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version 1.101, 2012/04/25 07:18:45 version 1.102, 2012/12/03 15:35:25
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 .Dt AUCAT 1  .Dt AUCAT 1
 .Os  .Os
 .Sh NAME  .Sh NAME
 .Nm aucat ,  .Nm aucat
 .Nm sndiod  .Nd audio/MIDI stream manipulation tool
 .Nd audio/MIDI server and stream manipulation tool  
 .Sh SYNOPSIS  .Sh SYNOPSIS
 .Nm aucat  .Nm aucat
 .Bk -words  .Bk -words
 .Op Fl dn  .Op Fl dMn
 .Op Fl b Ar nframes  
 .Op Fl C Ar min : Ns Ar max  .Op Fl C Ar min : Ns Ar max
 .Op Fl c Ar min : Ns Ar max  .Op Fl c Ar min : Ns Ar max
 .Op Fl e Ar enc  .Op Fl e Ar enc
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 .Op Fl v Ar volume  .Op Fl v Ar volume
 .Op Fl w Ar flag  .Op Fl w Ar flag
 .Op Fl x Ar policy  .Op Fl x Ar policy
 .Op Fl z Ar nframes  
 .Ek  .Ek
 .Nm sndiod  
 .Bk -words  
 .Op Fl dM  
 .Op Fl a Ar flag  
 .Op Fl b Ar nframes  
 .Op Fl C Ar min : Ns Ar max  
 .Op Fl c Ar min : Ns Ar max  
 .Op Fl e Ar enc  
 .Op Fl f Ar device  
 .Op Fl j Ar flag  
 .Op Fl L Ar addr  
 .Op Fl m Ar mode  
 .Op Fl q Ar port  
 .Op Fl r Ar rate  
 .Op Fl s Ar name  
 .Op Fl t Ar mode  
 .Op Fl U Ar unit  
 .Op Fl v Ar volume  
 .Op Fl w Ar flag  
 .Op Fl x Ar policy  
 .Op Fl z Ar nframes  
 .Ek  
 .Sh DESCRIPTION  .Sh DESCRIPTION
 The  The
 .Nm sndiod  .Nm
 daemon is an intermediate layer between  utility can play, record, mix, and convert audio files.
 audio or MIDI programs and the hardware.  
 It performs the necessary audio processing to  
 allow any program to work on any supported hardware.  
 By default,  
 .Nm sndiod  
 accepts connections from programs  
 running on the same system only;  
 it initializes only when programs are using its services,  
 allowing  
 .Nm sndiod  
 to consume a negligible amount of system resources the rest of the time.  
 Systems with no audio hardware can use  
 .Nm sndiod  
 to keep hot-pluggable devices usable by default at  
 virtually no cost.  
 .Pp  
 .Nm sndiod  
 operates as follows: it exposes at least one  
 .Em sub-device  
 that any number of audio programs can connect to and use as if it were  
 audio hardware.  
 During playback,  During playback,
 .Nm sndiod  .Nm
 receives audio data concurrently from all programs, mixes it and sends  reads audio data concurrently from all played files, mixes it and sends
 the result to the hardware device.  the result to the device.
 Similarly, during recording it duplicates audio data recorded  Similarly, during recording it duplicates audio data recorded
 from the device and sends it to all programs.  from the device and stores it into corresponding files.
 Since audio data flows through the  It can process audio data on the fly:
 .Nm sndiod  
 process, it has the opportunity to process audio data on the fly:  
 .Pp  .Pp
 .Bl -bullet -offset indent -compact  .Bl -bullet -offset indent -compact
 .It  .It
 Change the sound encoding to overcome incompatibilities between  Change the sound encoding.
 software and hardware.  
 .It  .It
 Route the sound from one channel to another,  Route the sound from one channel to another,
 join stereo or split mono.  join stereo or split mono.
 .It  .It
 Control the per-application playback volume as well as the  Control the per-file playback volume.
 master volume.  
 .It  .It
 Monitor the sound being played, allowing one program to record  Monitor the sound being played, allowing to playback mix
 what other programs play.  to be record.
 .El  .El
 .Pp  .Pp
 Processing is configured on a per sub-device basis, meaning that  
 the sound of all programs connected to the same sub-device will be  
 processed according to the same configuration.  
