Method and apparatus for transferring low bit rate digital voice messages using incremental messages

• US 6,772,126 B1
• Filed: 09/30/1999
• Issued: 08/03/2004
• Est. Priority Date: 09/30/1999
• Status: Expired due to Fees

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Simpson, Floyd, Finlon, Kenneth, Schwendeman, Robert, Huang, Jian-Cheng, Satyamurti, Sunil
• Primary Examiner(s): ABEBE, DANIEL DEMELASH
• Application Number:
  US09/410,006
• Time in Patent Office: 1,769 Days
• Field of Search: 704/230, 704/222, 704/219-221, 704/201, 704/500-504
• US Class Current: 704/500
• 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 system controller (106) is for transferring a low bit rate digital voice message. The system controller generates from an analog voice signal representing the voice message a set of speech model parameters, and generates a first derived set of speech model parameters from a first subset of the set of speech model parameters, the first derived set encoding the voice signal at a second voice quality and second vocoder rate that are less, respectively, than a first voice quality and vocoder rate. The system controller transmits (3610) the low bit rate-digital voice message comprising the first derived set of speech model parameters to a communication receiver (114). The communication receiver requests (3640) an incremental message when the quality of the voice message is unsatisfactory. The system controller generates and transmits (3555, 3650) an incremental message-and the communication receiver uses (3660) the incremental message to generate a higher quality voice message.

Claims

1. A terminal for transferring a digital voice message to a communication transceiver, the terminal comprising:

a central processor;

a memory coupled to the central processor, the memory including operating instructions that, when executed by the central processor, control the central processor to;

generate from an analog voice signal a series of digital samples organized as frames;

generate from the series of digital samples a set of speech model parameters for at least one frame, the set of speech model parameters encoding the voice signal at a first vocoder rate that synthesizes a first voice quality;

select a first subset of speech model parameters from the set of speech model parameters for transmission to the communication transceiver, the first subset of speech model parameters requiring a lower rate of transmission than the set of speech model parameters and synthesizing a second voice quality at the communication transceiver, the second voice quality being lower than the first voice quality; and

select a second subset of speech model parameters from the set of speech model parameters in response to receiving a quality improvement request from the communication transceiver, the second subset of speech model parameters supplementing the first subset of speech model parameters to synthesize a third voice quality that is higher than the second voice quality;

a transmitter, coupled to the central processor, that transmits at least one of the first subset of speech model parameters and the second subset of speech model parameters to the communication transceiver; and

a receiver, coupled to the central processor, that receives the quality improvement request from the communication transceiver.

2. A communication transceiver for receiving a digital voice message, the communication transceiver comprising:

a central processor;

a memory coupled to the central processor, the memory including operating instructions that, when executed by the central processor, control the central processor to;

decode a first set of speech model parameters to produce a first set of decoded speech model parameters, the first set of speech model parameters constituting a first subset of a set of speech model parameters that were encoded at a first vocoder rate to synthesize a first voice quality, the first set of speech model parameters synthesizing a second voice quality that is lower than the first voice quality and requiring a lower rate of transmission than the set of speech model parameters;

determine whether a voice quality higher than the second voice quality is desired based on speech synthesized from the first set of decoded speech model parameters;

generate a quality improvement request when a determination is made that a higher voice quality is desired;

decode a second set of speech model parameters to produce a second set of decoded speech model parameters, the second set of speech model parameters constituting a second subset of the set of speech model parameters that were encoded at the first vocoder rate; and

use the first set of decoded speech model parameters and the second set of decoded speech model parameters to reconstruct the digital voice message;

a receiver, coupled to the central processor, that receives the first set of speech model parameters and the second set of speech model parameters; and

a transmitter, coupled to the central processor, that transmits the quality improvement request.

3. A method used in a communication system to transfer a digital voice message to a communication transceiver, the method comprising the steps of:

generating from an analog voice signal a series of digital samples organized as a plurality of frames;

generating from the series of digital samples a set of speech model parameters for at least one frame, the set of speech model parameters encoding the voice signal at a first vocoder rate that synthesizes a first voice quality;

selecting a first subset of speech model parameters from the set of speech model parameters, the first subset of speech model parameters requiring a lower rate of transmission than the set of speech model parameters and synthesizing a second voice quality at the communication transceiver, the second voice quality being lower than the first voice quality;

transmitting the first subset of speech model parameters to the communication transceiver;

receiving a quality improvement request from the communication transceiver;

responsive to the quality improvement request,

selecting a second subset of speech model parameters from the set of speech model parameters, the second subset of speech model parameters being used with the first subset of speech model parameters to synthesize a third voice quality that is higher than the second voice quality; and

transmitting the second subset of speech model parameters to the communication transceiver.

4. The method according to claim 3, wherein a message containing the first subset of speech model parameters and a message containing the second subset of speech model parameters each include a common message identification number.

5. The method according to claim 3, wherein a message containing the second subset of speech model parameters includes an increment identifier.

