Data compression and expansion of an audio signal

• US 20040225496A1
• Filed: 06/21/2004
• Published: 11/11/2004
• Est. Priority Date: 10/10/1996
• Status: Active Grant

• Current Assignee: Koninklijke Philips N.V.
• Original Assignee: Koninklijke Philips N.V.
• Inventors: Van Der Vleuten, Renatus J., Oomen, Arnoldus W.J., Bruekers, Alphons A.M.L.
• Granted Patent: US 7,225,136 B2
• Time in Patent Office: Days
• US Class Current: 704/229
• CPC Class Codes: G11B 20/00007 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 Class Codes: G11B 2020/00065 Sigma-delta audio encoding
• CPC Class Codes: H03M 7/30 Compression speech analysis-synthesis for redundancy reduction G10L19/00; for image communication H04N; Expansion; Suppression of unnecessary data, e.g. redundancy reduction

Abstract

A data compression apparatus is disclosed for data compressing an audio signal. The data compression apparatus comprises an input terminal (1) for receiving the audio signal, a 1-bit A/D converter (4) for A/D converting the audio signal so as to obtain a bitstream signal, a lossless coder (10) for carrying out a lossless data compression step on the bitstream signal so as to obtain a data compressed bitstream signal, and an output terminal (14) for supplying the data compressed bitstream signal. Further, a recording apparatus and a transmitter apparatus comprising the data compression apparatus are disclosed. In addition, a data expansion apparatus for data expanding the data compressed bitstream signal supplied by the data compression apparatus is disclosed, as well as a reproducing apparatus and a receiver apparatus comprising the data expansion apparatus.

Claims

1. Data compression apparatus for data compressing an audio signal, the data compression apparatus comprising

input means for receiving the audio signal,

conversion means for carrying out a conversion on the audio signal so as to obtain a 1-bit bitstream signal, the conversion means comprising sigma-delta modulator means,

lossless coding means for carrying out a substantially lossless data compression step on the bitstream signal so as to obtain a data compressed bitstream signal, and

output means for supplying the data compressed bitstream signal.

2. Data compression apparatus as claimed in claim 1, wherein the audio signal is an analog audio signal and the conversion means being in the form of A/D conversion means for carrying out a 1-bit A/D conversion on the analog audio signal so as to obtain said bitstream signal.

3. Data compression apparatus as claimed in claim 1, wherein the lossless coding means comprise a variable length coder.

4. Data compression apparatus as claimed in claim 3, wherein the variable length coder is a Huffman coder.

5. Data compression apparatus as claimed in claim 3, wherein the variable length coder is an arithmetic coder.

7. Transmitter for transmitting an audio signal via a transmission medium, comprising the data compression apparatus as claimed in claim 1, wherein the transmitter further comprises

transmission means for applying the data compressed bitstream signal to the transmission medium.

8. Recording apparatus for recording an audio signal on a record carrier, comprising the data compression apparatus as claimed in claim 1, wherein the recording apparatus further comprises

writing means for writing the data compressed bitstream signal in a track on the record carrier.

9. Recording apparatus as claimed in claim 8, wherein the record carrier is an optical or a magnetic record carrier.

19. Transmitter as claimed in claim 7, wherein the transmitter further comprises error correction encoding means and/or channel encoding means, for error correction encoding and/or channel encoding the data compressed bitstream signal prior to applying the data compressed bitstream signal to the transmission medium.

20. Transmitter as claimed in claim 8, further comprising error correction encoding means and/or channel encoding means, for error correction encoding and/or channel encoding the data compressed bitstream signal prior to writing the data compressed bitstream signal on the record carrier.

6. Data compression method for data compressing an audio signal, the data compression method comprising the steps of

receiving the audio signal,

carrying out a conversion on the audio signal so as to obtain a 1-bit bitstream signal, the conversion step comprising a sigma-delta modulation step,

carrying out a substantially lossless data compression step on the bitstream signal so as to obtain a data compressed bitstream signal, and

supplying the data compressed bitstream signal.

10. Record carrier having a data compressed bitstream signal recorded on it in a track of said record carrier.

11. Data expansion apparatus for data expanding a data compressed audio signal so as to obtain a replica of an original audio signal, the data expansion apparatus comprising

input means for receiving the data compressed audio signal which is in the form of a data compressed bitstream signal,

lossless decoding means for carrying out a substantially lossless data expansion step on the data compressed bitstream signal so as to obtain a bitstream signal,

D/A conversion means for carrying out a D/A conversion on the bitstream signal so as to obtain the replica of the original audio signal,

output means for supplying the replica of the original audio signal.

12. Data expansion apparatus as claimed in claim 11, wherein the D/A conversion means comprise a sigma-delta demodulator.

13. Data expansion apparatus as claimed in claim 11, wherein the lossless decoding means comprise a variable length decoder.

