#2537: Handle some short videos

[hugohmk]

As discussed in issue #2537, FFmpeg could be used to handle some corner cases where MPlayer fails to read video info or generate thumbs. The proposed aproach only calls FFprobe/FFmpeg as a fallback to the current solution.

[lfcnassif]

Thank you @hugohmk!

Just to be sure, the license of this new dependency is not GPL, right?

@wladimirleite, if and when you have available time, would you mind to help reviewing this?

[hugohmk]

Hello @lfcnassif! I belive it is Apache 2.0 or GPL2+ with a "Classpath" exception, according to the license details found in the dependency's github page (https://github.com/bytedeco/javacpp-presets and https://github.com/bytedeco/javacpp-presets/tree/master/ffmpeg).

Its Maven repository page also states that it is under these licenses: "Apache License, Version 2.0", "GNU General Public License (GPL) version 2, or any later version" and "GPLv2 with Classpath exception".

There seems to be another version of this dependency (ffmpeg-platform-gpl, https://mvnrepository.com/artifact/org.bytedeco/ffmpeg-platform-gpl) that the author states it is contains "Optional GPL builds with (almost) everything enabled", but it doesn't make clear the licensing differences between the two.

Maybe the author (@saudet) could enlighten us about this issue.

[lfcnassif]

Thanks @hugohmk. I also understood it is dual licensed under Apache v2 or GPL v2+, I also found ffmpeg-platform-gpl, but I found it a bit confusing and asked to be sure.

[hugohmk]

I forgot to mention that FFmpeg itself is licensed under LGPLv2.1+, or GPLv2+ if compiled with some optional features and capabilities (https://www.ffmpeg.org/legal.html).

[lfcnassif]

Thanks! And I double checked an Apache licensed project (the new dependency) can use an LGPL dependency without licensing issues.

[saudet]

Maybe the author (@saudet) could enlighten us about this issue.

About ffmpeg-platform-gpl? If your application depends on a GPL-licensed library, it becomes licensed under GPL. So, for example, if IPED depends on functionality available only in ffmpeg-platform-gpl then IPED becomes automatically licensed under GPL. That's what it means.

[hugohmk]

Maybe the author (@saudet) could enlighten us about this issue.

About ffmpeg-platform-gpl? If your application depends on a GPL-licensed library, it becomes licensed under GPL. So, for example, if IPED depends on functionality available only in ffmpeg-platform-gpl then IPED becomes automatically licensed under GPL. That's what it means.

Thank you for the fast response @saudet, and congratulations on your work on bytedeco! In IPEDs case, I think either ffmpeg-platform or ffmpeg-platform-gpl dependency would bring similar licensing obligations, since FFmpeg is actually only being called as a CLI program, run in a separate process via ProcessBuilder (but I'm not 100% sure). But since I am not familliar with these licensing differences, your comment was very helpful.

[saudet]

If the application only launches executables in separate processes, then yes GPL doesn't typically apply to the application.

[lfcnassif]

... is actually only being called as a CLI program, run in a separate process via ProcessBuilder

It usually doesn't propagate GPL, but it might, see this GPL FAQ excerpt:

By contrast, pipes, sockets and command-line arguments are communication mechanisms normally used between two separate programs. So when they are used for communication, the modules normally are separate programs. But if the semantics of the communication are intimate enough, exchanging complex internal data structures, that too could be a basis to consider the two parts as combined into a larger program.

It's not the case of IPED, we would not exchange complex internal data structures with ffmpeg.

[hugohmk]

It's not the case of IPED, we would not exchange complex internal data structures with ffmpeg.

Great! So I guess there will be no issues using ffmpeg-platform-gpl then... If I'm not mistaken, MPlayer is licensed under GPLv2 as well.

[lfcnassif]

@hugohmk I'm not comfortable with linking to a library that have "gpl" in its name, unless @saudet confirms it is also Apache v2 licensed.

[saudet]

If only some users need the extra gpl dependency, you can leave it up to them to add it to their builds.