System and method for improved blackfield detection

• US 7,251,413 B2
• Filed: 04/26/2002
• Issued: 07/31/2007
• Est. Priority Date: 04/26/2002
• Status: Active Grant

• Current Assignee: DIRECTV, LLC (AT&T, Inc.)
• Original Assignee: Digital Networks North America, Inc. (DEI Holdings Incorporated)
• Inventors: Dow, Christopher, Chen, Tai-Ming, Briggs, Adam, Liu, Chuang-Chun, Parekh, Jateen, Coley, Chris
• Primary Examiner(s): Than; Thai Q.
• Assistant Examiner(s): Hasan; Syed Y.
• Application Number:
  US10/132,968
• Publication Number:
  US 20030202772A1
• Time in Patent Office: 1,922 Days
• Field of Search: 386/46, 386/80, 386/81, 386/83, 386/52, 386/59, 386/69, 348/700, 348/571, 348/460, 348/558, 348/46, 382/274, 725/52
• US Class Current: 386/248
• CPC Class Codes: G06F 16/785 using colour or luminescence
• CPC Class Codes: G06V 20/40 in video content extracting overlay text G06V20/62; video retrieval G06F16/70; processing of video elementary streams in video servers H04N21/234; processing of video elementary streams in video clients H04N21/44
• CPC Class Codes: G11B 2220/20 Disc-shaped record carriers
• CPC Class Codes: G11B 27/105 of operating discs
• CPC Class Codes: G11B 27/11 by using information not detectable on the record carrier
• CPC Class Codes: G11B 27/28 by using information signals recorded by the same method as the main recording G11B27/22 takes precedence
• CPC Class Codes: H04N 21/458 Scheduling content for creating a personalised stream, e.g. by combining a locally stored advertisement with an incoming stream; Updating operations, e.g. for OS modules ; time-related management operations arrangements for replacing or switching information during the broadcast or during the distribution H04H20/10
• CPC Class Codes: H04N 21/6543 for forcing some client operations, e.g. recording remote booting in general G06F9/4416
• CPC Class Codes: H04N 21/812 involving advertisement data advertising per se G06Q30/02
• CPC Class Codes: H04N 5/783 Adaptations for reproducing at a rate different from the recording rate

Abstract

Systems and methods for providing enhanced navigation of stored digital video content based upon an event index. Includes generation and storage of an event index, as well as navigation based on events in the event index. An example system is embodied in a digital video recorder that detects and stores black field and silent frame events for use in locating commercial groups. The commercial groups may be skipped or otherwise navigated based upon data pointers linking the stored events to corresponding locations in the video data file. Generation of the event index may involve comparing a luminance value for each frame to a luminance threshold value for a video presentation. The luminance threshold value may be based upon a transition point between a first group of luminance values corresponding to video content and a second group of luminance values corresponding to transition events, such as black fields.

Claims

1. A method of determining a video event threshold, comprising the steps of:

determining a plurality of luminance values for a plurality of video frames; and

determining a threshold value between a first group of the plurality of luminance values and a second group of the plurality of luminance values, the first group corresponding substantially to video content in the plurality of video frames and the second group corresponding substantially to transition events in the plurality of video frames, wherein the threshold value is determined by performing the steps of;

aggregating luminance data for the plurality of video frames;

assigning each video frame to a luminance band based upon a luminance score, resulting in a series of luminance bands;

constructing a luminance histogram from the series of luminance bands; and

calculating slope in the luminance histogram to define at least one notch in the luminance histogram, wherein the threshold value is selected from the at least one notch.

2. The method of claim 1, wherein the plurality of video frames comprises a video presentation and the plurality of luminance values corresponds to respective video frames of the video presentation.

3. The method of claim 2, further comprising the step of identifying a video event in the video presentation using the threshold value.

4. The method of claim 1, further comprising the step of

defining a plurality of luminance bands associated with continuous luminance ranges.

5. The method of claim 1, wherein the transition point is a luminance band selected from the plurality of luminance bands.

6. The method of claim 1, further comprising the step of defining a detection window limited to a portion of each of the plurality of video frames.

7. The method of claim 1, further comprising the step of modifying the threshold value based upon an aggressiveness setting.

8. A method of detecting a video event, comprising the steps of:

calculating a luminance value for a selected video frame in a video presentation, the video presentation including a plurality of video frames;

comparing the luminance value to a threshold value, the threshold value being determined by performing the steps of;

aggregating luminance data for the plurality of video frames;

assigning each video frame to a luminance band based upon a luminance score, resulting in a series of luminance bands;

constructing a luminance histogram from the series of luminance bands; and

calculating slope in the luminance histogram to define at least one notch in the luminance histogram, wherein the threshold value is selected from the at least one notch; and

identifying the selected video frame as a video event based upon the comparison between the luminance value and the threshold value.

