.\" $OpenBSD: aucat.1,v 1.103 2013/11/12 06:47:34 ratchov Exp $ .\" .\" Copyright (c) 2006 Alexandre Ratchov .\" .\" Permission to use, copy, modify, and distribute this software for any .\" purpose with or without fee is hereby granted, provided that the above .\" copyright notice and this permission notice appear in all copies. .\" .\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES .\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF .\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR .\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES .\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. .\" .Dd $Mdocdate: November 12 2013 $ .Dt AUCAT 1 .Os .Sh NAME .Nm aucat .Nd audio/MIDI stream manipulation tool .Sh SYNOPSIS .Nm aucat .Bk -words .Op Fl dMn .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 h Ar fmt .Op Fl i Ar file .Op Fl j Ar flag .Op Fl o Ar file .Op Fl q Ar port .Op Fl r Ar rate .Op Fl t Ar mode .Op Fl v Ar volume .Op Fl w Ar flag .Op Fl x Ar policy .Ek .Sh DESCRIPTION The .Nm utility can play, record, mix, and convert audio files. During playback, .Nm reads audio data concurrently from all played files, mixes it and sends the result to the device. Similarly, during recording it duplicates audio data recorded from the device and stores it into corresponding files. It can process audio data on the fly: .Pp .Bl -bullet -offset indent -compact .It Change the sound encoding. .It Route the sound from one channel to another, join stereo or split mono. .It Control the per-file playback volume. .It Monitor the sound being played, allowing to playback mix to be record. .El .Pp Finally, .Nm can accept MIDI messages usable for: .Pp .Bl -bullet -offset indent -compact .It Volume control. .It Start, stop and relocate playback and recording. .El .Pp For historic reasons .Nm has the same audio server capability as .Xr sndiod 1 , enabled when no files to play or record are provided. 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 programs. Hence it has the same server-centric options described in .Xr sndiod 1 . .Pp The options are as follows: .Bl -tag -width Ds .It Xo .Fl C Ar min : Ns Ar max , .Fl c Ar min : Ns Ar max .Xc The range of stream channel numbers for recording and playback directions, respectively. The default is 0:1, i.e. stereo. .It Fl d Increase log verbosity. .It Fl e Ar enc Encoding of the playback or recording stream (see below). The default is signed, 16-bit, native byte order. .It Fl f Ar device Use this .Xr sndio 7 audio device. Preceding per-device options apply to this device. Streams .Pq Fl io and control MIDI ports .Pq Fl q that are applied after will be attached to this device. Device mode and parameters are determined from streams attached to it. .It Fl h Ar fmt File format of the playback or record stream (see below). The default is auto. .It Fl i Ar file Add this file to the list of streams to play. If the option argument is .Sq - then standard input will be used. .It Fl j Ar flag Control whether stream channels are joined or expanded if the stream number of channels is not equal to the device number of channels. If the flag is .Va off then stream channels are routed to the corresponding device channel, possibly discarding channels not present in the device. If the flag is .Va on , then a single stream channel may be sent on multiple device channels, or multiple stream channels may be sent to a single device channel. For instance, this feature could be used to request mono streams to be sent on multiple outputs or to record a stereo input into a mono stream. The default is .Ar on . .It Fl M Create a MIDI thru box .Pq i.e. MIDI-only pseudo device . It merges any number of MIDI inputs and broadcasts the result to any number of MIDI outputs, similarly to a hardware MIDI thru box. Only MIDI ports .Pq Fl q and MIDI files can be attached to it. .It Fl n Create a loopback pseudo audio device. Send input streams to the output, processing them on the fly. This pseudo-device is useful to mix, demultiplex, resample or re-encode audio files offline. It requires at least one input .Pq Fl i and one output .Pq Fl o . .It Fl o Ar file Add this file to the list of recording streams. If the option argument is .Sq - then standard output will be used. .It Fl q Ar port Allow audio device properties to be controlled through this MIDI port. This includes per-stream volumes and the ability to synchronously start, stop and relocate streams created in MIDI Machine Control (MMC) slave mode .Pq Fl t . .It Fl r Ar rate Sample rate in Hertz of the stream. The default is 48000. .It Fl t Ar mode Select the way streams are controlled by MIDI Machine Control (MMC) messages. If the mode is .Va off (the default), then streams are not affected by MMC messages. If the mode is .Va slave , then streams are started synchronously by MMC start messages. .It Fl v Ar volume Software volume attenuation of the playback stream. 