"Almost" because this might contain copyright by michael, who agreed
with LGPL, but only once the core is LGPL. This is preparation for that
to happen.
Apart from that, the usual remarks apply. In particular, dec_video.c
started out quite chaotic with no modularization, but was later
basically gutted, and in general rewritten a bunch of times. Not going
to give a history lesson.
Special attention needs to be given to 3 patches by cehosos, who did not
agree to the relicensing:
240b743ebd: --field-dominance
e32cbbf7dc: reinit VO if aspect ratio changes
306f6243fd: use container aspect if codec aspect unset (?)
The first patch is pretty clearly still in the current code, and needs
to be disabled for LGPL.
The functionality of the second patch is still active, but implemented
completely different, and as part of general frame parameter changes (at
the time of the patch, MPlayer already reinitialized the VO on frame
size and pixel format changes - all this was merged into a single check
for changing image parameters).
The third patch makes me a bit more uncomfortable. It appears the code
was moved to dec_video.c in de68b8f23c, and further changed in
82f0d373, 0a0bb905, and bf13bd0d. You could claim that cehoyos'
copyright still sticks. Fortunately, we implement alternative aspect
detection, which is simpler and probably preferable, and which arguably
contains none of the original code and logic, and thus should be fully
safe.
While I don't know if cehoyos' copyright actually still applies, I'm
more comfortable with making the code GPL-only for now. Also change the
default to use the (in future) plain LGPL code, and deprecate the one
associated with the GPL code, so we can eventually remove the GPL code.
But it's also possible we decide that the copyright doesn't apply, and
undo the deprecation and GPL guards.
I expect that users won't notice anything. If you ask me, the old aspect
method was probably an accidental bug instead of intentional behavior.
Although, the new aspect method was broken too, so I had to fix it.
image_writer.c has code originating from vf_screenshot.c, vo_jpeg.c, and
potentially others. vo_image.c is based on a bunch of those VOs as well,
and the intention was to replace them with a single codebase.
vo_tga.c was written by someone who was not or not could be contacted,
but it doesn't matter anyway, as no code from that initial patch was
used.
One rather old patch (57f77bb41a) reordered by libjpeg patch API calls,
and the author of the patch was not contacted. But at least with the
smoothing_factor override removed, this pretty much exactly corresponds
to the official libjpeg API example (and might even reflect a change to
those - didn't dig deeper). This removes the -jpeg-smooth option. While
we're at it, remove all the other dropped jpeg options from the manpage
(which was forgotten in past changes).
The problem with fmt-conversion.h is that "lucabe", who disagreed with
LGPL, originally wrote it. But it was actually rewritten by "reimar"
later. The original switch statement was replaced with a lookup table.
No code other than the imgfmt2pixfmt() function signature survives.
Neither the format pairs (PIXFMT<->IMGFMT), nor the concept of mapping
them, can be copyrighted.
So changing the license should be fine, because reimar and all other
authors involved with the new code agreed to LGPL.
We also don't consider format pairs added later as copyrightable.
(The direct-mapping idea mentioned in the "Copyright" file seems
attractive, and I might implement in later anyway.)
Likewise, there might be some format names added to img_format.h, which
are not covered by relicensing agreements. These all affect "later"
additions, and they follow either the FFmpeg PIXFMT naming or some other
pre-existing logic, so this should be fine.
This file is an leftover from when img_format.h was changed from using
the ancient FourCCs (based on Microsoft multimedia conventions) for
pixel formats to a simple enum. The remaining cases still inherently
used FourCCs for whatever reasons.
Instead of worrying about residual copyrights in this file, just move it
into code we don't want to relicense (the ancient Linux TV code). We
have to fix some other code depending on it. For the most part, we just
replace the MP_FOURCC macro with libavutil's MKTAG (although the macro
definition is exactly the same). In demux_raw, we drop some pre-defined
FourCCs, but it's not like it matters. (Instead of
--demuxer-rawvideo-format use --demuxer-rawvideo-mp-format.)
It was an attempt to move some MPlayer filters (which were removed from
mpv) to external, loadable filters. That worked well, but then the
MPlayer filters were ported to libavfilter (independently), so they're
available again. Also there is a more widely supported and more advanced
loadable filter system supported by mpv: vapoursynth.
