Adaptive Encoding and Compression of Audio Broadcast Data

• US 20110039506A1
• Filed: 08/14/2009
• Published: 02/17/2011
• Est. Priority Date: 08/14/2009
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Powell, Richard Michael, Williams, Joseph M., Lindahl, Aram
• Granted Patent: US 8,706,272 B2
• Time in Patent Office: Days
• US Class Current: 455/130
• CPC Class Codes: G10L 19/20 using sound class specific coding, hybrid encoders or object based coding
• 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
• CPC Class Codes: H04M 1/72442 for playing music files

Abstract

Various techniques for adaptively encoding and compressing audio broadcast data to create a digital representation of the broadcast for storage on an electronic device are provided. In one embodiment, the audio broadcast data may be encoded and stored onto the electronic device using a particular codec and/or compression rate, the selection of which may be based upon one or more characteristics of the audio broadcast data signal, such as a genre parameter or a quality parameter. Particularly, the audio broadcast data may be encoded using either a music codec or a speech codec depending upon the genre parameter. Further, some embodiments may also provide for an adjustable compression bit-rate based at least partially upon the quality parameter of the audio broadcast.

Claims

1. A method, comprising:

receiving an audio broadcast signal on an electronic device;

determining one or more characteristics of the audio broadcast signal; and

adaptively encoding the audio broadcast signal based upon the one or more characteristics to generate a digital representation of the audio broadcast signal storable on the electronic device.

2. The method of claim 1, wherein determining the one or more characteristics comprises determining a genre parameter of the audio broadcast signal, and wherein adaptively encoding the audio broadcast signal comprises selecting a codec based upon the genre parameter and encoding the audio broadcast signal using the selected codec.

3. The method of claim 2, wherein determining the genre parameter of the audio broadcast signal comprises determining whether the audio broadcast signal contains speech data or music data, and wherein selecting the codec based upon the genre parameter and encoding the audio broadcast signal using the selected codec comprises:

if the genre parameter indicates that the audio broadcast signal contains speech data, selecting a speech codec and encoding the audio broadcast signal using the selected speech codec; and

if the genre parameter indicates that the audio broadcast signal contains music data, selecting a music codec and encoding the audio broadcast signal using the selected music codec.

4. The method of claim 3, wherein the speech codec is selected from one of an Adaptive Multi-Rate (AMR) codec, a Variable Multi-Rate (VMR) codec, a Code Excited Linear Prediction (CELP) codec, or a Speex codec, or any combination thereof, and wherein the music codec is selected from one of an Advanced Audio Coding codec, an Apple Lossless Audio Codec (ALAC), an Ogg Vorbis codec, or an MP3 codec, or any combination thereof.

5. The method of claim 2, wherein the genre parameter is determined by analyzing a broadcast metadata signal associated with the audio broadcast signal.

6. The method of claim 5, wherein the broadcast metadata signal comprises a Radio Data System (RDS) signal, an Amplitude Modulation Signaling System (AMSS) signal, a Program Associated Data (PAD) signal, or a Program Service Data (PSD) signal, or some combination thereof.

7. The method of claim 2, wherein the genre parameter is determined by performing a frequency analysis to determine the frequencies at which audio data in the audio broadcast signal is most concentrated.

8. The method of claim 7, wherein the genre parameter is determined to be speech data if the audio data in the audio broadcast signal is generally concentrated within a frequency range of between approximately 1000-6000 hertz.

9. The method of claim 7, wherein performing the frequency analysis comprises performing spectral or cepstral analysis, or some combination thereof.

10. A method, comprising

receiving an audio broadcast signal on an electronic device, the audio broadcast signal being transmitted by a broadcast source;

analyzing the audio broadcast signal to determine a quality parameter; and

adaptively encoding and compressing the audio broadcast signal based upon the quality parameter to generate a digital representation of the audio broadcast signal storable on the electronic device.

11. The method of claim 10, wherein the quality parameter is based upon a signal strength of the audio broadcast signal, a distortion level of the audio broadcast signal, white noise content in the audio broadcast signal, the number of artifacts in the audio broadcast signal, or some combination thereof.

12. The method of claim 10, wherein adaptively compressing the audio broadcast signal comprises selecting a compression bit-rate based at least partially upon the quality parameter.

13. The method of claim 12, comprising adjusting the selected compression bit-rate in response to a change in the quality parameter.