9. The method of claim 8, wherein the threshold value is calculated by identifying a point between a first group of luminance values and a second group of luminance values, the first group of luminance values corresponding substantially to video content in the video presentation and the second group of luminance values corresponding substantially to transition events in the video presentation.

10. The method of claim 9, wherein the first group of luminance values and the second group of luminance values are associated with a plurality of luminance bands corresponding to continuous luminance ranges.

11. The method of claim 10, wherein the point corresponds to a luminance band falling between a first peak of luminance bands corresponding to the first group and a second peak of luminance bands corresponding to the second group.

12. The method of claim 8, wherein the step of calculating the luminance value includes summing the luminance component of a plurality of pixels in the video frame.

13. The method of claim 8, further comprising the step of defining a detection window within the selected video frame, the detection window including a portion of the selected video frame used for calculating the luminance value.

14. A video playback device, comprising:

a luminance detector that calculates a luminance value for a selected video frame;

a threshold calculator that determines a threshold value between a first group of luminance values and a second group of luminance values, the first group of luminance values corresponding substantially to a video content and the second group of luminance values corresponding substantially to transition events, wherein the threshold value is determined by performing the steps of;

aggregating luminance data for the plurality of video frames;

assigning each video frame to a luminance band based upon its luminance score, resulting in a series of luminance bands;

constructing a luminance histogram from the series of luminance bands; and

calculating slope in the luminance histogram to define at least one notch in the luminance histogram, wherein the threshold value is selected from the at least one notch; and

an event handler that compares the luminance value from the luminance detector to the threshold value from the threshold calculator to identify a video event.

15. The video playback device of claim 14, further comprising a window definition module that defines a detection window within the selected video frame, the detection window including a portion of the selected video frame used for calculating the luminance value.

16. The video playback device of claim 14, wherein the first group of luminance values and the second group of luminance values are calculated from a plurality of other video frames in the same video presentation as the selected video frame.

17. The video playback device of claim 14, wherein the first group of luminance values and the second group of luminance values are associated with a plurality of luminance bands corresponding to continuous luminance ranges.

18. The video playback device of claim 17, wherein the threshold value is calculated based upon a luminance band falling between a first peak of luminance bands corresponding to the first group and a second peak of luminance bands corresponding to the second group.

19. The video playback device of claim 14, further comprising:

an audio characteristic detector that detects a predefined characteristic of an audio component of the selected video frame, the predefined characteristic being used by the event handler to identify the video event.

20. The video playback device of claim 14, further comprising:

an aggressiveness setting module that defines an adjustable tolerance for the event handling module to use in comparing the luminance value from the luminance detector to the threshold value from the threshold calculator to identify the video event.

21. The video playback device of claim 14, further comprising:

an event indexer that stores the video event identified by the event handler in an index file for use during playback of stored video presentations.

22. A computer readable storage medium that stores a set of software instructions, which when executed effectuate determination of a video event threshold, comprising instructions for:

determining a plurality of luminance values for a plurality of video frames; and

identifying a threshold value between a first group of the plurality of luminance values and a second group of the plurality of luminance values, the first group corresponding substantially to video content in the plurality of video frames and the second group corresponding substantially to transition events in the plurality of video frames, wherein the threshold value is determined by performing the steps of;

aggregating luminance data for the plurality of video frames;

assigning each video frame to a luminance band based upon its luminance score, resulting in a series of luminance bands;

constructing a luminance histogram from the series of luminance bands; and

calculating slope in the luminance histogram to define at least one notch in the luminance histogram, wherein the threshold value is selected from the at least one notch.

23. A computer readable storage medium that stores a set of software instructions, which when executed effectuate detection of a video event, the computer readable storage medium comprising instructions for:

calculating a luminance value for a selected video frame in a video presentation, the video presentation including a plurality of video frames;

comparing the luminance value to a threshold value, the threshold value calculated from a plurality of luminance values corresponding to respective video frames of the video presentation, and the threshold value being determined by performing the steps of;

aggregating luminance data for the plurality of video frames;

assigning each video frame to a luminance band based upon its luminance score, resulting in a series of luminance bands;

constructing a luminance histogram from the series of luminance bands; and

calculating slope in the luminance histogram to define at least one notch in the luminance histogram, wherein the threshold value is selected from the at least one notch; and

identifying the selected video frame as a video event based upon the comparison between the luminance value and the threshold value.