Bump ffmpeg version

[bluebandit21]

WIP, not finished yet.

This aims to bump FFMPEG to 4.4, a fairly recent release.
FFMPEG 2.1.3, what we are using currently, is from 2014, making it rather old...
Updating FFMPEG now instead of waiting for it to break at some point in the future seems prudent.

MacOS currently builds ffmpeg from source; I have preserved this.
Linux and Windows both use pre-built libraries.
@nico-abram updated the Windows pre-built libraries (thank you!) but the Linux side has still not been touched.

[bluebandit21]

Just need to figure out the Linux pre-built library side for this to be ready.

I believe the issue preventing easily doing so was figuring out what distribution's pre-built FFMPEG to use, since I'm not sure where the original libraries even came from.

Alternatively, it might make more sense to build FFMPEG like we do for mac, since I'm not sure why the two are different in the first place.

[nico-abram]

Are we actually building with ffmpeg on linux? I looked at the g++ and clang github actions logs for the latest develop commit and I can find no mention of "avcodec", "ffmpeg" or "MovieTexture_FFMpeg" within the build step logs. I can easily find these terms in the analogous mac and windows logs.

In this cmake file:

etterna/src/arch/CMakeLists.txt

Lines 76 to 88 in 2011156

	if(APPLE)
	list(APPEND SMDATA_ARCH_MOVIE_TEXTURE_SRC "MovieTexture/MovieTexture_FFMpeg.cpp")
	list(APPEND SMDATA_ARCH_MOVIE_TEXTURE_HPP "MovieTexture/MovieTexture_FFMpeg.h")
	elseif(MSVC)
	list(APPEND SMDATA_ARCH_MOVIE_TEXTURE_SRC "MovieTexture/MovieTexture_FFMpeg.cpp")
	list(APPEND SMDATA_ARCH_MOVIE_TEXTURE_HPP "MovieTexture/MovieTexture_FFMpeg.h")
	else() # Unix
	if (${HAS_FFMPEG})
	list(APPEND SMDATA_ARCH_MOVIE_TEXTURE_SRC "MovieTexture/MovieTexture_FFMpeg.cpp")
	list(APPEND SMDATA_ARCH_MOVIE_TEXTURE_HPP "MovieTexture/MovieTexture_FFMpeg.h")
	endif()

Only linux is conditionally not compiling the ffmpeg-dependant etterna C++ files. And grepping for "HAS_FFMPEG" in the entire repo brings up nothing at all, so we are not setting a default value for it nor enabling it in CI. That said, I can't see the actual compiler invocations in the build logs so I'm not sure if we are actually linking an ffmpeg version even if we're not compiling our files that depend on ffmpeg. Also, I can't find any precompiled binary artifacts in /extern/ffmpeg for linux (All of ./lib, ./windows and ./64bit seem to be windows files).

[bluebandit21]

It's been quite a while since I looked at this, so unfortunately my memory is a bit hazy.
I'm fairly certain that we link in a pre-compiled FFMPEG build on Linux (although I don't know if we actually use it or not)
-- I remember the stopper that made me stop making progress on this while I was working on it so long ago was that I couldn't find "a" pre-compiled Linux build for FFMPEG to upgrade to.

Looking at the CMakeLists under extern/ffmpeg,
It does have the lines

if(UNIX)
    file(GLOB LIBS lib/*.a)
endif()

which means we are linking those static libraries on Linux builds.

That said, if we're not actually using that for anything, removing that entirely and just deleting the lib/ directory seems like a perfectly fine solution to me on the Linux side :)

[nico-abram]

I wonder, does that mean it's linking these files then?

I'm scared to ask why these have "dll" in their filenames lol

[bluebandit21]

I believe so.

As for the "dll" in file names, I don't want to know either 0_0

[nico-abram]

There's an if(HAS_FFMPEG) for linux in this cmake script that includes the ffmpeg movieTexture which depends on ffmpeg:

etterna/src/arch/CMakeLists.txt

Lines 84 to 90 in 9a0b9fb

	else() # Unix
	if (${HAS_FFMPEG})
	list(APPEND SMDATA_ARCH_MOVIE_TEXTURE_SRC "MovieTexture/MovieTexture_FFMpeg.cpp")
	list(APPEND SMDATA_ARCH_MOVIE_TEXTURE_HPP "MovieTexture/MovieTexture_FFMpeg.h")
	endif()
	endif()

if(APPLE)
  list(APPEND SMDATA_ARCH_MOVIE_TEXTURE_SRC "MovieTexture/MovieTexture_FFMpeg.cpp")
  list(APPEND SMDATA_ARCH_MOVIE_TEXTURE_HPP "MovieTexture/MovieTexture_FFMpeg.h")
  
elseif(MSVC)
  list(APPEND SMDATA_ARCH_MOVIE_TEXTURE_SRC "MovieTexture/MovieTexture_FFMpeg.cpp")
  list(APPEND SMDATA_ARCH_MOVIE_TEXTURE_HPP "MovieTexture/MovieTexture_FFMpeg.h")
  
else() # Unix
  if (${HAS_FFMPEG})
    list(APPEND SMDATA_ARCH_MOVIE_TEXTURE_SRC "MovieTexture/MovieTexture_FFMpeg.cpp")
    list(APPEND SMDATA_ARCH_MOVIE_TEXTURE_HPP "MovieTexture/MovieTexture_FFMpeg.h")
  endif()
  
endif()

I couldn't find anywhere that sets/defines that HAS_FFMPEG variable though. I assume there might be a way of setting/overriding it via the cmake command line?

[DashDashDashDashDash]

Looking at the CMakeLists under extern/ffmpeg, It does have the lines

if(UNIX)
    file(GLOB LIBS lib/*.a)
endif()

which means we are linking those static libraries on Linux builds.

It seems like that isn't the case since

etterna/extern/CMakeLists.txt

Lines 81 to 83 in b656600

	if(MSVC) # Only required on Windows
	add_subdirectory(ffmpeg)
	endif()

makes it so that only Windows even reaches that file.
However, even if I force it to load the ffmpeg subdir by removing the if(MSVC) entirely (and also forcing HAS_FFMPEG inside arch/CMakeLists.txt to be true), the files don't seem to be used, giving out build errors that indicates it's using the system's installed ffmpeg libraries.

I apologize if this isn't the correct way to go about debugging this issue, but I felt like the if(MSVC) line was important enough to comment on.