
Playing DVDs / Audio CDs over the network
=========================================

xine can be used to play DVDs and Audio CDs over the network.

ok, but.... why?

there are some reasons people want to do that:

- because you may have a 200 discs DVD changer on your garage and you
  want to watch them on your room.

- because you don't want to have a lousy cdrom driver around when
  listening to your favorite music.

- because the computer that is hooked to the TV doesn't have a dvdrom.

- because you can :)


network block devices
---------------------

yes, network block device (nbd) could be an option for that. however:

- they don't support ioctls which are needed for cd audio playback and
dvd key exchange. (obs: one may write a custom ioctl code for enbd)

- a completely user space solution is more portable.

- the user space solution can handle failures more gratefuly and gives
better control of closing/opening the device.


installation for audio cds
--------------------------

- you must compile the cdda_server.c that comes with xine-lib sources:

  xine-lib$ cd misc
  xine-lib/misc$ make cdda_server
  gcc -W -Wall -g -o cdda_server cdda_server.c -ldl

  Your xine-lib source tree needs to be configured for that, so please
  run ./configure in the toplevel sourcedir on a fresh tree.

- start cdda_server at the machine that has the cdrom drive:

  xine-lib/misc$ ./cdda_server /dev/cdrom 3000

  note: 3000 is the port number to listen.

- start xine on the client machine with:

  $ xine cdda://server_address:3000/1

  that will play the first track of the CD. in order to use the
  GUI button for "CD" you have to change the setting media.audio_cd.device
  to point to the server.


installation for dvds
---------------------

- compile and run cdda_server (see above).

  note: you may also need to install libdvdcss or some equivalent
  library on your server.

- patch libdvdcss on the client.

  note: no CSS code is needed at all, so it would be possible to use a
  kind of "dummy" dvd library that is API compatible with libdvdcss.

  a sample patch is provided for libdvdcss-1.2.6, install it as follow:

  libdvdcss-1.2.6$ patch -p1 < ../xine-lib/misc/libdvdcss-1.2.6-network.patch
  libdvdcss-1.2.6$ ./bootstrap
  libdvdcss-1.2.6$ make
  libdvdcss-1.2.6$ make install

- start xine on the client machine with:

  $ xine dvd://server_address:3000/

  (don't forget the trailing slash)

  
protocol details
----------------

the network protocol is pretty simple. it consists of text-based commands
and replies over a TCP stream.

command format:

  <command> <arg0> <arg1> <arg2> ... \n

reply format:

  <error code> <n> <value0> <value1> ... \n
  followed by n bytes of binary data (like cd or dvd sectors)

cdda commands:

  cdda_open
  <error code> 0

  cdda_read <start_frame> <num_frames>
  <error code> <n>
  <n bytes (frames)>
  
  cdda_tochdr
  <error code> 0 <first_track> <last_track>

  cdda_tocentry
  <error code> 0 <track_mode> <first_frame_min> <first_frame_sec> <first_frame_frame>
  
dvd commands:

  dvd_open
  <error code> 0

  dvd_error
  <error code> <n>
  <n bytes (error string)>

  dvd_read <blocks> <flags>
  <error code> <n>
  <n bytes (blocks)>

  dvd_seek <block> <flags>
  <error code> 0

  dvd_title <block>
  <error code> 0
