The intelligent searchsystem makes it possible within a few seconds to find and to head for any position of a recording of several hours. It requires only two keys, one to move forward and one to move reverse.
The special trick is the jumping distance, which is refixed again by the system after each keystroke.
For this purpose, the system always locates the current seek area at first after each keystroke. If e.g. the key for moving forward has been pressed, the system knows that the searched position must be behind the current position (otherwise the user would have pressed the other key). The reverse case applies when pressing the reverse key. In this case the searched position must be before the current position. This is how the system limits the seek area more and more with each keystroke and accordingly adapts the jumping distance.
At first, the system starts with a small initial jumping distance of e.g. ten minutes or less. If the user presses the same jump key (thus always the same jumping direction) for several times, the statistic probability that the search destination is substantially far more distant is increased by each jump. This is why the jumping distance is increased by each jump. Tests and simulations have proven that a factor of the order of 1.4 is ideal for this. Thus, one jump respectively reaches 1.4 times wider than the previous one.
There are, however, two rules which can reduce the jumping distance:
1. A jump does never exceed the middle of the current seek area.
2. A jump does never exceed a fix predetermined maximum distance which e.g. can be 25 minutes. (The reason is that most of the television programs take 25 minutes or longer. If more than 25 minutes would be skipped at one time, it could be possible to skip the complete film by error without recognizing it.)
In this way it is possible by pressing the key for approx. 13 times to exactly head for any position to the second of a recording with a duration of e.g. four hours. However, there is still a problem: If the wrong key is pressed only one time (wrong jumping direction), the searched position is beyond the defined seek area. This means it would not be possible any more to find and to head for the searched position. In order to avoid this, the limitations of the seek area are removed again (that means reset to the initiate values). If the forward jump key is pressed three times in succession, the upper limitation of the seek area is reset. If, on the other hand, the reverse jump key is pressed three times in succession, the lower limitation of the seek area is reset. This makes errors adjustable at any time by jumping in the other (correct) direction a few times.
On average, this error correction requires 14.5 keystrokes to find the exact second of a searched position in a recording of four hours duration. The slightly higher value (compared with 13 keystrokes) results from the fact that in exceptional circumstances it is possible that a seek area limitation is reset although it has actually been right. Thus, the loss of effectiveness due to this error correction is consequently only just a minimum, so that the number of advantages (namely that errors are easily corrigible at any time) predominates substantially.
These ones are very appropriate as keyboard symbols for the jump keys. On the one hand, the curved arrows symbolize the jumping functions and on the other hand differ from the usual arrows, which are used e.g. for picture search.