[FFmpeg-user] Trying to solve drop in quality
johnrharlow at mac.com
Tue Nov 3 23:54:07 EET 2020
I figured it out. Pointing out that it was the GOP set me on the right path
I eliminated -g and changed:
On November 3, 2020 at 4:45 PM, Eduardo Alarcón <ealarcong at gmail.com> wrote:
El mar., 3 nov. 2020 a las 18:36, John Harlow via ffmpeg-user (<
ffmpeg-user at ffmpeg.org>) escribió:
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
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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