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• FFMPEG creates different output when overlaying the same image in jpg and png

  3 novembre 2020, par Cvetelin Andreev

  I'm having a different output when overlaying a video over png and jpg. I like what I get with the png, but my app is using user's images to overlay an animation on top and I don't have control over the image so sometimes users get different colors than expected. How can I avoid this ?

  


  I'm using the following command to overlay video onto image :

  


  ffmpeg -y -i white.png \
-i video.mov \
-filter_complex "[1:v][0:v]scale2ref='iw:ow/mdar'[scaled-overlay][image];\
[image][scaled-overlay]overlay[filtered]" \
-map "[filtered]" output.png.gif


  


  The video is an animation done with AE exported in Quicktime PNG.
The image is generated with ImageMagick's convert :

  


  convert -size 500x500 xc:white white_500.png


  


  The result is fine. However if I use the same command with a JPEG image (white, 500x500 downloaded from the Internet) the colors of the results are different (appear darker) :


  


  It works fine with JPEG generated with ImageMagick.

  


  All files and script here : https://drive.google.com/drive/folders/1GEA1ho_i-rcYY-OJcxgiUuBnGUoqiTkf?usp=sharing

  


  Thank you for your time !

  


• How to run this complex filter in Fluent FFMPEG ?

  11 septembre 2019, par Dan Weaver

  I’m trying to turn the following complex filter into a Fluent FFMPEG command but I can’t figure out how the mapping works.

  ffmpeg -i audio.mp3 -filter_complex "[0:a]showfreqs=s=200x100:colors=white|white,format=yuv420p[vid]" -map "[vid]" -map 0:a video.mp4

  This is what I have so far but I get an error about the ’vid’ stream.

  ffmpeg()
  
      .input("audio.mp3")
  
      .audioCodec("aac")
  
      .audioBitrate("320")
  
      .complexFilter(
  
        {
  
          filter: "showfreqs",
  
          options: { s: "200x100" },
  
          inputs: "0:a",
  
        },
  
        {
  
          filter: "format",
  
          options: { pix_fmts: "yuv420p" },
  
          outputs: ["vid"],
  
        }
  
      )
  
      .outputOptions(['-map "[vid]"', "-map 0:a"])
  
      .save(spectrumTmp)

  Error :

  ffmpeg exited with code 1: Stream map '"[vid]"' matches no streams.
To ignore this, add a trailing '?' to the map.

  If I add a trailing ’ ?’ in outputOptions I get a file with no video stream.

• Concatenating Smooth Streaming output to a single MP4 file - problems with A/V sync. What is CodecPrivateData ?

  14 février 2021, par user15180344

  I have a video in fragmented form which is an output of an Azure Media Services Live Event (Smooth Streaming).

  


  I'm trying to concatenate the segments to get a single MP4 file, however I've run into a A/V sync problem - no matter what I do (time-shifting/speeding up/slowing down/using FFmpeg filters), the audio delay is always floating. To get the output MP4 file, I tried concatenating the segments for video and audio streams (both at OS file level and with FFmpeg) and then muxing with FFmpeg.

  


  I've tried everything I found on the web and I'm always ending up with exactly the same result. What's important, when I play the source from the manifest file, it's all good. That made me skim through the manifest once again, and I realized there's CodecPrivateData value which I'm not using anywhere in the process. What is it ? Could it somehow help solving my problem ?