Pulse code modulation (PCM) data-marking

Patent metadata

Field	Value
Publication number	US-10522155-B2
Application number	US-201715693900-A
Country	US
Kind code	B2
Filing date	Sep 1, 2017
Priority date	Feb 21, 2017
Publication date	Dec 31, 2019
Grant date	Dec 31, 2019

Abstract

An encoding for data in an audio data stream may be indicated in the data stream using a footer stored in low-order bits of data frames in the audio data stream. When the audio data stream may include either Pulse Code Modulation (PCM) or Direct Stream Digital (DSD) data, PCM data may be marked with a footer to indicate the encoding as PCM. The footer may be a fixed value, an alternating fixed value, a predetermined sequence of values, or a value computed based on the PCM data. Examples of computed values for the footer marker may include an error code, an error correction code (ECC), and a scrambled code.

First claim

What is claimed is:

1. A method, comprising:
receiving an audio data stream;
analyzing a selected set of low-order bits of a plurality of frames from the audio data stream to determine whether a footer is present indicating the audio data stream is a first format;
decoding the received audio data stream according to the first format when the footer is present, wherein the decoding comprises decoding high-order bits of a frame of the plurality of frames that also comprises the footer based on the presence of the footer in the frame; and
decoding the received audio data stream according to a second format when the footer is not present.

2. The method of claim 1 , wherein the first format comprises multi-bit data and the second format comprises single-bit data.

3. The method of claim 1 , wherein the second format comprises direct stream digital (DSD) data and the first format comprises pulse code modulation (PCM) data.

4. The method of claim 1 , wherein the step of analyzing comprises: comparing the selected set of low-order bits to a predetermined footer value.

5. The method of claim 1 , wherein the step of analyzing comprises: comparing the selected set of low-order bits to a predetermined sequence of footer values.

6. The method of claim 5 , wherein the step of analyzing comprises: comparing the selected set of low-order bits to a predetermined sequence of alternating footer values.

7. The method of claim 1 , wherein the step of analyzing comprises: comparing the selected set of low-order bits for one of the plurality of frames to a footer value computed based on a payload of the one of the plurality of frames.

8. The method of claim 7 , wherein the step of comparing comprises comparing the selected set of low-order bits to a computed footer value comprising an error code computed from one or more of the plurality of frames.

9. The method of claim 8 , further comprising correcting one or more of the plurality of frames of the received audio data stream based, at least in part, on the error code of the computed footer value, wherein the error code of the computed footer value comprises an error correction code.

10. The method of claim 8 , wherein the error code of the computed footer value comprises a scrambled error code such that a reproduced audio has low distortion if one of the plurality of frames is reproduced as PCM audio data.

11. An apparatus, comprising:
an audio controller configured to perform steps comprising:
receiving an audio data stream;
analyzing a selected set of low-order bits of a plurality of frames from the audio data stream to determine whether a footer is present indicating the audio data stream is a first format;
decoding the received audio data stream according to the first format when the footer is present, wherein the decoding comprises decoding high-order bits of a frame of the plurality of frames that also comprises the footer based on the presence of the footer in the frame; and
decoding the received audio data stream according to a second format when the footer is not present.

12. The apparatus of claim 11 , wherein the second data comprises single-bit data and the first data comprises multi-bit data.

13. The apparatus of claim 11 , wherein the second data comprises direct stream digital (DSD) data and the first data comprises pulse code modulation (PCM) data.

14. The apparatus of claim 11 , wherein the step of analyzing comprises: comparing the selected set of low-order bits to a predetermined footer value.

15. The apparatus of claim 11 , wherein the step of analyzing comprises: comparing the selected set of low-order bits to a predetermined sequence of footer values.

16. The apparatus of claim 15 , wherein the step of analyzing comprises: comparing the selected set of low-order bits to a predetermined sequence of alternating footer values.

17. The apparatus of claim 11 , wherein the step of analyzing comprises: comparing the selected set of low-order bits for one of the plurality of frames to a footer value computed based on a payload of the one of the plurality of frames.

18. The apparatus of claim 17 , wherein the step of comparing comprises comparing the selected set of low-order bits to a computed footer value comprising an error code computed from one or more of the plurality of frames.

19. The apparatus of claim 18 , wherein the controller is further configured to perform steps comprising correcting one or more of the plurality of frames of the received audio data stream based, at least in part, on the error code of the computed footer value, wherein the error code of the computed footer value comprises an error correction code.

20. The apparatus of claim 18 , wherein the error code of the computed footer value comprises a scrambled error code such that a reproduced audio has low distortion if one of the plurality of frames is reproduced as PCM audio data.

Assignees

• Cirrus Logic Int Semiconductor Ltd
• Cirrus Logic Inc

Inventors

• Kamkar Shafagh
• Duewer Bruce E
• Hester Dylan A

Classifications

• G11B20/10

  Digital recording or reproducing · CPC title

• G10L19/005 Primary

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

• G10L19/22

  Mode decision, i.e. based on audio signal content versus external parameters · CPC title

• H04L5/00 Primary

  Arrangements affording multiple use of the transmission path · CPC title

• G11B20/00007

  Time or data compression or expansion (audio compression based on psychoacoustics G10L19/00; data processing for reproducing audio data at different playback speeds G10L21/04; video compression H04N19/00; data compression per se H03M7/30) · CPC title