init - 初始化项目

3rdparty/ffmpeg/readme.txt

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+* On Linux and other Unix flavors OpenCV uses default or user-built ffmpeg/libav libraries.
+  If user builds ffmpeg/libav from source and wants OpenCV to stay BSD library, not GPL/LGPL,
+  he/she should use --enabled-shared configure flag and make sure that no GPL components are
+  enabled (some notable examples are x264 (H264 encoder) and libac3 (Dolby AC3 audio codec)).
+  See https://www.ffmpeg.org/legal.html for details.
+
+  If you want to play very safe and do not want to use FFMPEG at all, regardless of whether it's installed on
+  your system or not, configure and build OpenCV using CMake with WITH_FFMPEG=OFF flag. OpenCV will then use
+  AVFoundation (OSX), GStreamer (Linux) or other available backends supported by opencv_videoio module.
+
+  There is also our self-contained motion jpeg codec, which you can use without any worries.
+  It handles CV_FOURCC('M', 'J', 'P', 'G') streams within an AVI container (".avi").
+
+* On Windows OpenCV uses pre-built ffmpeg binaries, built with proper flags (without GPL components) and
+  wrapped with simple, stable OpenCV-compatible API.
+  The binaries are opencv_videoio_ffmpeg.dll (version for 32-bit Windows) and
+  opencv_videoio_ffmpeg_64.dll (version for 64-bit Windows).
+
+  The pre-built opencv_videoio_ffmpeg*.dll is:
+  * LGPL library, not BSD libraries.
+  * Loaded at runtime by opencv_videoio module.
+    If it succeeds, ffmpeg can be used to decode/encode videos;
+    otherwise, other API is used.
+
+  FFMPEG build includes support for H264 encoder based on the OpenH264 library.
+  OpenH264 Video Codec provided by Cisco Systems, Inc.
+  See https://github.com/cisco/openh264/releases for details and OpenH264 license.
+  OpenH264 library should be installed separatelly. Downloaded binary file can be placed into global system path
+  (System32 or SysWOW64) or near application binaries (check documentation of "LoadLibrary" Win32 function from MSDN).
+  Or you can specify location of binary file via OPENH264_LIBRARY environment variable.
+
+  If LGPL/GPL software can not be supplied with your OpenCV-based product, simply exclude
+  opencv_videoio_ffmpeg*.dll from your distribution; OpenCV will stay fully functional except for the ability to
+  decode/encode videos using FFMPEG (though, it may still be able to do that using other API,
+  such as Video for Windows, Windows Media Foundation or our self-contained motion jpeg codec).
+
+  See license.txt for the FFMPEG copyright notice and the licensing terms.