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• Python - playing video using ffplay displays file in larger resolution

  10 décembre 2019, par derBrain

  I’m working on a simple script that plays a video using ffplay.
  The problem I’m running into is that the output file has a larger resolution than it should have.
  The resolution of the file to be played is 1280x720, however, when I open the file with ffplay, the output is scaled to 1920x1080.
  I even tried to downscale the output by factor 1.5 (to get it to play in 1280x720), but the quality is noticeably worse compared to playing the same file in VLC player.
  What am I missing here ?

  This is the code I’m using :

  dbFile = "file.mp4"
  
  open_dbFile = "ffplay {0} -window_title {1} -left 50 -top 50 -nostats".format(dbFile, "DB_file")
  
  sub.Popen(open_dbFile)

  this is the log :

  ffplay version N-95171-g6ca3d34ff8 Copyright (c) 2003-2019 the FFmpeg developers
  
    built with gcc 9.2.1 (GCC) 20190918
  
  
  
  configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libdav1d --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --enable-libmfx --enable-ffnvcodec --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt --enable-amf
  
    libavutil      56. 35.100 / 56. 35.100
  
    libavcodec     58. 59.101 / 58. 59.101
  
    libavformat    58. 33.100 / 58. 33.100
  
    libavdevice    58.  9.100 / 58.  9.100
  
    libavfilter     7. 59.100 /  7. 59.100
  
    libswscale      5.  6.100 /  5.  6.100
  
    libswresample   3.  6.100 /  3.  6.100
  
    libpostproc    55.  6.100 / 55.  6.100
  
  
  
  Metadata:
  
      major_brand     : mp42
  
      minor_version   : 0
  
      compatible_brands: isommp42
  
      creation_time   : 2017-12-24T15:03:27.000000Z
  
    Duration: 00:08:36.83, start: 0.000000, bitrate: 588 kb/s
  
      Stream #0:0(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv, bt709), 1280x720 [SAR 1:1 DAR 16:9], 459 kb/s, 29.97 fps, 29.97 tbr, 90k tbn, 59.94 tbc (default)
  
      Metadata:
  
        creation_time   : 2017-12-24T15:03:27.000000Z
  
        handler_name    : ISO Media file produced by Google Inc. Created on: 12/24/2017.
  
      Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 125 kb/s (default)
  
      Metadata:
  
        creation_time   : 2017-12-24T15:03:27.000000Z
  
        handler_name    : ISO Media file produced by Google Inc. Created on: 12/24/2017.
  
     1.59 A-V: -0.014 fd=   0 aq=   19KB vq=   30KB sq=    0B f=0/0

  Thanks for your help !
  db

• ffmpeg set output resolution by resizing image

  3 janvier 2020, par Martin

  I’m trying to use ffmpeg for rendering video where an audio file and image are taken as inputs, and turned into a video (basically a music video) with the audio file playing for the duration of the video.

  My current working command :

  ffmpeg -loop 1 -framerate 2 -i "front.png" -i "testWAVfile.wav" -vf "scale=2*trunc(iw/2):2*trunc(ih/2),setsar=1,format=yuv420p" -c:v libx264 -preset medium -tune stillimage -crf 18 -c:a aac -shortest -vf scale=1920:1080  "outputVideo.mp4"

  Will set the output resolution of the video to whatever the resolution of the image is. Is there a way I can resize the image to enlarge it by a couple multiplications so that the output video resolution will be higher ?

  Like if my front.png image was 800x800 pixels, I could add something to my ffmpeg command to triple the resolution, so that the output video resolution is 2400x2400 ?

• What resolution would be best for processing videos in firebase functions ? [closed]

  11 janvier 2020, par Nathan

  I’m making an app that is mainly used for sharing videos of maximum 30 seconds long. One video example could be a screen recording of someone’s computer screen or a game. I have this code that checks whether the uploaded video that has just been uploaded to firebase storage has been processed or not and if it hasn’t then I use ffmpeg to process the video (change the resolution etc.) with this command :

  const promise = spawn('./ffmpeg', ['-i', tempFilePath, '-vf', 'scale=1280:720', targetTempFilePath]);

  Now with these commands, the firebase function is giving me a timeout error when I upload 30 second clips since I’m only converting the video to 720. I was just wondering what compression settings would be sufficient enough for the video to :

  1. Be still a high enough quality in my app
  2. Not take ages processing the video in the function (10-20 second clips works perfectly well).

  I know the better option would be to use Googles App engine or something similar to process videos but I’d prefer it to avoid that at the moment, if I can’t process videos to a good enough quality without sacrificing efficiency then I will go to something like Google’s App engine, just need some advice and some pointers for it otherwise.

  EDIT :

  I’ve seen instagram compresses their videos to a resolution of 640x640 ? Would that be reasonable or is it dependent on the original clip’s resolution ?

  Thanks