 Multiple sub-devices can be defined, allowing multiple configurations  
 to coexist.  
 The user selects the configuration a given program will use  
 by selecting the sub-device the program uses.  
 .Pp  
 .Nm sndiod  
 can expose a MIDI port that can be used as a MIDI thru box  
 (aka a  
 .Dq hub  
 for MIDI messages),  
 allowing any program to send MIDI messages to  
 MIDI hardware or to another program in a uniform way.  
 Hardware ports can be subscribed to such MIDI thru boxes,  
 allowing multiple programs to share the MIDI port.  
 .Pp  
 Finally,  Finally,
 .Nm sndiod  .Nm
 exposes a control MIDI port usable for:  can accept MIDI messages usable for:
 .Pp  .Pp
 .Bl -bullet -offset indent -compact  .Bl -bullet -offset indent -compact
 .It  .It
 Volume control.  Volume control.
 .It  .It
 Common clock source for audio and MIDI programs.  Start, stop and relocate playback and recording.
 .It  
 Start, stop and relocate groups of audio programs.  
 .El  .El
 .Pp  .Pp
 The  For historic reasons
 .Nm  .Nm
 utility can play, record, mix, and convert regular audio files.  has the same audio server capability as
 It has the same processing capabilities as  .Xr sndiod 1 ,
 .Nm sndiod .  enabled when no files to play or record are provided.
 Both operate the same way, except that the former processes audio data stored  Both operate the same way, except that the former processes audio data stored
 in files, while the latter processes audio data provided or consumed by  in files, while the latter processes audio data provided or consumed by
 programs.  programs.
 Instead of a list of sub-devices,  Hence it has the same server-centric options described in
 .Nm  .Xr sndiod 1 .
 is given a list of files to play or record.  
 .Pp  .Pp
 The options are as follows:  The options are as follows:
 .Bl -tag -width Ds  .Bl -tag -width Ds
 .It Fl a Ar flag  
 Control whether  
 .Nm sndiod  
 opens the audio device only when needed or keeps it open all the time.  
 This applies to MIDI ports controlling the device as well.  
 If the flag is  
 .Va on  
 then the device is kept open all the time, ensuring no other program can  
 steal it.  
 If the flag is  
 .Va off ,  
 then it's automatically closed, allowing other programs to have direct  
 access to the device, or the device to be disconnected.  
 The default is  
 .Va off ,  
 except for the default device.  
 .It Fl b Ar nframes  
 The buffer size of the audio device in frames.  
 A frame consists of one sample for each channel in the stream.  
 This is the number of frames that will be buffered before being played  
 and thus controls the playback latency.  
 The default is 7680 or twice the block size  
 .Pq Fl z ,  
 if the block size is set.  
 .It Xo  .It Xo
 .Fl C Ar min : Ns Ar max ,  .Fl C Ar min : Ns Ar max ,
 .Fl c Ar min : Ns Ar max  .Fl c Ar min : Ns Ar max
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 The default is 0:1, i.e. stereo.  The default is 0:1, i.e. stereo.
 .It Fl d  .It Fl d
 Increase log verbosity.  Increase log verbosity.
 .Nm sndiod  
 logs on  
 .Em stderr  
 until it daemonizes.  
 .It Fl e Ar enc  .It Fl e Ar enc
 Encoding of the playback or recording stream (see below).  Encoding of the playback or recording stream (see below).
 The default is signed, 16-bit, native byte order.  The default is signed, 16-bit, native byte order.
 .It Fl f Ar device  .It Fl f Ar device
 Add this  Use this
 .Xr sndio 7  .Xr sndio 7
 audio device to devices used for playing and/or recording.  audio device.
 Preceding per-device options  Preceding per-device options apply to this device.
 .Pq Fl abwz  
 apply to this device.  
 Streams  Streams
 .Pq Fl ios  .Pq Fl io
 and control MIDI ports  and control MIDI ports
 .Pq Fl q  .Pq Fl q
 that are applied after will be attached to this device.  that are applied after will be attached to this device.
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 be sent on multiple outputs or to record a stereo input into a mono stream.  be sent on multiple outputs or to record a stereo input into a mono stream.
 The default is  The default is
 .Ar on .  .Ar on .
