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• python cut portion of video "Fastest way"

  23 mai 2020, par mhndev

  I'm trying to cut out portion of video file using python(3.7.1) and ffmpeg in my flask (1.0.2) application,
this is solution 1

  



      # solution 1
    from moviepy.editor import *
    from moviepy.video.io.ffmpeg_tools import ffmpeg_extract_subclip

    video = VideoFileClip('/app/videos/video.mkv'.subclip(10, 20)
    video.write_videofile('/app/videos/cutted_video.mp4')


  



  and here is result in flower panel screenshot.
as you can see cutting out two videos takes more than two seconds.

and this is solution 2

  



      # solution 2
    from moviepy.editor import *
    from moviepy.video.io.ffmpeg_tools import ffmpeg_extract_subclip


    ffmpeg_extract_subclip(
        '/app/videos/video.mkv',
        10,
        20,
        '/app/videos/cutted_video.mp4'
    )


  



  first solution works pretty well, but It takes about 1-2 seconds to cut the video out.
instead second solution works very fast ( less than 0.5 sec ) but the output video is just audio plus black screen.

  



  what is the fastest way to cut portion of video in python.
If there is any other library which is faster please tell me that.

  


• FFmpeg can 'encode' to mp3, but will not accept an 'input' mp3

  21 novembre 2011, par Jonathan Coe

  FYI : Fedora 8 running on Amazon EC2...

  Having a difficult time with FFmpeg doing a (what should be pretty simple) conversion. I can get FFmpeg to encode an mp3 file from an m4a file using the following :

  ffmpeg -i file1.m4a -acodec libmp3lame -ab 160k file2.mp3

  However, I cannot get it to to convert an mp3 -> mp3, it responds with "Unknown Format" using the following :

  ffmpeg -i file1.mp3 -acodec libmp3lame -ab 160k file2.mp3

  I get the following command string :

  FFmpeg version UNKNOWN, Copyright (c) 2000-2008 Fabrice Bellard, et al.
  
  
  
  
  
  configuration: --prefix=/usr --libdir=/usr/lib --shlibdir=/usr/lib --mandir=/usr/share/man --incdir=/usr/include/ffmpeg --enable-libmp3lame --enable-libvorbis --enable-libtheora --enable-libfaad --enable-libfaac --enable-libgsm --enable-libxvid --enable-libx264 --enable-liba52 --enable-liba52bin --enable-pp --enable-shared --enable-pthreads --enable-gpl --disable-strip
  
    libavutil version: 49.6.0
  
    libavcodec version: 51.50.1
  
    libavformat version: 52.7.0
  
    libavdevice version: 52.0.0
  
    built on Feb 14 2008 17:47:08, gcc: 4.1.2 20070925 (Red Hat 4.1.2-33)
  
  file1.mp3: Unknown format

  Any help would be hugely appreciated !

  Edit for clarity :
  The input file is in /ebs/queue/input.mp3 and the output is /ebs/converted/output.mp3

• ffmpeg framerate inconsistent

  16 septembre 2021, par user3190036

  ffmpeg is being run with the same arguments but different inputs in two separate places in my code. The framerate is set to 12fps with -framerate. In one case the output video matches the framerate pretty well every time. In the other case the video is coming back with 1 second of video for every 15 input frames, but again it is consistent. What could possibly be causing the discrepancy ?

  


  Arguments :
-y -framerate 12 -itsoffset -654ms -i "C :\path/%06d.JPG" -i "C :\path/audio.mp3" -map 0:v:0 -map 1:a:0 -vf scale=1280:720:force_original_aspect_ratio=decrease,pad=1280:720 :-1 :-1:color=black -acodec aac -vcodec libx264 -ar 48000 -pix_fmt yuv420p -movflags +faststart "C :\path\output.mp4"

  


  There are dozens of differences in the code that calls it but I can't understand how any of that would influence the framerate. I tried switching out the mp3 with one of an arbitrary different length to see if that had an effect but it did not. That leaves only the image inputs.

  


  edit : So it gets stranger. I reproduced both cases and modified the framerate value for each to check what happened. In almost every case I got more seconds of video than expected. I was doing these tests with 400 frames and 5 seconds of audio to ensure the lack of -shortest wasn't a factor. The only time I got a perfectly accurate framerate was when it was set to 1. In every other case (except the verbatim 12fps in the case that was always working) the video was too short by 5-15%. This makes it a bit of a mystery how either part of my code ever produced good results.