Partial spectral loss concealment in transform codecs

• US 20050163234A1
• Filed: 12/15/2004
• Published: 07/28/2005
• Est. Priority Date: 12/19/2003
• Status: Active Grant

• Current Assignee: Anisse Taleb
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Taleb, Anisse
• Granted Patent: US 7,356,748 B2
• Time in Patent Office: Days
• US Class Current: 375/259
• CPC Class Codes: G06F 21/56 Computer malware detection or handling, e.g. anti-virus arrangements
• CPC Class Codes: G06F 2221/03 Indexing scheme relating to G06F21/50, monitoring users, programs or devices to maintain the integrity of platforms
• CPC Class Codes: H04B 1/667 using a division in frequency subbands for TV signals H04N19/63
• CPC Class Codes: H04L 51/212 using filtering or selective blocking
• CPC Class Codes: H04L 63/1441 Countermeasures against malicious traffic countermeasures against attacks on cryptographic mechanisms H04L9/002
• CPC Class Codes: H04L 63/1483 service impersonation, e.g. phishing, pharming or web spoofing detection of rogue wireless access points H04W12/12
• CPC Class Codes: H04L 63/20 for managing network security; network security policies in general filtering policies H04L63/0227
• CPC Class Codes: H04N 19/48 using compressed domain processing techniques other than decoding, e.g. modification of transform coefficients, variable length coding [VLC] data or run-length data motion estimation in a transform domain H04N19/547; processing of decoded motion vectors H04N19/513
• CPC Class Codes: H04N 19/895 in combination with error concealment

Abstract

The invention concerns a frequency-domain error concealment technique for information that is represented, on a frame-by-frame basis, by coding coefficients. The basic idea is to conceal an erroneous coding coefficient by exploiting coding coefficient correlation in both time and frequency. The technique is applicable to any information, such as audio, video and image data, that is compressed into coding coefficients and transmitted under adverse channel conditions. The error concealment technique proposed by the invention has the clear advantage of exploiting the redundancy of the original information signal in time as well as frequency. For example, this offers the possibility to exploit redundancy between frames (inter-frame) as well as within frames (intra-frame). The use of coding coefficients from the same frame as the erroneous coding coefficient is sometimes referred to as intra-frame coefficient correlation and it is a special case of the more general frequency correlation.

Claims

1. A frequency-domain error concealment method for information represented, on a frame-by-frame basis, by coding coefficients, wherein said method comprises the step of concealing an erroneous coding coefficient in a frame by exploiting coding coefficient correlation in both time and frequency.

2. The frequency-domain error concealment method according to claim 1, wherein said erroneous coding coefficient is at least one of a partially erroneous coding coefficient and a totally lost coding coefficient.

3. The frequency-domain error concealment method according to claim 1, wherein said coding coefficients are quantized coding coefficients.

4. The frequency-domain error concealment method according to claim 1, wherein said step of concealing an erroneous coding coefficient comprises the steps of:

estimating a new coding coefficient based on at least one other coding coefficient within the same frame as the erroneous coding coefficient and at least one coding coefficient of at least one other frame;

replacing said erroneous coding coefficient by said new coding coefficient.

5. The frequency-domain error concealment method according to claim 4, wherein said information is represented by coding coefficients of a number of frequency bins, and said erroneous coding coefficient is detected for a certain frequency bin in a frame, and a new coding coefficient of said frequency bin is estimated at least partly based on at least one coding coefficient of at least one other frequency bin in said frame.

6. The frequency-domain error concealment method according to claim 5, wherein said new coding coefficient of said frequency bin is estimated also based on at least one coding coefficient of the same frequency bin in at least one other frame.

7. The frequency-domain error concealment method according to claim 6, wherein said new coding coefficient of said frequency bin is estimated also based on at least one coding coefficient of at least one other frequency bin in at least one other frame.

8. The frequency-domain error concealment method according to claim 1, wherein said step of concealing an erroneous coding coefficient comprises the steps of estimating a new coding coefficient and replacing said erroneous coding coefficient by said new coding coefficient, wherein said step of estimating a new coding coefficient comprises the step of predicting a spectral phase component based on approximate group delay matching between frames, using a predetermined approximation criterion.

9. The frequency-domain error concealment method according to claim 8, wherein said step of predicting a spectral phase component comprises the steps of;

estimating group delay from at least one other frame; and

calculating the spectral phase by at least approximately matching the group delay associated with the new spectral component to the estimated group delay.

10. The frequency-domain error concealment method according to claim 1, wherein said step of concealing an erroneous coding coefficient comprises the steps of estimating a new coding coefficient and replacing said erroneous coding coefficient by said new coding coefficient, wherein said step of estimating a new coding coefficient comprises the step of predicting a spectral amplitude component based on spectral energy matching between frames.

11. The frequency-domain error concealment method according to claim 10, wherein said step of predicting a spectral amplitude component comprises the steps of:

calculating a weighting factor by matching the energy of spectral coefficients of the same frame as the erroneous coding coefficient with the energy of corresponding spectral coefficients of at least one other frame; and

calculating the spectral amplitude based on the spectral amplitude of the same frequency bin of said at least one other frame and said weighting factor.

12. The frequency-domain error concealment method according to claim 1, wherein said coding coefficients are complex spectral transform coefficients.

13. The frequency-domain error concealment method according to claim 12, wherein a new complex spectral coding coefficient of a certain frequency bin is estimated by predicting spectral amplitude and phase separately and subsequently combining the predicted spectral amplitude and phase into a new complex spectral coding coefficient.

14. The frequency-domain error concealment method according to claim 13, wherein the spectral amplitude is predicted based on the spectral amplitude of the same frequency bin of at least one other frame and a weighting factor, said weighting factor being calculated by matching the energy of spectral coefficients of said frame with the energy of corresponding spectral coefficients of said at least one other frame.

15. The frequency-domain error concealment method according to claim 13, wherein the spectral phase is predicted by estimating group delay from at least two spectral phase components of at least one other frame, and calculating the spectral phase by at least approximately matching the group delay associated with the new spectral component to the estimated group delay.

16. The frequency-domain error concealment method according to claim 1, wherein said information includes at least one of audio, video, and image data.

17. A frequency-domain error concealment arrangement for information represented, on a frame-by-frame basis, by coding coefficients, wherein said arrangement comprises means for concealing an erroneous coding coefficient in a frame based on coding coefficient correlation in both time and frequency.

18. The frequency-domain error concealment arrangement according to claim 17, wherein said erroneous coding coefficient is at least one of a partially erroneous coding coefficient and a totally lost coding coefficient.

19. The frequency-domain error concealment arrangement according to claim 17, wherein said means for concealing an erroneous coding coefficient comprises:

means for estimating a new coding coefficient based on at least one other coding coefficient within the same frame as the erroneous coding coefficient and at least one coding coefficient of at least one other frame; and

means for replacing said erroneous coding coefficient by said new coding coefficient.

20. The frequency-domain error concealment arrangement according to claim 19, said information is represented by coding coefficients of a number of frequency bins, and said erroneous coding coefficient is detected for a certain frequency bin in said frame, and said estimating means is operable for estimating a new coding coefficient of said frequency bin at least partly based on at least one coding coefficient of at least one other frequency bin in said frame.

21. The frequency-domain error concealment arrangement according to claim 20, wherein said estimating means is operable for estimating said new coding coefficient of said frequency bin also based on at least one coding coefficient of the same frequency bin in at least one other frame.

22. The frequency-domain error concealment arrangement according to claim 21, wherein said estimating means is operable for estimating said new coding coefficient of said frequency bin also based on at least one coding coefficient of at least one other frequency bin in at least one other frame.

23. The frequency-domain error concealment arrangement according to claim 17, wherein said means for concealing an erroneous coding coefficient comprises means for estimating a new coding coefficient and means for replacing said erroneous coding coefficient by said new coding coefficient, wherein said means for estimating a new coding coefficient comprises means for predicting a spectral phase component based on approximate group delay matching between frames, using a predetermined approximation criterion.

24. The frequency-domain error concealment arrangement according to claim 23, wherein said means for predicting a spectral phase component comprises:

means for estimating group delay from at least one other frame; and

means for calculating the spectral phase by at least approximately matching the group delay associated with the new spectral component to the estimated group delay.

25. The frequency-domain error concealment arrangement according to claim 17, wherein said means for concealing an erroneous coding coefficient comprises means for estimating a new coding coefficient and means replacing said erroneous coding coefficient by said new coding coefficient, wherein said means for estimating a new coding coefficient comprises means for predicting a spectral amplitude component based on spectral energy matching between frames.

26. The frequency-domain error concealment arrangement according to claim 25, wherein said means for predicting a spectral amplitude component comprises:

means for calculating a weighting factor by matching the energy of spectral coefficients of the same frame as the erroneous coding coefficient with the energy of corresponding spectral coefficients of at least one other frame; and

means for calculating the spectral amplitude based on the spectral amplitude of the same frequency bin of said at least one other frame and said weighting factor.

27. The frequency-domain error concealment arrangement according to claim 17, wherein said coding coefficients are complex spectral transform coefficients.

28. The frequency-domain error concealment arrangement according to claim 27, wherein said estimating means is operable for estimating a new complex spectral coding coefficient of a given frequency bin by predicting spectral amplitude and phase separately and subsequently combining the predicted spectral amplitude and phase into a new complex spectral coding coefficient.

29. The frequency-domain error concealment arrangement according to claim 28, wherein said estimating means is operable for predicting the spectral amplitude based on the spectral amplitude of the same frequency bin of at least one other frame and a weighting factor, wherein said estimating means is operable for calculating said weighting factor by matching the energy of spectral coefficients of said frame with the energy of corresponding spectral coefficients of said at least one other frame.

30. The frequency-domain error concealment arrangement according to claim 28, wherein said estimating means is operable for predicting the spectral phase by estimating group delay from at least two spectral phase components of at least one other frame and calculating the spectral phase by at least approximately matching the group delay associated with the new component to the estimated group delay.

31. The frequency-domain error concealment arrangement according to claim 17, wherein said information includes at least one of audio, video, and image data.

32. A decoder having a frequency-domain error concealment arrangement for information represented, on a frame-by-frame basis, by coding coefficients, wherein said frequency-domain error concealment arrangement comprises means for concealing an erroneous coding coefficient in a frame based on coding coefficient correlation in both time and frequency.

33. A receiver having a frequency-domain error concealment arrangement for information represented, on a frame-by-frame basis, by coding coefficients, wherein said frequency-domain error concealment arrangement comprises means for concealing an erroneous coding coefficient in a frame based on coding coefficient correlation in both time and frequency.