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 [AT] lists.net
For more info, see our website at
http://mjpeg.sourceforge.net/
SEE ALSO
mjpegtools(1), lavplay(1)