[FFmpeg-user] Issue in video compression

Ted Park kumowoon1025 at gmail.com
Thu Jun 11 18:34:15 EEST 2020


Hi,

> The description of preset file that has been used is as follows:-
> 
> vcodec=libx264
> vprofile=main
> level=30
> b:v=800000
> bufsize=800000
> 
> But the output .mp4 file is not getting compressed. 

My first thought is that the b:v=800000 in the preset file is leading to a constant bit-rate encode. Is the file in question about an hour and 2 minutes long? If it’s close, then I would say that is what’s happening. If there is a file size constraint, you should encode using multiple passes, or if it is just the case that you would like a somewhat smaller file to work with, you can use constant quality (vs. constant bitrate) encoding settings, using -crf to control the output filesize by trial and error, instead of explicitly specifying the video bitrate

Regards,
Ted Park


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