Method and apparatus for processing compressed video data streams

• US 6,370,199 B1
• Filed: 04/05/1999
• Issued: 04/09/2002
• Est. Priority Date: 04/03/1998
• Status: Expired due to Term

• Current Assignee: MK Systems USA Inc. (JP Morgan Chase & Co)
• Original Assignee: Tandberg Telecom AS (Cisco Systems, Inc.)
• Inventors: Jordan, John Paul, Bock, Alois Martin
• Primary Examiner(s): BRITTON, HOWARD W
• Application Number:
  US09/286,371
• Time in Patent Office: 1,100 Days
• Field of Search: 375/240.28, 348/705, 725/36
• US Class Current: 375/240.28
• CPC Class Codes: G06T 9/004 Predictors, e.g. intraframe, interframe coding
• CPC Class Codes: H04N 21/23424 involving splicing one content stream with another content stream, e.g. for inserting or substituting an advertisement
• CPC Class Codes: H04N 21/44016 involving splicing one content stream with another content stream, e.g. for substituting a video clip

Abstract

The present invention relates to the field of digital broadcasting, and more particularly the insertion of digital video streams into other digital video streams. Compressed digital video streams, such as those compressed using the common MPEG-2 system, use a sequence of frames to compress a video sequence. Part of the encoding method to compress frames involves making predictions based on past or future frames. Where part of a compressed video stream is to be inserted into another existing video stream, problems may arise at the insertion point due to dependencies on past or future frames which occur outside of the insertion point. The effect of this is that the decoding process lacks information on which to make its predictions, and this could cause a decoder to reset or display frames out of order. The present invention overcomes this problem in a way which allows frame accurate insertion to be achieved without compromising quality. The present invention can be used to pre-process a compressed video stream ready for insertion, or can be used to dynamically insert a compressed video stream into an existing compressed video stream.

Claims

1. A method of processing a compressed digital bit-stream including a sequence of temporally referenced frames, at least some of which are coded in dependence on information in preceding or succeeding frames, to allow the bit-stream to be inserted into another such digital bit-stream, the method comprising the steps of:

identifying the presence of one or more frames at a given insertion point which are coded in dependence upon one or more frames beyond the insertion point; and

modifying the sequence so as to remove any such dependency and maintain continuity of the temporal references.

2. The method of claim 1, wherein the step of modifying the sequence includes changing the type of frames in the sequence.

3. The method of claim 1 wherein the step of modifying the sequence includes changing the type of frames to null frames.

4. The method of claim 1, wherein the step of modifying the sequence, further includes selectively modifying the temporal references to ensure that the frames will be displayed in the correct order by a decoder.

9. The method of transmitting a digital bit-stream processed according to the method of claim 1.

5. Apparatus for processing a compressed digital bit-stream including a sequence of temporally referenced frames, at least some of which are coded in dependence on information in preceding or succeeding frames, to allow the bit-stream to be inserted into another such digital bit-stream, the apparatus comprising the steps of:

a detector for identifying the presence of one or more frames at a given insertion point which are coded in dependence upon one or more frames beyond the insertion point; and

a processor for modifying the sequence so as to remove any such dependency and maintain continuity of the temporal referencing.

6. The apparatus of claim 5, wherein the processor is adapted to modifying the sequence by changing the type of frames within the sequence.

7. The apparatus of claim 6, wherein the processor is adapted for modifying the sequence by changing the type of frames to null frames.

8. The apparatus of claim 5, wherein the processor is adapted for selectively modifying the temporal references to ensure that the frames will be displayed in the correct order by a decoder.

10. The apparatus for transmitting a digital bit-stream created by the apparatus of claim 5.

11. A method of processing a compressed digital bit-stream including a sequence of temporally referenced frames, at least some of which are coded in dependence on information in preceding or succeeding frames, to allow the bit-stream to be inserted into another such digital bit-stream, the method comprising the steps of:

identifying the presence of one or more frames at a given insertion point which are coded in dependence upon one or more frames beyond the insertion point; and

modifying the sequence so as to remove any such dependency and maintain continuity of the temporal references.

12. An apparatus for processing a compressed digital bit-stream including a sequence of temporally referenced frames, at least some of which are coded in dependence on information in preceding or succeeding frames, to allow the bit-stream to be inserted into another such digital bit-stream, the apparatus comprising the steps of:

a detector for identifying the presence of one or more frames at a given insertion point which are coded in dependence upon one or more frames beyond the insertion point; and

a processor for modifying the sequence so as to remove any such dependency and maintain continuity of the temporal referencing.