Method and apparatus for encoding/decoding MPEG-4 bsac audio bitstream having ancillary information

• US 20050129109A1
• Filed: 11/24/2004
• Published: 06/16/2005
• Est. Priority Date: 11/26/2003
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Lee, Shihwa, Kim, Dohyung, Kim, Junghoe, Oh, Eunmi, Kim, Sangwook
• Granted Patent: US 7,974,840 B2
• Time in Patent Office: Days
• US Class Current: 375/240.10
• CPC Class Codes: G10H 1/0058 Transmission between separate instruments or between individual components of a musical system G10H1/0083 takes precedence
• CPC Class Codes: G10L 19/24 Variable rate codecs, e.g. for generating different qualities using a scalable representation such as hierarchical encoding or layered encoding

Abstract

A method of and an apparatus for encoding/decoding an MPEG-4 bit sliced arithmetic coding (BSAC) audio bitstream having ancillary information. A time domain audio signal is converted to a frequency domain audio signal and quantized. A number of data bits is counted and a number of available bits per layer is obtained. The number of available bits per layer is modified considering the size of ancillary information. Actual audio data is encoded in units of layers and ancillary information is embedded in the encoded bitstream. A header is decoded and a layer structure of an audio bitstream is calculated to determine the size of the ancillary information as a difference between a size of data up to a top layer and a size of a frame. The ancillary information is extracted to improve meta data and sound quality of audio contents.

Claims

1. A method of encoding an MPEG-4 BSAC audio bitstream having ancillary information, the method comprising:

converting a time domain audio signal to a frequency domain audio signal and quantizing the audio signal using a psychoacoustic model;

counting a number of bits of bitrate controlled audio data;

obtaining a number of available bits per layer using a number of bits to be used and a number of layers to be used;

modifying the number of available bits per layer by obtaining a size of the ancillary information;

encoding actual audio data in units of layers; and

embedding the ancillary information in the encoded bitstream.

2. The method of claim 1, wherein the ancillary information is information related to sound quality improvement.

3. The method of claim 1, wherein the ancillary information is information related to music tunes.

4. The method of claim 1, wherein the ancillary information is information related to multi-channel data.

5. An apparatus for encoding an MPEG-4 BSAC audio bitstream having ancillary information, the apparatus comprising:

a quantization processor converting a time domain audio signal in to a frequency domain audio signal and quantizing the frequency domain audio signal using a psychoacoustic model;

an available bit calculator obtaining a number of available bits per layer using a number of bits and a number of layers of audio data;

an available bit modifier modifying the number of available bits per layer calculated by the available bit calculator by obtaining a size of the ancillary information; and

a bit packing unit encoding actual audio data according to the number of available bits per layer modified by the available bit modifier and the embedding ancillary information in an encoded bitstream.

6. The apparatus of claim 5, wherein the available bit calculator comprises:

a bit counter counting a number of bits of bitrate controlled audio data; and

a by-layer available bit calculator obtaining the number of available bits per layer using the number of bits counted by the bit counter and a predetermined number of layers.

7. A method of decoding an MPEG-4 BSAC audio bitstream having ancillary information, the method comprising:

decoding a header of an audio bitstream;

calculating a layer structure of the audio bitstream by obtaining a size of a frame from the header information;

obtaining a size of data up to a top layer and a size of a frame from the layer structure and determining a difference between the size of the data up to the top layer and the size of the frame as a size of the ancillary information;

extracting the ancillary information from the audio bitstream according to the size of the ancillary information; and

decoding the audio bitstream up to a top layer according to the calculated layer structure.

8. The method of claim 7, wherein the extracted ancillary information is information related to sound quality improvement.

9. The method of claim 7, wherein the extracted ancillary information is meta data of audio for an audio data user.

10. A method of decoding an MPEG-4 BSAC audio bitstream having ancillary information, the method comprising:

decoding a header of a bitstream;

calculating a layer structure of the bitstream by obtaining a size of a frame from the header information;

decoding audio data corresponding to a size of audio data up to a top layer from the layer structure of the bitstream; and

extracting a remaining bitstream as the ancillary information and decoding the ancillary information.

11. The method of claim 10, wherein the extracted ancillary information is information related to sound quality improvement.

12. The method of claim 10, wherein the extracted ancillary information is meta data of audio for an audio data user.

13. A method of discriminating whether ancillary information is embedded in audio data encoded with MPEG-4 BSAC audio data, the method comprising:

decoding a header of a bitstream;

calculating a layer structure of the bitstream by obtaining a size of a frame from the header information; and

obtaining a size of data up to a top layer and a size of the frame from the layer structure and discriminating whether ancillary information exists using a difference between the size of the data up to the top layer and the size of the frame.

14. An apparatus for decoding an MPEG-4 BSAC audio bitstream having ancillary information, the apparatus comprising:

a bit unpacking unit decoding a header of an audio bitstream;

a layer structure calculator calculating a layer structure of the audio bitstream by obtaining a size of a frame from header information;

an ancillary information calculator obtaining a size of data up to a top layer and a size of a frame from the layer structure and determining a difference between the size of the data up to the top layer and the size of the frame as a size of the ancillary information;

an ancillary information extractor extracting the ancillary information from the audio bitstream according to the size of the ancillary information; and

an audio decoder decoding the audio bitstream up to the top layer according to the calculated layer structure.

15. A computer readable medium having recorded thereon a computer readable program for performing a method of encoding an MPEG-4 BSAC audio bitstream having ancillary information, the computer readable medium comprising instructions for enabling a computer to:

convert a time domain audio signal to a frequency domain audio signal and quantize the audio signal using a psychoacoustic model;

count a number of bits of bitrate controlled audio data;

obtain a number of available bits per layer using a number of bits to be used and a number of layers to be used;

modify a number of available bits per layer by obtaining a size of the ancillary information;

encode actual audio data in units of layers; and

embed the ancillary information in the encoded bitstream.

16. A computer readable medium having recorded thereon a computer readable program for performing the a method of decoding an MPEG-4 BSAC audio bitstream having ancillary information, the computer readable medium comprising instructions for enabling a computer to:

decode a header of an audio bitstream;

calculate a layer structure of the audio bitstream by obtaining a size of a frame from the header information;

obtain a size of data up to a top layer and a size of a frame from the layer structure and determine a difference between the size of the data up to the top layer and the size of the frame as a size of the ancillary information;

extract the ancillary information from the audio bitstream according to the size of the ancillary information; and

decode the audio bitstream up to a top layer according to the calculated layer structure.