Provided by: sndio-tools_1.9.0-0.3_amd64 bug


     aucat — audio files manipulation tool


     aucat [-dn] [-b size] [-c min:max] [-e enc] [-f device] [-g position] [-h fmt] [-i file]
           [-j flag] [-o file] [-p position] [-q port] [-r rate] [-v volume]


     The aucat utility can play, record, mix, and process audio files on the fly.  During
     playback, aucat reads audio data concurrently from all played files, mixes it and plays the
     result on the device.  Similarly, it stores audio data recorded from the device into
     corresponding files.  An off-line mode could be used to process audio files without
     involving audio hardware.  Processing includes:

              Change the sound encoding.
              Route the sound from one channel to another.
              Control the per-file playback volume.

     Finally, aucat can accept MIDI messages usable for:

              Volume control.
              Start, stop and relocate playback and recording.

     The options are as follows:

     -b size
             The buffer size of the audio device in frames.  Default is 7680.

     -c min:max
             The range of audio file channel numbers.  The default is 0:1, i.e. stereo.

     -d      Increase log verbosity.

     -e enc  Encoding of the audio file.  The default is s24.  Encoding names use the following
             scheme: signedness (s or u) followed by the precision in bits, the byte-order (le or
             be), the number of bytes per sample, and the alignment (msb or lsb).  Only the
             signedness and the precision are mandatory.  Examples: u8, s16le, s24le3, s24le4lsb.

     -f device
             Use this sndio(7) audio device.  Device mode and parameters are determined from
             audio files.  Default is default.

     -g position
             Go to the given time position and start playback or recording there.  This option is
             equivalent to an incoming MMC relocate message with the same position.  The position
             is expressed as the number of samples (at device sample rate).

     -h fmt  Audio file type.  The following file types are supported:

             raw   Headerless file.
             wav   Microsoft WAV file format.
             aiff  Apple's audio interchange file format.
             au    Sun/NeXT audio file format.
             auto  Try to guess, depending on the file name.  This is the default.

     -i file
             Play this audio file.  If the option argument is ‘-’ then standard input will be

     -j flag
             Control whether source channels are joined or expanded if they don't match the
             destination number of channels.  If the flag is off, then each source channel is
             routed to a single destination channel, possibly discarding channels.  If the flag
             is on, then a single source may be sent to multiple destinations and multiple
             sources may be mixed into a single destination.  For instance, this feature could be
             used to convert a stereo file into a mono file mixing left and right channels
             together.  The default is off.

     -n      Off-line mode.  Read input files and store the result in the output files,
             processing them on the fly.  This mode is useful to mix, demultiplex, resample or
             re-encode audio files off-line.  It requires at least one input (-i) and one output

     -o file
             Record into this audio file.  If the option argument is ‘-’ then standard output
             will be used.

     -p position
             Time offset where the beginning of the file belongs.  The first sample of the file
             will be played or recorded when the device reaches the given position.  The position
             is expressed as the number of samples (at device sample rate).

     -q port
             Control audio device properties through this MIDI port.  This includes per-stream
             volumes and the ability to synchronously start, stop and relocate audio files.

     -r rate
             Sample rate in Hertz of the audio file.  The default is 48000.

     -v volume
             Software volume attenuation of the file to play.  The value must be between 1 and
             127, corresponding to -42dB and -0dB attenuation in 1/3dB steps.  The default is
             127, i.e. no attenuation.

     On the command line, per-file parameters (-cehjrv) must precede the file definition (-io).

     If aucat is sent SIGHUP, SIGINT or SIGTERM, it terminates recording to files.


     aucat can be controlled through MIDI (-q) as follows: a MIDI channel is assigned to each
     stream, and the volume is changed using the standard volume controller (number 7).

     The master volume can be changed using the standard master volume system exclusive message.

     All audio files are controlled by the following MMC messages:

           relocate  All files are relocated to the requested time position.  If it is beyond the
                     end of a file, the file is temporarily disabled until a valid position is

           start     Playback and/or recording is started.

           stop      Playback and/or recording is stopped and all files are rewound back to the
                     starting position.

     MIDI control is intended to be used together with sndiod(8).  For instance, the following
     command will create two devices: the default snd/0 and a MMC-controlled one snd/0.mmc:

           $ sndiod -r 48000 -z 480 -s default -t slave -s mmc

     Programs using snd/0 behave normally, while programs using snd/0.mmc wait for the MMC start
     signal and start synchronously.  Then, the following command will play a file on the
     snd/0.mmc audio device, giving full control to MIDI software or hardware connected to the
     midithru/0 MIDI port:

           $ aucat -f snd/0.mmc -q midithru/0 -i file.wav

     At this stage, aucat will start, stop and relocate automatically following all user actions
     in the MIDI sequencer, assuming it's configured to transmit MMC on midithru/0.  Furthermore,
     the MIDI sequencer could be configured to use the snd/0 port as MTC clock source, assured to
     be synchronous to playback of file.wav.


     Mix and play two files while recording a third file:

           $ aucat -i file1.wav -i file2.wav -o file3.wav

     Record channels 2 and 3 into one stereo file and channels 6 and 7 into another stereo file
     using a 44.1kHz sampling rate for both:

           $ aucat -r 44100 -c 2:3 -o file1.wav -c 6:7 -o file2.wav

     Split a stereo file into two mono files:

           $ aucat -n -i stereo.wav -c 0:0 -o left.wav \
                   -c 1:1 -o right.wav


     cdio(1), audio(4), sndio(7), audioctl(8), mixerctl(8), sndiod(8)


     Resampling is low quality.

     There are limitations inherent to the wav, aiff, and au file formats: not all encodings are
     supported, file sizes are limited to 2GB, and the files must support the lseek(2) operation
     (e.g. pipes do not support it).