 .It Fl L Ar addr  
 Specify a local network address  
 .Nm sndiod  
 should listen;  
 .Nm sndiod  
 will listen on TCP port 11025+n, where n is the unit number  
 specified with  
 .Fl U .  
 Without this option,  
 .Nm sndiod  
 listens on the  
 .Ux Ns -domain  
 socket only, and is not reachable from any network.  
 If the option argument is  
 .Sq -  
 then  
 .Nm sndiod  
 will accept connections from any address.  
 .It Fl M  .It Fl M
 Create a MIDI thru box  Create a MIDI thru box
 .Pq i.e. MIDI-only pseudo device .  .Pq i.e. MIDI-only pseudo device .
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 .Fl m Ar midi  .Fl m Ar midi
 .Pc  .Pc
 can be attached to it.  can be attached to it.
 Exposed sub-devices by  
 .Nm sndiod  
 behave like software MIDI ports,  
 allowing any MIDI-capable application to send MIDI messages to  
 MIDI hardware or to another application in a uniform way.  
 .It Fl m Ar mode  .It Fl m Ar mode
 Set the stream mode.  Set the stream mode.
 Valid modes are  Valid modes are
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 .Sq -  .Sq -
 then standard output will be used.  then standard output will be used.
 .It Fl q Ar port  .It Fl q Ar port
 Expose the audio device clock on this  Allow audio device properties to be controlled
 .Xr sndio 7  through this MIDI port.
 MIDI port and allow audio device properties to be controlled  
 through MIDI.  
 This includes per-stream volumes and the ability to  This includes per-stream volumes and the ability to
 synchronously start, stop and relocate streams created in  synchronously start, stop and relocate streams created in
 MIDI Machine  MIDI Machine
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 .It Fl r Ar rate  .It Fl r Ar rate
 Sample rate in Hertz of the stream.  Sample rate in Hertz of the stream.
 The default is 48000.  The default is 48000.
 .It Fl s Ar name  
 Add  
 .Ar name  
 to the list of sub-devices to expose.  
 This allows clients to use  
 .Nm sndiod  
 instead of the physical audio device for audio input and output  
 in order to share the physical device with other clients.  
 Defining multiple sub-devices allows splitting a physical audio device  
 into logical devices having different properties (e.g. channel ranges).  
 The given  
 .Ar name  
 corresponds to the  
 .Dq option  
 part of the  
 .Xr sndio 7  
 device name string.  
 .It Fl t Ar mode  .It Fl t Ar mode
 Select the way streams are controlled by MIDI Machine Control (MMC)  Select the way streams are controlled by MIDI Machine Control (MMC)
 messages.  messages.
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 (the default), then streams are not affected by MMC messages.  (the default), then streams are not affected by MMC messages.
 If the mode is  If the mode is
 .Va slave ,  .Va slave ,
 then streams are started synchronously by MMC start messages;  then streams are started synchronously by MMC start messages.
 additionally, the server clock is exposed as MIDI Time Code (MTC)  
 messages allowing MTC-capable software or hardware to be synchronized  
 to audio streams.  
 .It Fl U Ar unit  
 Unit number to use when running in server mode.  
 Each  
 .Nm sndiod  
 server instance has an unique unit number,  
 used in  
 .Xr sndio 7  
 device names.  
 The default is 0.  
 The unit number must be set before any  
 .Fl L  
 is used.  
 .It Fl v Ar volume  .It Fl v Ar volume
 Software volume attenuation of the playback stream.  Software volume attenuation of the playback stream.
 The value must be between 1 and 127,  The value must be between 1 and 127,
 corresponding to \-42dB and \-0dB attenuation in 1/3dB steps.  corresponding to \-42dB and \-0dB attenuation in 1/3dB steps.
 In server mode, clients inherit this parameter.  
 Reducing the volume in advance allows a client's volume to stay independent  
 from the number of clients as long as their number is small enough.  
 18 volume units (i.e. \-6dB attenuation) allows the number  
 of playback streams to be doubled.  
 The default is 127 i.e. no attenuation.  The default is 127 i.e. no attenuation.
 .It Fl w Ar flag  .It Fl w Ar flag
 Control  Control
 .Nm  .Nm
 and  
 .Nm sndiod  
 behaviour when the maximum volume of the hardware is reached  behaviour when the maximum volume of the hardware is reached
 and a new stream is connected.  and a new stream is connected.