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. .It Fl w Ar flag Control .Nm behaviour when the maximum volume of the hardware is reached and a new stream is connected. This happens only when stream volumes are not properly set using the .Fl v option. If the flag is .Va on , then the master volume (corresponding to the mix of all playback streams) is automatically adjusted to avoid clipping. Using .Va off makes sense when all streams are recorded or produced with properly lowered volumes. The default is .Va on . .It Fl x Ar policy Action when the output stream cannot accept recorded data fast enough or the input stream cannot provide data to play fast enough. If the policy is .Dq ignore (the default) then samples that cannot be written are discarded and samples that cannot be read are replaced by silence. If the policy is .Dq sync then recorded samples are discarded, but the same amount of silence will be written once the stream is unblocked, in order to reach the right position in time. Similarly silence is played, but the same amount of samples will be discarded once the stream is unblocked. If the policy is .Dq error then the stream is closed permanently. .Pp If a stream is created with the .Fl t option, the .Dq ignore action is disabled for any stream connected to it to ensure proper synchronization. .El .Pp On the command line, per-device parameters must precede the device definition .Pq Fl fMn , and per-stream parameters .Pq Fl Ccehjmrtvx must precede the stream definition .Pq Fl io . MIDI ports .Pq Fl q and stream definitions .Pq Fl io must follow the definition of the device .Pq Fl fMn to which they are attached. .Pp If no audio devices .Pq Fl fMn are specified, settings are applied as if the default device is specified. .Pp If .Nm aucat is sent .Dv SIGHUP , .Dv SIGINT or .Dv SIGTERM , it terminates recording to files. .Pp File formats are specified using the .Fl h option. The following file formats are supported: .Bl -tag -width s32lexxx -offset indent .It raw Headerless file. This format is recommended since it has no limitations. .It wav Microsoft WAVE file format. There are limitations inherent to the file format itself: not all encodings are supported, file sizes are limited to 2GB, and the file must support the .Xr lseek 2 operation (e.g. pipes do not support it). .It auto Try to guess, depending on the file name. .El .Pp Encodings are specified using the .Fl e option. The following encodings are supported: .Pp .Bl -tag -width s32lexxx -offset indent -compact .It s8 signed 8-bit .It u8 unsigned 8-bit .It s16le signed 16-bit, little endian .It u16le unsigned 16-bit, little endian .It s16be signed 16-bit, big endian .It u16be unsigned 16-bit, big endian .It s24le signed 24-bit, stored in 4 bytes, little endian .It u24le unsigned 24-bit, stored in 4 bytes, little endian .It s24be signed 24-bit, stored in 4 bytes, big endian .It u24be unsigned 24-bit, stored in 4 bytes, big endian .It s32le signed 32-bit, little endian .It u32le unsigned 32-bit, little endian .It s32be signed 32-bit, big endian .It u32be unsigned 32-bit, big endian .It s24le3 signed 24-bit, packed in 3 bytes, little endian .It u24le3 unsigned 24-bit, packed in 3 bytes, big endian .It s24be3 signed 24-bit, packed in 3 bytes, little endian .It u24be3 unsigned 24-bit, packed in 3 bytes, big endian .It s20le3 signed 20-bit, packed in 3 bytes, little endian .It u20le3 unsigned 20-bit, packed in 3 bytes, big endian .It s20be3 signed 20-bit, packed in 3 bytes, little endian .It u20be3 unsigned 20-bit, packed in 3 bytes, big endian .It s18le3 signed 18-bit, packed in 3 bytes, little endian .It u18le3 unsigned 18-bit, packed in 3 bytes, big endian .It s18be3 signed 18-bit, packed in 3 bytes, little endian .It u18be3 unsigned 18-bit, packed in 3 bytes, big endian .El .Sh MIDI CONTROL .Nm can be controlled through MIDI .Pq Fl q as follows: a MIDI channel is assigned to each stream, and the volume is changed using the standard volume controller (number 7). Similarly, when the audio client changes its volume, the same MIDI controller message is sent out; it can be used for instance for monitoring or as feedback for motorized faders. .Pp The master volume can be changed using the standard master volume system exclusive message. .Pp Streams created with the .Fl t option are controlled by the following MMC messages: .Bl -tag -width relocateXXX -offset indent .It relocate Files are relocated to the requested time position. If the requested position is beyond the end of file, playback of the file is temporarly disabled until a valid position is requested. .It start Files are started. .It stop Files are stopped and rewound back to the starting position. .El .Pp MIDI control is intended to be used together with .Xr sndiod 1 . For instance, the following command will create two devices: the default .Va snd/0 and a MMC-controlled one .Va snd/0.mmc : .Bd -literal -offset indent $ sndiod -r 48000 -z 400 -s default -t slave -s mmc .Ed .Pp Programs using .Va snd/0 behave normally, while programs using .Va snd/0.mmc wait for the MMC start signal and start synchronously. Then, the following command will play a file on the .Va snd/0.mmc audio device, giving full control to MIDI software or hardware connected to the .Va midithru/0 MIDI port: .Bd -literal -offset indent $ aucat -f snd/0.mmc -t slave -q midithru/0 -i file.wav .Ed .Pp At this stage, .Nm will start, stop and relocate automatically following all user actions in the MIDI sequencer, assuming it's configured to transmit MMC on .Va midithru/0 . Furthermore, the MIDI sequencer could be configured to use the .Va snd/0 port as MTC clock source, assured to be synchronous to playback of .Pa file.wav . .Sh EXAMPLES Mix and play two stereo streams, the first at 48kHz and the second at 44.1kHz: .Bd -literal -offset indent $ aucat -r 48000 -i file1.raw -r 44100 -i file2.raw .Ed .Pp Record channels 2 and 3 into one stereo file and channels 6 and 7 into another stereo file using a 96kHz sampling rate for both: .Bd -literal -offset indent $ aucat -j off -r 96000 -C 2:3 -o file1.raw -C 6:7 -o file2.raw .Ed .Pp Split a stereo file into two mono files: .Bd -literal -offset indent $ aucat -n -j off -i stereo.wav -C 0:0 -o left.wav -C 1:1 \e -o right.wav .Ed .Sh SEE ALSO .Xr audioctl 1 , .Xr cdio 1 , .Xr mixerctl 1 , .Xr sndiod 1 , .Xr audio 4 , .Xr sndio 7 .Sh BUGS Resampling is low quality; down-sampling especially should be avoided when recording. .Pp Processing is done using 16-bit arithmetic, thus samples with more than 16 bits are rounded. 16 bits (i.e. 97dB dynamic) are largely enough for most applications though.