I am aware of the effect on how different max and min gop sizes can influence the compression, thanks.
I hoped for something more than the usual fps*10 stuff.
Won't change min keyint, since using fps seems wrong for normal content.
May I ask who recommends that and why? (I would understand values like 1-5, but fps seems like a bad idea.)
Will think about an adding an option to set, 'output fps'*10, but be aware that if you change the frame rate through filtering, this can change other settings.
i.e. for x264, lookahead is limited to min(gop_size,250) (<- in the source code of x264). So if you change the filtering to for example output 60fps lookahead would increase to 250, but would not go down when you later change the fps to 23.976. Similar b-frame and other settings can change if you change the fps while finding the right filtering settings. Also, the option will not be available when using Blu-Ray compatibility or similar.
=> not really sure if this is a good idea, but I will think about it.
Cu Selur
(27.09.2024, 18:02)Selur Wrote: [ -> ]I am aware of the effect on how different max and min gop sizes can influence the compression, thanks.
I hoped for something more than the usual fps*10 stuff.
Won't change min keyint, since using fps seems wrong for normal content.
May I ask who recommends that and why? (I would understand values like 1-5, but fps seems like a bad idea.)
Will think about an adding an option to set, 'output fps'*10, but be aware that if you change the frame rate through filtering, this can change other settings.
i.e. for x264, lookahead is limited to min(gop_size,250) (<- in the source code of x264). So if you change the filtering to for example output 60fps lookahead would increase to 250, but would not go down when you later change the fps to 23.976. Similar b-frame and other settings can change if you change the fps while finding the right filtering settings. Also, the option will not be available when using Blu-Ray compatibility or similar.
=> not really sure if this is a good idea, but I will think about it.
Cu Selur
It's just what I saw recommended on many forums for a long time (Doom9, Videohelp, Reddit...), and since many softwares like those I mentioned use it, I thought it was the best formula.
I use it especially for 60fps videos, but do you think that keeping keyint 250 for 60fps is a good idea ?
Nowadays, I would recommend to use openGOP instead of a fixed gop size unless you have some ancient hardware or software decoder.
When using a fixed gop, the idea of fps*10 was to find a balance between compression gain and keeping the content faster seekable for old hardware.
Remember this is only the max value (assuming the encoder inserts gops dynamically, which most modern encoders do, unless told otherwise).
Reasons (I see) for closed gop nowadays are:
a. (old) hardware or software compatibility
b. medium/format restriction (i.e. Blu-ray, UHD-Bluray)
c. you encode an intermedia file
d. you need a specific gop size (set min=max gop size) for some reason (i.e. academic)
if none of the above is a problem, use open gop.
Cu Selur
Ps.: uploaded a new dev which has an 'Adjust gop max to output fps' (to x264&265), have no use for it personally, but maybe it helps folks that do batch encoding with fixed gops.
(27.09.2024, 19:18)Selur Wrote: [ -> ]Nowadays, I would recommend to use openGOP instead of a fixed gop size unless you have some ancient hardware or software decoder.
When using a fixed gop, the idea of fps*10 was to find a balance between compression gain and keeping the content faster seekable for old hardware.
Remember this is only the max value (assuming the encoder inserts gops dynamically, which most modern encoders do, unless told otherwise).
Reasons (I see) for closed gop nowadays are:
a. (old) hardware or software compatibility
b. medium/format restriction (i.e. Blu-ray, UHD-Bluray)
c. you encode an intermedia file
d. you need a specific gop size (set min=max gop size) for some reason (i.e. academic)
if none of the above is a problem, use open gop.
Cu Selur
Ps.: uploaded a new dev which has an 'Adjust gop max to output fps' (to x264&265), have no use for it personally, but maybe it helps folks that do batch encoding with fixed gops.
OK thanks for the clarification. Actually, one of the reason I tend to use closed GOP (aside from hardware compatibility) is to make more precise cuts losslessly.
Thank you for the updated version
Quote:to make more precise cuts losslessly.
So, you are creating an intermediate file.
For my taste, fps*10 is way too large of a gap for precise cutting, but I suspect you are probably not really doing a lossless cut (only cut on IDR frames).
I suspect that you use some software which does some smart-re-encoding of the split gops.
Cu Selur
(28.09.2024, 05:33)Selur Wrote: [ -> ]Quote:to make more precise cuts losslessly.
So, you are creating an intermediate file.
For my taste, fps*10 is way too large of a gap for precise cutting, but I suspect you are probably not really doing a lossless cut (only cut on IDR frames).
I suspect that you use some software which does some smart-re-encoding of the split gops.
Cu Selur
Most of time it's just a precaution, for example when I make projects where I edit videos, I can delete the source, and still change my mind and adjust the editing losslessly, or also in cases where I want to keep some scenes of a video in addition to the source.
I also find that fps*10 is large for precise cutting, thankfully it's generally good enough in those cases.
Actually I don't do smart cut (except in some cases). I mainly use softwares that allow true lossless cut on IDR frames.