 This happens only when stream volumes  This happens only when stream volumes
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 .Dq ignore  .Dq ignore
 action is disabled for any stream connected to it  action is disabled for any stream connected to it
 to ensure proper synchronization.  to ensure proper synchronization.
 .It Fl z Ar nframes  
 The audio device block size in frames.  
 This is the number of frames between audio clock ticks,  
 i.e. the clock resolution.  
 If a stream is created with the  
 .Fl t  
 option,  
 and MTC is used for synchronization, the clock  
 resolution must be 96, 100 or 120 ticks per second for maximum  
 accuracy.  
 For instance, 100 ticks per second at 48000Hz corresponds  
 to a 480 frame block size.  
 The default is 960 or half of the buffer size  
 .Pq Fl b ,  
 if the buffer size is set.  
 .El  .El
 .Pp  .Pp
 On the command line,  On the command line,
 per-device parameters  per-device parameters must precede the device definition
 .Pq Fl abwz  
 must precede the device definition  
 .Pq Fl fMn ,  .Pq Fl fMn ,
 and per-stream parameters  and per-stream parameters
 .Pq Fl Ccehjmrtvx  .Pq Fl Ccehjmrtvx
 must precede the stream definition  must precede the stream definition
 .Pq Fl ios .  .Pq Fl io .
 MIDI ports  MIDI ports
 .Pq Fl q  .Pq Fl q
 and stream definitions  and stream definitions
 .Pq Fl ios  .Pq Fl io
 must follow the definition of the device  must follow the definition of the device
 .Pq Fl fMn  .Pq Fl fMn
 to which they are attached.  to which they are attached.
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 are specified,  are specified,
 settings are applied as if  settings are applied as if
 the default device is specified.  the default device is specified.
 If no  
 .Nm sndiod  
 sub-devices  
 .Pq Fl s  
 are specified for a device, a default server sub-device is  
 created attached to it.  
 If a device  
 .Pq Fl fMn  
 is defined twice, both definitions are merged:  
 parameters of the first one are used but streams  
 .Pq Fl ios  
 and MIDI control ports  
 .Pq Fl q  
 of both definitions are created.  
 The default  
 .Xr sndio 7  
 device used by  
 .Nm sndiod  
 is  
 .Pa rsnd/0 ,  
 and the default sub-device exposed by  
 .Nm sndiod  
 is  
 .Pa snd/0 .  
 .Pp  .Pp
 If  If
 .Nm sndiod  
 or  
 .Nm aucat  .Nm aucat
 is sent  is sent
 .Dv SIGHUP ,  .Dv SIGHUP ,
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 .It u18be3  .It u18be3
 unsigned 18-bit, packed in 3 bytes, big endian  unsigned 18-bit, packed in 3 bytes, big endian
 .El  .El
 .Sh SERVER MODE  
 .Nm sndiod  
 can be used  
 to overcome hardware limitations and allow applications  
 to run on fixed sample rate devices or on devices  
 supporting only unusual encodings.  
 .Pp  
 Certain applications, such as synthesis software,  
 require a low latency audio setup.  
 To reduce the probability of buffer underruns or overruns, especially  
 on busy machines, the server can be started by the super-user, in which  
 case it will run with higher priority.  
 Any user will still be able to connect to it,  
 but for privacy reasons only one user may have  
 connections to it at a given time.  
 .Sh MIDI CONTROL  .Sh MIDI CONTROL
 .Nm  .Nm
 can expose the audio device clock on registered  can be controlled through MIDI
 MIDI ports  
 .Pq Fl q  .Pq Fl q
 and allows audio device properties to be controlled  as follows:
 through MIDI.  a MIDI channel is assigned to each stream, and the volume
 Additionally,  
 .Nm sndiod  
 creates a MIDI port with the same name as the exposed audio  
 sub-device to which MIDI programs can connect.  
 .Pp  
 A MIDI channel is assigned to each stream, and the volume  
 is changed using the standard volume controller (number 7).  is changed using the standard volume controller (number 7).
 Similarly, when the audio client changes its volume,  Similarly, when the audio client changes its volume,
 the same MIDI controller message is sent out; it can be used  the same MIDI controller message is sent out; it can be used
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 option are controlled by the following MMC messages:  option are controlled by the following MMC messages:
 .Bl -tag -width relocateXXX -offset indent  .Bl -tag -width relocateXXX -offset indent
 .It relocate  .It relocate
 Streams are relocated to the requested time position  Files are relocated to the requested time position.
 relative to the beginning of the stream, at which playback  
 and recording must start.  