In conclusion, vf_dlopen is not useful anymore, confusing, and requires
quite a bit of code (and probably wouldn't survive the rewrite of the
mpv video filter chain, which has to come at some point). It has some
implicit dependencies on internal conventions, like possibly the format
names dropped in the previous commit.
We also deprecated it last release. Drop it.
It seems "lucabe" didn't actually write the current fmt-conversion.c/.h
code. He added the first version of the pixfmt mapping, which was later
changed into a table. So his agreement might not be required for
copyright purposes. Still, all those later additions of pixfmts by
various authors may or may not matter, so the situation is still
complex.
Quite chaotic history, which code being moved, refactored, duplicated,
unified a bunch of times. But I think everything is covered by LGPL
agreements.
In one case, cehoyos (who didn't agree) applied a patch by someone who
agreed, but didn't change anything (except weirdly adding German
translations). In another case, cehoyos moved code covered by LGPL
agreements (without changing it), which was later used for some other
code. We consider both cases not relevant for copyright.
win_state.c/.h is similar, but pending for reply by the author of
2ab259e68 (I guess).
This file didn't have a license in the first place. The fact that this
file was supposed to be a template, to be copied and modified by
individual users, might weaken the assumption that it's GPL. (It was
only later that mpv replaced the duplicate code in input.c with
input.conf essentially.)
All involved authors agreed to LGPL. On exception is an anonymous
contribution in commit 116ca0c768. This "veal" could not be found.
So the I key is noted as exception. input.conf does not support
conditional guards, so I'm not sure what to do here. Either we could
argue it's a joint work, or the fact that the I key won't work anyway
with a LGPL mpv might count.
etc/builtin.conf and etc/encoding-profiles.conf are mpv original things,
written by developers who agreed to LGPL. So mark them as LGPL too.
Surprisingly long history, but it's covered by LGPL agreements. One
exception is a7fc969ff6: someone who hasn't asked changes the
copyright year, but that change was obviously overwritten again later.
Since michael was somewhat involved in it, wait with the actual license
change until the core is relicensed. Thus mark it as "Almost LGPL.".
The worrisome part about mp_image.c is that it was created by cehoyos
(which disagreed with LGPL) in commit f2dee327b2. But it turns out it
was a patch by someone else (who agreed with LGPL).
For some reason, the patch was actually slightly modified by cehoyos for
no reason (messed with the include statements), so we mess them back,
just to be sure.
Other than this, there were some commits that added support for new
IMGFMTs over the years. Some of these were by people we didn't ask or we
didn't get permission from. But since the original mp_image code was
replaced by more generic code using FFmpeg pixdesc, none of these
changes are left anyway.
One additional change by cehoyos (115bfb9762) has been removed as well
(when "direct rendering" was dropped from the filter chain).
All authors agreed.
The author of 1ee8ce75 did not respond, but it was a mpv pull request,
and at this time DOCS/contribute.md and the "Copyright" file stated that
all contributions must include LGPL relicensing permission. But you
could claim that this was too "hidden". Sort of a corner case, I guess,
but not my problem.
Since this demuxer is based on code by michael, this file can become
LGPL only once the mpv core becomes LGPL, and this is preparation for
it.
There were quite a lot of changes for rearranging preferred libavformat
vs. internal MPlayer demuxers, codec mappings, and filename extensions,
but all this got removed, so some of the relevant authors weren't asked.
cehoyos, who disagreed with LGPL, made a few changes in the past (mostly
codec mapping and deinterlacing related things), but all of them were
removed, mostly due to libavformat API cleanups.
adland, who could not be reached, did commit 057916ee65, but it's easy
to essentially revert the change (this is what the source changes in
this commit do), so we don't need to think about it.
Chris Welton, who could not be reached, made a simple change in commit
958c41d9b6. Fortunately, the API changed again, and his changes were
removed, so we don't need to think about this either.
There is an anonymous contribution in commit 085f35f4b4 - since this
did not introduce any original code, and the probe code was heavily
rewritten multiple times, I don't consider it relevant.
iive agreed only to LGPL 3.0+ only. All of his relevant changes are for
XvMC, for which mpv completely dropped support back in mplayer2 times.
But you could claim that the get_format code represents some residual
copyright (everything else added by iive was removed, only get_format
still is around in some form). While I doubt that this is relly
copyright-relevant, consider it is for now.
michael is the original author of vd_lavc.c, so this file can become
LGPL only after the core becomes LGPL.
cehoyos did not agree with the LGPL relicensing, but all of his code is
gone.
