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qarecord

NAME

qarecord - an audio recording tool

SYNOPSIS

qarecord [ alsa-options ] [ general-options ]
qarecord --jack [ general-options ]
qarecord { --help | --version }

DESCRIPTION

qarecord is a simple but solid recording tool. qarecord works well with both stereo and multichannel recordings, with both ALSA and JACK, and in both 16 bit and 32 bit mode. By using a large ringbuffer for the captured data, buffer overruns are avoided. qarecord has a Qt based GUI with graphical peak meters.

MIDI trigger

In addition to the buttons in the GUI, recording can be started and stopped via MIDI. qarecord uses the ALSA sequencer for this purpose.

File naming

A save file dialog appears the first time recording is activated, or through selecting New... in the File menu. If that file already exists, the old file will be renamed (to filename.oldx.wav), where x is an incrementing number. Should the file grow larger than the split limit, the file will be closed and recording will continue in a new file filename.partx.wav, where x is an incrementing number.

Scheduling and priorities

qarecord has one high-priority thread that fetches data from ALSA and one normal priority thread that writes the data to disk. This will work best if the user is allowed to run realtime priority (rtprio) threads, see limits.conf(5) for more information. In JACK mode, the same reasoning applies, but it is handled by JACK, see jackd(1) for more information.

A ringbuffer is used to buffer the data before it is written to disk.

OPTIONS

General options

--32bit

If specified, a 32 bit WAVE will be the output format. If not specified, a 16 bit WAVE file will be recorded.

--buffersize bytes

The size of the ringbuffer in bytes. The default (1048576) should be sufficient for most purposes. It must be a multiple of the frame size (channels * bytes per channel).

--channels num

Number of channels to record. The default is 2, which means a stereo recording.

--jack

If specified, qarecord works as a JACK client. If not specified, qarecord uses ALSA for recording.

--meterrange dB

Specifies the dynamic range of the peak meters. The default value of 85 means that the meter will show signals between -85 dB and 0 dB.

--midiChannel channel

Specifies what MIDI channel the MIDI trigger should listen to. The default is 16, the valid range is 1..16.

--midiNote num

Specifies what MIDI notes the MIDI trigger should listen to. This note will be used to trigger recording, the next note will trigger pause, and note+2 will trigger stop. The default is 21, which translates to note A1 being used to record, A#1 for pause, and B1 for stop.

--split MB

Start a new wave file every MB megabytes. Default is 2000.

ALSA specific options

--device ALSA device

The ALSA device name to use for capture. The default is plughw:0, which means the first soundcard.

--fragments num

Number of fragments, or periods. Used with the periodsize option to determine the hardware buffer size. The default is 2.

--periodsize frames

Number of frames between ALSA signals that new data is available. The hardware buffer size will be periodsize * fragments. A large hardware buffer size might decrease the risc for a buffer underrun. The default is 2048.

--rate Hz

Sample rate. The default is 44100.

Standard options

--help

Print possible command-line options and exit.

--version

Print version information and exit.

NOTES

Errors and warnings are written to stderr(3).

Due to limitations in the WAVE file format, larger files than 4 GB cannot be recorded.

AUTHORS

Matthias Nagorni, Frank Kober, Guido Scholz and David Henningsson. This manual page was written by David Henningsson <qarecord@epost.diwic.se>.

SEE ALSO

jackd(1), limits.conf(5).