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).
- -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]
- 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:
For more info, see our website at
SEE ALSO
mjpegtools(1),
lavplay(1)