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• FFMPEG : Set Opacity of audio waveform color

  13 août 2018, par Software Development Consultan

  I was trying to do transparency in waveform generated. It seems there is not direct option in ’showwaves’ filter so I came across ’colorkey’ which might help.

  I am trying with following :

  ffmpeg -y -loop 1 -threads 0 -i background.png -i input.mp3 -filter_complex "[1:a]aformat=channel_layouts=mono,showwaves=s=1280x100:rate=7:mode=cline:scale=sqrt:colors=0x0000ff,colorkey=color=0x0000ff:similarity=0.01:blend=0.1[v] ; [0:v][v] overlay=0:155 [v1]" -map "[v1]" -map 1:a -c:v libx264 -crf 35 -ss 0 -t 5 -c:a copy -shortest -pix_fmt yuv420p -threads 0 test_org.mp4

  So I wanted to blue color waveform and wanted to set opacity of that 1 to 0 let say. But it seems this generates blackbox which is actual background of ’1280x100’. I want to keep background of waveform transparent and just wanted to change opacity of waveform only.

  Result of my command : enter image description here

  

  Can you please let me know your suggestion

  @Gyan, this is with reference to following question which you have answered.

  Related last question

  Thanks, Hardik

• FFMPEG Layering two .mov files color issue

  21 février 2023, par JDC

  I have two folders containing numbered .mov files all the same length, one folder for front and one for back. I'm using ffmpeg to combine the front and back videos with matching numbers into one output video (the front video has an alpha channel). The below command works, but in the output video the front layer has slightly incorrect colors compared to the input (reds are too yellow for example). The back layer in the output looks correct. Both input files use the bt709 color space (checked with ffprobe). Is there something in the overlay options which is causing the front layer to look incorrect, or something I'm doing wrong with the colorspace options ?

  


  


  for f in Video_Back/Video_Back_*.mov ; do
num=$(echo "$f" | sed -n 's/.*Video_Back_([0-9]5).mov$/\1/p')
if [ -f "Video_Front/Video_Front_$num.mov" ] ; then
ffmpeg -color_primaries bt709 -color_trc gamma28 -colorspace bt709 -i "$f" -color_primaries bt709 -color_trc gamma28 -colorspace bt709 -i "Video_Front/Video_Front_$num.mov" -filter_complex "[1:v]format=rgba[fg] ;[0:v][fg]overlay=shortest=1:alpha=straight,eq=gamma=1.0[mixed]" -map "[mixed]" -map 0:a:0 -c:v libx264 -crf 18 -preset veryfast -c:a copy "Video_Merged/Video_Merged_$num.mp4"
fi
done

  


  


• avfilter/vf_scale : set proper out frame color range

  31 décembre 2015, par Thomas Mundt

  avfilter/vf_scale : set proper out frame color range
  Prevents that following scalers in the filter chain will do unintentional color range conversions.
  
  Fixes Ticket #5096
  Signed-off-by : Thomas Mundt <loudmax@yahoo.de>
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavfilter/vf_scale.c