017, par user779159

  I get a screenshot from a remote video file using ffmpeg with a command like ffmpeg -ss $TIME -i $URL -frames:v 1 -filter:v $FILTER file.jpg (-ss comes before -i for fast seeking https://trac.ffmpeg.org/wiki/Seeking). $FILTER is how I want to transform the screenshot, like cropping/resizing. In this case it’s "crop=iw-5:ih-5, scale=100:100:force_original_aspect_ratio=increase, crop=100:100")

  If I want to get 3 screenshots, at 3 seconds, 5 seconds, and 14 seconds, I need to run this command 3 separate times, passing 3, 5, and 14 as $TIME. But is it possible to run the command once but have it output multiple screenshot files for the different times ?

  And would ffmpeg do that in a way where it would make the round-trip remote request just 1 time instead of 3 ? In that case it would be more efficient. If not, then maybe it’s better to make the 3 requests separately since I could do it in parallel.