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• Script to cut video by silence part with FFMPEG

  11 février 2020, par fricadelle

  This is a question that is raised here How to split video or audio by silent parts or here How can I split an mp4 video with ffmpeg every time the volume is zero ?

  So I was able to come up with a straightforward bash script that works on my Mac.

  Here it is (only argument is the name of the video to be cut, it will generate a file start_timestamps.txt with the list of silence starts if the file does not exist and reuse it otherwise) :

  #!/bin/bash
  
  
  
  INPUT=$1
  
  
  
  filename=$(basename -- "$INPUT")
  
  extension="${filename##*.}"
  
  filename="${filename%.*}"
  
  
  
  SILENCE_DETECT="silence_detect_logs.txt"
  
  TIMESTAMPS="start_timestamps.txt"
  
  
  
  if [ ! -f $TIMESTAMPS ]; then
  
      echo "Probing start timestamps"
  
      ffmpeg -i "$INPUT" -af "silencedetect=n=-50dB:d=3" -f null - 2> "$SILENCE_DETECT"
  
      cat "$SILENCE_DETECT"| grep "silence_start: [0-9.]*" -o| grep -E '[0-9]+(?:\.[0-9]*)?' -o > "$TIMESTAMPS"
  
  fi
  
  
  
  PREV=0.0
  
  number=0
  
  
  
  cat "$TIMESTAMPS"| ( while read ts
  
  do
  
      printf -v fname -- "$filename-%02d.$extension" "$(( ++number ))"
  
      DURATION=$( bc <<< "$ts - $PREV")
  
      ffmpeg -y -ss "$PREV" -i "$INPUT" -t "$DURATION" -c copy "$fname"
  
      PREV=$ts
  
  done
  
  printf -v fname -- "$filename-%02d.$extension" "$(( ++number ))"
  
  ffmpeg -y -ss "$PREV" -i "$INPUT" -c copy "$fname" )

  Unfortunately it does not seem to work :

  I have a video that is basically a collection of clips, each clip being introduced by a 5 second silence with a static frame with a title on it. So I want to cut the original video so that each chunk is the 5 seconds "introduction" + video until the next introduction. Hope it’s clear.

  Anyway, in my script I first find all silence_start using ffmpeg silencedetect plugin. I get a start_timestamps.txt that read :

  141.126
  
  350.107
  
  1016.07
  
  etc.

  Then for example I would call (I don’t need to transcode again the video), knowing that (1016.07 - 350.107) = 665.963

  ffmpeg -ss 350.107 -i Some_video.mp4 -t 665.963 -c copy "Some_video02.mp4"

  The edge cases being the first chunk that has to go from 0 to 141.126 and the last chunk that has to go from last timestamp to end of the video.

  Anyway the start_timestamps seem legit. But my output chunks are completely wrong. Sometimes the video does not even play anymore in Quicktime. I don’t even have my static frame with the title in any of the videos...

  Hope someone can help. Thanks.

  EDIT Ok as explained in the comments, if I echo $PREV while commenting out the ffmpeg command I get a perfectly legit list of values :

  0.0
  
  141.126
  
  350.107
  
  1016.07
  
  etc.

  With the ffmpeg command I get :

  0.0
  
  141.126
  
  50.107
  
  016.07
  
  etc.

  bash variable changes in loop with ffmpeg shows why.

  I just need to append < /dev/null to the ffmpeg command or add -nostdin argument. Thanks everybody.

• How to add watermark to the video part of this huge ffmpeg command that adds intro and outro with crossfade ?

  3 juillet 2017, par Jeflopo

  I wrote a command that crossfade merge an intro, an outro, with a video :

  

  ffmpeg -i intro.mp4 -i video.mp4 -i outro.mp4 -filter_complex "
  
  [0:v]trim=start=0:end=9,setpts=PTS-STARTPTS,scale=480x360,setsar=sar=16/9[intro]; 
  
  [0:v]trim=start=9:end=10,setpts=PTS-STARTPTS,scale=480x360,setsar=sar=16/9[firstfadeoutclip]; 
  
  [1:v]trim=start=0:end=1,setpts=PTS-STARTPTS,scale=480x360,setsar=sar=16/9[firstfadeinclip]; 
  
