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• Why after rendering with ffmpeg, file size did not decrease ?

  15 avril 2021, par ptrra

  PROBLEM : After rendering a certain video with ffmpeg file size increased from 4GB to 6GB.
  
ORIGINAL VIDEO : EE1.mkv
  
FFMPEG COMMAND : ffmpeg -i EE1.mkv -c:a copy -c:v libx264 -crf 23 -preset medium -profile:v high out.mp4
  
QUESTIONS : Why did the file size increase ? What am I doing wrong ?

  


   !DETAILS !
  
After a few years I made about 30 gaming videos (130GB) and with the current covid-19 situation I started recording my online classes (about 40 videos or 150GB). Now because I'm lacking space on my 1TB external HDD I started getting into ffmpeg. Before I was only using obs-studio and not good parameters for recording.

  


  I was using CBR mode for recording, either 5000KB or 15000KB bit rate with varying x264 presets and profiles because I was also experimenting with them. Usually superfast preset with high profile. So I wanted to convert all those videos with ffmpeg using CRF 23, medium preset and high profile. A note that when I'm recording with obs-studio it's set to record in matroska format (.mkv).

  


  When I was rendering my online classes videos with these settings I managed to achieve 10x better compression with the same quality. And when rendering my gaming videos I managed to achieve up to 3x better compression with the same quality. However there is this one video that when rendered with the same parameters the file size increases.

  


  The EE1.mkv should be recorded with CBR 15000KB bit rate, with superfast preset and high profile. Also the game that is recorded in this video is Empire Earth which needs around 8000KB for it to look good. Everything more than 8000KB is not needed.

  


  Thank you all for your help.

  


• FFMPEG - What are some recommended parameters for x265 (libx265) ?

  7 janvier 2019, par dd_code

  I am working on re-encoding some footage (x264), including some grainy footage. I am interested in CRF-only bitrate management (I want to avoid artifacts during demanding scenes).
  What are recommended parameters to be set instead of leaving them at their defaults ?

  Here is what I got so far, pretty simple :

  ffmpeg -i in.mkv -vf unsharp=3:3:1 -c:v libx265 -tune:v grain -crf 24 -c:a copy out.mkv

  (this example has grain tune as many files are grainy, and without it it washes it out and all the "detail by noise" is lost + I am applying a light sharpening filter, I find there is always a room to sharpen a bit without causing noticeable sharpening artifacts)

  If I am not mistaken all the params one does consider are ones contained in the presets, but is there some other or one of those which is a good practice to adjust manually to achieve a better result ? I was wondering specifically about P,I,B-frames and AQ (but I guess there are some other as well).

• fftools/textformat/tw_avio : Use avio_closep()

  14 avril, par Andreas Rheinhardt

  fftools/textformat/tw_avio : Use avio_closep()
  Avoids leaving dangling pointers behind.
  Reviewed-by : softworkz . <softworkz-at-hotmail.com@ffmpeg.org>
  
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] fftools/textformat/tw_avio.c