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       dvbackup — Converter from arbitrary data to a DV stream


       dvbackup  [--version]   [-n|--ntsc-mode]   [-d|--decode]  [-t|--verify]
       [-b|--set-backup-title=TITLE]  [--set-picture=PPM-FILE]  [-v|--verbose]
       [-p|--prefix=COUNT]   [--test=COUNT]   [-r|--recover]  [--enable-audio]
       [-?|--help]  [--usage]


       This manual page documents briefly the dvbackup tool.

       This manual page was written for the Debian  distribution  because  the
       original program does not have a manual page.

       As you probably know, current digital camcorders can save approximately
       13 GB of data on those tiny DV cartridges at a speed of 3.6  MB/second.
       That’s  fast. Very fast. It’s faster than most DAT streamers which only
       work at 1 MB/sec or less. We can not use all of the  data,  but  10  GB
       should be good enough for everyone.

       That’s nice, but how can we use this to save data on it? And here comes
       the fun part: If you read the  DV  documentation  carefully,  you  will
       notice  that  the  AC  DCT  coefficients  of the video data blocks (8x8
       pixels in size) get a fixed amount of space in the DV data stream,  but
       can  be  terminated earlier with a certain code sequence. So let’s have
       some fun: We terminate the AC coefficients immediately leaving only the
       DC  coefficient  for  a  fancy penguin picture and use the rest for our
       backup data. Future implementations could easily add a  little  picture
       showing the currently written file or something like that.

       Then  there  is  the audio data, which is written uncompressed onto the
       tape. That means: We tell the camcorder at the beginning of each frame,
       that  we won’t use audio at all but fill the space reserved for it with
       data. Easy, but somewhat hacky. In fact, I don’t know, if this works on
       every  camcorder  and not only on mine (a Sony VX700). Your mileage may

       To finally bring the data on  tape,  you  have  to  use  an  additional
       utility,  called  dvconnect,  which  is  (hopefully soon) included into
       libdv. Take a look at the patch manager if it’s  not  in  already.  And
       then it’s time to rock and roll:

       Advantages of dvbackup over other backup technologies

                 relatively  cheap (the cheapest camcorder will be enough, but
                 if you have already one...)

                 the tapes are quite cheap

                 open standard: if your streamer, aah camcorder dies  you  can
                 rescue  your data with any other one (except PAL/NTSC need to
                 fit), you are not bound to a special company

                 it’s  faster  than  many  streamers  and  it  will  be   more
                 comfortable - you can use the search-index function to "jump"
                 to a recording

                 tapes (re)wind faster than many streamers

                 you do not need to rewind the tape to eject it

       Disadvantages of dvbackup

                 you do not get any warranty :-)

       Usage of the Unix client

                 Press record on your camcorder. (Or  use  your  favorite  avc
                 control program for this. For the VX700 this doesn’t work and
                 you have to hack something together, that uses LANC. I  might
                 publish my "solution" for this soon...)

                 Type   "find   .  |cpio  -o  -H  crc  |dvbackup  --prefix=125
                 |dvconnect -s" to stream directly  to  your  camcorder.  This
                 most  likely  does  only  work  on  very  fast  harddisks and
                 filesystems. You might try something like "find . |cpio -o -H
                 crc    |dvbackup   --prefix=125   |dvconnect   -s   -b   500"
                 Alternatively, you can write the data  in  several  parts  on
                 tape. Just go experimenting, and mail me the resulting backup

                 Stop your camcorder and rewind.

                 Now it’s time to verify: Press play on tape ;-)

                 Type "dvconnect |dvbackup -t" and watch for crc  errors.  The
                 data  corruption  bug mentioned for version 0.0.1 seems to be
                 fixed so there is no excuse in not using  this  little  nifty
                 program ;-)

                 If  you  want  to  restore:  Do a simple "dvconnect |dvbackup
                 -d|cpio -imV". CPIO will also  happily  tell  you  about  CRC
                 errors.  So you might want to check using cpio’s archive test
                 mode too. But keep in mind, that cpio’s CRC function  is  not
                 that fast!


       This  manual  page was written by Robert Jordens for
       the Debian system (but may be used by others).  Permission  is  granted
       to  copy, distribute and/or modify this document under the terms of the
       GNU General Public License, Version 2. On Debian systems, the full text
       of   this   license   can  be  found  in  the  file  /usr/share/common-