as software developer, i can't understand how does software's like SMPlayer or VLC or UMPlayer do there revenue , they all open-source they all downloaded Millions of times they all professional software not amateur at all . that i know as software developer takes allot of time and effort to build , but hell how they make a leaving out of it ?
Simple answer is they aren't. The work on these projects was donated freely by the programmers. This is not their full time job but a side project
That's not to say that you can't make money from open source projects. Red hat for example makes a huge amount selling support for their free software.
Are you assuming that VLC, SMPlayer were created with making profit in mind? Because that may not be the case.
In case of VLC Wikipedia writes: "The VideoLan project was originally started as an academic project in 1996 (....) it is now developed by contributors worldwide and is coordinated by the VideoLAN non-profit organization." (see: http://en.wikipedia.org/wiki/VLC_media_player )
The videoLAN organisation works with volunteer developers and asks for donations for server costs and for organizing events. Some of the VLC developers have set up companies offering services to mone4 ize their experience gained in the project. (see: http://www.videolan.org/videolan/partners.html )
It seems that profit can be 'bolted on' afterwards by adding services to the product or process for businesses that uses open source software. Most examples are in B2B market.
Business market examples:
Governement market example:
Consumer market example: