Compressed video editor with transition buffer matcher

• US 6,301,428 B1
• Filed: 12/09/1997
• Issued: 10/09/2001
• Est. Priority Date: 12/09/1997
• Status: Expired due to Term

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: LSI Logic Corporation (Broadcom, Inc.)
• Inventors: Linzer, Elliot N.
• Primary Examiner(s): TRAN, THAI Q
• Application Number:
  US08/987,495
• Time in Patent Office: 1,400 Days
• Field of Search: H04/N.576, H04/N.592, H04/N.5917, H04/N.726, 386/4, 386/33, 386/52-64, 386/111-112, 375/240, 375/240.01, 375/240.02, 375/240.03, 375/240.04, 375/240.05, 375/240.06, 375/240.07, 382/251, 382/253
• US Class Current: 386/278
• CPC Class Codes: G06T 9/00 Image coding bandwidth or redundancy reduction for static pictures H04N1/41; coding or decoding of static colour picture signals H04N1/64; methods or arrangements for coding, decoding, compressing or decompressing digital video signals H04N19/00
• CPC Class Codes: G11B 2220/90 Tape-like record carriers
• CPC Class Codes: G11B 27/024 on tapes G11B27/028, G11B27/029 take precedence
• CPC Class Codes: G11B 27/034 on discs G11B27/036, G11B27/038 take precedence
• CPC Class Codes: H04N 21/23406 involving management of server-side video buffer
• 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 21/2365 Multiplexing of several video streams
• CPC Class Codes: H04N 21/23655 Statistical multiplexing, e.g. by controlling the encoder to alter its bitrate to optimize the bandwidth utilization
• CPC Class Codes: H04N 21/2383 Channel coding or modulation of digital bit-stream, e.g. QPSK modulation arrangements for detecting or preventing errors in the information received by adapting the channel coding H04L1/0009; analogue front ends or means for connecting modulators, demodulators or transceivers to a transmission line H04L27/0002
• CPC Class Codes: H04N 21/44004 involving video buffer management, e.g. video decoder buffer or video display buffer
• CPC Class Codes: H04N 21/44016 involving splicing one content stream with another content stream, e.g. for substituting a video clip

Abstract

In accordance with a first embodiment of the invention, a method for editing video is provided. In accordance with the invention, a previously compressed first digital video bit stream is decoded to obtain a decoded digital video signal. In response to statistical values which characterize the previously compressed first digital video bit stream, the decoded digital video signal is re-encoded to form a second digital video bit stream such than an ending fullness of a vbv does not fall below a predetermined threshold. Optionally, an effect may be added to the decoded digital video signal before re-encoding. A second embodiment of the invention is directed to a method for splicing a first compressed digital video bit stream and a second compressed digital video bit stream. The first compressed digital video bit stream has a plurality of entry points. Each of the entry points has an associated threshold buffer fullness, such that if an actual vbv fullness, just before removal of the bits of a first picture following the entry point equals or exceeds the associated threshold fullness, the portion of the first compressed digital bit stream following the entry point may be decoded without causing the vbv to underflow. Using an encoder, the second compressed digital video bit stream is generated. The second compressed digital video bit stream results in an ending fullness of a vbv one picture time after removal of the bits corresponding to a last picture of the second compressed digital video bit stream. This ending fullness equals or exceeds the threshold fullness associated with one of the entry points. The first and second compressed digital video bit streams are then spliced so that the last picture of the second compressed digital bit stream is immediately followed said one of the entry points in the first compressed digital video bit stream. A third embodiment of the invention provides a method and system for determining and recording a minimal ending vbv fullness at each of a plurality of entry points in a compressed variable bit rate video bit stream.

Claims

1. A method for editing video comprising the steps of:

(a) decoding a previously compressed first digital video bit stream to obtain a decoded digital video signal,

(b) in response to statistical values which characterize the previously compressed first digital video bit stream, re-encoding the decoded digital video signal to form a second digital video bit stream such that an ending fullness of a video buffer verifier, one picture time after bits corresponding to a last picture of said decoded video signal have been removed therefrom, does not fall below a predetermined threshold.

2. The method of claim 1 wherein said statistics are obtained during an encoding process which results in said previously compressed digital video bit stream.

3. The method of claim 1 wherein said statistics are obtained directly from said previously compressed digital video bit stream.

4. The method of claim 1 wherein one of said statistical values is associated each of a plurality of segments of said decoded digital video signal, and wherein said re-encoding process comprises the step of allocating a pro rata share of a total number of encoded bits to each of said segments based on the associated statistical value, said total number of encoded bits being chosen to achieve said ending video buffer verifier fullness one picture time after bits corresponding to a last picture of said decoded video signal have been removed therefrom.

5. The method of claim 4 wherein each segment is a macroblock.

6. The method of claim 4 wherein each segment is a row of macroblocks.

7. The method of claim 4 wherein each segment is a picture.

8. The method of claim 4 wherein the statistical value associated with each picture is determined from an average base quantization scale times a number bits used to encode the segment in the previously compressed digital video bit stream.

9. The method of claim 1 further comprising the step of splicing a third digital video bit stream to the second digital video bit stream resulting from re-encoding the decoded digital video signal.

10. The method of claim 9 wherein said ending fullness of said video buffer verifier one picture time after the bits corresponding to the last picture of said decoded video signal have been removed therefrom, is large enough such that said video buffer verifier will not underflow when the bits corresponding to the pictures of said third digital video bit stream are removed therefrom.

11. The method of claim 1 wherein said predetermined threshold is less than the capacity of said video buffer verifier.

12. The method of claim 1 wherein said decoded digital video signal is provided with an effect before said re-encoding step.

13. The method of claim 1 wherein said predetermined number is chosen so that when said second compressed digital video bit stream is spliced with a third compressed digital video bit stream, said third compressed digital video bit stream will not cause a video buffer verifier to underflow.

14. A method for editing video comprising the steps of:

(a) decoding a previously compressed first digital video bit stream to obtain a decoded digital video signal, and

(b) in response to statistical values which characterize the previously compressed first digital video bit stream, re-encoding the decoded digital video signal to form a second compressed digital video bit stream, such that the number bits in said second compressed digital video bit stream does not exceed a predetermined number.

15. An apparatus for editing video comprising:

(a) a decoder for decoding a previously compressed first digital video bit stream to obtain a decoded digital video signal, and

(b) an encoder which operates in response to statistical values which characterize the previously compressed first digital video bit stream for re-encoding the decoded digital video signal to form a second digital video bit stream, such that an ending fullness of a video buffer verifier, one picture time after bits corresponding to a last picture of said decoded video signal have been removed therefrom, does not fall below a predetermined threshold.

16. The apparatus of claim 15 wherein said statistics are obtained during an encoding process which results in said previously compressed digital video bit stream.

17. The apparatus of claim 15 wherein said statistics are obtained directly from said previously compressed video bit stream.

18. An apparatus for editing video comprising:

(a) a decoder for decoding a previously compressed first digital video bit stream to obtain a decoded digital video signal, and

(b) an encoder which operates in response to statistical values which characterize the previously compressed first digital video bit stream for re-encoding the decoded digital video signal to form a second digital video bit stream, such that the number bits in said second digital video bit stream does not exceed a predetermined number.

19. The apparatus of claim 18 wherein said statistics are obtained during an encoding process which results in said previously compressed digital video bit stream.

20. The apparatus of claim 18 wherein said statistics are obtained directly from said previously compressed video bit stream.