6. The method according to claim 3, wherein the set of speech model parameters comprises at least two speech model parameter types of a group of speech model parameter types consisting of:

quantized line spectral frequency vectors, harmonic residue vectors, pitch values, global voicing values, band voicing values, and gain values and non-quantized line spectral frequency vectors, harmonic residue vectors, pitch values, global voicing values, band voicing values, and gain values.

7. The method according to claim 3, wherein the first subset of speech model parameters comprises a subsequence of vector parameters of a first type selected from a sequence of vector parameters of the first type that are from the set of speech model parameters, wherein the sequence of vector parameters of the first type comprises one vector parameter of the first type from each frame.

8. The method according to claim 3, wherein the step of generating the set of speech model parameters includes the step of dynamically segmenting the set of speech model parameters to produce the first subset of speech model parameters and the second subset of speech model parameters.

9. The method according to claim 3, wherein the step of generating the set of speech model parameters comprises the steps of:

generating a set of speech model parameters for each frame, each set including a vector parameter of a first type; and

quantizing the vector parameter of the first type in each frame by determining a first index of a first quantization level that indicates a table vector that is closest in value to the vector parameter of the first type in each frame.

10. The method according to claim 9, wherein the first subset of speech model parameters includes vector parameters of the first type determined by a second index having a second quantization level that is less than the first quantization level.

11. The method according to claim 3, further comprising the step of dynamically segmenting the plurality of frames into groups of frames and wherein the step of selecting a first subset of speech model parameters comprises the step of selecting speech parameters for a subgroup of a first group of frames.

12. The method according to claim 3, wherein the first subset of speech model parameters comprises at least two speech model parameter types of a group of speech model parameter types consisting of:

quantized line spectral frequency vectors, pitch values, global voicing values, band voicing values and gain values; and

wherein the second subset of speech model parameters comprises quantized harmonic residue vectors.

13. A method used in a communication system to transfer a digital voice message between a terminal and a communication transceiver, the method comprising the steps of:

at the terminal;

generating from a voice signal a series of digital samples organized as frames;

generating from the series of digital samples a set of speech model parameters for each frame, the set of speech model parameters encoding the voice signal at a first vocoder rate that synthesizes a first voice quality;

selecting a first subset of speech model parameters from the set of speech model parameters for transmission to the communication transceiver, the first subset of speech model parameters requiring a lower rate of transmission than the set of speech model parameters and synthesizing a second voice quality at the communication transceiver, the second voice quality being lower than the first voice quality;

selecting a second subset of speech model parameters from the set of speech model parameters in response to receiving a quality improvement request from the communication transceiver, the second subset of speech model parameters supplementing the first subset of speech model parameters to synthesize a third voice quality that is higher than the second voice quality; and

transmitting at least one of the first subset of speech model parameters and the second subset of speech model parameters to the communication transceiver;

at the communication transceiver;

receiving and decoding the first subset of speech model parameters to produce a first set of decoded speech model parameters;

determining whether a voice quality higher than the second voice quality is desired based on speech synthesized from the first set of decoded speech model parameters;

transmitting the quality improvement request when a determination is made that a higher voice quality is desired;

receiving and decoding the second subset of speech model parameters to produce a second set of decoded speech model parameters; and

using the first set of decoded speech model parameters and the second set of decoded speech model parameters to reconstruct the digital voice message.

14. A method used in a communication transceiver of a communication system to transfer a digital voice message, the method comprising the steps of:

receiving and decoding a first set of speech model parameters to produce a first set of decoded speech model parameters, the first set of speech model parameters constituting a first subset of a set of speech model parameters that were encoded at a first vocoder rate to synthesize a first voice quality, the first set of speech model parameters synthesizing a second voice quality that is lower than the first voice quality and requiring a lower rate of transmission than the set of speech model parameters;

determining whether a voice quality higher than the second voice quality is desired based on speech synthesized from the first set of decoded speech model parameters;

transmitting a quality improvement request when a determination is made that a higher voice quality is desired;

receiving and decoding a second set of speech model parameters to produce a second set of decoded speech model parameters, the second set of speech model parameters constituting a second subset of the set of speech model parameters that were encoded at the first vocoder rate; and

using the first set of decoded speech model parameters and the second set of decoded speech model parameters to reconstruct the digital voice message.

15. The method according to claim 14, wherein a message containing the first set of speech model parameters, the quality improvement request, and a message containing the second set of speech model parameters each include a common message identification number.

16. The method according to claim 14, wherein a message containing the second set of speech model parameters includes an increment identifier.

17. The method according to claim 14, wherein the first set of speech model parameters comprises at least two speech model parameter types of a group of speech model parameter types consisting of:

quantized line spectral frequency vectors, pitch values, global voicing values, band voicing values and gain values; and

.wherein the second set of speech model parameters comprises quantized harmonic residue vectors.

18. The method according to claim 14, wherein the set of speech model parameters that were encoded at the first vocoder rate were generated from a series of digital samples organized in a plurality of frames, wherein the plurality of frames were dynamically segmented into groups of frames and wherein the first set of speech model parameters comprises speech model parameters for a subgroup of a first group of frames.