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• When using MoviePy to resize a video how do I know what bitrate to use to maintain quality when writing the new video to disk

  4 juillet 2016, par Michael

  Expanding on this question How To Resize a Video Clip Python about using MoviePy to resize a video.

  When it comes time to write the resized video to disk
  How do I select a bitrate value so there is as little loss of quality as possible ?

  The original video is 4.8M on disk and is .mp4

  Bit rate set when writing to disk

      clip_resized.write_videofile(ResizedClip,bitrate="5000k")

  Gives a file of 8.3MB in size

  No bit rate set

      clip_resized.write_videofile(ResizedClip)

  Gives a file of 3.3MB

• Audio/Video de-synchronisation when playing a video on Chrome

  30 novembre 2020, par Sonia Seddiki

  I've been recently working on a project where I try to play a "custom-made" video on an HTML5 player. By custom-made, I mean I concatenate a bunch of videos together using FFmpeg concat demuxer, each of them having the same properties (FPS, bitrate, resolution, timebase, etc).

  


  Now, I'm having a few issues regarding audio/video synchronisation, with a twist : it does not happen on every video player. The video is perfectly synchronised when read on Firefox, but not on Chrome. It is synchronised when read on a "local" video player like VLC.

  


  I assume it has to do with how the video data is presented to the player. I read a little about PTS, DTS, I-P-B frames and I guess the final output may be a little messed up ? But I don't really have a strong lead to follow here.

  


  I tried to find info on how the HTML5 player was implemented by both browsers, but couldn't find much (again, I'm probably not googling this right). Does anyone here know a bit more about the technical aspect of how a video is actually played in a browser ? Or any clue as to why this de-synchronisation doesn't happen on every platform ?

  


  Thank you so much for your help !

  


• FFMPEG video compression take too much time to compress the video

  1er janvier 2015, par Usman Afzal

  Video Upload Stats

  15 Sec Video on Samsung galaxy S5

  Using back camera : 6.86 MB [15.8 sec]

  Compress File Size : 1.33 MB

  Compression Time : 40-50 sec

  Following command I have used to compress this video file.

  [/data/data/{app-package-name}/app_bin/ffmpeg, -y, -i, /storage/emulated/0/Android/data/{app-package-name}/files/my-video-library/videos/1420020518900.mp4, -strict, -2, -b:v, 700k, -s, 640x360, -r, 30, -vcodec, libx264, -acodec, aac, -ac, 1, -b:a, 64k, -ar, 44100, -vf, vflip, /storage/emulated/0/Android/data/{app-package-name}/files/my-video-store/videos/acbfc5d3-b6c1-4cb8-89db-13aa49003760.mp4]