[FFmpeg-user] Trying to solve drop in quality

Eduardo Alarc├│n ealarcong at gmail.com
Tue Nov 3 23:45:09 EET 2020


El mar., 3 nov. 2020 a las 18:36, John Harlow via ffmpeg-user (<
ffmpeg-user at ffmpeg.org>) escribi├│:

> The -g is definitely the quality problem. I tried setting it various to
> 30*1000/1001, 60*1000/1001 120*1000/1001, 180*1000/1001, 360/1000/1001and
> even 15*1000/1001.
>
>
>
> Any of those changes show up in mediainfo as:
>
> Format settings                          : CABAC / 4 Ref Frames
> Format settings, CABAC                   : Yes
> Format settings, Reference frames        : 4 frames
>
>
>
> I would have thought the interval for the ref frames was either 2 seconds
> (60*1000/1001) or 2 per ts segment
>
> which would be (basically) 180*1000/1001.
>
>
> I'm not sure how to get to Reference Frames 2.
>
> -g is the gop size in frames, integer, not time, if you want a key frame
every 2 seconds you should use -g 60,  when using 30fps.
With gop 2, you are getting a keyframe every 2 frames, so basically your
video is a huge collection of jpeg images


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