                        WRITTEN OFFER FOR SOURCE CODE
                             zApp and zRemote
                                 BitRouter


COMPONENTS COVERED BY THIS OFFER
--------------------------------

zApp is distributed with the following third-party components in binary form.
The full license text of each accompanies this file in the same directory.

  FFmpeg             GPL v2       source available on request (see below)
  x264               GPL v2       statically linked into our FFmpeg build
  x265               GPL v2       statically linked into our FFmpeg build
  VLC plugins        GPL v2       source available on request
  libvlc             LGPL v2.1    source available on request
  Qt                 LGPL v3      source available on request
  Material Symbols   Apache 2.0   attribution only; no source obligation

zRemote is distributed with Qt and Material Symbols only. It contains no
libvlc and no FFmpeg.


THE OFFER
---------

For a period of at least three years from the date you received this copy of
the software - and for as long as BitRouter offers support or spare parts for
this version - BitRouter will give any third party who possesses this software
the complete corresponding source code for the components listed above, under
the terms of the license that applies to each.

To obtain that source, write to:

         support@zapperbox.com

and it will be sent to you, at no charge, by whatever means is practical for
its size - normally a download link, or a copy on a physical medium
customarily used for software interchange for a fee no greater than
BitRouter's reasonable cost of performing that distribution.

When requesting source, please state the product (zApp or zRemote), the
version, the platform (Windows or macOS), and which component you want the
source for. The version is shown in the application's About box.

This offer is valid to anyone in possession of this software. You do not need
to be the person who originally obtained it, and you do not need to have
bought anything.


IDENTIFYING THE FFMPEG BUILD
----------------------------

The FFmpeg executable shipped with zApp - ffmpeg.exe on Windows, ffmpeg on
macOS - is not a stock upstream or third-party build. BitRouter builds it from
source, enabling only the codecs and formats zApp's export feature actually
uses, and links x264 and x265 into it statically, so what ships is one
executable rather than a binary accompanied by a set of libraries.

Because it is our own build, its complete corresponding source is exactly
three source trees at pinned versions, one small patch BitRouter applies to
FFmpeg, and the script that configures and builds them. The Windows and macOS
binaries are built from the same trees and patch but with different configure
lines, so both scripts are listed:

    FFmpeg   n8.1.2       (commit 38b8833)
    x264     stable       (commit b35605a)
    x265     4.2          (commit e444744)

    patch to FFmpeg, in the zApp source tree:
        tools/ffmpeg-patches/0001-mp4-ac4-passthrough.patch
        (lets FFmpeg copy AC-4 audio into an MP4 file unchanged)

    build scripts, in the zApp source tree:
        tools/build-ffmpeg.sh      (Windows)
        tools/build-ffmpeg-mac.sh  (macOS, universal arm64 + x86_64)

The script records the full configure line, and the binary itself will print
it:

    ffmpeg -version

Note this build is configured WITHOUT --enable-version3. The libraries that
would require GPL v3 are not compiled in, and both encoders it does link -
x264 and x265 - are GPL v2 or later, so the whole binary is GPL v2. Its
license text is in ffmpeg-LICENSE.txt beside this file.


LGPL COMPONENTS AND RELINKING
-----------------------------

Qt and libvlc are dynamically linked and are shipped as separate library files
rather than being bound into the executables. You may therefore replace either
with a modified version by substituting the library files in the installation
directory. That arrangement is what satisfies the LGPL's relinking
requirement; no relinkable object files are needed.


NO WARRANTY
-----------

The GPL and LGPL components are distributed in the hope that they will be
useful, but WITHOUT ANY WARRANTY - without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the individual
license texts in this directory for the full terms.
