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• Adding text to movie using ffmpeg

  23 août 2014, par microspace

  I use git to track *.ass subtitle files.
  Here is example of *.ass file :

  [Script Info]
  
  ; Script generated by Aegisub 3.1.2
  
  ; http://www.aegisub.org/
  
  Title: Default Aegisub file
  
  ScriptType: v4.00+
  
  
  
  [V4+ Styles]
  
  Format: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, OutlineColour,    BackColour, Bold, Italic, Underline, StrikeOut, ScaleX, ScaleY, Spacing, Angle, BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV, Encoding
  
  Style: Default,Arial,20,&H00FFFFFF,&H000000FF,&H00000000,&H00000000,0,0,0,0,100,100,0,0,1,2,2,2,10,10,10,1
  
  Style: titr,DejaVu     
  
  
  
  Sans,20,&H007DDBFA,&H000000FF,&H00000000,&HFF000000,0,0,0,0,100,100,0,0,1,2,2,1,10,10,10,1
  
  
  
  [Events]
  
  Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
  
  Dialogue: 0,0:00:00.46,0:00:11.22,Default,,0,0,0,,Если это можно было бы
  
  Dialogue: 0,0:00:03.44,0:00:08.96,titr,,0,0,0,,{\pos(20,240)\fad(600,600)}бывший министр

  After commit I burn subtitles into video :

  ffmpeg -i video.avi -vf "ass=subtitle.ass" out.avi

  My goal is to show commit date for 10 second at the start of movie. This should be done automatically.

  1) It can be easily done with by modifying subtitle.ass itself, but I can’t do it after commit and there are other reasons.

  2) It can be done by ffmpeg from command line : How to use ffmpeg to add a text to avi video ?

  Problem is that in this case text will be shown for the whole lenght of movie.

  3) I can copy *.ass file to temporary directory, insert date, render and delete *.ass file.

  Is there a simpler way ?

• FFmpeg : MD5 hash of M3U8 playlists generated from same input video with different segment durations (after applying video filter) don't match

  30 juillet 2020, par Saurabh P Bhandari

  Here are a few commands I am using to convert and transize a video in MP4 format to a M3U8 playlist.

  


  For a given input video (MP4 format), generate multiple video segments with segment duration 30 seconds.

  


  ffmpeg -loglevel error -i input.mp4 -dn -sn -an -c:v copy -bsf:v h264_mp4toannexb -copyts -start_at_zero -f segment -segment_time 30 30%03d.mp4 -dn -sn -vn -c:a copy audio.aac


  


  Apply a video filter (in this case scaling) on each segment and convert it to a M3U8 format.

  


  ls 30*.mp4 | parallel 'ffmpeg -loglevel error -i {} -vf scale=-2:144 -hls_list_size 0 {}.m3u8'


  


  Store the list of m3u8 files generated in list.txt in this format file 'segment-name.m3u8'

  


  for f in 30*.m3u8; do echo "file '$f'" >> list.txt; done


  


  Using concat demuxer, combine all segment files (which are in M3U8 format) and the audio to get one final m3u8 playlist pointing to segments with duration of 10 seconds.

  


  ffmpeg -loglevel error -f concat -i list.txt -i audio.aac -c copy -hls_list_size 0 -hls_time 10 output_30.m3u8


  


  ---

  


  I can change the segment duration in the first step from 30 seconds to 60 seconds, and compare the MD5 hash of the final M3U8 playlist generated in both the cases using this command :

  


  ffmpeg -loglevel error -i <input m3u8="m3u8" playlist="playlist" /> -f md5 -&#xA;

  


  The MD5 hash of the output files differ, i.e., video streams of output_30.m3u8 and output_60.m3u8 are not the same.

  


  Can anyone elaborate on this ?

  


  (I expected the MD5 hash to be the same)

  


• ffmpeg : md5 of m3u8 playlists generated from same input video with different segment durations (after applying video filter) don't match

  15 juillet 2020, par Saurabh P Bhandari

  Here are a few commands I am using to convert and transize a video in mp4 format to a m3u8 playlist.

  


  For a given input video (mp4 format), generate multiple video only segments with segment duration 30s

  


  ffmpeg -loglevel error -i input.mp4 -dn -sn -an -c:v copy -bsf:v h264_mp4toannexb -copyts -start_at_zero -f segment -segment_time 30 30%03d.mp4 -dn -sn -vn -c:a copy audio.aac


  


  Apply video filter (in this case scaling) on each segment and convert it to a m3u8 format

  


  ls 30*.mp4 | parallel 'ffmpeg -loglevel error -i {} -vf scale=-2:144 -hls_list_size 0 {}.m3u8'


  


  Store the list of m3u8 files generated in list.txt in this format file 'segment-name.m3u8'

  


  for f in 30*.m3u8; do echo "file '$f'" >> list.txt; done


  


  Using concat demuxer, combine all segment files (which are in m3u8 format) and the audio to get one final m3u8 playlist pointing to segments with duration of 10s.

  


  ffmpeg -loglevel error -f concat -i list.txt -i audio.aac -c copy -hls_list_size 0 -hls_time 10 output_30.m3u8


  


  ---

  


  I can change the segment duration in the first step from 30s to 60s, and compare the md5 of the final m3u8 playlist generated in both the cases using this command

  


  ffmpeg -loglevel error -i <input m3u8="m3u8" playlist="playlist" /> -f md5 - &#xA;

  


  The md5 of the output files differ i.e video streams of output_30.m3u8 and output_60.m3u8 are not the same.

  


  Can anyone elaborate on this ?

  


  (I expected the md5 to be the same)