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• avfilter/vf_scale : add optional "ref" input

  24 avril 2024, par Niklas Haas

  avfilter/vf_scale : add optional "ref" input
  This is automatically enabled if the width/height expressions reference
  
  any ref_* variable. This will ultimately serve as a more principled
  
  replacement for the fundamentally broken scale2ref.
  See-Also : https://trac.ffmpeg.org/ticket/10795
  

  • [DH] Changelog
  • [DH] doc/filters.texi
  • [DH] libavfilter/vf_scale.c

• How to "filter" a file through command line before apache sends it to client ?

  1er septembre 2020, par Timothe Jahan

  I have large collection of video files which are available on our website.
For each video we have multiple quality and language, so in order to save space we store only 1 file, which contains all audio and video tracks.

  


  Our streaming server can handle these multitrack files in order to serve only the useful part to each user, but we also make them available for download through the apache web server.
Currently, when a user request a file (certain quality, certain language), we first create a temporary file with only his needs, and give him for download.
I would like to remove this intermediate step and extract on the fly.
Extraction can be done by ffmpeg, but I need to have apache "pipe" the file through ffmpeg before sending the bytes out. Do you have any way of doing this.

  


  example :

  


  


  Filename_multi.mp4 [SD,HD,fr,en,ru]
User request : Filename_HD_fr.mp4 [HD,fr]
Apache fetch the file Filename_multi.mp4 and pipe it through an ffmpeg command and send the bytes as > they are encoded, not waiting for the end.

  


  


  Note this is on linux, and the ffmpeg part is not a problem.

  


  Thx
Timothé

  


• Different results using qt-faststart and "ffmpeg -movflags +faststart"

  31 mars 2020, par Juan Ignacio Sánchez

  I have a set of videos generated by security cameras, which have the MOOV atom at the end of the file, like this :

  ftyp (32 bytes)
  
  free (8 bytes)
  
  mdat (29647845 bytes)
  
  moov (42054 bytes)

  I want to serve these files using progressive downloads (pseudo streaming) and it’s the only acceptable way to do it.

  Knowing that I tried to use tools like qt-faststart or directly ffmpeg with the corresponding flags (-movflags +faststart). Other detail is that I’m running this on a low profile machine, and FFmpeg takes like 6 8 seconds to finish (even using -c copy) and the other tool results to be much more efficient since it only moves some bytes, taking less than a second to finish. The thing here is that qt-faststart produces a video that can’t be pseudo streamed but ffmpeg does it. Here are some comparisons :

  ffmpeg :

  ftyp (32 bytes)
  
  moov (42422 bytes)
  
  free (8 bytes)
  
  mdat (29647845 bytes)

  qt-faststart :

  ftyp (32 bytes)
  
  moov (42054 bytes)
  
  free (8 bytes)
  
  mdat (29647845 bytes)

  As you can see, FFmpeg adds some extra bytes on the MOOV atom, can anyone point me in some research direction ? Thank you all.