Patent ID: 8437619

Claim:
A method of modifying a digital data stream composed of a sequence of frames, where each frame represents an image and includes a data field specifying a presentation time stamp value for the frame, comprising: a. initializing a first variable with a frame interval value based on a nominal frame rate; b1. receiving a first frame and reading the presentation time stamp value of the first frame; b2. assigning, to a second variable, the presentation time stamp value of the first frame; b3. assigning, to a third variable for representing the first frame's clock time based on presentation time stamp, the value of the second variable; b4. assigning, to a fourth variable for representing a frame's clock time based on presentation time stamp, the value of the second variable; b5. assigning, to a fifth variable for representing a stream time stamp of interest, a value of zero; c1. receiving a next frame and reading the presentation time stamp value of said next frame; c2. assigning, to the second variable, the presentation time stamp value of said next frame; c3. assigning, to a difference variable, the value of the second variable minus the fourth variable; c4. assigning, to the fourth variable, the value of the second variable; c5. assigning, to the fifth variable, a sum of the values of the fifth variable and the first variable; and d. testing whether there is a discontinuity in presentation time stamp value between said next frame and the previous frame and, if so: assigning, to a sixth variable for representing the value of the stream time stamp of interest at a point of discontinuity in presentation time stamp, the value of the fifth variable; assigning, to the third variable, the value of the second variable; and storing said next frame in a database using the value of the fifth variable as an index.