[Linphone-developers] What is the difference between X264 and H264 (bit confused)

[Rodrigo Pimenta Carvalho]

Hi.

By reading web pages, discussions, makefiles and READ-MEs files, I have 
observed that we have X264 and H264.
I  have then compiled linphone with the flag HAVE_X264, as recommended, to 
support the video transmission.

But, what is the difference between X264 and H264? Is the first an 
implementation of the second?
If I use HAVE_X264, so am I using codec H264?
Whether X264 can be used under GPL, should I still worry about license for H264?

Any hint will be very helpful!

Thanks a lot.
Rodrigo Pimenta Carvalho.