Some others could not be reached, but their code is gone as well. In
particular, vdpau support, which was originally done by Nvidia, had
larger impact on vd_lavc.c, but vdpau support was first refactored a few
times (for the purpose of modularization) and moved to different files,
and then decoding was completely moved to libavcodec.
Lastly, assigning the "opaque" field was moved by Gwenole Beauchesne in
commit 8e5edec13e. Agreement is pending (due to copyright apparently
owned by the author's employer). So just undo the change, so we don't
have to think about whether the change is copyrightable.
All relevant authors of the current code have agreed.
As always, there are the usual historical artifacts that could be
mentioned. For example, there used to be a large number of decoders
by various authors who were not asked, but whose code was all 100%
removed. (Mostly due to FFmpeg providing all codecs.)
One point of contention is that Nick Kurshev might have refactored the
old audio decoder code in 2001. Basically, there are hints that it might
have been done by him, such as Arpi's commit message stating that the
code was imported from MPlayerXP (Nick's fork), or all the files having
his name in the "maintainer" field. On the other hand, the murky history
of ad.h weakens this - it could be that Arpi started this work, and Nick
took it (and possibly finished it).
In any case, Nick could not be reached, so there is no agreement for
LGPL relicensing from him. We're changing the license anyway, and assume
that his change in itself is not copyrightable. He only moved code, and
in addition used the equivalent video decoder framework (done by Arpi,
who agreed) as template. For example, ad_functions_s was basically
vd_functions_s, which the signature of the decode callback changed to
the same as audio_decode(). ad_functions_s also had a comment that said
it interfaces with "video decoder drivers" (I'm fixing this comment in
this commit).
I verified that no additional code was added that is copyright-relevant,
still in today's code, and not copied from the existing code at the time
(either from the previous audio decoder code or the video framework
code). What apparently matters here is that none of the old code was not
written by Nick, and the authors of the old code have given his
agreement, and (probably) that Nick didn't add actual new code (none
that would have survived), that was not trivially based on the old one
(i.e. no new copyrightable "work").
A copyright expert told me that this kind of change can be considered
not relevant for copyright, so here we go.
Rewriting this would end with the same code anyway, and the naming
conventions can't be copyrighted.
All authors of the current code have agreed.
The code probably originates from a software named GySmail (as the
copyright header indicates). As far as I can tell, it was written by
Arpi (who has agreed), possibly with unknown co-authors. This is most
likely OK, as none of the original code is around anymore anyway. I
could not find a working download of GySmail, that actually contained
the original getch2.c code.
This also has a wild history of random people adding ifdef guards to
control ioctl() vs. tcgetattr() calls. (See for example 2b1310abba4c1.)
Later, the ioctl() was removed in favor of the POSIX tcgetattr(), and
the ifdeffery was removed. So these people were not contacted.
All authors of the current code have agreed (as far as this commit
requires).
options.c/options.h will take more effort, because it contains all the
option declarations, and thus is touched extremely often.
m_option.c is technically still GPL, because of commit 2c82d5a1d8
(michael has agreed to LGPL, but only once the core of mpv is LGPL).
The geometry parsing code in m_option.c was originally by someone who
could not be reached. However, it was heavily rewritten anyway, and only
the syntax remains (i.e. not copyright-relevant).
parse_commandline.c contains a change by "adland" (commit 1d0ac71ae8),
who could not be reached - this this specific part is GPL only.
Fortunately, it matters only for DVD (and even then is more like a hack,
but whatever).
There are some other relevant changes, but they have all been reverted,
moved somewhere else, deleted, or replaced.
All authors have agreed.
mpv.exe.manifest probably can't have a copyright header, so it doesn't.
These files don't add license info to the executables. And of course the
executable license is still GPL.
The history goes back to 2001 or so, but everyone involved with still
existing code has agreed.
One person who could not be reached yet (elevengu) has changes in this,
which as far as I can tell were overwritten anyway at a later point.
All relevant authors have agreed to the relicensing.
Problem cases:
eca47b1a5e: someone else gets credited for the "idea" of this change,
but it doesn't seem like it was a patch (otherwise reimar would have
said "patch"). Also, the associated code got essentially removed again
anyway. (The option parsing was rewritten fully.)
ffb529e4eb: anonymous/unknown author, but the code was fully removed
anyway. The struct was removed, and the modern code does explicit
read/write calls.