 If the requested position is beyond the end of file,  If the requested position is beyond the end of file,
 the stream is temporarly disabled until a valid position is requested.  playback of the file is temporarly disabled until a valid
 This message is ignored by audio  position is requested.
 .Nm sndiod  
 clients, but the given time position is sent to MIDI ports as an MTC  
 .Dq "full frame"  
 message forcing all MTC-slaves to relocate to the given  
 position (see below).  
 .It start  .It start
 Put all streams in starting mode.  Files are started.
 In this mode,  
 .Nm sndiod  
 or  
 .Nm aucat  
 waits for all streams to become ready  
 to start, and then starts them synchronously.  
 Once started, new streams can be created  
 .Pq Nm sndiod  
 but they will be blocked  
 until the next stop-to-start transition.  
 .It stop  .It stop
 Put all streams in stopped mode (the default).  Files are stopped and rewound back to the starting position.
 In this mode, any stream attempting to start playback or recording  
 is paused.  
 Files  
 .Pq Nm aucat  
 are stopped and rewound back to the starting position,  
 while client streams  
 .Pq Nm sndiod  
 that are already  
 started are not affected until they stop and try to start again.  
 .El  .El
 .Pp  .Pp
 Streams created with the  MIDI control is intended to be used together with
 .Fl t  .Xr sndiod 1 .
 option export the  
 .Nm sndiod  
 device clock using MTC, allowing non-audio  
 software or hardware to be synchronized to the audio stream.  
 Maximum accuracy is achieved when the number of blocks per  
 second is equal to one of the standard MTC clock rates (96, 100 and 120Hz).  
 The following sample rates  
 .Pq Fl r  
 and block sizes  
 .Pq Fl z  
 are recommended:  
 .Pp  
 .Bl -bullet -offset indent -compact  
 .It  
 44100Hz, 441 frames (MTC rate is 100Hz)  
 .It  
 48000Hz, 400 frames (MTC rate is 120Hz)  
 .It  
 48000Hz, 480 frames (MTC rate is 100Hz)  
 .It  
 48000Hz, 500 frames (MTC rate is 96Hz)  
 .El  
 .Pp  
 For instance, the following command will create two devices:  For instance, the following command will create two devices:
 the default  the default
 .Va snd/0  .Va snd/0
 and a MIDI-controlled  and a MMC-controlled one
 .Va snd/0.mmc :  .Va snd/0.mmc :
 .Bd -literal -offset indent  .Bd -literal -offset indent
 $ sndiod -r 48000 -z 400 -s default -t slave -s mmc  $ sndiod -r 48000 -z 400 -s default -t slave -s mmc
 .Ed  .Ed
 .Pp  .Pp
 Streams connected to  Programs using
 .Va snd/0  .Va snd/0
 behave normally, while streams connected to  behave normally, while programs using
 .Va snd/0.mmc  .Va snd/0.mmc
 wait for the MMC start signal and start synchronously.  wait for the MMC start signal and start synchronously.
 Regardless of which device a stream is connected to,  Then, the following command will play a file on the
 its playback volume knob is exposed.  
 .Pp  
 For instance, the following command will play a file on the  
 .Va snd/0.mmc  .Va snd/0.mmc
 audio device, and give full control to MIDI software or hardware  audio device, giving full control to MIDI software or hardware
 connected to the  connected to the
 .Va snd/0.thru  .Va midithru/0
 MIDI port:  MIDI port:
 .Bd -literal -offset indent  .Bd -literal -offset indent
 $ aucat -f snd/0.mmc -t slave -q midithru/0 -i file.wav  $ aucat -f snd/0.mmc -t slave -q midithru/0 -i file.wav
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 At this stage,  At this stage,
 .Nm  .Nm
 will start, stop and relocate automatically following all user  will start, stop and relocate automatically following all user
 actions in the MIDI sequencer.  actions in the MIDI sequencer, assuming it's configured to
 Note that the sequencer must use  transmit MMC on
   .Va midithru/0 .
