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• Why is the ffmpeg `-vsync passthrough` option not extracting the same number of frames as shown in the printed info ?

  3 juin 2022, par aininja

  I am using ffmpeg to extract all the frames in a video. To get the timestamps of each frame, I'm using the -vf showinfo filter and matching the frame numbers. The problem is that sometimes the number of frames shown in the info doesn't match up with the number of frames extracted. Why could this be happening ? Is there some default output option that I need to change to avoid this ? Is this non-deterministic behavior a bug ?

  


  The commands used to extract and inspect the frames are :

  


  $ mkdir frames
$ ffmpeg -i video.mp4 -f image2 -vf showinfo -vsync passthrough -q:v 1 frames/%05d.jpg 2> info.txt
$ NUM_FRAMES_INFO=$(cat info.txt | grep pts_time | wc -l)
$ NUM_FRAMES_JPGS=$(ls frames/*.jpg | wc -l)
$ echo ${NUM_FRAMES_INFO} ?= ${NUM_FRAMES_JPGS}


  


  For most videos, this produces the correct outputs all the time. For some videos, however, there is a mismatch occasionally. Also worth mentioning is that MP4 videos are the only ones used and tested. These videos generally only had a single video stream in them.

  


• how input the file text to ffmpeg ? simple text

  18 juillet 2023, par manuel

  the file text.txt :

  


  ./folder1/folder2/AAA.avi
./folder2/AAB.avi
.ABA.avi
./folder6/BBA.avi
...
...


  


  for bash :

  


  batchfiles="text.txt"
ffmpeg -i $batchfiles $batchfiles.mp4


  


  result error :

  


  text.txt: Invalid data found when processing input


  


  how resolve it ? I'm sure that I'm wrong code...can you help me ? thank you

  


• How to add background image for text with text size on a video in FFmpeg ?

  24 octobre 2019, par manwtein

  Is there way to add a background image under the text on the video in FFmpeg ?

  I can add black background using ’box’, but i need to add some certain image. I tried to use ’drawtext’ on a image and then overlayed it on the video, but i don’t know text’s width and height for scaling the image.

  "-i",
  
  "D:/AndroidProjects/Movies/VideoSamples/VideoShort1.mp4",
  
  "-i",
  
  "D:/AndroidProjects/Movies/ImageSamples/SampleImage.jpeg",
  
  "-filter_complex",
  
  "[0:v]drawtext=text='Example':fontcolor=#DB7093:fontsize=120:box=1:boxcolor=black@0.8:boxborderw=5:x='(w/2) - (tw/2)':y='h - ((h/2) - (th/2))",
  
  "-s",
  
  "1280x720",
  
  "-y",
  
  "D:/AndroidProjects/Movies/FFmpegSampleShort0.mp4"

  I expect to get video with some image background under my text instead black color.