40789473d2: author was not contacted, but this code was removed
anyway. The magic number (0x7ffff000) is still in the new code, but I
don't think that is copyright relevant.
c750b8ab2d: the message was entirely removed.
All contributors of the current code have agreed. ao.c requires a
"driver" entry for each audio output - we assume that if someone who
didn't agree to LGPL added a line, it's fine for ao.c to be LGPL
anyway. If the affected audio output is not disabled at compilation
time, the resulting binary will be GPL anyway, and ootherwise the
code is not included.
The audio output code itself was inspired or partially copied from
libao in 7a2eec4b59 (thus why MPlayer's audio code is named libao2).
Just to be sure we got permission from Aaron Holtzman, Jack Moffitt, and
Stan Seibert, who according to libao's SVN history and README are the
initial author. (Something similar was done for libvo, although the
commit relicensing it forgot to mention it.)
242aa6ebd4: anders mostly disagreed with the LGPL relicensing, but we
got permission for this particular commit.
0ef8e55573: nick could not be reached, but the include statement was
removed again anyway.
879e05a7c1: iive agreed to LGPL v3+ only, but this line of code was
removed anyway, so ao_null.c can be LGPL v2.1+.
9dd8f241ac: patch author could not be reached, but the corresponding
code (old slave mode interface) was completely removed later.
Most authors have agreed. Like with vo.c, we don't take module
declarations into consideration (see 0e09533c73).
Notable issues:
115bfb9762: the author has (probably) not agreed. The vf.c changes were
removed with the removal of filter DR, though (see c54fc507da).
7b25afd742: the same author adds VOCTRLs for deinterlacing switching at
runtime. Put them under a HAVE_GPL ifdef just to be sure. (It looks like
we could remove the VOCTRLs immediately, as they're needed only for some
compatibility things, but no need to do that yet.)
02b199e5e9: the author had a conditional agreement to LGPL, which
doesn't allow us to change it just yet, but the code added here was
completely removed anyway. (These days, the pts is passed as mp_image
field, and put_image is gone.)
3532cd532e: same author, but code removed with DR removal.
f0626e2f8d: same author, but code was moved to mp_image.c.
e5b4b495c3: agreed to LGPLv3+ only, but the code was removed in
cfa1f9e082 anyway.
086c324692: author was not asked - minor warning fix, but no mpv
includes malloc.h anymore.
e9d0a1d609: author was not asked - removed again in 33b62af947.
c260a1139d: author could not be reached - but this code was removed when
mpv changed the image allocation code to essentially use FFmpeg's
pixdesc.
This case is a bit weird, because MPlayer certainly also has a file
named af_format.c. Both appear to have the function of converting audio
data between sample formats.
However, mpv's af_format.c is a rewrite, and doesn't actually do
conversion by itself. It's similar to vf_format.c, and forces the
generic filter chain code to insert conversion filters, instead of doing
conversion explicitly.
mpv's current af_format.c started out as af_force.c in d9582ad0a4. It
was renamed to af_format.c in e60b8f181d, while the old af_format.c was
split into two new filters. In 943c785619 the filename was changed to
af_format.c as well.
The new af_format.c does not contain any libaf code, except for some
potentially copy & pasted skeleton and boilerplate code. (We don't
account for this in per-filter file licenses, as the old libaf code
has to be removed fully, at which point the filters will have to be
ported to another framework, which will removed that boilerplate code.)
The old filters based on af_format.c were progressively replaced and
removed. Support for non-native endian and formats with signedness
different from native FFmpeg was completely removed in 831d7c3c40.
The old 24 bit conversion code was removed in 552dc0d564 (made
unnecessary by 5a9f817bfd).
Also list hwdec_vaglx.c as GPL-only, which doesn't have anything to do
with this commit.
It seems libsmbclient has been GPLv3 for years. Also, it's certainly not
LGPL (unlike some of its support libs like talloc). Thus, mpv built with
Samba support is GPLv3.
Disable it by default, so we don't have to go through the trouble to
indicate the correct license in our output, and we don't trick people
into distributing stuff under the wrong license.
This has a messy history all back to the initial commit with multiple
refactors, but it seems almost all authors agreed.