   Furthermore, the MIDI sequencer could be configured to use the
 .Va snd/0  .Va snd/0
 as the MTC source, i.e. the audio server, not the audio player.  port as MTC clock source, assured to be synchronous to playback of
 .Sh ENVIRONMENT  .Pa file.wav .
 .Bl -tag -width "AUCAT_COOKIE" -compact  
 .It Ev AUCAT_COOKIE  
 File containing user's session cookie.  
 .It Ev AUDIODEVICE  
 .Xr sndio 7  
 audio device to use if the  
 .Fl f  
 option is not specified.  
 .El  
 .Sh EXAMPLES  .Sh EXAMPLES
 Mix and play two stereo streams,  Mix and play two stereo streams,
 the first at 48kHz and the second at 44.1kHz:  the first at 48kHz and the second at 44.1kHz:
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 $ aucat -n -j off -i stereo.wav -C 0:0 -o left.wav -C 1:1 \e  $ aucat -n -j off -i stereo.wav -C 0:0 -o left.wav -C 1:1 \e
         -o right.wav          -o right.wav
 .Ed  .Ed
 .Pp  
 Start server using default parameters, creating an  
 additional sub-device for output to channels 2:3 only (rear speakers  
 on most cards), exposing the  
 .Pa snd/0  
 and  
 .Pa snd/0.rear  
 devices:  
 .Bd -literal -offset indent  
 $ sndiod -s default -c 2:3 -s rear  
 .Ed  
 .Pp  
 Start server creating the default sub-device with low volume and  
 an additional sub-device for high volume output, exposing the  
 .Pa snd/0  
 and  
 .Pa snd/0.max  
 devices:  
 .Bd -literal -offset indent  
 $ sndiod -v 65 -s default -v 127 -s max  
 .Ed  
 .Pp  
 Start server configuring the audio device to use  
 a 48kHz sample frequency, 240-frame block size,  
 and 2-block buffers.  
 The corresponding latency is 10ms, which is  
 the time it takes the sound to propagate 3.5 meters.  
 .Bd -literal -offset indent  
 $ sndiod -r 48000 -b 480 -z 240  
 .Ed  
 .Sh SEE ALSO  .Sh SEE ALSO
 .Xr audioctl 1 ,  .Xr audioctl 1 ,
 .Xr cdio 1 ,  .Xr cdio 1 ,
 .Xr mixerctl 1 ,  .Xr mixerctl 1 ,
   .Xr sndiod 1 ,
 .Xr audio 4 ,  .Xr audio 4 ,
 .Xr sndio 7  .Xr sndio 7
 .Sh BUGS  .Sh BUGS
 The  
 .Nm  
 utility assumes non-blocking I/O for input and output streams.  
 It will not work reliably on files that may block  
 (ordinary files block, pipes don't).  
 To avoid audio underruns/overruns or MIDI jitter caused by file I/O,  
 it's recommended to use two processes: a  
 .Nm sndiod  
 server handling audio and MIDI I/O and a  
 .Nm  
 client handling disk I/O.  
 .Pp  
 Resampling is low quality; down-sampling especially should be avoided  Resampling is low quality; down-sampling especially should be avoided
 when recording.  when recording.
 .Pp  .Pp
 Processing is done using 16-bit arithmetic,  Processing is done using 16-bit arithmetic,
 thus samples with more than 16 bits are rounded.  thus samples with more than 16 bits are rounded.
 16 bits (i.e. 97dB dynamic) are largely enough for most applications though.  16 bits (i.e. 97dB dynamic) are largely enough for most applications though.
 .Pp  
 If  
 .Fl a Ar off  
 is used,  
 .Nm sndiod  
 creates sub-devices to expose first  
 and then opens the audio hardware on demand.  
 Technically, this allows  
 .Nm sndiod  
 to attempt to use one of the sub-devices it exposes as an audio device,  
 creating a deadlock.  
 To avoid this,  
 .Fl a Ar off  
 is disabled for the default audio device, but nothing prevents the user  
 from shooting himself in the foot by creating a similar deadlock.  
 .Pp  
 The ability to merge multiple inputs is provided to allow multiple  
 applications producing MIDI data to keep their connection open while  
 idling; it does not replace a fully featured MIDI merger.  
Legend:
Removed from v.1.101  
changed lines
  Added in v.1.102