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• Getting motion vector side data from ffmpeg from the compressed domain (without performing full decode)

  4 mai 2019, par John Allard

  The ffmepg source code comes with a file extract_mvs.c which is quite helpful in showing how to extract the motion vectors from an h264-encoded video file. Unfortunately, it performs a full decode before getting the motion vectors from the side data of the stream.

  One should be technically able to (as was confirmed by FFMPEG developer Carl Eugen in this thread https://ffmpeg.org/pipermail/libav-user/2016-December/009913.html) get the motion vectors from the compressed domain before performing a full decode step. This would obviously be less computationally intensive as one wouldn’t have to perform a full decode.

  Is it possible to do this with ffmpeg/libavcodec as is ? I know Carl said that it wasn’t possible but that was 3 years ago. If it is not currently possible, does anyone have any hints on how one would go about modifying the ffmpeg source code to do this ?

  Thanks

• FFMpeg overlay and fade images and text in and out at over video background

  28 décembre 2019, par grootester

  Prior to applying the drawbox and drawtext text option I was able to fade in and out images easily. However, attempting to incorporate the drawtext produces unwanted errors. Any ideas how this could be rememdied ? Love to show multi-line text (different fonts) centered over box at specific times with fade in fade out times that works alongside images fading in out at specific times.

  ffmpeg -i vids/testVid.mp4 -loop 1 -i slideshow/pic1.png -loop 1 -i slideshow/pic2.png -loop 1 -i slideshow/pic3.png -i slideshow/pic4.png -filter_complex "[0:v]drawbox=x=40:y=40:w=250:h=75:color=white,drawtext=fontfile=arialb.ttf:fontsize=24:font color=black:text=Micky Mouse,drawtext=fontfile=arial.ttf:fontsize=24 : font color=black:text=January 1st 1938 — December 19th 2019fade=st=0:d=1:alpha=1,fade=out:st=5:d=1:alpha=1,trim=0:6,setpts=PTS+4/TB[ovr1] ; [2]fade=st=0:d=1:alpha=1,fade=out:st=5:d=1:alpha=1,trim=0:6,setpts=PTS+10/TB[ovr2] ; [3]fade=st=0:d=1:alpha=1,fade=out:st=5:d=1:alpha=1,trim=0:6,setpts=PTS+16/TB[ovr3] ; [4]fade=st=0:d=1:alpha=1,fade=out:st=5:d=1:alpha=1,trim=0:6,setpts=PTS+22/TB[ovr4] ; [0:v][ovr1]overlay=(main_w-overlay_w)/2 :(main_h-overlay_h)/2:enable=’between(t,4,10)’[base1] ; [base1][ovr2]overlay=(main_w-overlay_w)/2 :(main_h-overlay_h)/2:enable=’between(t,10,16)’[base2] ; [base2][ovr3]overlay=(main_w-overlay_w)/2 :(main_h-overlay_h)/2:enable=’between(t,16,22)’[base3] ; [base3][ovr4]overlay=(main_w-overlay_w)/2 :(main_h-overlay_h)/2:enable=’between(t,22,28)’[out]" -map "[out]" -c:v libx264 -c:a copy -flags +global_header -crf 27 -preset veryfast -s 1920x1080 -y slideshow/outTest.mp4

• Bat file to create a list of files and there paths in the same directory as the bat file

  4 janvier 2020, par punktilend

  I want to create a bat file that creates a list of files and there paths (MyList.txt). Saves that file to the same directory the bat file is being run in.

  This is what I am trying to accomplish with the MyList.txt. I would like to have the files in order as well.

  file 'E:\Adobe\Projects\Work\191215 December\1\CONTENTS\CLIPS001\AA3023\AA302301.MXF'
  
  file 'E:\Adobe\Projects\Work\191215 December\1\CONTENTS\CLIPS001\AA3023\AA302302.MXF'
  
  file 'E:\Adobe\Projects\Work\191215 December\1\CONTENTS\CLIPS001\AA3023\AA302303.MXF'
  
  file 'E:\Adobe\Projects\Work\191215 December\1\CONTENTS\CLIPS001\AA3023\AA302304.MXF'

  After this, I would like FFMPEG to concat those files ffmpeg -f concat -safe 0 -i MyList.txt -c copy -map 0 Output.mxf and output that to the same directory as well, but I think it will do that currently.

  This is what I have come up with so far :

  @echo off
  
  ECHO Creating MXF Concat List
  
  dir /a /-p /o:gen > "%~dp1MXF_list.txt"
  
  ffmpeg -f concat -safe 0 -i MXF_list.txt -c copy -map 0 Output.mxf