README 
   ex3_mpg_main  v1.2.2c              2003.01.26

This plugin can extract frames and audiodata from
MPEG encoded Videofiles.

START:
======
After successful Installation (See INSTALL) the Plugin
can be started from the GIMP Menus:

  Xtns/Split video to Frames/MPEGdvd
  <Image>/Video/Split video to Frames/MPEGdvd


INPUT:
======
ex3_mpg_main is based on the free libmpeg3 (by Adam Williams).

This library can decode
- MPEG1 and 
- MPEG2 (used on DVD's)
  (see libmpeg3 Docs for more details of supported Videos)
  
  Note:
  CSS enctrypted DVD's may require root privilegs
  to read them correctly.


OUTPUT:
=======
The resulting audiodata is stored in uncompressed RIFF WAV PCM Files.

The resulting frames can be stored in any gimp supported
Image format, ready to use them with GIMP Video Menu Funtions
(also known as GAP).
The Image fileformat is selected by extension.
(.xcf .jpg  .ppm  .bmp .... )


Optional you can use one resulting multilayer image where
all the extraced frames are stored as layers.


GUI
===

Video Entry:
  Here you can type the name of an MPEG encode Videofile.
  
  The "..." Button pops up a Filebrowser Dialog to select
  a Videofile.
  
  (DVD Videos usually are named something like vts_01_01.vob )


Position Slider and Spinbutton:
  With this Slider/Spinbutton you can set the current Position
  in the Video.

View Button:
  Opens (or refreshes) a View of the Frame at the Current
  Position in the Video.
  
View Checkbutton:
  If activated, the View is updated
  automatically everytime the Position changes.

Step1:
  Advance position to the next Frame in the Video
  and Update the View.

Step:
  Advance position using Stepsize (from Widget below)
  and Update the View.

Backstep:
  Decrease position to the previos Frame with
  a different position in the Video
  and Update the View.
  (Maybe this does a Backstep to previous I-frame)


Play:
  Automatic Step from frame to frame, using the
  framerate specified in the Spinbutton Playbackspeed
  (in frames/sec)

  Note:
  - This Plugin is NOT a DVD Playbacksoftware !
    (The max Speed on my PII 300Mhz machine
     is 7 frames/sec for MPEG1
     or 2 frames/sec for MPEG2 )

    When you choose a Playbackspeed, that is too fast for
    your Machine, the result can be a still image,
    because the View Update cant follow.    
  - There is no Audioplayback


Pause:
  Stop Playback.


Set Begin Button:
  Set Mark for the begin of selected range
  equal to current Position.

Set End Button:
  Set Mark for the end of selected range
  equal to current Position.

Goto Begin:
  Set Current position to Begin Marker
    
Goto End:
  Set Current position to End Marker



Estimate Button:

  For MPEG2 encoded Videos the Total number can not be
  calculated exactly. (The value returned by libmpeg3 
  is not correct, but a good guess)

  The Estimate Button reads the entire video and
  tries to estimate a more realistic value
  for Total frame number and playing time while reading.

  You may stop this by OK (accepting the etimated number)
  or by CANCEL (continue using the number libmpeg3 told us)
  
  Frame Numbers are initially marked with '?'.
  The Mark changes to '~' for estimated framenumbers.
  Exact framenumbers the Mark have no Mark.
  

Extract Videotrack Spinbutton:
  Enter the Number of the Videotrack to extract.
  - Use track Number 0 if you dont want to extract frames.
  - Some MPEG2 encoded Videos may have more tracks

Extract Audiotrack Spinbutton:
  Enter the Number of the Audiotrack to extract.
  - Use track Number 0 if you dont want to extract Audiodata.
  - Some MPEG2 encoded Videos may have more tracks
    typical used in multialingul DVD's,
     there may be tracks for english, french, german ...
     and each of the tracks can have one  (mono)
     or more (stero, ???) channels.
   
    if the selected track has one channel the output
    will be a Mono PCM-Wavefile with 16 bit samples.
    
    if the selected track has two (or more) channels the output
    will be a Stereo PCM-Wavefile with 16 bit samples.
    (if there are more than 2 channels the extra channels 
     are ignored)
 
