dvbcut patched to add navigation buttons.

dvbcut patched to add navigation buttons.

(derived from svn 11, Sep 24 2006)

The modes are

• Fr : Step by frames.
• I-Fr : Step by I-frames
• Aspect : Step by frames which describe a change in aspect ratio. (see below)
  
• Black : Step by frames which are entirely black (does not work)
  
• Time : Step by approximate time

The current mode is highlighted (I-Fr is the default).

The nav buttons change the current position, depending on the current mode.
The digit shown on each button is not the number of units moved, but is just a marker.
The number of units moved is (intended to be) configurable, depends on the current mode, and is usually non-linear.
e.g. for each mode, my nav buttons are programmed to move the current position by ...

• Fr: 1,5,10,25,100 (frames)
  
• I-Fr: 1,2,5,10,50 (I-frames)
  
• Aspect: 1,2,3,4,5 (changes of aspect)
  
• Black: broken
  
• Time: 1,10,60,180,300 (seconds)
  

In each case the movement to the new position is accompanied by "fast-play",
i.e. all or some I-Frames ares displayed.

• Fr: all I-Frames are shown
• I-Fr: all I-frames are shown
• Aspect: some I-Frames are shown
• Time: movement is "quiet" until some I-Frame is found "close" to the target, then all I-Frames are shown.
  

There was originally intended to be a ValN label (value) for each nav button, to
display the magnitude of the step associated with each - but this was never
implemented.

The context nav button fast-plays a small region around the current position.
It does this:

1. Remember current position as "currentpos"
2. Jump back 10 Iframes. (remember this as "leftpos")
3. Pause 1 second.
4. Fast-play forward until currentpos
5. Pause 1 second.
6. Fast-play forward until find 10-Iframes.
7. Pause 1 second.
8. Jump back to leftpos.
9. Fast-play forward to currentpos.

Footnotes:
Aspect: Navigating by change-of-aspect is particularly useful when processing an "old" tv program in 4:3 format which is interrupted by "new" adverts in widescreen.