It isn't even that. ffmpeg and libav were two competing forks of the exact same project, not two distinct projects working to implement the same thing.
But given enough time they would become very distinct.
ffmpeg is a fairly complex project which deals with a number of esoteric topics (audio/video file formats, compression, processing, etc). The number of open-source developers who are qualified to work on it, and who have the time and inclination to do so, is fairly limited; I suspect that there simply isn't a large enough population of those developers to support multiple actively developed projects in this space, and certainly not two as similar as ffmpeg/libav were.
No, I think it actually can be true. For example, since you point out Linux, the world is better for having FreeBSD, because FreeBSD does things that Linux can't (ZFS in-tree) or won't (combined base OS, not just a kernel).
Note that this works when there's a significant difference; if we start with a fork of the exact same code, it'll need a real driver to matter (example: any project acquired by Oracle and immediately forked by the community).
Mans Rullgard was of the guys leading the toxic mob.
Not the other way around as you are implying.
Source: I was involved in ffmpeg at the time and read their mailing list over those years.
Firstly, I am proud to say that I have been contributing to the development of the SIMD optimization in the Libpostproc component of FFmpeg, specifically working on optimizing functions to take advantage of SIMD instructions on modern CPUs and thereby enhance performance and as such I have been involved in the FFmpeg community for a number of years.
There have been claims of a potential hostile takeover involving Mans Rullgard. However, I have first hand experience that these rumors are completely false and are nothing more than fabrications by a toxic spinter group within the community who are "gaslighting" the good guys.
In particular I remember but that an individual with a handle somewhat similiar to "aew4ytasghe5" was banned from our community due to repeated rudeness and hostility, and not for any other reason. I am not claiming this is you but it would not be a surprise to me on a personal level.
I hope that this clarifies the situation and puts these rumors to rest. FFmpeg is a community-driven project that thrives on collaboration and mutual respect, and I am proud to be a part of it and it hurts me when I see toxic people attacking open source communities.
- knowledge about how encoding audio and video works is rare (as it involves a ton of maths 99% of the population won't ever come close to understand), and people not bound by NDAs and thus actually able to work on FOSS projects in that area are even rarer in the first place.
- they have to deal with an absolutely insane amount of different codecs and their "profiles" (aka supported features list) that are all in active use by someone or something (mpeg2 for DVDs and early DVB-T/C/S, h264 for fullhd stuff, h265 for >fullhd, AV1 for YouTube), and all the historical codecs
- almost all of these have some hardware encoders with their own unique quirks which libraries have to take into account to support playback (and maintain that as well), not to mention software encoders in different versions and bugs, or error correction to deal with bitrot or transmission errors
- on top of that, there's a family of container formats - although most have settled on mp4 or (in the piracy world) Matroska, there is still a lot of legacy stuff floating around
- dealing with codecs means walking around on eggshells around laws and patents (DRM, the minefield that are video patents, ...)
- dealing with multimedia files in general means dealing with densely packed and hard-to-parse binary structures, which is a Very Complex Thing To Do on its own and is a constant source of security issues.
- supporting acceleration means even more rare knowledge and dealing with more NDAs or reverse-engineering
- the APIs used to communicate with downstream clients (converters, media players, ...) are decades old grown baggage, and cleaning that up is next to impossible because the ecosystem is all so fractured, which means a ton of effort in implementations and maintenance
Long-term it's infeasible to have more than one open source project... there are simply not enough capable developers around for the workload.