Packet loss concealment for sub-band codecs

• US 8,706,479 B2
• Filed: 11/06/2009
• Issued: 04/22/2014
• Est. Priority Date: 11/14/2008
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Zopf, Robert W., Pilati, Laurent
• Primary Examiner(s): Opsasnick, Michael N
• Application Number:
  US12/614,153
• Publication Number:
  US 20100125454A1
• Time in Patent Office: 1,628 Days
• Field of Search: 704/219
• US Class Current: 704/219
• CPC Class Codes: G10L 19/005 Correction of errors induced by the transmission channel, if related to the coding algorithm
• CPC Class Codes: G10L 19/0204 using subband decomposition

Abstract

Packet loss concealment systems and methods are described that may be used in conjunction with a Bluetooth® Low-Complexity Sub-band Coding (LC-SBC) codec or other sub-band codecs, including but not limited to an MPEG-1 Audio Layer 3 (MP3) codec, an Advanced Audio Coding (AAC) codec, and a Dolby AC-3 codec.

Claims

1. A method for performing packet loss concealment (PLC) in a sub-band codec, comprising:

receiving a plurality of sub-band signals generated by decoding an encoded audio signal;

combining the sub-band signals to generate a full-band audio signal; and

responsive to determining that a frame of the encoded audio signal is lost;

applying a PLC algorithm to the full-band audio signal to generate a PLC output signal; and

generating a full-band output audio signal based on the PLC output signal, wherein generating the full-band output audio signal based on the PLC output signal comprises processing the PLC output signal in an analysis filter bank to produce a plurality of re-encoded sub-band signals and combining the re-encoded sub-band signals to generate the full-band output audio signal, wherein at least one of the receiving, combining, applying and generating steps is performed by a processor or an integrated circuit.

2. The method of claim 1, wherein the sub-band codec is one of a Low-Complexity Sub-band Coding (LC-SBC) codec that is implemented in accordance with a Bluetooth protocol, an MPEG-1 Audio Layer 3 (MP3) codec, an Advanced Audio Coding (AAC) codec or a Dolby AC-3 codec.

3. The method of claim 1, wherein applying a PLC algorithm to the full-band audio signal includes applying periodic waveform extrapolation to the full-band audio signal.

4. The method of claim 1, further comprising:

responsive to determining that a frame of the encoded audio signal represents a first good frame after a period of packet loss;

generating the output audio signal by combining a segment of the PLC output signal and a segment of a full-band audio signal generated by decoding the first good frame.

8. The method of claim 1, wherein the re-encoded sub-band signals are un-quantized sub-band signals.

9. The method of claim 1, further comprising:

responsive to determining that the frame of the encoded audio signal is not lost;

generating a full-band output audio signal based on the full-band audio signal.

10. The method of claim 4, wherein combining the segment of the PLC output signal and the segment of the full-band audio signal generated by decoding the first good frame comprises overlap-adding the segment of the PLC output signal and the segment of the full-band audio signal generated by decoding the first good frame.

5. A system, comprising:

a synthesis filter bank configured to combine a plurality of sub-band signals to generate a full-band output audio signal;

a packet loss concealment (PLC) module configured to apply a PLC algorithm to the full-band output audio signal to generate a PLC output signal;

an analysis filter bank configured to decompose the PLC output signal into a plurality of re-encoded sub-band signals;

logic configured to generate a plurality of decoded sub-band signals by decoding an encoded audio signal; and

a plurality of sub-band signal generators, each of which is configured to select between a corresponding decoded sub-band signal and a corresponding re-encoded sub-band signal for provision to the synthesis filter bank.

6. The system of claim 5, wherein each sub-band signal generator is configured to select between a corresponding decoded sub-band signal and a corresponding re-encoded sub-band signal for provision to the synthesis filter bank based on a state of a bad frame indicator.

7. The system of claim 5, wherein the PLC module is configured to apply the PLC algorithm to the full-band output audio signal by applying periodic waveform extrapolation to the full-band output audio signal.

11. The system of claim 5, wherein the plurality of re-encoded sub-band signals are a plurality of un-quantized sub-band signals.

12. The system of claim 5, wherein each of the plurality of sub-band signal generators are configured to select the corresponding decoded sub-band signal for provision to the synthesis filter bank in response to a determination that a good frame of an encoded audio signal from which the plurality of sub-band signals are decoded is received.

13. The system of claim 12, wherein each of the plurality of sub-band signal generators are configured to select the corresponding re-encoded sub-band signal for provision to the synthesis filter bank in response to a determination that a frame of the encoded audio signal is lost.

14. A computer readable storage device having computer program instructions embodied in said computer readable storage medium for enabling a processor to perform packet loss concealment (PLC) in a sub-band codec, the computer program instructions including instructions executable to perform operations comprising:

receiving a plurality of sub-band signals generated by decoding an encoded audio signal;

combining the sub-band signals to generate a full-band audio signal; and

responsive to determining that a frame of the encoded audio signal is lost;

applying a PLC algorithm to the full-band audio signal to generate a PLC output signal; and

generating a full-band output audio signal based on the PLC output signal, wherein generating the full-band output audio signal based on the PLC output signal comprises processing the PLC output signal in an analysis filter bank to produce a plurality of re-encoded sub-band signals and combining the re-encoded sub-band signals to generate the full-band output audio signal.

15. The computer readable storage device of claim 14, wherein the sub-band codec is one of a Low-Complexity Sub-band Coding (LC-SBC) codec that is implemented in accordance with a Bluetooth protocol, an MPEG-1 Audio Layer 3 (MP3) codec, an Advanced Audio Coding (AAC) codec or a Dolby AC-3 codec.

16. The computer readable storage device of claim 14, wherein applying a PLC algorithm to the full-band audio signal includes applying periodic waveform extrapolation to the full-band audio signal.

17. The computer readable storage device of claim 14, wherein the operations further comprise:

responsive to determining that a frame of the encoded audio signal represents a first good frame after a period of packet loss;

generating the output audio signal by combining a segment of the PLC output signal and a segment of a full-band audio signal generated by decoding the first good frame.

18. The computer readable storage device of claim 14, wherein the re-encoded sub-band signals are un-quantized sub-band signals.

19. The computer readable storage device of claim 14, wherein the operations further comprise:

responsive to determining that the frame of the encoded audio signal is not lost;

generating a full-band output audio signal based on the full-band audio signal.

20. The computer readable storage device of claim 17, wherein combining the segment of the PLC output signal and the segment of the full-band audio signal generated by decoding the first good frame comprises overlap-adding the segment of the PLC output signal and the segment of the full-band audio signal generated by decoding the first good frame.