86 lines
2.7 KiB
Text
86 lines
2.7 KiB
Text
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HOW TO ACTIVATE LIBSAMPLERATE
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(a.k.a SRC/Secret Rabbit Code)
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AS PJMEDIA'S SAMPLE RATE CONVERSION BACKEND
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by
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Benny Prijono
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PJSIP
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Background
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----------
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Secret Rabbit Code (aka libsamplerate) is a sample rate conversion
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library, available from http://www.mega-nerd.com/SRC/index.html.
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It is licensed under dual license, GPL and proprietary.
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Supported Platforms
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-------------------
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libsamplerate is available for Win32 with Visual Studio and the
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Makefile based targets (such as Linux, MacOS X, *nix, etc.).
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It's not supported for WinCE/Windows Mobile and Symbian since it is
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a floating point based implementation.
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Installation
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------------
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- Download libsamplerate from http://www.mega-nerd.com/SRC/index.html
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- Untar libsamplerate-0.1.2.tar.gz into third_party directory
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cd third_party
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tar xzf libsamplerate-0.1.2.tar.gz
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- Rename libsamplerate-0.1.2 directory name to libsamplerate
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On Windows:
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ren libsamplerate-0.1.2 libsamplerate
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On Linux/Unix/MacOS X:
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mv libsamplerate-0.1.2 libsamplerate
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Visual Studio Build
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-------------------
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For Visual Studio projects, only static linkage is supported
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by PJMEDIA build system. If dynamic linking is desired, edit
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pjmedia/src/pjmedia/resample_libresample.c to prevent it from
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linking with the static library, and configure your project
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to link with libsamplerate DLL library.
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To build libresample static library with Visual Studio:
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- Open third_party/build/samplerate/libsamplerate_static.dsp
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- Build the project for both Debug and Release build
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libresample dynamic library can be produced by following the
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instructions in libresample source directory.
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Makefile build
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--------------
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- Build and install libsamplerate (configure && make && make install).
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Please follow the instructions in libsamplerate documentation.
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- Re-run PJSIP's "configure" script with this option:
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./configure --enable-libsamplerate
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this will detect the presence of libsamplerate library and add it
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to the input library list.
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Enabling libsamplerate for PJMEDIA's resample
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---------------------------------------------
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For both Visual Studio and Makefile based build system, add this in
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config_site.h:
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#define PJMEDIA_RESAMPLE_IMP PJMEDIA_RESAMPLE_LIBSAMPLERATE
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Limitations
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-----------
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Sample rate 22050 Hz is only supported with 20ms ptime, and sample rate 11025 Hz is only supported with 40ms ptime. This is the limitation of PJMEDIA rather than libsamplerate.
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