Frame-Rate Conversion

• US 20110019083A1
• Filed: 07/16/2010
• Published: 01/27/2011
• Est. Priority Date: 07/27/2009
• Status: Active Grant

• Current Assignee: MaxLinear Communications, LLC (f/k/a Entropic Communications, LLC) (Maxlinear Incorporated)
• Original Assignee: Entropic Communications Incorporated (Maxlinear Incorporated)
• Inventors: Cordes, Claus Nico, Znamenskiy, Dmitry Nikolaevich
• Granted Patent: US 8,842,742 B2
• Time in Patent Office: Days
• US Class Current: 348/441
• CPC Class Codes: H04N 7/0112 one of the standards corresponding to a cinematograph film standard
• CPC Class Codes: H04N 7/0127 by changing the field or frame frequency of the incoming video signal, e.g. frame rate converter

Abstract

A method of generating presentation time stamps, PTSs, for motion-compensated frame-rate conversion of a sequence of frames. In one aspect, the method comprises for each new frame: determining an average difference between the capture time-stamps of recent consecutive new frames; and generating the PTS based on the capture time-stamp of a previous new frame and the average difference. In another aspect, the method comprises detecting a first cadence and a second different cadence in the sequence of frames; and generating a PTS for each new frame defined by the first cadence, such that in each case the difference between the PTSs of consecutive new frames is intermediate between the true interval between those frames according to the first cadence and the true interval between them according to the second cadence.

Claims

1. A method of generating presentation time stamps, for motion-compensated frame-rate conversion of a sequence of frames at least some of which are new frames, each frame of the sequence having an associated capture time-stamp, the method comprising for each new frame:

determining an average difference between the capture time-stamps of recent consecutive new frames; and

generating the presentation time stamps based on the capture time-stamp of a previous new frame and the average difference.

2. The method of claim 1, comprising generating the presentation time stamps based on a presentation time stamp of the most recent previous new frame or the capture time-stamp of the most recent previous new frame;

the capture time stamp of the current new frame; and

the average difference.

3. The method of claim 2, further comprising ensuring that:

the presentation time stamp that is generated for each frame is greater than or equal to the capture time-stamp of that frame;

or

the presentation time stamp that is generated does not to exceed a predetermined maximum latency.

4. The method of claim 3 wherein, for irregular film cadences and cadence transitions, the generated PTS for at least every second new frame is equal to the capture time stamp of that frame.

5. The method of claim 4, comprising:

detecting a first cadence, corresponding to a first pattern of occurrence

of new frames and repeated frames, in a first spatial area of the sequence; and

detecting a second cadence, corresponding to a second pattern of occurrence of new frames, in a second, different spatial area of the sequence,

wherein the presentation time stamps are generated for each of the new frames of the first pattern according to the first detected cadence,

the method further comprising modifying said presentation time stamps by biasing them toward the capture time stamp of the nearest new frame of the second pattern according to the second detected cadence.

6. The method of claim 4 comprising:

detecting a first cadence, corresponding to a first pattern of occurrence

of new frames in a first spatial area of the sequence; and

detecting a second cadence, corresponding to a second, different pattern of occurrence of new frames in a second, different spatial area of the sequence,

wherein a PTS is generated for each new frame defined by the first pattern, such that in each case the difference between the PTSs of consecutive new frames is intermediate between the true interval between those frames according to the first cadence and the true interval between them according to the second cadence.

7. A method of generating presentation time stamps, for motion-compensated frame-rate conversion of a sequence of frames at least some of which are new frames, the method comprising for each frame:

detecting a first cadence, corresponding to a first pattern of occurrence of new frames in a first spatial area of the sequence;

detecting a second cadence, corresponding to a second, different pattern of occurrence of new frames in a second, different spatial area of the sequence; and

generating a presentation time stamp for each new frame defined by the first pattern, such that in each case the difference between the presentation time stamps of consecutive new frames is intermediate between the true interval between those frames according to the first cadence and the true interval between them according to the second cadence.

8. A method claim 7 further comprising:

selecting a reference frame for each presentation time stamp;

obtaining motion vectors for each reference frame, describing transformations between that reference frame and the next, based on the generated presentation time stamps; and

synthesizing frames for presentation between consecutive reference frames, by interpolation using the motion vectors.

9. The method of claim 8, wherein the reference frame selected for each generated presentation time stamps is the frame having the capture time-stamp that is most nearly equal to the presentation time stamps.

10. A computer program product comprising a computer usable medium having a computer readable program code adapted to be executed to implement a method for generating presentation time stamps for motion-compensated frame-rate conversion of a sequence of frames at least some of which are new frames, each frame of the sequence having an associated capture time-stamp, the method comprising for each new frame:

determining an average difference between the capture time-stamps of recent consecutive new frames; and

generating the presentation time stamps based on the capture time-stamp of a previous new frame and the average difference.

11. (canceled)

12. A time stamp translator apparatus, for generating presentation time stamps, for motion-compensated frame-rate conversion of a sequence of frames at least some of which are new frames, each frame of the sequence having an associated capture time-stamp, the translator adapted to, for each new frame:

determine an average difference between the capture time-stamps of recent consecutive new frames; and

generate the presentation time stamps based on the capture time-stamp of a previous new frame and the average difference.

13. The translator apparatus of claim 12, wherein the apparatus:

receives an indication of a first cadence, corresponding to a first pattern of occurrence of new frames detected in a first spatial area of the sequence;

receives an indication of a second cadence, corresponding to a second, different pattern of occurrence of new frames detected in a second, different spatial area of the sequence; and

generates a presentation time stamp for each new frame defined by the first pattern, such that in each case the difference between the presentation time stamps of consecutive new frames is intermediate between the true interval between those frames according to the first cadence and the true interval between them according to the second cadence.

14. A time stamp translator apparatus, for generating presentation time stamps, for motion-compensated frame-rate conversion of a sequence of frames at least some of which are new frames, the translator adapted to, for each frame:

detect a first cadence, corresponding to a first pattern of occurrence of new frames in a first spatial area of the sequence;

detect a second cadence, corresponding to a second, different pattern of occurrence of new frames in a second, different spatial area of the sequence; and

generate a presentation time stamp for each new frame defined by the first pattern, such that in each case the difference between the presentation time stamps of consecutive new frames is intermediate between the true interval between those frames according to the first cadence and the true interval between them according to the second cadence.

15. A frame rate conversion apparatus, for frame rate conversion of a sequence of frames at least some of which are new frames, each frame of the sequence having an associated capture time-stamp, the apparatus comprising:

a translator apparatus that generates presentation time stamps for motion-compensated frame-rate conversion of a sequence of frames at least some of which are new frames, each frame of the sequence having an associated capture time-stamp, by determining an average difference between the capture time-stamps of recent consecutive new frames, and generating the presentation time stamps based on the capture time-stamp of a previous new frame and the average difference; and

a motion-compensated frame rate conversion unit that;

receives presentation time stamps generated by the translator;

selects a reference frame for each presentation time stamp;

obtains motion vectors for each reference frame, describing transformations between that reference frame and the next, based on the generated presentation time stamps; and

synthesizes frames for presentation between consecutive reference frames, by interpolation using the motion vectors.