Time-domain inter-channel prediction

Patent metadata

Field	Value
Publication number	US-10475457-B2
Application number	US-201816003704-A
Country	US
Kind code	B2
Filing date	Jun 8, 2018
Priority date	Jul 3, 2017
Publication date	Nov 12, 2019
Grant date	Nov 12, 2019

Abstract

A method includes decoding a low-band portion of an encoded mid channel to generate a decoded low-band mid channel. The method also includes filtering the decoded low-band mid channel according to one or more filter coefficients to generate a low-band filtered mid channel. The method also includes generating an inter-channel predicted signal based on the low-band filtered mid channel and the inter-channel prediction gain. The method further includes generating a low-band left channel and a low-band right channel based on an up-mix factor, the decoded low-band mid channel, and the inter-channel predicted signal.

First claim

What is claimed is:

1. A device comprising:
a receiver configured to receive a bitstream that includes an encoded mid channel and an inter-channel prediction gain;
a low-band mid channel decoder configured to decode a low-band portion of the encoded mid channel to generate a decoded low-band mid channel;
a low-band mid channel filter configured to filter the decoded low-band mid channel according to one or more filter coefficients to generate a low-band filtered mid channel;
an inter-channel predictor configured to generate an inter-channel predicted signal based on the low-band filtered mid channel and the inter-channel prediction gain;
an up-mix processor configured to generate a low-band left channel and a low-band right channel based on an up-mix factor, the decoded low-band mid channel, and the inter-channel predicted signal;
a high-band mid channel decoder configured to decode a high-band portion of the encoded mid channel to generate a decoded high-band mid channel;
an inter-channel prediction mapper configured to generate a predicted high-band side channel based on the inter-channel prediction gain and a filtered version of the decoded high-band mid channel; and
an inter-channel bandwidth extension decoder configured to generate a high-band left channel and a high-band right channel based on the decoded high-band mid channel and the predicted high-band side channel.

2. The device of claim 1 , wherein the bitstream also includes an indication of a side channel prediction error, and wherein the low-band left channel and the low-band right channel are further generated based on the side channel prediction error.

3. The device of claim 1 , wherein the inter-channel prediction gain is estimated using a closed-loop analysis at an encoder such that an encoder-side side channel is substantially equal to a predicted side channel, the predicted side channel based on a product of the inter-channel prediction gain and an encoder-side filtered mid channel.

4. The device of claim 3 , wherein an encoder-side mid channel is filtered according to the one or more filter coefficients to generate the encoder-side filtered mid channel.

5. The device of claim 3 , wherein the side channel prediction error corresponds to a difference between the encoder-side side channel and the predicted side channel.

6. The device of claim 1 , wherein the inter-channel prediction gain is estimated using a closed-loop analysis at an encoder such than a high-frequency portion of an encoder-side side channel is substantially equal to a high-frequency portion of a predicted side channel, the high-frequency portion of the predicted side channel based on a product of the inter-channel prediction gain and a high-frequency portion of an encoder-side mid channel.

7. The device of claim 1 , wherein the low-band filtered mid channel includes an adaptive codebook component of the decoded low-band mid channel or a bandwidth expanded version of the decoded low-band mid channel.

8. The device of claim 1 , further comprising:
a first combination circuit configured to combine the low-band left channel and the high-band left channel to generate a left channel; and
a second combination circuit configured to combine the low-band right channel and the high-band right channel to generate a right channel.

9. The device of claim 8 , further comprising an output device configured to output the left channel and the right channel.

10. The device of claim 1 , wherein the inter-channel bandwidth extension decoder comprises:
a high-band residual generation unit configured to apply a residual prediction gain to the predicted high-band side channel to generate a high-band residual channel; and
a third combination circuit configured to combine the decoded high-band mid channel and the high-band residual channel to generate a high-band reference channel.

11. The device of claim 10 , wherein the inter-channel bandwidth extension decoder further comprises:
a first spectral mapper configured to perform a first spectral mapping operation on the decoded high-band mid channel to generate a spectrally-mapped high-band mid channel; and
a first gain mapper configured to perform a first gain mapping operation on the spectrally-mapped high-band mid channel to generate a first high-band gain-mapped channel.

12. The device of claim 11 , wherein the inter-channel bandwidth extension decoder further comprises:
a second spectral mapper configured to perform a second spectral mapping operation on the high-band residual channel to generate a spectrally-mapped high-band residual channel; and
a second gain mapper configured to perform a second gain mapping operation on the spectrally-mapped high-band residual channel to generate a second high-band gain-mapped channel.

13. The device of claim 12 , wherein the inter-channel bandwidth extension decoder further comprises:
a fourth combination circuit configured to combine the first high-band gain-mapped channel and the second high-band gain-mapped channel to generate a high-band target channel; and
a channel selector configured to:
receive a reference channel indicator; and
based on the reference channel indicator:
designate one of the high-band reference channel or the high-band target channel as the high-band left channel; and
designate the other of the high-band reference channel or the high-band target channel as the high-band right channel.

14. The device of claim 1 , further comprising a high-band mid channel filter configured to filter the decoded high-band mid channel to generate the filtered version of the decoded high-band mid channel.

15. The device of claim 14 , wherein the high-band mid channel filter and the low-band mid channel filter are integrated into a single component.

16. The device of claim 1 , wherein the low-band mid channel decoder, the mid channel decoder, the mid channel filter, the up-mix processor, the high-band mid channel decoder, the inter-channel prediction mapper, and the inter-channel bandwidth extension decoder are integrated into a base station.

17. The device of claim 1 , wherein the low-band mid channel decoder, the mid channel decoder, the mid channel filter, the up-mix processor, the high-band mid channel decoder, the inter-channel prediction mapper, and the inter-channel bandwidth extension decoder are integrated into a mobile device.

18. A method comprising:
receiving a bitstream that includes an encoded mid channel and an inter-channel prediction gain;
decoding a low-band portion of the encoded mid channel to generate a decoded low-band mid channel;
filtering the decoded low-band mid channel according to one or more filter coefficients to generate a low-band filtered mid channel;
generating an inter-channel predicted signal based on the low-band filtered mid channel and the inter-channel prediction gain;
generating a low-band left channel and a low-band right channel based on an up-mix factor, the decoded low-band mid channel, and the inter-channel predicted signal;
decoding a high-band portion of the encoded mid channel to generate a decoded high-band mid channel;
generating a predicted high-band side channel based on the inter-channel prediction gain and a filtered version of the decoded high-band mid channel; and
generating a high-band left channel and a high-band right channel based on the decoded high-band mid channel and the predicted high-band side channel.

19. The method of claim 18 , wherein the inter-channel prediction gain is estimated using a closed-loop analysis at an encoder su

Assignees

• Qualcomm Inc

Inventors

• Atti Venkatraman
• Chebiyyam Venkata Subrahmanyam Chandra Sekhar
• Sinder Daniel Jared

Classifications

• G10L21/038

  using band spreading techniques · CPC title

• G10L19/005

  Correction of errors induced by the transmission channel, if related to the coding algorithm · CPC title

• G10L19/008 Primary

  Multichannel audio signal coding or decoding using interchannel correlation to reduce redundancy, e.g. joint-stereo, intensity-coding or matrixing · CPC title

• G10L19/26

  Pre-filtering or post-filtering · CPC title

• G10L19/0204

  using subband decomposition · CPC title