The SRT build system uses CMake 2.8.12 or above.
A wrapper script named configure
is also available. The configure script can simplify the build process, such as
by trying to automatically detect the OpenSSL path in a system. Note that you must
have the Tcl interpreter installed to use this script.
Here is a link to a demo showing how CMake can be used to build SRT: Quickstart: Running SRT and FFmpeg on Ubuntu.
Additional information on building for Windows is available in the Building SRT for Windows document and in the SRT CookBook.
The following table lists available build options in alphabetical order. Option details are given further below.
| Option Name | Since | Type | Default | Short Description |
|---|---|---|---|---|
CMAKE_INSTALL_PREFIX |
1.3.0 | STRING |
OFF | Standard CMake variable that establishes the root directory for installation, inside of which a GNU/POSIX compatible directory layout will be used. |
CYGWIN_USE_POSIX |
1.2.0 | BOOL |
OFF | Determines when to compile on Cygwin using POSIX API. |
ENABLE_APPS |
1.3.3 | BOOL |
ON | Enables compiling sample applications (srt-live-transmit, etc.). |
ENABLE_BONDING |
1.5.0 | BOOL |
OFF | Enables the Connection Bonding feature. |
ENABLE_CXX_DEPS |
1.3.2 | BOOL |
OFF | The pkg-confg file (srt.pc) will be generated with the libstdc++ library as a dependency. |
ENABLE_CXX11 |
1.2.0 | BOOL |
ON | Enable compiling in C++11 mode for those parts that may require it. Default: ON except for GCC<4.7 |
ENABLE_CODE_COVERAGE |
1.4.0 | BOOL |
OFF | Enables instrumentation for code coverage. |
ENABLE_DEBUG |
1.2.0 | INT |
ON | Allows release/debug control through the CMAKE_BUILD_TYPE variable. |
ENABLE_ENCRYPTION |
1.3.3 | BOOL |
ON | Enables encryption feature enabled, with dependency on an external encryption library. |
ENABLE_GETNAMEINFO |
1.3.0 | BOOL |
OFF | Enables the use of getnameinfo to allow using reverse DNS to resolve an internal IP address into a readable internet domain name. |
ENABLE_HAICRYPT_LOGGING |
1.3.1 | BOOL |
OFF | Enables logging in the haicrypt module, which serves as a connector to an encryption library. |
ENABLE_HEAVY_LOGGING |
1.3.0 | BOOL |
OFF | Enables heavy logging instructions in the code that occur often and cover many detailed aspects of library behavior. Default: OFF in release mode. |
ENABLE_INET_PTON |
1.3.2 | BOOL |
ON | Enables usage of the inet_pton function used to resolve the network endpoint name into an IP address. |
ENABLE_LOGGING |
1.2.0 | BOOL |
ON | Enables normal logging, including errors. |
ENABLE_MONOTONIC_CLOCK |
1.4.0 | BOOL |
ON* | Enforces the use of clock_gettime with a monotonic clock that is independent of the currently set time in the system. |
ENABLE_PROFILE |
1.2.0 | BOOL |
OFF | Enables code instrumentation for profiling (only for GNU-compatible compilers). |
ENABLE_RELATIVE_LIBPATH |
1.3.2 | BOOL |
OFF | Enables adding a relative path to a library for linking against a shared SRT library by reaching out to a sibling directory. |
ENABLE_SHARED |
1.2.0 | BOOL |
ON | Enables building SRT as a shared library. |
ENABLE_SHOW_PROJECT_CONFIG |
1.5.0 | BOOL |
OFF | When ON, the project configuration is displayed at the end of the CMake Configuration Step. |
ENABLE_STATIC |
1.3.0 | BOOL |
ON | Enables building SRT as a static library. |
ENABLE_STDCXX_SYNC |
1.4.2 | BOOL |
