On Wed, 09 Jan 2013 21:10:06 +0100 Jonas Smedegaard wrote: > Hi Francesco,
Hi, thanks a lot for your very fast reply! > > Quoting Francesco Poli (2013-01-09 19:18:02) > > On Wed, 09 Jan 2013 06:51:10 +0000 Debian Bug Tracking System wrote: > > > > [...] > > > [ Jonas Smedegaard ] > > > * Rewrite copyright file using copyright format 1.0. > > > Closes: bug#694657. Thanks to Francesco Poli. > > > > You're welcome, Jonas! > > Thanks to you, indeed. > > > > > > I have a question, though. > > At the beginning of the new debian/copyright file, I read the following > > comment: > > > > | Comment: > > | Because the libavcodec-extra-* package (since libavcodec-extra-54) > > | links against libraries licensed under Apache-2.0 (not compatible with > > | LGPL), effective license of that package and libav-dbg is GPL-3+. > > > > This does not look too clear to me. > > > > Which license is the libavcodec-extra-* package released under? > > LGPL-2.1+ or GPL-2+ ? > > GPL-2+. I fail to understand how that can be misunderstood from that > comment. Well, I think it _can_ be misunderstood because... it's not what it is written there! :-/ By looking at the debian/copyright file, it seems to me that the _source files_ that are compiled to produce the _binary_ package libavcodec-extra-* are under LGPL-2.1+ So this (and GPL-2+, thanks to the explicit conversion-to-GPL clause included in LGPL-2.1) seems to be the set of licenses we start with. Then, we have to look at the linked works, in order to determine the effective license for the _binary_ package. The comment only talks about libraries under Apache-2.0, which is not compatible with GPL-2. This seems to drop GPL-2, leaving the choice among GPL-3+ and LGPL-2.1+. Hence, by reading the comment (and the rest of the debian/copyright file), it really looks like the effective license is "GPL-3+ or LGPL-2.1+ (excluding GPL-2)". Moreover, the comment states that Apache-2.0 is incompatible with LGPL: I think this is incorrect and misleading. > > > > By looking at the rest of the debian/copyright file, it seems to me > > that the answer is LGPL-2.1+ : can you confirm, please? > > What a debian/copyright file covers is _source_ licensing. That's why > it is merely a comment. Indeed: I looked at the debian/copyright file in order to figure out the license for the _source_ files that end up compiled into the _binary_ files shipped by the _binary_ package libavcodec-extra-* > > The effective license of a binary package is that license among the many > many licenses involved in that binary work which is compatible with all > the other ones. This not only involves the source parts of that same > project, but also the parts linking in during build. Fully agreed. > So even if you > cannot find a single GPL-3+ licensed piece anywhere in this project, the > very purpose of libavcodec-extra-* (as compared to libavcodec-*) is to > link against GPL-licensed parts. This is the part that's not clear. Where is this stated? The comment does clarifies this subtlety. And I cannot see it documented in the binary package description, either: http://packages.debian.org/experimental/libavcodec-extra-54 Unless I start digging into the debian/copyright files of all the dependencies, and find out that * libx264-123 is under GPL-2+ * libxvidcore4 is also under GPL-2+ * a small part of libmp3lame0 is under GPL-1+ Is this (together with the linking with Apache-2.0 libraries) the reason why the _binary_ package libavcodec-extra-* is effectively under GPL-3+, rather than "GPL-3+ or LGPL-2.1+ (excluding GPL-2)" ? If this is the case, then I think the comment should be clarified (and also the binary package description). > > ...and even if none of those _other_ GPL-licensed parts are explicitly > GPL-3+, ome parts are Apache-2.0 which is incompatible with GPL-2, > rendering GPL-2+ licensed parts essentially equal to GPL-3+. > > Whew. Hope that whole pile made sense. :-) Maybe (assuming I understood you correctly...). But the comment is far too short to explain all this! > > > > > If this is really the case, then, although it's true that Apache-2.0 > > is not compatible with GPL-2, I don't think it's accurate to say that > > Apache-2.0 is not compatible with LGPL... > > Correct. One need to check the long description and build-dependencies > of libavcodec-extra-* to get an epiphany here. If one has to dig into all the dependencies anyway, then the comment does not seem to be too useful... [...] > > This seems to imply that I cannot distribute a program under a > > GPL-3-incompatible license (for instance, BSD-4-clause) linked with > > libavcodec-extra-*: I don't see any reason why such a program should > > be considered as legally undistributable... > > Not sure what you are trying to say here. > > It is legal to distribute libavcodec-extra-* and it is legal to > distribute GPL-3-incompatible code. Not if one wants to distribute the two together, linked with each other, though. At least, this is what is said by the FSF legal theory of linking... > > Purpose of that comment is to make (developer) users aware that despite > Licenses listed in this copyright file, that binary package (and the > -dbg package) has been "infested" with strong copyleft licenses. > > > > Please clarify the situation, and let's see whether we can find a > > clearer formulation for the above-quoted comment. > > I don't mind us discussing it here, but do find this a different matter > than the issue you filed this bugreport about. You are right that I should have filed a separate bug report. Sorry about my laziness... :-( I can do that, if you want me to do so. Just tell me! Anyway, let's see whether you think that the following re-formulation is accurate: | Comment: | Because the libavcodec-extra-* package links against libraries | licensed under GPL-2+ and (since libavcodec-extra-54) against libraries | under Apache-2.0 (compatible with GPL-3, but not with GPL-2), effective | license of that package and libav-dbg is GPL-3+ (rather than LGPL-2.1+). A similar clarification may be applied to the description of the libavcodec-extra-* binary package. I hope I clarified what I meant. -- http://www.inventati.org/frx/frx-gpg-key-transition-2010.txt New GnuPG key, see the transition document! ..................................................... Francesco Poli . GnuPG key fpr == CA01 1147 9CD2 EFDF FB82 3925 3E1C 27E1 1F69 BFFE
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