Allwinner CedarX Media Codec Library GPL/LGPL Compliance Update

Last month, I wrote about potential open source licenses and VP6 copyright infringement by Allwinner with their CedarX media codec library, and then since there’s been a few developments.

First, Allwinner sent me an email saying they’ve now updated Cedarx library and referring my previous article. Here’s an extract:

Here, I have some update of the Allwinner’s open-source status.

We have done a lot of discussion with the developers from the linux-sunxi communication about the software license of CedarX. For each question or requirement asked by the developers, Allwinner has identify and try to give the best solution.

Now, we believe Allwinner’s CedarX license is fully compliant and resolves concerns from the community. And you can take the announcement[email protected]/msg10597.html as a reference.

Allwinner is always supporting the open-source, and try to do better and better. You can see some update on the github, and some feedback from developers:

It’s difficult to make everyone happy, but we believe Allwinner will do better and better, and give more and more help to the developers, and we believe Allwinner will be accepted by more and more developers.

The announcement claims “the CedarX media codec framework is now released with full open source code under the LGPL license”. That actually means there’s an open source API to access the closed source binaries that’s released under the LGPL license. The good news is the VP6 code that could infringe on On2/Google copyrights has now been removed and they are using ffmpeg instead.

So I asked on linux-sunxi IRC channel to find out if there was real progress made, and soon after some more details were released on linux-sunxi mailing list, and the part that looks really bad is:

264FillDefaultRefList() and a lot of code around it is straight out of the libavcodec h264 decoder. The original name for that function is ff_h264_fill_default_ref_list() in libavcodec/h264_refs.c: This is new, as some totally different code for h264 was available in the previous versions of the cedarx binaries.

This looks like Allwinner reached a new low, as it would mean Allwinner purposely renamed some function from LGPL code to make it look like it was their own. However, another email on arm-netbook mailing list by a soon-to-be Allwinner’s software engineer gives some more light to what actually happened here:

I can explain the whole process in a whole detail, because I was directly involved in the process of this decision and I can tell where this is going right now:

The rename was done to fix the LGPL violations by adding a wrapper for the GPLed libraries which will be LGPLed and published. This way we have Binary<->LGPLed open source code<->GPL libraries

Next step will be to drop the whole “we ship our own SDK”-thing and move over to stream our code into the existing open source alternatives.

But until the FOSS libraries have all the functionality from the shipped SDK we can not just stop supporting our customers in China. Also we can not suddenly make it open source for the following reasons:

  • Some engineers and managers do not fully comply with the GPLing of their code yet.
  • The code has awful coding style and my armcc refuses to compile at least 2/3 of the code because of the Chinese comments.
  • Also some of the engineers obviously have never heard the term “revision control” which makes it even harder to locate the actual version of the source code from which the binary was compiled from… -.-‘

So Allwinner has not make it right just yet, but at least they are trying, and even hiring western engineers to try fixing the licensing issues. I’m just not sure the current plan for binary<->LGPL wrapper<->GPL is actually valid, but at least they have longer term plan to upstream changes to open source project, at least that’s the way to understand the email above. Beside legal and technical work, moving from closed source “license infringing” code to properly licensed code is also a social engineering task, as all stakeholders in the company and possibly their customers must be convinced proper licensing is the way to go, and not the business as usual “just copy code from the net” and ignore licensing terms as Allwinner and many other companies have done in the past.

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