ON* | Enables the standard C++11 thread and chrono libraries to be used by SRT instead of the pthreads. |
ENABLE_TESTING |
1.3.0 | BOOL |
OFF | Enables compiling of developer testing applications (srt-test-live, etc.). |
ENABLE_THREAD_CHECK |
1.3.0 | BOOL |
OFF | Enables #include <threadcheck.h>, which implements THREAD_* macros" to support better thread debugging. |
ENABLE_UNITTESTS |
1.3.2 | BOOL |
OFF | Enables building unit tests. |
OPENSSL_CRYPTO_LIBRARY |
1.3.0 | STRING |
OFF | Configures the path to an OpenSSL crypto library. |
OPENSSL_INCLUDE_DIR |
1.3.0 | STRING |
OFF | Configures the path to include files for an OpenSSL library. |
OPENSSL_SSL_LIBRARY |
1.3.0 | STRING |
OFF | Configures the path to an OpenSSL SSL library. |
PKG_CONFIG_EXECUTABLE |
1.3.0 | BOOL |
OFF | Configures the path to the pkg-config tool. |
PTHREAD_INCLUDE_DIR |
1.3.0 | STRING |
OFF | Configures the path to include files for a pthread library. |
PTHREAD_LIBRARY |
1.3.0 | STRING |
OFF | Configures the path to a pthread library. |
USE_BUSY_WAITING |
1.3.3 | BOOL |
OFF | Enables more accurate sending times at the cost of potentially higher CPU load. |
USE_CXX_STD |
1.4.2 | STRING |
OFF | Enforces using a particular C++ standard (11, 14, 17, etc.) when compiling. |
USE_ENCLIB |
1.3.3 | STRING |
openssl | Encryption library to be used (openssl, openssl-evp (since 1.5.1), gnutls, mbedtls). |
USE_GNUSTL |
1.3.4 | BOOL |
OFF | Use pkg-config with the gnustl package name to extract the header and library path for the C++ standard library. |
USE_OPENSSL_PC |
1.3.0 | BOOL |
ON | Use pkg-config to find OpenSSL libraries. |
OPENSSL_USE_STATIC_LIBS |
1.5.0 | BOOL |
OFF | Link OpenSSL statically. |
USE_STATIC_LIBSTDCXX |
1.2.0 | BOOL |
OFF | Enforces linking the SRT library against the static libstdc++ library. |
WITH_COMPILER_PREFIX |
1.3.0 | STRING |
OFF | Sets C/C++ toolchains as <prefix><c-compiler> and <prefix><c++-compiler>, overriding the default compiler. |
WITH_COMPILER_TYPE |
1.3.0 | STRING |
OFF | Sets the compiler type to be used (values: gcc, cc, clang, etc.). |
WITH_EXTRALIBS |
1.3.0 | STRING |
OFF | Option required for unusual situations when a platform-specific workaround is needed and some extra libraries must be passed explicitly for linkage. |
WITH_SRT_NAME |
1.3.0 | STRING |
OFF | Configure the SRT library name adding a custom <prefix>. |
* See the option description for more details.
If you choose to use CMake directly for the build configuration stage, you must specify option values in the CMake format:
-D<OPTION>=<VALUE>
For more information please refer to the official CMake documentation.
The following example shows how to disable the inclusion of sample SRT applications
(such as srt-live-transmit) in the build configuration, where ./ specifies
the relative path to the main CMakeLists.txt file located in the root folder
of the SRT project.
In this example CMake is run from the root SRT directory:
cmake ./ -DENABLE_APPS=OFFSRT build options known to CMake are listed in the CMakeLists.txt file as:
option(<name> <description> <default value>).
For example:
option(CYGWIN_USE_POSIX "Should the POSIX API be used for cygwin. Ignored if the system isn't cygwin." OFF)
With CMake you would specify this option as:
cmake -DCYGWIN_USE_POSIX=ON or cmake -DCYGWIN_USE_POSIX=OFF
where “-D” is the CMake command to set a build variable to a certain value.
This script is similar in design to the
Autotools
configure script, and so accepts --long-options, with or without values. It
handles two kinds of options:
-
options that are directly translated to
cmakevariables. -
special options to be resolved inside the script that may do some advanced checks; these should later be converted into a set of specific
cmakevariable declarations
The directly translated options always undergo a simple transformation:
- all letters are converted to uppercase
- dashes are converted to underscores
- plus (+) symbols are converted to X
- when no value is supplied, a default value of 1 is applied
To set the CYGWIN_USE_POSIX option using the configure script you would call
configure --cygwin-use-posix
which is transformed by the script into -DCYGWIN-USE-POSIX and then passed
to cmake to enable POSIX (set to ON). To disable the option (set to OFF) using
the configure script you would call
configure –-disable-cygwin-use-posix
In another example, to enable compiling in C++11 mode with the CMake command
ENABLE-C++11 using the configure script you would call
configure --enable-c++11
which is transformed by the script into -DENABLE_CXX11=1 and then passed
to cmake.
Additionally, if you specify --disable-<X>, the configure script
will automatically turn it into an associated --enable-<X> option,
passing 0 as its value. For example, --disable-encryption will
be translated for cmake into -DENABLE_ENCRYPTION=0.
The CMake options available for building SRT are listed below, along with the
equivalent configure format.
--cmake-install-prefix=<path>
Used to configure an alias to the --cmake-install-prefix variable that
establishes the root directory for installation, inside of which a GNU/POSIX
compatible directory layout will be used. As on all known build systems, this
defaults to /usr/local on GNU/POSIX compatible systems, with lower level
GNU/POSIX directories created inside: /usr/local/bin,/usr/local/lib, etc.
--cygwin-use-posix (default:OFF)
Set to ON to compile SRT on Cygwin using the POSIX API (otherwise it will use MinGW environment).
--enable-apps (default: ON)
Enables compiling user applications.
⬆️ Back to List of Build Options
--enable-bonding (default: OFF)
Enables the Connection Bonding feature.
Similar to SMPTE-2022-7 over managed networks, Connection Bonding adds seamless stream protection and hitless failover to the SRT protocol. This technology relies on more than one IP network path to prevent disruption to live video streams in the event of network congestion or outages, maintaining continuity of service.
This is accomplished using the socket groups introduced in SRT v1.5. The general concept of socket groups means having a group that contains multiple sockets, where one operation for sending one data signal is applied to the group. Single sockets inside the group will take over this operation and do what is necessary to deliver the signal to the receiver.
Two modes are supported:
-
Broadcast - In Broadcast mode, data is sent redundantly over all the member links in a group. If one of the links fails or experiences network jitter and/or packet loss, the missing data will be received over another link in the group. Redundant packets are simply discarded at the receiver side.
-
Main/Backup - In Main/Backup mode, only one (main) link at a time is used for data transmission while other (backup) connections are on standby to ensure the transmission will continue if the main link fails. The goal of Main/Backup mode is to identify a potential link break before it happens, thus providing a time window within which to seamlessly switch to one of the backup links.
With the Connection Bonding feature disabled, bonding API functions are present, but return an error.
--enable-c++-deps (default: OFF)
When ON, the pkg-confg file (srt.pc) will be generated with the libstdc++
library as a dependency. This may be required in some cases where you have an
application written in C which therefore won't link against libstdc++ by default.
--enable-c++11 (default: ON except for GCC<4.7)
When ON, enables compiling in C++11 mode for those components that may require it. Components that don't require it will still be compiled in C++03 mode, although which components are affected may change in future.
If this option is turned OFF, it affects building a project in two ways:
- an alternative C++03 implementation can be used, if available
- otherwise the component that requires it will be disabled
Components that currently require C++11 and have no alternative implementation are:
- unit tests
- user and testing applications (such as
srt-live-transmit) - some of the example applications
It should be possible to compile the SRT library without C++11 support. However, any alternative C++03 implementation may be unsupported on certain platforms.
⬆️ Back to List of Build Options
--enable-code-coverage (default: OFF)
When ON, enables instrumentation for code coverage. Note that this is only available on platforms with a GNU-compatible compiler.
--enable-debug=<0,1,2>
This option allows control through the CMAKE_BUILD_TYPE variable:
- 0 (default):
Release(highly optimized, no debug info) - 1:
Debug(not optimized, full debug info) - 2:
RelWithDebInfo(highly optimized, but with debug info)
Please note that when the value is other than 0, the
--enable-heavy-logging option is also turned ON by default.
--enable-encryption (default: ON)
When ON, the encryption feature is enabled. This involves a dependency on an external encryption library (default: openssl). If you disable encryption, the library will be unable to set encryption options. It will be compatible with a peer that has encryption enabled, but just won't use encryption for the connection.
--enable-getnameinfo (default: OFF)
When ON, enables the use of getnameinfo with options that allow using reverse
DNS to resolve an internal IP address into a readable internet domain name, so
that it can be shown nicely in the log file. This option is turned OFF by default
because it may have an impact on general performance. It is recommended only for
development when testing on a local network.
--enable-haicrypt-logging (default: OFF)
When ON, enables logging in the haicrypt module, which serves as a connector to an encryption library. Logging here might be seen as unsafe, therefore this option is turned OFF by default.
⬆️ Back to List of Build Options
--enable-heavy-logging (default: OFF in release mode)
When ON, this option enables logging instructions in the code, which are considered
heavy as they occur often and cover many detailed aspects of library behavior.
Turning this option ON will allow you to use the debug level of logging and get
detailed information as to what happens inside the library. Note, however, that
this may influence processing by changing timings, use less preferred thread
switching layouts, and generally worsen the functionality and performance of
the library. For these reasons this option is turned OFF by default.
--enable-inet-pton (default: ON)
When ON, enables usage of the inet_pton function by applications, which should
be used to resolve the network endpoint name into an IP address. This may not be
available in some versions of Microsoft Windows, in which case you can change the
setting to OFF. When this option is OFF, however, IP addresses cannot be resolved
by name, as the inet_pton function gets a poor-man's simple replacement that can
only resolve numeric IPv4 addresses.
--enable-logging (default: ON)
When ON, enables logging. When you turn this option OFF, the library will not report any runtime information, including errors, through the logging system. This option may be useful if you suspect the logging system of impairing performance.
--enable-monotonic-clock (default: OFF)
NOTE: The library can get stuck if the system clock is used instead of
monotonic or C++11 steady. Since v1.4.4 ENABLE_MONOTONIC_CLOCK is enabled by
default on POSIX-type systems if support for CLOCK_MONOTONIC is detected.
On Windows ENABLE_STDCXX_SYNC is enabled by default. It is highly recommended
to use either of those (ENABLE_STDCXX_SYNC excludes ENABLE_MONOTONIC_CLOCK).
When ON, this option enforces the use of clock_gettime to get the current
time, instead of gettimeofday. This function forces the use of a monotonic
clock that is independent of the currently set time in the system.
The condition variables (CV), for which the *_timedwait() functions are used
with time specification based on the time obtained from clock_gettime,
must be appropriately configured. For now, this is only done for the
garbage collector controlling CV, not every CV used in SRT. The consequence
of enabling this option, however, may be portability issues resulting from
the fact that the clock_gettime function may be unavailable in some SDKs, or
that an extra -lrt option is sometimes required (this requirement will be
autodetected).
The problem is based on the fact that POSIX functions that use timeout
specification (all of *_timedwait) expect the absolute time value.
A relative timeout value can be then only specified by adding it to
the current time, which can be specified using either the system or monotonic
clock (as configured in the resources used in the operation).
However the current time of the monotonic clock can only be obtained by
the clock_gettime function.
⬆️ Back to List of Build Options
--enable-profile (default: OFF)
When ON, enables code instrumentation for profiling (only available for GNU-compatible compilers).
