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).