Sound Pusher — real-time encoded audio output for OS X
Provides a virtual 5.1-channel audio output device whose contents are real-time encoded to
AC3 and sent as digital
SPDIF stream to a real audio device output.
WARNING: Please turn down the speaker / headphone volume before running this application, as any component misinterpreting a compressed audio stream as "normal" audio signals may result in unexpectedly loud noise.
The application has been developed on OS X 10.11 "El Capitan", but should work on OS X 10.10 "Yosemite" as well. It requires a compatible audio device capable of outputting compressed
AC3 audio formats (format IDs
iac3). All testing was done with
There are two component required to make this work:
LoopbackAudio— A user-space CoreAudio driver (aka
AudioServerPlugin) that provides a 5.1 output stream whose contents are mirrored ("looped back") to its own input stream. This allows applications to process the audio output of the system (if it is sent to the
LoopbackAudio.drivermust be installed (copied) into the
SoundPusher— An application that continuously reads audio from the
LoopbackAudiodevice, encodes in into a compressed format, and then sends that compressed stream to a (hopefully) real sound device's digital output stream. This is controlled through its menu bar extra.
Once the driver is installed and
SoundPusher running, you should be able to select supported digital output devices which will forward any sound output sent to the
Loopback Audio device to the designated digital output.
SoundPusher will set the default output device to
Loopback Audio if it was previously set to the device used for digital output.
Contact & Support
Please report any issues on GitHub.
FFmpeg — libavcodec, libavformat
Here's a script that builds a cut-down version of FFmpeg that includes all that's required for SoundPusher:
#!/bin/sh ./configure --prefix=$FFMPEG_HOME --cc=clang --disable-static --enable-shared --disable-all --disable-doc --disable-everything --disable-pthreads --disable-iconv --disable-securetransport --disable-audiotoolbox --disable-videotoolbox --disable-vda --enable-avutil --enable-swresample --enable-avcodec --enable-avformat --enable-encoder=ac3 --enable-muxer=spdif make -j8 make install # update shared library install names cd $FFMPEG_HOME/lib AVUTIL_ID=`otool -D libavutil.dylib | tail -1` AVCODEC_ID=`otool -D libavcodec.dylib | tail -1` AVFORMAT_ID=`otool -D libavformat.dylib | tail -1` SWRESAMPLE_ID=`otool -D libswresample.dylib | tail -1` for lib in libavutil libavcodec libavformat libswresample do install_name_tool -id @rpath/$lib.dylib -change $AVUTIL_ID @rpath/libavutil.dylib -change $AVCODEC_ID @rpath/libavcodec.dylib -change $AVFORMAT_ID @rpath/libavformat.dylib -change $SWRESAMPLE_ID @rpath/libswresample.dylib $lib.dylib done
This software is built on the experience of others: