Adaptive vertical macroblock alignment for mixed frame video sequences

• US 20060072668A1
• 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 7,839,933 B2
• Time in Patent Office: Days
• US Class Current: 375/240.240
• 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 19/136 Incoming video signal characteristics or properties
• CPC Class Codes: H04N 19/172 the region being a picture, frame or field
• CPC Class Codes: H04N 7/012 Conversion between an interlaced and a progressive signal for graphics images G09G2310/0229

Abstract

A video codec provides for adaptive vertical macroblock alignment of mixed interlaced and progressive video sequences. With adaptive vertical macroblock alignment, a video codec enforces a macroblock alignment height restriction on per picture basis, rather than requiring that all frames in a sequence adhere to a uniform height restriction. The video codec can then apply less padding to progressive and like type pictures that have smaller macroblock alignment increments, than to interlaced type pictures with larger alignment increments, which can save significant compression overhead.

Claims

1. A method of decoding video with adaptive vertical macroblock alignment, comprising:

reading an indication from a compressed video bit stream whether a video sequence encoded in the bit stream includes interlaced content;

if so, decoding video content of frames in the video sequence as having padding to vertical macroblock alignments that vary adaptively based on type of the frame; and

otherwise, decoding video content of frames in the video sequence as having padding to a uniform vertical macroblock alignment.

2. The method of claim 1, wherein said decoding video in the case the video sequence includes interlaced content comprises:

decoding non-interlaced type frames as having padding to a first size increment of vertical macroblock alignment; and

decoding interlaced type frames as having padding to a second size increment of vertical macroblock alignment.

3. The method of claim 1, wherein said decoding video in the case the video sequence includes interlaced content comprises:

decoding progressive and interlace frame type frames as having padding to a first size increment of vertical macroblock alignment; and

decoding interlaced field type frames as having padding to a second size increment of vertical macroblock alignment.

12. The at least one computer-readable program carrying medium of claim 11, wherein determining the first vertical macroblock alignment restriction has a smaller alignment increment than the second vertical macroblock alignment restriction.

4. A method of decoding a compressed video bit stream with adaptive vertical macroblock alignment, comprising:

determining a vertical macroblock alignment restriction per frame based on frame type;

decoding the compressed picture content of the frame; and

extracting actual picture content for the frame from the compressed picture content excluding padding to the determined vertical macroblock alignment restriction.

5. The method of claim 4, wherein determining the vertical macroblock alignment comprises:

determining that a frame of a non-interlaced type has a first vertical macroblock alignment restriction; and

determining that a frame of an interlaced type has a second vertical macroblock alignment restriction different than the first vertical macroblock alignment restriction.

6. The method of claim 5, wherein determining the first vertical macroblock alignment restriction has a smaller alignment increment than the second vertical macroblock alignment restriction.

7. The method of claim 4, wherein determining the vertical macroblock alignment comprises:

determining that a progressive or interlaced frame type frame has a first vertical macroblock alignment restriction; and

determining that an interlaced field type frame has a second vertical macroblock alignment restriction different than the first vertical macroblock alignment restriction.

8. The method of claim 7, wherein determining the first vertical macroblock alignment restriction has a smaller alignment increment than the second vertical macroblock alignment restriction.

9. At least one computer-readable program carrying medium carrying a software program thereon executable on a processor to perform a method of decoding a compressed video bit stream with adaptive vertical macroblock alignment, comprising:

determining a vertical macroblock alignment restriction per frame based on frame type;

decoding the compressed picture content of the frame; and

extracting actual picture content for the frame from the compressed picture content excluding padding to the determined vertical macroblock alignment restriction.

10. The at least one computer-readable program carrying medium of claim 9, wherein determining the vertical macroblock alignment comprises:

determining that a frame of a non-interlaced type has a first vertical macroblock alignment restriction; and

determining that a frame of an interlaced type has a second vertical macroblock alignment restriction different than the first vertical macroblock alignment restriction.

11. The at least one computer-readable program carrying medium of claim 9, wherein determining the vertical macroblock alignment comprises:

determining that a progressive or interlaced frame type frame has a first vertical macroblock alignment restriction; and

determining that an interlaced field type frame has a second vertical macroblock alignment restriction different than the first vertical macroblock alignment restriction.

13. A video decoder, comprising:

means for determining per compressed video frame which of at least two vertical macroblock alignment restrictions applies to a respective compressed video frame based on a frame type of the respective compressed video frame;

means for determining an amount of padding added to extend picture content of the respective compressed video frame to comply with the determined vertical macroblock alignment restriction of the respective compressed video frame; and

means for decoding the compressed video frame; and

means for removing the padding from the decoded compressed video frame to yield reconstructed picture content of the respective compressed video frame.

14. The video decoder of claim 13, wherein the at least two vertical macroblock alignment restrictions include restriction to a first alignment increment for interlaced type frames and restriction to a second alignment increment for non-interlaced type frames, where the second alignment increment is smaller than the first alignment increment.

15. The video decoder of claim 13, wherein the at least two vertical macroblock alignment restrictions include restriction to a first alignment increment for interlaced field type frames and restriction to a second alignment increment for progressive and interlaced frame type frames, where the second alignment increment is smaller than the first alignment increment.