14. Data expansion apparatus as claimed in claim 13, wherein the variable length decoder is a Huffman decoder.

15. Data expansion apparatus as claimed in claim 13, wherein the variable length decoder is an arithmetic decoder.

17. Receiver for receiving an audio signal via a transmission medium, comprising the data expansion apparatus as claimed in claim 11, wherein the receiver further comprises

receiving means for retrieving the data compressed bitstream signal from the transmission medium.

18. Reproducing apparatus for reproducing an audio signal from a record carrier, comprising the data expansion apparatus as claimed claim 11, wherein the reproducing apparatus further comprises

reading means for reading the data compressed bitstream signal from a track on the record carrier.

21. Receiver as claimed in claim 17, wherein the receiver further comprises channel decoding means and/or error correction means, for channel decoding and/or error correcting the signal retrieved from the transmission medium so as to obtain said data compressed bitstream signal.

22. Reproducing apparatus as claimed in claim 18, further comprising channel decoding means and/or error correction means, for channel decoding and/or correcting the signal read from the record carrier so as to obtain said data compressed bitstream signal.

16. Data expansion method for data expanding a data compressed audio signal so as to obtain a replica of an original audio signal, the data expansion method comprising the steps of

receiving the data compressed audio signal which is in the form of a data compressed bitstream signal,

carrying out a substantially lossless data expansion step on the data compressed bitstream signal so as to obtain a bitstream signal,

carrying out a D/A conversion on the bitstream signal so as to obtain the replica of the original audio signal,

supplying the replica of the original audio signal.

23. Data compression apparatus for data compressing an audio signal, the data compression apparatus comprising

input means for receiving the audio signal,

conversion means for carrying out a conversion on the audio signal so as to obtain a 1-bit bitstream signal, the conversion means comprising sigma-delta modulator means,

lossless coding means for carrying out a substantially lossless data compression step on the bitstream signal so as to obtain a data compressed bitstream signal, and

output means for supplying the data compressed bitstream signal,

said lossless compression means comprising

an entropy encoder for entropy encoding the bitstream signal in response to a probability signal so as to obtain said data compressed bitstream signal,

prediction means for carrying out a prediction step on the bitstream signal, and

probability signal determining means for determining said probability signal from said prediction means.

24. Data compression apparatus as claimed in claim 23, wherein the prediction means comprise prediction filter means for carrying out a prediction filter operation on the bitstream signal so as to obtain a multi value output signal, and wherein said probability determining means are adapted to derive said probability signal from said multi value output signal.

25. Data compression method for data compressing an audio signal, the data compression method comprising the steps of

receiving the audio signal,

carrying out a conversion on the audio signal so as to obtain a 1-bit bitstream signal, the conversion step comprising a sigma-delta modulation step,

carrying out a substantially lossless data compression step on the bitstream signal so as to obtain a data compressed bitstream signal, and

supplying the data compressed bitstream signal, said lossless compression step comprising the substeps of

entropy encoding the bitstream signal in response to a probability signal so as to obtain said data compressed bitstream signal,

carrying out a prediction step on the bitstream signal, and

determining said probability signal from said prediction means.

26. Data compression method as claimed in claim 25, wherein the prediction step comprises the substep of carrying out a prediction filter operation on the bitstream signal so as to obtain a multi value output signal, and wherein said probability determining step comprises the substep of deriving said probability signal from said multi value output signal.

27. Data expansion apparatus for data expanding a data compressed audio signal so as to obtain a replica of an original audio signal, the data expansion apparatus comprising

input means for receiving the data compressed audio signal which is in the form of a data compressed bitstream signal,

lossless decoding means for carrying out a substantially lossless data expansion step on the data compressed bitstream signal so as to obtain a bitstream signal,

D/A conversion means for carrying out a D/A conversion on the bitstream signal so as to obtain the replica of the original audio signal,

output means for supplying the replica of the original audio signal,

wherein said lossless decoding means comprise

an entropy decoder for entropy decoding the data compressed bitstream signal in response to a probability signal so as to obtain said bitstream signal, and

probability signal generator means for supplying said probability signal.

28. Data expansion apparatus as claimed in claim 27, wherein said entropy decoder is an arithmetic decoder.

29. Data expansion method for data expanding a data compressed audio signal so as to obtain a replica of an original audio signal, the data expansion method comprising the steps of

receiving the data compressed audio signal which is in the form of a data compressed bitstream signal,

carrying out a substantially lossless data expansion step on the data compressed bitstream signal so as to obtain a bitstream signal,

carrying out a D/A conversion on the bitstream signal so as to obtain the replica of the original audio signal,

supplying the replica of the original audio signal,

wherein said lossless decoding step comprises the substeps of

entropy decoding the data compressed bitstream signal in response to a probability signal so as to obtain said bitstream signal, and

supplying said probability signal.

30. Data expansion method as claimed in claim 29, wherein said entropy decoding step comprises an arithmetic decoding step.