Method and apparatus for analog and digital audio blend for HD radio receivers

Patent metadata

Field	Value
Publication number	US-9596044-B2
Application number	US-201514622260-A
Country	US
Kind code	B2
Filing date	Feb 13, 2015
Priority date	Feb 13, 2015
Publication date	Mar 14, 2017
Grant date	Mar 14, 2017

Abstract

A method and apparatus are provided for blending analog and digital portions of a composite digital radio broadcast signal by processing compressed audio packets to compute corresponding digital audio quality indicator values, storing the compressed audio packets in an audio blend buffer, processing audio information from each compressed audio packet stored in the audio blend buffer with an audio decoder to generate decompressed digital audio signal samples, and using the digital audio quality indicator values to guide a blending process for combining analog audio signal samples with the digital audio signal samples to produce an audio output by preventing unnecessary blending back and forth between analog and digital if the digital audio quality indicator values indicate that the compressed audio packets are degraded or impaired.

First claim

What is claimed is:

1. A method for processing a composite digital radio broadcast signal to smooth signal blending, comprising:
separating a received composite digital radio broadcast signal into an analog audio portion and a digital audio portion;
demodulating the analog audio portion of the composite digital radio broadcast signal to produce analog audio signal samples;
demodulating the digital audio portion of the composite digital radio broadcast signal to produce digital audio signal samples by:
demodulating the digital audio portion of the composite digital radio broadcast signal to produce a digital audio signal,
decoding the digital audio signal using an upper layer decoding process to compute a plurality of compressed audio packets,
processing each compressed audio packet in the compressed audio domain to compute a corresponding digital audio quality indicator value prior to performing audio decoding on said compressed audio packet,
storing each compressed audio packet in an audio blend buffer for storing a plurality of compressed audio packets, and
performing audio decoding on audio information from each compressed audio packet stored in the audio blend buffer with an audio decoder which is connected to an output of the audio blend buffer to generate decompressed digital audio signal samples; and

digitally combining the analog audio signal samples with the digital audio signal samples to produce an audio output by preventing or delaying blending from analog to digital when indicated by one or more corresponding digital audio quality indicator values.

2. The method of claim 1 , where the composite digital radio broadcast signal comprises an over-the-air in-band on-channel digital radio broadcast signal.

3. The method of claim 1 , where demodulating the digital audio portion of the composite digital radio broadcast signal to produce a digital audio signal comprises performing deinterleaving, code combining, forward error correction (FEC) decoding, and error flagging on the digital audio portion of the composite digital radio broadcast signal to produce a baseband digital signal.

4. The method of claim 3 , where decoding the digital audio signal comprises performing audio transport decoding of the digital baseband signal to compute the plurality of compressed audio packets.

5. The method of claim 1 , where processing each compressed audio packet to compute the corresponding digital audio quality indicator value comprises parsing and checking each compressed audio packet for data corruption.

6. The method of claim 1 , where processing each compressed audio packet to compute the corresponding digital audio quality indicator value comprises performing a consistency check for each header on each compressed audio packet.

7. The method of claim 1 , where each compressed audio packet stored in the audio blend buffer is simultaneously processed to compute the corresponding digital audio quality indicator value.

8. The method of claim 1 , where each compressed audio packet is stored in the audio blend buffer after being processed to compute the corresponding digital audio quality indicator value.

9. The method of claim 8 , further comprising storing the corresponding digital audio quality indicator value in a memory storage device comprising:
a look ahead buffer for storing K look ahead digital audio quality indicator values corresponding to K compressed audio packets stored in an audio packet buffer; and
a current buffer for storing M current digital audio quality indicator values corresponding to the plurality of compressed audio packets stored in the audio blend buffer.

10. The method of claim 9 , further comprising:
calculating a future digital audio quality metric based on the K look ahead quality indicator values, and
calculating a current digital audio quality metric based on the M quality indicator values,
where digitally combining the analog audio signal samples with the digital audio signal samples comprises preventing or delaying blending from analog to digital when a current digital audio quality metric has a first value indicating that the compressed audio packets stored in the audio blend buffer are undistorted and a future digital audio quality metric has a second value indicating that future compressed audio packets are distorted.

11. The method of claim 1 , further comprising:
storing supplemental program service (SPS) audio packets in an audio packet buffer; and
storing main program service (MPS) audio packets in the audio blend buffer,
where demodulating the digital audio portion further comprises switching between SPS audio packets and MPS audio packets for input into the audio decoder.

12. A receiver for processing a composite digital radio broadcast signal comprising at least one recordable storage medium having stored thereon executable instructions and data which, when executed by at least one processing device, cause the at least one processing device to demodulate a digital audio portion of the composite digital radio broadcast signal to produce digital audio signal samples by:
demodulating the digital audio portion of the composite digital radio broadcast signal to produce a digital audio signal,
decoding the digital audio signal using an upper layer decoding process to compute a plurality of compressed audio packets,
processing each compressed audio packet to compute a corresponding digital audio quality indicator value prior to performing audio decoding on said compressed audio packet,
storing each compressed audio packet in an input buffer which is connected to provide compressed audio packets for input to an audio decoder, and
performing audio decoding on audio information from each compressed audio packet stored in the input buffer with the audio decoder which generates decompressed digital audio signal samples.

13. The receiver of claim 12 , further comprising:
a digital demodulator for demodulating the digital audio portion of the composite digital radio broadcast signal to produce the digital audio signal,
an audio transport decoder for decoding the digital audio signal using the upper layer decoding process to compute the plurality compressed audio packets,
an audio estimator for processing each compressed audio packet to compute the corresponding digital audio quality indicator value,
an audio blend buffer in the input buffer for storing each compressed audio packet, and
an audio decoder connected to an output of the audio blend buffer for processing audio information from each compressed audio packet stored in the audio blend buffer to generate decompressed digital audio signal samples.

14. The receiver of claim 12 , where the executable instructions and data cause the at least one processing device to process each compressed audio packet to compute a corresponding digital audio quality indicator value by performing a consistency check for each header on each compressed audio packet stored in the input buffer or parsing each compressed audio packet stored in the input buffer to check for data corruption.

15. The receiver of claim 12 , where the input buffer comprises an audio packet buffer connected to an audio blend buffer, and where the executable instructions and data cause the at least one processing device to store each compressed audio packet in the audio blend buffer while simultaneously processing each compressed audio packet to compute a corresponding digital audio quality indicator value.

16. The receiver of claim 12 , where the input buffer comprises an audio packet buffer connected to an audio blend buffer, and where t

Assignees

• Ibiquity Digital Corp

Inventors

• Nekhamkin Michael
• Domazetovic Andrej
• Yen Raymond
• Thulasingam Sivakumar

Classifications

• H04H20/26 Primary

  Arrangements for switching distribution systems · CPC title

• G10L21/04

  Time compression or expansion · CPC title

• H04H2201/18

  in band on channel [IBOC] · CPC title

• H04H20/88 Primary

  Stereophonic broadcast systems {(multiplex system in general H04J)} · CPC title

• G10L19/0019

  Physics · mapped topic