Method and apparatus for compressing and analyzing video and for creating a reference video

• US 5,627,765 A
• Filed: 07/25/1994
• Issued: 05/06/1997
• Est. Priority Date: 07/25/1994
• Status: Expired due to Fees

• Current Assignee: Avid Technology Incorporated
• Original Assignee: Avid Technology Incorporated
• Inventors: Robotham, John, Moorby, Philip, Mason, Philip, DiLascia, Paul
• Primary Examiner(s): Ramirez, Ellis B.
• Application Number:
  US08/279,939
• Time in Patent Office: 1,016 Days
• Field of Search: 364/514 R, 364/514 A, 364/715.02, 348/409, 348/420, 348/412, 348/400, 348/386, 348/387, 345/202
• US Class Current: 708/203
• CPC Class Codes: G11B 27/034 on discs G11B27/036, G11B27/038 take precedence
• 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: G11B 27/34 Indicating arrangements indicating means incorporated in magazine or cassette G11B23/046 and G11B23/0875; indicating measured values in general G01D
• CPC Class Codes: H04N 19/146 Data rate or code amount at the encoder output
• CPC Class Codes: H04N 19/587 involving temporal sub-sampling or interpolation, e.g. decimation or subsequent interpolation of pictures in a video sequence
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 5/144 Movement detection for video coding H04N19/503; analysis of motion in general G06T7/20
• CPC Class Codes: H04N 5/147 Scene change detection

Abstract

The method and apparatus for generating a reference video sequence of images includes performing a grid analysis of each of the frames of the video sequence, assigning a color value to that frame, calculating the difference in total color value between frames in the video sequence, establishing a threshold value for transitions and dropping those frames whose transitions from frame to frame are below the threshold value. The reference video analysis may be performed on a single user system or over a network system including a number of workstations.

Claims

1. A method for compressing a sequence of a plurality of video frames on a computer system, comprising the steps of:

analyzing each of the frames to determine a value for a selected characteristic of each frame;

assigning a characteristic value to each frame dependent on the analysis of the selected characteristic;

establishing a threshold level related to a characteristic value;

comparing the characteristic value of succeeding frames to preceding frames;

deleting from the sequence those frames whose characteristic value is less than the threshold value;

whereby the plurality of video frames are compressed into a video sequence the number of whose frames is reduced in number and;

displaying the compressed video sequence.

2. The method of claim 1 wherein the step of analyzing each frame includes the step of establishing a grid pattern for each frame, the grid pattern corresponding to a selected number of pixels on each frame, the step of analyzing further including the calculation of the characteristic value at each pixel on the grid.

3. The method of claim 2, wherein the characteristic value is the color value for each pixel.

4. The method of claim 3, wherein an overall characteristic value for each frame is calculated by the further step of summing the individual color values at each pixel.

5. The method of claim 4, wherein the summing step is performed in accordance with the formula:

space="preserve" listing-type="equation">TCC=Σ

Sij Red(Pij)+Green(Pij)+Blue(Pij)

where TCC represents the Total Color Value of the frame;

where P represents a pixel located in frame;

where Pij represents the value of the pixel located at the ith row and the jth vertical column in the grid of pixels;

where Red, Green and Blue represent the color values for the three colors red, green and blue of the pixel in the ith row and jth column.

6. The method of claim 2 wherein the selected characteristic of each frame is the color value of each pixel in the grid.

7. The method of claim 6 further comprising the step of determining an overall color value for each frame is calculated by the further step of summing the individual color values at each pixel.

8. The method of claim 7 wherein the summing step is performed in accordance with the formula:

space="preserve" listing-type="equation">TCC=Sij Red(Pij)+Green(Pij)+Blue(Pij)

where TCC represents the Total Color Value of the frame;

where P represents a pixel located in frame;

where Pij represents the value of the pixel located at the ith row and the jth vertical column in the grid of pixels;

where Red, Green and Blue represent the color values for the three colors red, green and blue of the pixel in the ith row and jth column.

9. The method of claim 8 wherein the step of establishing a threshold level related to the characteristic value comprises the step of determining a value related to TCC.

10. The method of claim 1 further comprising the step of deleting frames of the video sequence whose TCC is less than the value established in the step of establishing a threshold value and retaining those frames of the video sequence which equal or exceed the threshold level TCC.

11. A method of visualizing for a user the informational content of a sequence of video frames in a computer system, the computer system including a display screen for displaying the video frames, comprising the steps of:

establishing a grid pattern for each video frame, the grid pattern corresponding to a selected number of pixels on each frame, the step of analyzing further including the calculation of the characteristic value at each pixel on the grid, wherein the grid is formed of pixels in i rows and j columns;

selecting a slice of each frame in the video sequence which is i rows wide and j columns high, wherein i and j are less than the total number of i rows and j columns of the frame;

arranging each slice of each frame in accordance with the sequence of video frames; and

;

displaying the arranged slices of video frames on the display screen.

12. The method of claim 11, further comprising selecting a slice which is 1 pixels wide and j columns high.

13. The method of claim 11, further comprising the step of selecting a slice which is a center slice of the i rows.

14. The method of claim 11 wherein the display screen includes a display of a timeline representing the time duration of the video sequence, the timeline being displayed in close proximity to the arranged slices of the video frames, the timeline further comprising a marker displayed on the timeline to be selectively moved along the timeline, whereby the marker may be moved along the timeline, enabling the user to associate a particular time in the timeline with a particular video frame represented by a video frame slice.

16. The method of claim 11 further comprising the step of displaying on the display screen with the displayed arranged slices the full sequence of video frames in a compressed reduced format.

15. A method for dividing a sequence of a plurality of video frames on a computer system into scenes, the computer system including a display screen for displaying indicia of a change of scene along a longitudinally-disposed portion of the display screen, comprising the steps of:

analyzing each of the frames to determine a value for a selected characteristic of each frame;

assigning a characteristic value to each frame dependent on the analysis of the selected characteristic;

establishing a threshold level related to a change of scene;

comparing the characteristic value of succeeding frames to preceding frames;

indicating a change of scene when the characteristic value exceeds the threshold level;

displaying the indicia of scene change along the longitudinally-disposed portion of the display screen for each a change of scene;

whereby the longitudinally-disposed portion of the display screen displays a sequence of indicia indicating changes of scene.

17. In a network system having a central file server, a plurality of computer workstations, the file server and the workstations being connected to communicate with the file server for the purpose of retrieving and processing video images stored on the file server and wherein the level of activity varies with the use of the workstations, a method of increasing the throughput of video images from the file server to a selected workstation, comprising the steps of:

analyzing each of the frames to determine a value for a selected characteristic of each frame;

assigning a characteristic value to each frame dependent on the analysis of the selected characteristic;

comparing the characteristic value of succeeding frames to preceding frames;

establishing a threshold level related to a characteristic value and to the level of activity on the network system such that as activity on the network system increases, the threshold level increases and as the activity on the network decreases, the threshold level decreases;

deleting from the sequence those frames who characteristic value is less than the threshold value;

whereby frames are deleted as a proportional function of the activity on the network system before being displayed at a workstation; and

,

displaying the compressed video sequence.