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• ffmpeg programatically set the export date to download date using python

  16 janvier 2021, par Vladimir Tarasov

  i'm currently using the code below to export a youtube-dl converted video (with ffmpeg and youtube-dl for python)
how could i programatically set the good options for ffmpeg to add the download date (at least today's date) to the .mp3 file ?

  


  ydl_opts = {
    'format': 'bestaudio/best',
    'outtmpl': path + urlToTitleYT(link) + '.mp3',
    'postprocessors': [{
        'key': 'FFmpegExtractAudio',
        'preferredcodec': 'mp3',
        'preferredquality': '320',
    }],
}

with youtube_dl.YoutubeDL(ydl_opts) as ydl:
    ydl.download([link])



  


• ffmpeg output file size grows faster than linearly with movie length

  14 janvier 2021, par Jakob Filser

  I'm using ffmpeg to string together some .bmp images into a movie. In total, there are 1001 frames, amounting to 0:40 length. The command I'm using is

  


  ffmpeg -f image2 -i render.%05d.bmp -c:v libx264 -s 512:268 render.mp4


  


  The output file is 33,2 MB large, which is about twice the size of a full HD (about 16 times the pixels !) video of the same length. Apart from the file size being unreasonably large, I realized it grows faster than linearly (can't tell exactly if it is quadratic, exponential etc.) with the number of frames. After 100 frames it is about 1536 KB large (which is already too large), after 500 frames it is already 15104 KB, and after 1001 it finally arrives at 34085 KB.

  


  My educated guess would be that for each frame it stores some information about all of the previous frames again, which makes absolutely no sense.

  


  What am I doing wrong ? Before you recommend libx265 to me : It turns the entire video green.

  


• Transparent movie with video format qtrle unplayable in QuickTime

  1er janvier 2021, par 220284

  I use the python library Manim to generate mathematical animations. I want to use the animations in Keynote presentations. Manim has the option to produce movie clips with a transparent background. Unfortunately, QuickTime won't play the files generated by Manim. Here's the metadata for a file produced by Manim

  


  Metadata:
    major_brand     : qt  
    minor_version   : 512
    compatible_brands: qt  
    encoder         : Lavf58.45.100
  Duration: 00:01:07.00, start: 0.000000, bitrate: 6635 kb/s
    Stream #0:0: Video: qtrle (rle  / 0x20656C72), argb(progressive), 1280x960, 6632 kb/s, 60 fps, 60 tbr, 15360 tbn, 15360 tbc (default)
    Metadata:
      handler_name    : VideoHandler
      encoder         : Lavc58.91.100 qtrle


  


  Ideally, I would want to use ffmpeg to turn these files into movie clips with transparent background which are playable in QuickTime. Can this be done ?

  


  As a work around, I imported the files into Final Cut Pro and exported them again using Apple Pro Res 4444, but this resulted in huge file sizes.