Provided by: mjpegtools_2.1.0+debian-6build1_amd64 
NAME
lavrec - Record MJPEG-video from a zoran/video4linux-device
SYNOPSIS
lavrec [options] filename(s)
DESCRIPTION
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.
OPTIONS
lavrec accepts the following options:
filename
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.
--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).
--software-encoding-yuvp
This option adds support for the EM28XX USB driver. As this driver is V4L2. As the original BTTV
software implementation assumes that the driver supports V4L it will not work with the EM28XX
driver, not even with the V4L1 emulation layer. This option enables two things:
It enables the V4L2 calls to make interaction with this driver possible
It select the cards YUV Packed format and converts this in software to YUV Planar The process
is after this the same as for the BTTV driver. ome things of note are the fact that the EM28XX
driver expects 48KHz audio recording. If you choose slower things will work, but a lot of
deleted/inserted frames will occur. The lower the sample rate, the worse this problem gets.
Recording at 48KHz is therefore recommended. This code was tested and found working with a
DVC100 Pinnacle Dazzle. This option should work with any EM28XX, but this hasnt been tested. It
might work for any other V4L2 device that outputs YUV packed format, this has however not been
tested. Feedback would be appreciated.
-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
By default, lavrec will look at the extension of the first file (*.avi, *.qt) and choose a format
based on that.
-i/--input [p|P|n|N|s|S|t|T|f|a]
or
-i/--input input[:norm]
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.
-d/--decimation num
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 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 don´t support subframe capture.
-q/--quality num
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%.
-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 unlimited. 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
possible. 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.
Often-supported 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 changing 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.
--max-file-frames num
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.
--file-flush num
Flush the file to disk after every num frames captured.
-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 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 /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 people, 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/
SEE ALSO
mjpegtools(1), lavplay(1)