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ambdec(1) [debian man page]

AMBDEC(1)						      General Commands Manual							 AMBDEC(1)

ambdec - Ambisonic decoder for first and second order SYNOPSIS
ambdec [options] ambdec_cli config_file DESCRIPTION
This manual page documents briefly the ambdec and ambdec_cli commands. AmbDec is an Ambisonics decoder for up to 36 speakers. It can be used for both horizontal and full 3-D systems of first, second and third order. The decoding matrices are fully user-configurable. AmbDec has some advanced features not found on most decoders: Dual frequency band operation. Optimal Ambisonics reproduction requires a different decoder for low and high frequencies. This is so mainly because human perception of sound direction uses different mechanisms at low and high frequencies. The crossover filters used in AmbDec are phase-aligned (the two outputs are exactly in phase at all frequencies). The combined response is equivalent to a first-order all-pass network, which is very probably inaudible. Speaker distance compensation. If the speakers are not all at the same distance to the center of the listening area, this must be compen- sated by including the right delays and gain corrections. Near-field effect compensation. Ambisonics works by reconstructing the spherical harmonic components of a sound field at the center of the listening area, using all speakers to synthesize each of them. All non-zero order components show a near-field effect depending on the ratio wavelength=distance, and increasing for rising order. One example of this is the well known 'proximity effect' of directional micro- phones ('directional' is equivalent to 'using non-zero order components'). Except in very large installations, where the speaker distances will be large enough so the listening area is not in the near field, this effect must be compensated for in order to obtain a correct reconstruction of a sound field. OPTIONS
ambdec accepts the following command line options: -h Show summary of options. -c FILE Load configuration from FILE. -p PATH Load presets from PATH. -V VOLUME Set initial volume in dB. AUTHOR
ambdec was written by Fons Adriaensen <>. This manual page was written by Alessio Treglia <>, for the Debian project (and may be used by others). 2010/03/14 AMBDEC(1)

Check Out this Related Man Page

SPEAKER-TEST(1) 					      General Commands Manual						   SPEAKER-TEST(1)

speaker-test - command-line speaker test tone generator for ALSA SYNOPSIS
speaker-test [-options] DESCRIPTION
speaker-test generates a tone that can be used to test the speakers of a computer. OPTIONS
-c | --channels NUM NUM channels in stream -D | --device NAME PCM device name NAME -f | --frequency FREQ sine wave of FREQ Hz --help Print usage help -b | --buffer TIME Use buffer size of TIME microseconds. When 0 is given, use the maximal buffer size. The default value is 0. -p | --period TIME Use period size of TIME microseconds. When 0 is given, the periods given by -P option is used. The default value is 0. -P | --nperiods ERIODS Use number of periods. The default value is 4. -r | --rate RATE stream of RATE Hz -t | --test pink|sine|wav -t pink means use pink noise (default). Pink noise is perceptually uniform noise -- that is, it sounds like every frequency at once. If you can hear any tone it may indi- cate resonances in your speaker system or room. -t sine means to use sine wave. -t wav means to play WAV files, either pre-defined files or given via -w option. You can pass the number from 1 to 3 as a backward compatibility. -l | --nloops COUNT Specifies the number of loops. Zero means to run infinitely. When -s option below with a valid channel is given, speaker-test will perform always a single-shot without looping. -s | --speaker CHANNEL Do a single-shot speaker test for the given channel. The channel number starts from 1. The channel number corresponds to left, right, rear-left, rear-right, center, LFE, side-left, side-right, and so on. For example, when 1 is passed, it tests the left channel only once rather than both channels with looping. -w | --wavfile Use the given WAV file for the playback instead of pre-defined WAV files. -W | --wavdir Specify the directory containing WAV files for playback. The default path is /usr/share/sounds/alsa. USAGE EXAMPLES
Produce stereo sound from one stereo jack: speaker-test -Dplug:front -c2 Produce 4 speaker sound from two stereo jacks: speaker-test -Dplug:surround40 -c4 Produce 5.1 speaker sound from three stereo jacks: speaker-test -Dplug:surround51 -c6 To send a nice low 75Hz tone to the Woofer and then exit without touching any other speakers: speaker-test -Dplug:surround51 -c6 -s1 -f75 AUTHOR
The speaker-test program was written by James Courtier-Dutton. Pink noise support was added by Nathan Hurst. Further extensions by Takashi Iwai. speaker-test 20 September 2004 SPEAKER-TEST(1)

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