⬆️ Back to List of Build Options
--enable-relative-libpath (default: OFF)
When ON, enables adding a relative path to a library. This allows applications to
be linked against a shared SRT library by reaching out to a sibling ../lib
directory, provided that the library and applications are installed in POSIX/GNU
style directories. This might be useful when installing SRT and applications
in a directory in which the library subdirectory is not explicitly defined
among the global library paths. Consider, for example, this application and its
required library:
/opt/srt/bin/srt-live-transmit/opt/srt/lib64/libsrt.so
By using the --enable-relative-libpath option, the srt-live-transmit
application has a relative library path defined inside as ../lib64. A dynamic
linker will find the required libsrt.so file by this path: ../lib64/libsrt.so.
This way the dynamic linkage will work even if the /opt/srt/lib64 path isn't added
to the system paths in /etc/ld.so.conf or in the LD_LIBRARY_PATH environment
variable.
This option is OFF by default because of reports that it may cause problems with default installations.
--enable-shared and --enable-static (default for both: ON)
When ON, enables building SRT as a shared and/or static library, as required for
your application. In practice, you would only disable one or the other
(e.g. by --disable-shared). Note that you can't disable both at once.
--enable-show-project-config (default:OFF)
When ON, the project configuration is displayed at the end of the CMake configuration step of the build process.
--enable-stdcxx-sync (default: OFF)
NOTE: The library can get stuck if the system clock is used instead of
monotonic or C++11 steady. Since v1.4.4 ENABLE_STDCXX_SYNCis enabled by
default on Windows. On POSIX-type systems, an alternative ENABLE_MONOTONIC_CLOCK option is enabled by default if support for CLOCK_MONOTONIC is detected. It is highly recommended
to use either of those (ENABLE_STDCXX_SYNC excludes ENABLE_MONOTONIC_CLOCK).
When ON, this option enables the standard C++ thread and chrono libraries
(available since C++11) to be used by SRT instead of the pthreads libraries.
--enable-testing (default: OFF)
When ON, enables compiling of developer testing applications.
⬆️ Back to List of Build Options
--enable-thread-check (default: OFF)
When ON, enables #include <threadcheck.h>, which implements THREAD_* macros
to support better thread debugging. Included to support an existing project.
--enable-unittests (default: OFF)
When ON, this option enables unit tests, possibly with the download and installation of the Google test library in the build directory. The tests will be run as part of the build process. This is intended for developers only.
--openssl-crypto-library=<filepath>
Used to configure the path to an OpenSSL crypto library. Ignored when encryption
is disabled (ENABLE_ENCRYPTION = OFF). See USE_ENCLIB for the list of supported libraries.
⬆️ Back to List of Build Options
--openssl-include-dir=<path>
Used to configure the path to include files for an OpenSSL library.
--openssl-ssl-library=<filepath>
Used to configure the path to an OpenSSL SSL library.
--pkg-config-executable=<filepath>
Used to configure the path to the pkg-config tool.
⬆️ Back to List of Build Options
--pthread-include-dir=<path>
Used to configure the path to include files for a pthread library. Note that
this is useful only on Windows. On Linux and macOS this path should be available
in the system.
--pthread-library=<filepath>
Used to configure the path to a pthread library.
--use-busy-waiting (default: OFF)
When ON, enables more accurate sending times at the cost of potentially higher CPU load.
This option will cause more empty loop running, which may cause more CPU usage. Keep in mind, however, that when processing high bitrate streams the share of empty loop runs will decrease as the bitrate increases. This way higher CPU usage would still be productive, while without system-supported waiting this option may increase the likelihood of switching to the right thread at the time when it is expected to be revived.
⬆️ Back to List of Build Options
--use-c++-std=<standard>
Enforces using a particular C++ standard when compiling. When using this option remember that:
- Allowed values are: 98, 03, 11, 14, 17 and 20
- If you use 98/03 and
--enable-apps, apps will be still using C++11 - This option is only supported on GNU and Clang compilers (will be ignored on others).
