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• Input seeking for frame at specified timestamp with Py-AV

  9 décembre 2019, par neonScarecrow

  I have a project already using Py-AV and am trying to replicate a specific ffmpeg command. The goal is to get a frame roughly around the specified timestamp.

  Here’s the ffmpeg commmand :
  https://trac.ffmpeg.org/wiki/Seeking

  ffmpeg -ss 14 -i https://some_url.mp4 -frames:v 1 frame_at_14_seconds.jpg

  Here’s my code :

      #return one frame around 14 seconds into the movie
  
      target_sec = 14 
  
      container = av.open('https://some_url.mp4', 'r')
  
      container.streams.video[0].thread_type = 'AUTO'
  
      video_stream = next(s for s in container.streams if s.type == 'video')
  
      time_base = float(video_stream.time_base)
  
      target_timestamp = int(target_sec / time_base) + video_stream.start_time
  
      video_stream.seek(target_timestamp)
  
      for frame in container.decode(video_stream):
  
          frame.to_image().save('frame_at_14_seconds.jpg')
  
          break

  Additionally, I have found any documentation about this, but does anyone know if either command (ffmpeg/av.open) is downloading the entire file to a tmp file behind the scenes. I’m looking for a less memory-intensive way to read a frame for every second in an up to 60 second video.

• Unrecognized options even though compiled FFmpeg on Ubuntu manually

  11 février 2016, par Kathy Lee

  I would like to convert a video from .avi to .mp4 with same quality using ffmpeg but the command I put in the terminal always report some errors saying that there are unrecognized options.

  I have compiled the ffmpeg manually following the steps in http://trac.ffmpeg.org/wiki/CompilationGuide/Ubuntu

  After compiling the ffmpeg, I used the command below the compress the video

  ffmpeg -i input.avi -c:v libx264 -crf 19 -preset slow -c:a libfaac -b:a 192k -ac 2 output.mp4

  But the error message is saying "Unrecognized option ’crf’" :

  ffmpeg version 2.8.5 Copyright (c) 2000-2016 the FFmpeg developers
  
  built with gcc 4.8 (Ubuntu 4.8.4-2ubuntu1~14.04)
  
  configuration: --enable-nonfree --enable-pic --enable-shared
  
  libavutil      54. 31.100 / 54. 31.100
  
  libavcodec     56. 60.100 / 56. 60.100
  
  libavformat    56. 40.101 / 56. 40.101
  
  libavdevice    56.  4.100 / 56.  4.100
  
  libavfilter     5. 40.101 /  5. 40.101
  
  libswscale      3.  1.101 /  3.  1.101
  
  libswresample   1.  2.101 /  1.  2.101
  
  Unrecognized option 'crf'.
  
  Error splitting the argument list: Option not found

  Then I tried to omit flag -crf, but I got error saying

  Unrecognized option 'preset'.
  
  Error splitting the argument list: Option not found

  Then I omitted flag -preset, it says I do not have libx264....

  [mjpeg @ 0x164f2c0] Changeing bps to 8
  
  Input #0, avi, from 'backup_bush.avi':
  
    Duration: 00:01:40.70, start: 0.000000, bitrate: 12409 kb/s
  
      Stream #0:0: Video: mjpeg (MJPG / 0x47504A4D), yuvj420p(pc, bt470bg/unknown/unknown), 400x250 [SAR 1:1 DAR 8:5], 12407 kb/s, 30 fps, 30 tbr, 30 tbn, 30 tbc
  
  Unknown encoder 'libx264'

  I am very confused what is going on because I have complied ffmpeg step by step and also installed the dependencies such as libx264 as described in http://trac.ffmpeg.org/wiki/CompilationGuide/Ubuntu. The command I used to configure ffmpeg is

   ./configure   --prefix="$HOME/ffmpeg_build"   --pkg-config-flags="--static"   --extra-cflags="-I$HOME/ffmpeg_build/include"   --extra-ldflags="-L$HOME/ffmpeg_build/lib"   --bindir="$HOME/bin"   --enable-gpl   --enable-libass   --enable-libfdk-aac   --enable-libfreetype   --enable-libmp3lame   --enable-libopus   --enable-libtheora   --enable-libvorbis   --enable-libvpx   --enable-libx264   --enable-nonfree

  Why these errors happen ? How can I fix them to allow me to convert the video from .avi to .mp4 ?

  Thank you very much !

• nomenclature #3324 : Déplacer les fonctions typographiques dans un plugin séparé

  29 octobre 2014, par Fil Up

  Quelques autres améliorations à faire (pas très difficile, mais pointilleux : faire des cas tests).

  1. toujours rendre les espaces insécables (même en anglais) quand l’espace est déjà présente (a ! => a !)

  2. en français-français, ajouter les espaces insécables, mais pas en français-suisse (enfin, différemment)
  http://fr.wikipedia.org/wiki/Comparatif_des_différents_codes_typographiques_francophones#Diff.C3.A9rences_entre_les_typographies_fran.C3.A7aise_et_suisse

  3. remplacer les insécables qui vont bien par des fines (en option avec réglage ou define). Le code est déjà fait, il suffit de l’intégrer (avec les tests idoines) cf. http://core.spip.org/issues/1461