[FFmpeg-user] "documented implicitly" [was: Re: Why is format=rgb24 required after maskedmerge?]

Mark Filipak markfilipak.windows+ffmpeg at gmail.com
Thu Aug 20 05:14:21 EEST 2020

On 08/19/2020 01:43 PM, Jim DeLaHunt wrote:
> On 2020-08-19 07:34, Paul B Mahol wrote:
>> You are deeply confused about our filters.
>> Any filter can change pixel formats to one that they accepts thus gbrp
>> is picked instead of packed rgb, this is already documented
>> implicitly.
> Wow, "documented implicitly". This is such a classic FFmpeg project statement. The role of 
> documentation is to explain, explicitly, at a suitable level of detail. What does "documented 
> implicitly" even mean?
> I think this thread points out is that FFmpeg documentation is inadequate. It is hard to prove a 
> negative, but I suspect that the term "pixel format" is not actually defined in the FFmpeg 
> documentation. I suspect that the statement, "Any filter can change pixel formats" is not stated 
> either. Certainly the maskedmerge filter documentation[1] doesn't mention pixel formats at all, much 
> less say what pixel formats the filter sets for its output.
> I have attempted to improve the documentation, to make it explain explicitly instead of fail to 
> document. I encountered a great deal of resistance to those patches, because they make the 
> documentation more explicit, because they have more words, and because documentation has so little 
> value in this project relative to executable code.
> And yet "You are deeply confused about our filters". In other words, the documentation has failed to 
> explain to you what FFmpeg does, the project has failed to write or welcome improved documentation, 
> you do not understand how FFmpeg works — and somehow this is your fault.
> [1] http://ffmpeg.org/ffmpeg-all.html#maskedmerge

I have a theory, Jim. I think the developers don't document things (or comment their code) for 2 
reasons: 1, They want to be able to change methods and behaviors without having to maintain 
documentation, and 2, They want to make money doing consulting jobs for people who commit ffmpeg for 
their projects, then give up trying to write ffmpeg command lines.

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