Exceptions:
2aa6acd974: patch by someone who could not be reached. Whether or not
this code is still in mpv is unknown, but the affected code was moved to
stream.c at one point anyway.
3859bbd9fe: not sure if this is a patch by the mentioned person (I
assume not) or the committer (who agreed to LGPL), but it seems the
change is too trivial to affect copyright. It seems even the FD check
can be dropped, which I'm doing in this commit.
58846451f0: author doesn't reply. But reverting this and letting
someone who has never seen this commit before redo it would lead to
exactly the same code. So I'm claiming that the change is not
copyrightable.
All authors have agreed.
One minor exception is 21a9221e7b (patch by someone who wasn't asked),
but we just remove the added line again. It seems unneeded.
Most contributors have agreed. vo.c requires a "driver" entry for each
video output - we assume that if someone who didn't agree to LGPL added
a line, it's fine for vo.c to be LGPL anyway. If the affected video
output is not disabled at compilation time, the resulting binary will be
GPL anyway.
One problem are the changes by Nick Kurshev (usually using "nick" as SVN
username). He could not be reached. I believe all changes to his files
are actually gone, but here is a detailed listing:
fa1d5742bc: nick introduces a new VO API. It was removed in 64bedd9683.
Some of this was replaced by VOCTRLs are introduced in 7c51652a1b,
obviously replacing at least some functionality by his API.
b587a3d642: nick adds a vo_tune_info_t struct. Removed in 64bedd9683
too.
9caad2c29a: nick adds some VOCTRLs, which were silently removed in
8cc5ba5ab8 (they became unused probably with the VIDIX removal).
340183b0e9: nick adds VO-based screenshots, which got removed in
2f4b840f62. Strangely the same name was introduced in 01cf896a2f again,
but this is a coincidence and worked differently (also it was removed
yet again in 2858232220).
104c125e6d: nick adds an option for "direct rendering". It was renamed
in 6403904ae9 and fully removed in e48b21dd87.
5ddd8e92a1: nick adds code to check the VO driver preinit arg to every
single VO driver. The argument itself and any possibly remaining code
associated with it was removed in 1f5ffe7d30.
f6878753fb: nick adds header inclusion guards. We assume this is not
relevant for copyright.
Some of nick's code was merely moved to other files, such as the
equalizer stuff added in 555c676683 and moved in 4db72f6a80 and
12579136ff, and don't affect copyright of these files anymore.
Other notes:
fef7b17c34: a patch by someone who wasn't asked for relicensing added a
symbol that was removed again in 1b09f4633.
4a8a46fafd: author probably didn't agree to LGPL, but the function
signature was changed later on anyway, and nothing of this is left.
7b25afd742: the same author adds a symbol to what is vo.h today, which
this relicensing commit removes, as it was unused. (It's not clear
whether the mere symbol is copyrightable, but no need to take a risk.)
3a406e94d7, 9dd8f241ac: slave mode things by someone who couldn't be
reached. This aspect of the old slave mode was completely removed.
bbeb54d80a: patch by someone who was not asked, but the added code was
completely removed again.
All authors of the current code have agreed.
For most of its life, MPlayer used Microsoft structs like WAVEFORMATEX
to describe media content. It appears these were copied from wine in
61c5a99851. Copyright is unclear, but mpv completely removed use of
these structs anyway. (demux_mkv.c still contains code to read these
fields from a byte stream, but the struct is fully gone.)
42f97b2b82: cehoyos (who probably didn't agree with LGPL) applied a
patch by someone who agreed. It's unknown whether cehoyos modified the
patch (and thus his copyright would apply), but the changed code was
removed anyway. (The code was first moved somewhere else, then removed.)
efd53eed61: the patch author was not asked. Although the mkv_sh_sub_t
struct was later moved to stheader.h, the added field was removed
without replacement.
f6878753fb: nick, who could not be reached, added an include guard, but
the guard was changed several times later, and it's probably not
copyrightable anyway.
afb0fd5ea1: the same nick adds a field that was later replaced and
finally removed again in 8cd6b20571.
All authors have agreed.
The initial commit d33703496c as well as the current code contain this
line:
* inspired by SoundTouch library by Olli Parviainen
We assume this is about the algorithm (not the code), and the author of
the original patch actually wrote all code himself.
