Provided by: squeezelite_1.4-1_amd64 
NAME
squeezelite - Lightweight headless Squeezebox emulator
SYNOPSIS
squeezelite [options]
DESCRIPTION
Squeezelite is a small headless Logitech Squeezebox emulator. It is aimed at supporting
high quality audio including USB DAC based output at multiple sample rates.
The player is controlled using, and media is streamed from, a Logitech Media Server
instance running somewhere on the local network.
OPTIONS
This program supports the following options:
-h Show a summary of the available command-line options.
-s <server>[:<port>]
Connect to the specified Logitech Media Server, otherwise uses automatic discovery
to find server on the local network. This option should only be needed if automatic
discovery does not work, or the server is not on the local network segment (e.g.
behind a router).
-o <output device>
Specify the audio output device; the default value is default. Use the -l option
to list available output devices. - can be used to output raw samples to standard
output.
-l List available audio output devices to stdout and exit. These device names can be
passed to the -o option in order to select a particular device or configuration to
use for audio playback.
-a <params>
Specify parameters used when opening an audio output device. For ALSA, the format
<b>:<p>:<f>:<m> is used where <b> is the buffer time in milliseconds (values less
than 500) or size in bytes (default 40ms); <p> is the period count (values less
than 50) or size in bytes (default 4 periods); <f> is the sample format (possible
values: 16, 24, 24_3 or 32); <m> is whether to use mmap (possible values: 0 or 1).
For PortAudio, the value is simply the target latency in milliseconds. When the
output is sent to standard output, the value can be 16, 24 or 32, which denotes the
sample size in bits.
-b <stream>:<output>
Specify internal stream and output buffer sizes in kilobytes.
-c <codec1>,...
Restrict codecs to those specified, otherwise load all available codecs; known
codecs: flac, pcm, mp3, ogg, aac, wma, alac. mad or mpg can be supplied instead of
mp3 to use a specific decoder library.
-d <category>=<level>
Set logging level. Categories are: all, slimproto, stream, decode or output.
Levels can be: info, debug or sdebug. The option can be repeated to set different
log levels for different categories.
-f <logfile>
Send logging output to a log file instead of standard output or standard error.
-m <mac addr>
Override the player's MAC address. The format must be colon-delimited hexadecimal,
for example: ab:cd:ef:12:34:56. This is usually automatically detected, and should
not need to be provided in most circumstances.
-n <name>
Set the player name. This name is used by the Logitech Media Server to refer to the
player by name. This option is mututally exclusive with -N.
-N <filename>
Allow the server to set the player's name. The player name is stored in the file
pointed to by <filename> so that it can persist between restarts. This option is
mututally exclusive with -n.
-p <priority>
Set real time priority of output thread (1-99; default 45). Not applicable when
using PortAudio.
-r <rates>
Specify sample rates supported by the output device; this is required if the output
device is switched off when squeezelite is started. The format is either a single
maximum sample rate, a range of sample rates in the format <min>-<max>, or a comma-
separated list of available rates.
-u|-R [params]
Enable upsampling of played audio. The argument is optional; see RESAMPLING (below)
for more information. The options -u and -R are synonymous.
-D Output device supports DSD over PCM (DoP). DSD streams will be converted to DoP
before output. If this option is not supplied, DSD streams will be converted to PCM
and resampled, so they can be played on a PCM DAC.
-v Enable visualiser support. This creates a shared memory segment that contains some
of the audio being played, so that an external visualiser can read and process this
to create visualisations.
-z Cause squeezelite to run as a daemon. That is, it detaches itself from the terminal
and runs in the background.
-t Display version and license information.
RESAMPLING
Audio can be resampled or upsampled before being sent to the output device. This can be
enabled simply by passing the -u option to squeezelite, but further configuration can be
given as an argument to the option.
Resampling is performed using the SoX Resampler library; the documentation for that
library and the SoX rate effect many be helpful when configuring upsampling for
squeezelite.
The format of the argument is
<recipe>:<flags>:<attenuation>:<precision>:<passband_end>:<stopband_start>:<phase_response>
recipe
This part of the argument string is made up of a number of single-character flags:
[v|h|m|l|q][L|I|M][s][E|X]. The default value is hL.
v, h, m, l or q
are mutually exclusive and correspond to very high, high, medium, low or quick
quality.
L, I or M
correspond to linear, intermediate or minimum phase.
s changes resampling bandwidth from the default 95% (based on the 3dB point) to 99%.
E exception - avoids resampling if the output device supports the playback sample
rate natively.
X resamples to the maximum sample rate for the output device ("asynchronous"
resampling).
Examples
-u vLs would use very high quality setting, linear phase filter and steep cut-off.
-u hM would specify high quality, with the minimum phase filter.
-u hMX would specify high quality, with the minimum phase filter and async
upsampling to max device rate.
flags
The second optional argument to -u allows the user to specify the following arguments
(taken from the soxr.h header file), in hex:
#define SOXR_ROLLOFF_SMALL 0u /* <= 0.01 dB */
#define SOXR_ROLLOFF_MEDIUM 1u /* <= 0.35 dB */
#define SOXR_ROLLOFF_NONE 2u /* For Chebyshev bandwidth. */
#define SOXR_MAINTAIN_3DB_PT 4u /* Reserved for internal use. */
#define SOXR_HI_PREC_CLOCK 8u /* Increase 'irrational' ratio accuracy. */
#define SOXR_DOUBLE_PRECISION 16u /* Use D.P. calcs even if precision <= 20. */
#define SOXR_VR 32u /* Experimental, variable-rate resampling. */
Examples
-u :2 would specify SOXR_ROLLOFF_NONE.
NB: In the example above the first option, <quality>, has not been specified so
would default to hL. Therefore, specifying -u :2 is equivalent to having specified
-u hL:2.
attenuation
Internally, data is passed to the SoX resample process as 32 bit integers and output from
the SoX resample process as 32 bit integers. Why does this matter? There is the
possibility that integer samples, once resampled may be clipped (i.e. exceed the maximum
value). By default, if you do not specify an attenuation value, it will default to -1db. A
value of 0 on the command line, i.e. -u ::0 will disable the default -1db attenuation
being applied.
NB: Clipped samples will be logged. Keep an eye on the log file.
Examples
-u ::6 specifies to apply -6db (ie. halve the volume) prior to the resampling
process.
precision
The internal 'bit' precision used in the re-sampling calculations (ie. quality).
NB: HQ = 20, VHQ = 28.
Examples
-u :::28 specifies 28-bit precision.
passband_end
A percentage value between 0 and 100, where 100 is the Nyquist frequency. The default if
not explicitly set is 91.3.
Examples
-u ::::98 specifies passband ends at 98 percent of the Nyquist frequency.
stopband_start
A percentage value between 0 and 100, where 100 is the Nyquist frequency. The default if
not explicitly set is 100.
Examples
-u :::::100 specifies that the stopband starts at the Nyquist frequency.
phase_response
A value between 0-100, where 0 is equivalent to the recipe M flag for minimum phase, 25 is
equivalent to the recipe I flag for intermediate phase and 50 is equivalent to the recipe
L flag for linear phase.
Examples
-u ::::::50 specifies linear phase.
SEE ALSO
https://code.google.com/p/squeezelite/
http://www.communitysqueeze.org/squeezelite_about.jsp
http://www.communitysqueeze.org/squeezelite_upsample.jsp
sox(1) - for further information about resampling