[FFmpeg-user] What is the usage for -cgop/+cgop and -g options.

["zhilizhao(赵志立)"]

> On Jan 27, 2021, at 4:26 PM, Hongyi Zhao <hongyi.zhao at gmail.com> wrote:
> 
> On Wed, Jan 27, 2021 at 10:52 AM pdr0 <pdr0 at shaw.ca> wrote:
>> 
>> Hongyi Zhao wrote
>>> I noticed there are -cgop/+cgop and -g options used by ffmpeg. But I
>>> really can't figure out the usage of them. Any hints will be highly
>>> appreciated.
>> 
>> -g is the maximum gop length (the maximum keyframe interval) . Some
>> codecs/settings have adaptive GOP and I frame placement, but it will never
>> exceed that value
> 
> I've tried to search through the whole source code repo and still
> can't find any definitive explanation about this parameter.

Use `ffmpeg -h full` for quick reference.

For source code, ref. libavcodec//options_table.h

> 
>> cgop is for specifying closed GOP
> 
> Same for this one.
> 
> Best
> -- 
> Assoc. Prof. Hongyi Zhao <hongyi.zhao at gmail.com>
> Theory and Simulation of Materials
> Hebei Polytechnic University of Science and Technology engineering
> NO. 552 North Gangtie Road, Xingtai, China
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