lavrec - Record MJPEG-video from a zoran/video4linux-device
lavrec [options] filename(s)
lavrec can be used to record video in MJPEG format (either quicktime or
AVI) from a zoran video-capture device, such as the Miro/Pinnacle
DC10(+), the Iomega Buz or Linux Media Labs’ LML33, or from a generic
video4linux device, such as the cheap Bt848 or Bt878 based TV-cards
that are being sold in every computer shop around the corner.
lavrec accepts the following options:
The file to record to (*.avi, *.qt). Use a % to record to
multiple files (using file%02d.avi will record to file00.avi,
file01.avi, etc). You can also give more than one filename,
which will have the same effect. This will avoid problems
resulting from filetype or filesystem size limits. AVI, for
example, has a 2 GB limit, as does ext2fs in 2.2.x kernels.
By default, lavrec will capture in a mode that is only suitable
for recording from hardware MJPEG devices. Using this option
will make lavrec use software-JPEG-encoding (using libjpeg)
which enables MJPEG-video-capture from many generic video4linux
devices (such as Bt848/Bt878-based ones).
The format in which the video should be saved to the harddisk.
a - MJPEG AVI
A - MJPEG AVI with fields exchanged
q - Quicktime
By default, lavrec will look at the extension of the first file
(*.avi, *.qt) and choose a format based on that.
The recording source and the video source standard format.
p - PAL through Composite or 1st Bt8x8 input
P - PAL through SVHS- or 2nd Bt8x8 input
t - PAL through TV-tuner- or 3rd Bt8x8 input
n - NTSC through Composite or 1st Bt8x8 input
N - NTSC through SVHS- or 2nd Bt8x8 input
T - NTSC through TV-tuner- or 3rd Bt8x8 input
s - SECAM through Composite or 1st Bt8x8 input
S - SECAM through SVHS- or 2nd Bt8x8 input
f - SECAM through TV-tuner- or 3rd Bt8x8 input
a - (or every other letter) Autosense (default)
The input can be specified using either single letters or an
input number with an optional norm, where the number specifies
the n’th input of the card, ranging from 1 to 10. Using a
numerical input is necessary when using input four or higher
with a card that has more than three inputs, for instance the
AverMedia 6 Eyes. When using numeric input with the norm it
must contain the whole norm name; valid names are pal, ntsc and
secam. You can use numeric input selection for cards with only
three inputs, too, which most Zoran based cards has.
"-i 2:pal" used with a Buz would be equivalent to "-i P",
recording from the S-Video input in PAL format.
Recording decimation, either 1, 2 or 4. This will decimate the
size of the recorded video horizontally and vertically. To use
different horizontal and vertical decimations, use two numbers,
the first one being the horizontal and the second one being the
vertical (-d 12). Note: this option can only be used during
For hardware recording: An X-style geometry string, giving the
geometry of the undecimated subframe to record. The default is
the full frame, so 720x576/480+0+0 for Buz/LML33-users and
640x480+0+0 or 768x576+0+0 for DC10(+)-users. For software
recording: The size of the video to be captured. Currently,
width and height need to be a multiple of 16. You always
capture the full frame since most video4linux devices don´t
support subframe capture.
Quality of the JPEG-video to be recorded (in percent). This
must be a number between 0 and 100. Lower quality should
generally mean lower filesize, higher quality will take more
diskspace but will give more detailed perfectness in the
resulting recorded video. Default is 50%.
Choose the channel to record from (xawtv-style). By default,
lavrec will just use the current TV channel.
Recording time in seconds. The default is unlimited. To stop
capturing video while recording, use Ctrl-C.
Single-frame capture mode. This means that one can capture
individual frames from the capture device.
time-lapse factor, which means that only every <num>th frame is
saved to the recording file.
If this option is given, lavrec will wait for the user to press
enter before starting to record.
This option turns off all possible interactivity options and
limits console output as much as possible. Useful for
Audio size in bits, either 0, 8 or 16 (default). 0 means no
Audio sampling rate in Hz. This must be a sampling rate which
is supported by the soundcard. Often-supported audio sampling
rate values are 11025, 22050 or 44100 (default).
Capture in stereo. By default, lavrec captures in mono.
Recording level. This must be a value between 0 (no sound) and
100 (loud recording). -1 (default) means to not touch the mixer
settings at all.
Mute sound output while recording. This can be useful when
recording sound from the microphone to disable echos. This
option is disabled by default.
Recording source, either (l)ine-in, (m)icrophone or (c)d-rom.
The default is to record from line-in (l).
Use the read() system call rather than the mmap() system call
for audio recording. This may fix many audio recording
Audio/video synchronization level efforts. (0) means no
synchronization, (1) means that lavrec will replicate frames
for lost frames. (2) means that lavrec will replicate frames
for lost frames and do sync correction. Default is 2.
Number of MJPEG-buffers. Default is 32. Try changing this
number if you have many lost frames.
MJPEG buffersize in kilobytes. The default is 256 kB.
The maximum file size per JPEG file. By default, lavrec uses
the maximum possible size for that specific recording format.
The maximum number of frames per per JPEG file. By default, the
number of frames is only limited by other factors, such as
maximum file size.
Flush the file to disk after every num frames captured.
Verbosity level (0, 1 or 2). Default is 0.
The following environment variables can be recognized by lavrec:
The video device. Default is /dev/video
The audio device. Default is /dev/dsp
The mixer device. Default is /dev/mixer
Lavrec will output the current recording state. Typically, this looks
0.06.14:22 int: 00040 lst:0 ins:0 del:0 ae:0 td1=0.014 td2=0.029
The first part is the time that has been spent recording (hours -
minutes - seconds - frames). int is the interval (in milliseconds)
between two captured frames (this should be around 40 for PAL/SECAM and
33 for NTSC). lst is the number of lost frames. ins and del are the
number of frames inserted and deleted for sync correction. ae is the
number of audio errors. td1 and td2 are the audio/video time-
TYPICAL RECORDING SESSIONS
Okay, that’s a lot of options. Now how would I normally record video?
Let’s assume you want to record at VCD resolution (352x288) from PAL
source. You might want some higher quality than default (80%). You use
default audio options and record to an AVI file. That having said, your
recording command line would look like:
From hardware MJPEG devices (S-video input)
lavrec --format=a --input=P --quality=80 --decimation=2
From normal video4linux devices
lavrec --software-encoding --format=a --input=p --quality=80
lavrec should be able to detect automatically whether to use software
JPEG encoding or whether to use the card’s hardware JPEG encoding
features (if available).
Besides that, software JPEG encoding seems, for some people, to cause
small out-of-sync’ness. SMP support for JPEG encoding is currently
This man page was written by Ronald Bultje.
If you have questions, remarks, problems or you just want to contact
the developers, the main mailing list for the MJPEG-tools is:
For more info, see our website at