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).

           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]

   -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  dont
           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.

           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.

           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
           cron/scheduled recordings.

   -a/--audio-bitsize num
           Audio size in bits, either 0, 8 or 16  (default).  0  means  no

   -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).

           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.

           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).

           Use the read() system call rather than the mmap()  system  call
           for   audio  recording.  This  may  fix  many  audio  recording

   -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.


   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-
   difference (out-of-sync'ness).


   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
           --geometry=352x288 /path/to/file.avi


   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


   mjpegtools(1), lavplay(1)


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