mikebrady/shairport-sync 3.0

Version 3. Support for 24- and 32-bit DACs, Apple's ALAC decoder, more...

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Big Update

Version 3 brings in support for 24-bit and 32-bit (and 8 bit!) DACs and for DACs running at multiples of 44,100 samples per second.

The most obvious audible change is if you are using software volume control and can take advantage of 32- or 24-bit DACs. Dithering can now occur on a 32-bit or 24-bit sample rather than on a 16-bit sample, making the noise floor very much lower. This is the case, for example, with a Pimoroni PHAT DAC.

Here is the list of new features:

New Features

• 8-bit, 16-bit, 24-bit, 24-bit three-byte (S24_3LE and S24_3BE) and 32-bit output to ALSA devices.
• 44,100, 88,200, 176,400 and 352,800 sample per second output. This is done using simple sample replication and without interpolation.
• Internal processing including software volume control and interpolation is done after sample size and rate conversion.
• Apple ALAC decoder support. This needs the libalac library, available at ALAC, to be installed. Add the flag --with-apple-alac to the ./configure arguments. Then you can choose the Apple ALAC decoder in the configuration file.
• Support for mbed TLS has been added and the use of PolarSSL is deprecated, as mbed TLS is a development of PolarSSL and PolarSSL itself is not being developed further.
• Choose Network Interface. Add a new setting, for advanced users only, in the general section. Use the interface setting to allow you to specify the interface on which to provide the AirPlay service. Omit the setting to get the default, which is to choose the interfaces automatically.
• Set Max Volume. Add a new setting, for advanced users only, in the general section. Use the volume_max_db setting to allow you to specify the maximum level to set on the hardware mixer (if chosen) or the built-in software mixer otherwise. The software mixer's range is 0.0 dB to -96.1 dB. The setting must be a number with a decimal point, e.g. 21.3.
• An experimental new back end for libsoundio, a C library for cross-platform real-time audio input and output. Many thanks to Serg Podtynnyi. Please see #433 for more details.

Pesky Changes You Cannot Ignore

• Processor load is up by about 11%.
• Settings have changed -- basically, any timings that were denominated in frames are now in seconds. Please refer to the shairport-sync.conf.sample file for details.
• Sox-based interpolation at higher sample rates may overload your CPU.