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• What are the correct conversion steps to generate a video from PDF with ffmpeg and mp4box

  25 juin 2020, par Michael Rall

  I need to convert a PDF-Document to a DASH-compatible stream. Every page of the PDF should be displayed for one second. Quality should be rather good, so that text and line graphics can still be read clearly. Additionally I want to be able to seek every page, so keyframes(?) should be (exactly) every second.

  


  Im using poppler-tools to extract the pdf-pages as png's -> works

  


  Im using ffmpeg to convert the single images to an x264 encoded mp4 video -> works (but maybe problematic)

  


  string.Format("-r 1 -i \"{0}.page_%d.png\" -r 24 -vcodec libx264 -pix_fmt yuv420p {0}.output.mp4", basePath)


  


  Im using MP4Box to convert that video to dash -> works (but needs improvement)

  


  string.Format("-dash 1000 -frag 1000 -rap -segment-name {1}_dash_$RepresentationID$_$Number$ -url-template {0}.output.mp4 -out \"{0}.{2}\"", basePath, tempDataId, STREAM_MANIFEST_FILE_POSTFIX)


  


  Now I have 2 Problems/Questions

  


  

  1. Are the settings for framerate, quality, outputformat correct for the goals I want to achieve

  


  2. When displaying the resulting DASH-Stream in the Demo-Player from https://github.com/Dash-Industry-Forum/dash.js/wiki it plays the stream, but as soon as I try to seek the player starts loading forever. Setting the position to start and let it play again works. The network tab in my browser-debugger shows that the player tries to load the segments and gets them successfully.

  


  


  I guess its a problem with keyframes, fragments or similar. Can somebody correct my conversion steps ?

  


  kind regards

  


• How to add arbitrary or custom metadata in MP4 ?

  13 avril 2021, par 大大大大萝卜凉

  The MP4 muxer in ffmpeg only allows certain metadata by default. I would like to add :

  


  com.android.model: Mi 10 Pro
xyz: +22.9835+113.3621/
com.android.version: 1
com.android.manufacturer: Xiaomi


  


  How can I add this with ffmpeg ?

  


• avformat/matroskaenc : Fix writing of markers

  28 août 2023, par Steinar H. Gunderson

  avformat/matroskaenc : Fix writing of markers
  When the marker writing code was merged from libav to FFmpeg
  
  in dc62016c, it failed to take into account that the meaning of
  
  cluster_pos had changed in bda5b662 ; in particular, the special
  
  value for “I'm not currently working on a cluster” had changed
  
  from 0 to -1. This makes the avio_write_marker() call never
  
  be called. Update the if statement to fix it.
  Fixes : Ticket9843
  
  Signed-off-by : Steinar H. Gunderson <steinar+ffmpeg@gunderson.no>
  
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DH] libavformat/matroskaenc.c