Efficient repeat padding for hybrid video sequence with arbitrary video resolution

• US 20060072669A1
• Filed: 10/06/2004
• Published: 04/06/2006
• Est. Priority Date: 10/06/2004
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Lin, Chih-Lung, Srinivasan, Sridhar, Hsu, Pohsiang, Holcomb, Thomas W.
• Granted Patent: US 7,822,123 B2
• Time in Patent Office: Days
• US Class Current: 375/240.240
• CPC Class Codes: H04N 19/102 characterised by the element, parameter or selection affected or controlled by the adaptive coding
• CPC Class Codes: H04N 19/119 Adaptive subdivision aspects, e.g. subdivision of a picture into rectangular or non-rectangular coding blocks
• CPC Class Codes: H04N 19/16 for a given display mode, e.g. for interlaced or progressive display mode
• CPC Class Codes: H04N 19/172 the region being a picture, frame or field
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/46 Embedding additional information in the video signal during the compression process H04N19/517, H04N19/68, H04N19/70 take precedence
• CPC Class Codes: H04N 19/563 Motion estimation with padding, i.e. with filling of non-object values in an arbitrarily shaped picture block or region for estimation purposes
• CPC Class Codes: H04N 19/59 involving spatial sub-sampling or interpolation, e.g. alteration of picture size or resolution
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/70 characterised by syntax aspects related to video coding, e.g. related to compression standards

Abstract

A video codec provides efficient repeat padding of hybrid video sequences having arbitrary video resolution. The video codec repeat pads to expand the active content of pictures in the video sequence out to meet an adaptive vertical macroblock alignment restriction that varies by picture type. For progressive type pictures, the video codec repeats the last row or horizontal boundary edge of the active content. For interlaced type pictures, the video coded repeats the last two rows (last row of each interlaced field) of the active content. This repeat padding differing by picture type provides a better prediction (lower prediction error residual) for macroblocks in following predicted frames whose motion vector points into the padded region.

Claims

1. A method of repeat padding for hybrid video sequences in a video codec, comprising:

determining a picture type of frames in a hybrid video sequence;

for frames having a first picture type, expanding from an active content frame size of the respective picture to a padded frame size meeting a macroblock alignment restriction appropriate to the first picture type using a first form of repeat padding; and

for frames having a second picture type, expanding from an active content frame size of the respective picture to a padded frame size meeting a macroblock alignment restriction appropriate to the second picture type using a second form of repeat padding.

2. The method of claim 1, wherein the first picture type is a progressive mode frame and expanding using the first form of repeat padding comprises:

for each row in a padded region after the active content, repeating the last row of the active content.

3. The method of claim 2, wherein the second picture type is an interlaced mode frame and expanding using the second form of repeat padding comprises:

for rows in a padded region after the active content, repeating the last two rows of the active content.

4. The method of claim 1, wherein the second picture type is an interlaced mode frame and expanding using the second form of repeat padding comprises:

for rows in a padded region after the active content, repeating the last two rows of the active content.

5. The method of claim 1, wherein the second picture type is an interlaced mode frame and expanding using the second form of repeat padding comprises:

for rows in a padded region after the active content, repeating the last row of each interlaced field of the active content.

6. The method of claim 1, wherein the first picture type is a progressive mode frame and expanding using the first form of repeat padding comprises:

for each row after the active content up to the macroblock alignment restriction appropriate to progressive mode frames, repeating the last row of the active content.

7. The method of claim 6, wherein the macroblock alignment restriction appropriate to progressive mode frames is a multiple of the macroblock height.

8. The method of claim 7, wherein the macroblock height is 16 pixels.

9. The method of claim 6, wherein the second picture type is an interlaced mode frame and expanding using the second form of repeat padding comprises:

for rows after the active content up to the macroblock alignment restriction appropriate to interlaced mode frames, repeating the last two rows of the active content.

10. The method of claim 9, wherein the macroblock alignment restriction appropriate to interlaced mode frames is a multiple of twice the macroblock height.

11. The method of claim 10, wherein the macroblock height is 16 pixels.

12. At least one computer-readable program carrying medium carrying a software program thereon executable on a processor to perform a method of padding for hybrid video sequences in a video codec, comprising:

determining a picture type of frames in a hybrid video sequence; and

varying a selection of the padding content with which frames of the hybrid video sequence are padded based on the picture type of the respective frame; and

repeatedly adding the padding content selection after the active content in the respective frame to expand the frame to a padded frame size.

13. The at least one computer-readable program carrying medium of claim 12, wherein the varying the padding content selection further comprises:

for progressive frames of the hybrid video sequence, selecting a last row of active content in the respective picture as the padding content selection; and

for interlaced frames of the hybrid video sequence, selecting a last row of each field of the active content in the respective picture as the padding content selection.

14. The at least one computer-readable program carrying medium of claim 12, wherein the method further comprises adaptively varying the padded frame size based on frame type.

15. The at least one computer-readable program carrying medium of claim 12, wherein adaptively varying the padded frame size comprises:

for progressive frames of the hybrid video sequence, setting the padded frame size of the respective frame to be a next multiple of the macroblock height; and

for interlaced frames of the hybrid video sequence, setting the padded frame size of the respective frame to be a next multiple of twice the macroblock height.

16. The at least one computer-readable program carrying medium of claim 15, wherein the macroblock height is 16 pixels.

17. The at least one computer-readable program carrying medium of claim 15, wherein the varying the padding content selection further comprises:

for progressive frames of the hybrid video sequence, selecting a last row of active content in the respective picture as the padding content selection; and

for interlaced frames of the hybrid video sequence, selecting a last row of each field of the active content in the respective picture as the padding content selection.

18. A video encoder, comprising:

means for determining a picture type of a frame in a hybrid video sequence;

means for determining an active picture size of the frame;

means for determining a padded picture size of the frame based on the picture type;

means for selecting a portion of the active picture content to be repeated after the active picture content to expand from the active picture size to the padded picture size, where the portion selected varies based on the picture type; and

means for repeating the selected portion to expand from the active picture size to the padded picture size.

19. A video encoder of claim 18, wherein the means for selecting comprises:

in the case of a progressive-type picture, selecting the last row of the active content as the portion; and

in the case of an interlaced-type picture, selecting the last two rows of the active content as the portion.

20. A video encoder of claim 18, wherein the means for determining the padded picture size comprises:

in the case of a progressive-type picture, determining a padded picture height of the frame to be a next larger multiple of a macroblock height; and

in the case of an interlaced-type picture, determining the padded picture height of the frame to be a next larger multiple of twice the macroblock height.