I know about presets but faster presets lose the video quality. Are there any hardware requirements I need to consider? Or are there any settings that I need to tweak? And lastly where do I place the -threads flag to encode video (before input or after input), I saw topics on thread but they were confusing.

This is the command I am using now:

ffmpeg -i input.mp4 \
            -codec:v libx264 -tune zerolatency -profile:v main -preset medium -crf 23 -maxrate 1000k -bufsize 10000k -s hd720 -codec:a libfdk_aac -pix_fmt yuv420p -movflags +faststart -threads 4 highoutput.mp4 \
            -codec:v libx264 -tune zerolatency -profile:v main -preset medium -crf 23 -maxrate 500k -bufsize 5000k -s hd480 -codec:a libfdk_aac -pix_fmt yuv420p -movflags +faststart -threads 4 lowoutput.mp4

Your help and guidance will be very much appreciated. Thank you.

  • 1
    Faster presets do less work to come up with the same quality if you're using Constant Rate Factor (-crf). So AFAIK the trade-off isn't less quality, but bigger files.
    – stib
    Aug 15, 2015 at 13:49
  • @stib Is there any way to maintain the bitrate?
    – Robin
    Aug 15, 2015 at 16:52
  • Doesn't using -crf override any bitrate options on the command line? I seem to recall that being the case.
    – WineSoaked
    Aug 15, 2015 at 20:13
  • @WineSoaked Is it? I saw this post telling me otherwise.
    – Robin
    Aug 16, 2015 at 9:58


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