14. The method of claim 13, wherein the change in the quality parameter is caused at least in part by a change in the position of the electronic device relative to the broadcast source.

15. The method of claim 14, wherein the broadcast source comprises one of a frequency modulation (FM) broadcast source, an amplitude modulation (AM) broadcast source, or a satellite broadcast source.

16. The method of claim 13, comprising not encoding or compressing the audio broadcast signal if the change in the quality parameter results in the quality parameter being below a minimum quality threshold level.

17. An electronic device, comprising:

an audio broadcast receiver configured to receive an audio broadcast signal;

processing logic configured to process the audio broadcast signal to generate a digital representation of the audio broadcast signal, wherein the processing logic comprises;

signal analysis logic configured to determine at least one of a genre parameter and a quality parameter of the audio broadcast signal; and

encoder/decoder logic configured to select a codec from a plurality of codecs based upon the genre parameter and to encode the audio broadcast signal based upon the selected codec to generate the digital representation of the audio broadcast signal; and

a storage device configured to store the digital representation of the audio broadcast signal.

18. The electronic device of claim 17, wherein the encoder/decoder logic is configured to select a speech codec if the determined genre parameter indicates that the audio broadcast signal is primarily speech data, and to select a music codec if the determined genre parameter indicates that the audio broadcast signal is primarily music data.

19. The electronic device of claim 18, wherein the encoder/decoder logic is configured to encode the audio broadcast signal in mono if the audio broadcast signal is primarily speech data and to encode the audio broadcast signal in stereo if the audio broadcast signal is primarily music data.

20. The electronic device of claim 18, comprising a display device, wherein the speech codec and the music codec are determined by a user of the electronic device via a configuration screen accessible through a graphical user interface displayable on the display device.

21. The electronic device of claim 18, wherein determining whether the audio broadcast signal is primarily speech or music data comprises using the signal analysis logic to extract program information from a broadcast metadata signal transmitted with the audio broadcast signal as a sub-carrier signal.

22. The electronic device of claim 17, wherein the encoder/decoder logic is additionally configured to select a compression bit-rate based at least partially upon the quality parameter.

23. The electronic device of claim 22, wherein the selection of the compression bit-rate is also based upon the genre parameter, wherein a first compression bit-rate is selected based upon the quality parameter and the genre parameter when the genre parameter indicates that the audio broadcast signal is primarily speech data, and wherein a second compression bit-rate is selected based upon the quality parameter and the genre parameter when the genre parameter indicates that the audio broadcast signal is primarily music data, wherein the first compression bit-rate is lower than the second compression bit-rate.

24. The electronic device of claim 17, comprising encryption logic configured to encrypt the digital representation of the audio broadcast signal prior to storage on the storage device.

25. The electronic device of claim 24, wherein the encryption logic is configured to encrypt the digital representation of the audio broadcast signal using an Advanced Encryption Standard (AES) format or a Data Encryption Standard (DES) format, or some combination thereof.

26. One or more tangible computer-readable storage media having instructions encoded thereon for execution by a processor, the instructions comprising:

code to determine a quality parameter of an audio broadcast signal;

code to evaluate the quality parameter against at least one set of quality binning thresholds; and

code to select a compression bit-rate based upon the evaluation.

27. The one or more tangible computer-readable storage media of claim 26, comprising:

code to determine a genre parameter of the audio broadcast signal, the genre parameter indicating whether the audio broadcast signal is primarily speech-based or music-based; and

code to select a speech codec or a music codec based upon the genre parameter.

28. The one or more tangible computer-readable storage media of claim 27, wherein the at least one set of quality binning thresholds comprises a first set of quality binning thresholds and a second set of quality binning thresholds, and wherein the code to evaluate the quality parameter against the at least one set of quality binning thresholds comprises:

code to evaluate the quality parameter against the first set of quality binning thresholds if the genre parameter indicates that the audio broadcast signal is primarily speech-based; and

code to evaluate the quality parameter against the second set of quality binning thresholds if the genre parameter indicates that the audio broadcast signal is primarily music-based.

29. The one or more tangible computer-readable storage media of claim 28, wherein the first set of quality binning thresholds represents bit-rates that are generally lower than the second set of quality binning thresholds.

30. The one or more tangible computer-readable storage media of claim 28, comprising code to encode and compress the audio broadcast signal based upon the selection of the speech or music codec and the selection of the compression bit-rate.