All authors have agreed.
One exception is 71247a97b3, whose author was not asked, but we deem
the change as trivial. (And technically it was replaced when the audio
chain dropped non-native endian sample formats.)
All authors have agreed to the relicensing.
The code was pretty much rewritten by Stefano Pigozzi. Since the rewrite
happened incrementally, and seems to include refactored portions of
older code, this relicensing was done on the pre-refactor code do.
The original commit adding this AO (as ao_macosx.c) credits Timothy J.
Wood as original author. He was asked and agreed to LGPL. It's not
entirely sure from which project this code came from, but it's probably
libao. In that project, Stanley Seibert made some changes to it (who as
a major developer of libao was asked just to be sure), and also Ralph
Giles and Ben Hines made two small changes. The latter were not asked,
but none of their code survived anyway.
Or maybe it would be better to write "confirm" than "change".
The MP_SELECT_LE_BE macro definition has some similarity with some old
MPlayer definition, but it's different code with a different idea, so I
don't think it's affected by that.
The BYTE_ORDER etc. macro definitions are similar to those found in
various system headers (this code emulates the ones often found in
<sys/types.h>), but I don't think there is a copyright problem either.
This didn't have a header and this was implied LGPL, but this was not
entirely correct. It turns out the printf attribute code was leaked in
from talloc, which is "LGPL v3 or later". talloc was added to the
mplayer2 code base in 27a30e310e. This remaining code was an oversight.
Since we want to reduce LGPL v3 code, replace this code with the one
from ta/ta.h. This code was explicitly written newly to get rid of
talloc and its license in 0933f12d28.
All authors have agreed to the relicensing.
iive has insisted on "LGPL v3 or later", which makes the file LGPL v3.
His commits are the following: 84ec5775089b0d8c680f. All other
contributions are LGPL v2.1. I hope we can remove these changes
completely one day to make this file LGPL v2.1.
iive also authored commit 3934b160a8, but this code is completely gone
today. (fork() and shared memory use was removed completely in favor of
threads.)
All authors have agreed, with the following exceptions:
e68d7f6858: wight wasn't asked (I think...), but even if he modified the
patch he applied, all code added by it was removed again later.
cb7768f9bb: nick could not be reached, but the declarations he added as
well as the full timer.c file were deleted again in cff81fe498 and
f800a42e45 (did it really take 6 years to remove unused declarations?).
ffaf4af230: it looks like this person wasn't contacted, but the code
added was removed again in f544bcf105.
This comes with estimated level of difficulty. Files which were already
LGPL are listed too, to avoid potential confusion.
Some entries use shell wildcards.
msg.c is "partial" due to "michael", whose work can be changed to LGPL
only once the core is LGPL. It's explained in the Copyright file. I
prefer to do the relicensing incrementally (due to the overwhelming
workload). Changing the license before that happens would be legally
questionable, but nothing can stop us from essentially marking it as
"will be LGPL".
All authors have agreed to LGPL, with the following exceptions:
9df11ee8bf: the author (probably) didn't agree, but the line that is
added is later fully removed.
35e90f1556: was not asked, but all iconv code was 100% removed from the
mp_msg mechanism (we alwas require UTF-8 now).
4e4f3f806e: the change by michael.
50a86fcc34: the identify variable was move, and completely removed the
latest in commit 48bd03dd91.
1f6c494641: did not agree, but due to a major mp_msg change the added
line became unnecessary and was removed.
da63498bf9: was not reachable, but the MPlayer GUI is gone from mpv
anyway (also commit fc4d6e617d removed these specific additions a long
time ago).
All controbutors have agreed. In one case, someone who is unaccounted
for changed a glyph in some trivial way; we simply replaced the glyph
with another one in 1e4d3a2440 to avoid any potential problems
(although that change was probably not copyrightable anyway).
The "Files without Copyright notice are licensed as LGPLv2.1+."
statement makes it sound like the manpage and some other stuff are LGPL.
But the rule actually affects only some source files that were added in
mpv.
Change the wording, and also explicitly list the licenses for some non
source files. There might be more such cases.
There are claims that nnedi3.c doesn't constitute its own new
implementation, but is derived from existing HLSL or OpenCL shaders
distributed under the LGPLv3 license.
Until these are resolved, do the "correct" thing and require
--enable-gpl3 to build nnedi.
