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When linking the main tools, the object files to link are set up
via the variable OBJS-<name>, but for the tools, we've only
used the target's list of dependencies.
In most cases, this has been fine, but it has caused specifying
the libraries to link in a duplicate fashion; the linking command
has looked like this:
$CC -Llibavutil ... tools/tool.o libavutil/libavutil.a -lavutil
Normally, the libraries to link are handled with "-Llibavutil -lavutil";
when linking the main fftools, this is how they are linked.
In the case of the binaries under the "tools" directory (within the
make variable TOOLS), we've passed the full set of dependencies
to the linker, via $^, which does contain the names of the
dependency libraries as well.
When libraries are built as regular static libraries, or shared
unix libraries, this has all worked fine. When libraries are
built as DLLs for Windows, though, the norm is not to pass the
actual DLL to the linker, but an import library.
Mingw tools generally can handle linking directly against a DLL
as well, but MSVC tools don't support that, and error out with
a very cryptic error message:
libavdevice\avdevice.dll : fatal error LNK1107: invalid or corrupt file: cannot read at 0x2D8
By omitting these parts of the dependencies, linking of these tool
executables succeed in MSVC builds with shared libraries enabled.
Signed-off-by: Martin Storsjö <martin@martin.st>
FFmpeg README
FFmpeg is a collection of libraries and tools to process multimedia content such as audio, video, subtitles and related metadata.
Libraries
libavcodecprovides implementation of a wider range of codecs.libavformatimplements streaming protocols, container formats and basic I/O access.libavutilincludes hashers, decompressors and miscellaneous utility functions.libavfilterprovides means to alter decoded audio and video through a directed graph of connected filters.libavdeviceprovides an abstraction to access capture and playback devices.libswresampleimplements audio mixing and resampling routines.libswscaleimplements color conversion and scaling routines.
Tools
- ffmpeg is a command line toolbox to manipulate, convert and stream multimedia content.
- ffplay is a minimalistic multimedia player.
- ffprobe is a simple analysis tool to inspect multimedia content.
- Additional small tools such as
aviocat,ismindexandqt-faststart.
Documentation
The offline documentation is available in the doc/ directory.
The online documentation is available in the main website and in the wiki.
Examples
Coding examples are available in the doc/examples directory.
License
FFmpeg codebase is mainly LGPL-licensed with optional components licensed under GPL. Please refer to the LICENSE file for detailed information.
Contributing
Patches should be submitted to the ffmpeg-devel mailing list using
git format-patch or git send-email. Github pull requests should be
avoided because they are not part of our review process and will be ignored.