lavrec(1)
NAME
lavrec - Record MJPEG-video from a zoran/video4linuxdevice
SYNOPSIS
lavrec [options] filename(s)
DESCRIPTION
lavrec can be used to record video in MJPEG format (either
quicktime, movtar 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 cor
ner.
OPTIONS
lavrec accepts the following options:
- filename
- The file to record to (*.avi, *.qt, *.movtar). 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. - --software-encoding
- 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). - -f/--format [a|A|q|m]
- The format in which the video should be saved to
the harddisk.a - MJPEG AVI
A - MJPEG AVI with fields exchanged
q - Quicktime
m - Movtar - By default, lavrec will look at the extension of
the first file (*.avi, *.qt, *.movtar) and choose
a format based on that. - -i/--input [p|P|n|N|s|S|t|T|f|a]
- 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) - -d/--decimation num
- Recording decimation, either 1, 2 or 4. This will
decimate the size of the recorded video horizon
tally 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 hardware recording. - -g/--geometry WxH(+X+Y)
- 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 donīt support
subframe capture. - -q/--quality num
- Quality of the JPEG-video to be recorded (in per
cent). This must be a number between 0 and 100.
Lower quality should generally mean lower file
size, higher quality will take more diskspace but
will give more detailed perfectness in the result
ing recorded video. Default is 50%. - -C/--channel LIST:CHAN
- Choose the channel to record from (xawtv-style).
By default, lavrec will just use the current TV
channel. - -t/--time num
- Recording time in seconds. The default is unlim
ited. To stop capturing video while recording, use
Ctrl-C. - -S/--single-frame
- Single-frame capture mode. This means that one can
capture individual frames from the capture device. - -T/--time-lapse num
- time-lapse factor, which means that only every
<num>th frame is saved to the recording file. - -w/--wait
- If this option is given, lavrec will wait for the
user to press enter before starting to record. - -B/--batch
- This option turns off all possible interactivity
options and limits console output as much as pos
sible. Useful for cron/scheduled recordings. - -a/--audio-bitsize num
- Audio size in bits, either 0, 8 or 16 (default). 0
means no audio. - -r/--audio-bitrate num
- Audio sampling rate in Hz. This must be a sampling
rate which is supported by the soundcard. Oftensupported audio sampling rate values are 11025,
22050 or 44100 (default). - -s/--stereo
- Capture in stereo. By default, lavrec captures in
mono. - -l/--audio-volume num
- 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. - -m/--mute
- Mute sound output while recording. This can be
useful when recording sound from the microphone to
disable echos. This option is disabled by default. - -R/--audio-source [l|m|c]
- Recording source, either (l)ine-in, (m)icrophone
or (c)d-rom. The default is to record from line-in
(l). - -U/--use-read
- Use the read() system call rather than the mmap()
system call for audio recording. This may fix many
audio recording problems. - -c/--synchronization [0|1|2]
- 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. - -n/--mjpeg-buffers num
- Number of MJPEG-buffers. Default is 32. Try chang
ing this number if you have many lost frames. - -b/--mjpeg-buffer-size num
- MJPEG buffersize in kilobytes. The default is 256
kB. - --max-file-size num
- The maximum file size per JPEG file. By default,
lavrec uses the maximum possible size for that
specific recording format. - --file-flush num
- Flush the file to disk after every num frames cap
tured. - -v/--verbose num
- Verbosity level (0, 1 or 2). Default is 0.
ENVIRONMENT
The following environment variables can be recognized by
lavrec:
- LAV_VIDEO_DEV
- The video device. Default is /dev/video
- LAV_AUDIO_DEV
- The audio device. Default is /dev/dsp
- LAV_MIXER_DEV
- The mixer device. Default is /dev/mixer
OUTPUT
Lavrec will output the current recording state. Typically,
this looks like:
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-difference (out-of-sync'ness).
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 res
olution (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 --decima
tion=2 /path/to/file.avi - From normal video4linux devices
- lavrec --software-encoding --format=a --input=p
--quality=80 --geometry=352x288 /path/to/file.avi
BUGS
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 peo
ple, to cause small out-of-sync'ness. SMP support for JPEG
encoding is currently work-in-progress.
AUTHOR
- 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: - mjpeg-users@lists.sourceforge.net
- For more info, see our website at
- http://mjpeg.sourceforge.net/