  [1:v]trim=start=1:end=24,setpts=PTS-STARTPTS,scale=480x360,setsar=sar=16/9[video]; 
  
  [1:v]trim=start=24:end=25,setpts=PTS-STARTPTS,scale=480x360,setsar=sar=16/9[secondfadeoutclip]; 
  
  [2:v]trim=start=0:end=1,setpts=PTS-STARTPTS,scale=480x360,setsar=sar=16/9[secondfadeinclip]; 
  
  [2:v]trim=start=1:end=10,setpts=PTS-STARTPTS,scale=480x360,setsar=sar=16/9[outro]; 
  
  [firstfadeoutclip]format=pix_fmts=yuva420p, fade=t=out:st=0:d=1:alpha=1[firstfadeoutalpha]; 
  
  [firstfadeinclip]format=pix_fmts=yuva420p, fade=t=in:st=0:d=1:alpha=1[firstfadeinalpha]; 
  
  [secondfadeoutclip]format=pix_fmts=yuva420p, fade=t=in:st=0:d=1:alpha=1[secondfadeoutalpha]; 
  
  [secondfadeinclip]format=pix_fmts=yuva420p, fade=t=in:st=0:d=1:alpha=1[secondfadeinalpha]; 
  
  [firstfadeoutalpha]fifo[firstfadeoutfifo]; 
  
  [firstfadeinalpha]fifo[firstfadeinfifo]; 
  
  [secondfadeoutalpha]fifo[secondfadeoutfifo]; 
  
  [secondfadeinalpha]fifo[secondfadeoinfifo]; 
  
  [firstfadeoutfifo][firstfadeinfifo]overlay[firstcrossfade]; 
  
  [secondfadeoutfifo][secondfadeoinfifo]overlay[secondcrossfade]; 
  
  [intro][firstcrossfade][video][secondcrossfade][outro]concat=n=5[output]; 
  
  [0:a][1:a] acrossfade=d=1 [audio]" 
  
  -vcodec libx264 -map "[output]" -map "[audio]" "output.mp4"

  This huge command works fine.

  But now what I want to do is to add a watermark to the video part :

  [1:v]trim=start=1:end=24,setpts=PTS-STARTPTS,scale=480x360,setsar=sar=16/9[video];

  And I want to do it by merging this command (watermark) into that one above :

  ffmpeg -i "1080p.mp4" -filter_complex "
  
  movie=logo-wm.png[watermark];
  
  [watermark][0:V]scale2ref=(1917*iw/1920)/3.5:(322*iw/1920)/3.5[wm][v]; 
  
  [v][logo]overlay=main_w-overlay_w-20:20" "output.mp4"

  The whole (1917*iw/1920)/3.5:(322*iw/1920)/3.5 scales the watermark proportionally using the scale2ref= filter. The 1917 is the width of my watermark image, and 322 is the height

  It is overlayed in the top right corner with main_w-overlay_w-20:20

  But I can’t make it work I tried to add it by copying the parameters to the filter of [1:v] input. And by adding another input for the watermark that if I’m right it would be [3:v] instead of using the movie= filter. But I can’t.

  I know that I could do it in two steps, but I would like to do it at once, in just one command.

  May anyone help me to merge them ? Thank you in advance !

• Revision f1781e86b7 : Refactoring of rate control - part 1 Moves all rate control variables to a sepa

  6 novembre 2013, par Deb Mukherjee

  Changed Paths :
   Modify /vp9/encoder/vp9_firstpass.c

  
   Modify /vp9/encoder/vp9_mbgraph.c

  
   Modify /vp9/encoder/vp9_onyx_if.c

  
   Modify /vp9/encoder/vp9_onyx_int.h

  
   Modify /vp9/encoder/vp9_ratectrl.c

  
   Modify /vp9/encoder/vp9_ratectrl.h

  
   Modify /vp9/encoder/vp9_temporal_filter.c

  
  
  Refactoring of rate control - part 1

  Moves all rate control variables to a separate structure,
  removes some currently unused variables,
  moves some rate control functions to vp9_ratectrl.c,
  and splits the encode_frame_to_data_rate function.

  Change-Id : I4ed54c24764b3b6de2dd676484f01473724ab52b