--use-enclib=<name>
Encryption library to be used. Possible options for <name>:
- openssl (default)
- openssl-evp (OpenSSL EVP API, since 1.5.1)
- gnutls (with nettle)
- mbedtls
--use-gnustl
Use pkg-config with the gnustl package name to extract the header and
library path for the C++ standard library (instead of using the compiler
built-in one).
--use-openssl-pc (default: ON)
When ON, uses pkg-config to find OpenSSL libraries. You can turn this OFF to
force cmake to find OpenSSL by its own preferred method.
--openssl-use-static-libs (default: OFF)
When ON, OpenSSL libraries are linked statically.
When pkg-config(-DUSE_OPENSSL_PC=ON) is used, static OpenSSL libraries are listed in SSL_STATIC_LIBRARIES. See <prefix>_STATIC in CMake's FindPkgConfig.
On Windows additionally links crypt32.lib.
--use-static-libstdc++ (default: OFF)
When ON, enforces linking the SRT library against the static libstdc++ library.
This may be useful if you are using SRT library in an environment where it would
by default link against the wrong version of the C++ standard library, or when
the library in the version used by the compiler is not available as shared.
⬆️ Back to List of Build Options
--with-compiler-prefix=<prefix>
Sets C/C++ toolchains as <prefix><c-compiler> and <prefix><c++-compiler>.
This option will override the default compiler autodetected by cmake.
It is handled inside cmake. It sets the variables CMAKE_C_COMPILER and
CMAKE_CXX_COMPILER. The values for the above <c-compiler> and <c++-compiler>
are controlled by the --with-compiler-type option.
When this option is not supplied, one of the following system-default compilers
will be used:
- On Mac OS (Darwin): clang
- On other POSIX systems: gcc
- On other systems: compiler obtained from the
CMAKE_C_COMPILERvariable
Instead of --with-compiler-prefix you can use --cmake-c-compiler
and --cmake-c++-compiler options. This can be thought of
as a shortcut, useful when you have a long path to the compiler command.
NOTE: The specified prefix is meant to simply precede the compiler type. If your prefix is a full path to the compiler, it must include the terminal path separator character, as this can also be used as a prefix for a platform-specific cross compiler. For example, if the path to the C compiler is:
/opt/arm-tc/bin/arm-linux-gnu-gcc-7.4,
then you should specify:
--with-compiler-prefix=/opt/arm-tc/bin/arm-linux-gnu-
and --with-compiler-type=gcc-7.4.
--with-compiler-type=<name>
Sets the compiler type to be used as <c-compiler> and <c++-compiler>
respectively:
- gcc (default): gcc and g++
- cc: cc and c++
- others: use
<name>as C compiler and<name>++as C++ compiler
This should be the exact command used when specifying a C compiler, possibly
with version suffix, e.g. clang-1.7.0. If this option is used together
with --with-compiler-prefix, its prefix will be added in front.
⬆️ Back to List of Build Options
--with-extralibs=<library-list>
This is an option for unusual situations where a platform-specific workaround is needed, and some extra libraries must be passed explicitly for linkage. The argument is a space-separated list of linker options or library names.
There are some known situations where it may be necessary:
-
Some older Linux systems do not ship
clock_gettimefunctions by default in theirlibc, and need an extralibrt. If you are using POSIX monotonic clocks (see--enable-monotonic-clock), it might be required to add-lrdthrough this option. Although this situation is usually autodetected (and the option added automatically), it does sometimes fail. -
On some systems (e.g. OpenSuSE), if you use C++11 sync (see
--enable-stdc++-sync), the gcc compiler relies ongthreads, which relies onpthreads, and happens to define inline source functions in the header that refer topthread_create. The compiler, however, doesn't link againstpthreadsby default. To work around this, add-pthreadsusing this option.
--with-srt-name=<prefix>
Overrides the SRT library name, adding a custom <prefix>