Arrangement and a method for handling an audio signal

• US 20050169245A1
• Filed: 03/04/2002
• Published: 08/04/2005
• Est. Priority Date: 03/04/2002
• Status: Abandoned Application

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Hindersson, Lars
• Application Number:
  US10/506,595
• Publication Number:
  US 20050169245A1
• Time in Patent Office: Days
• US Class Current: 370/352
• CPC Class Codes: G06F 3/162 Interface to dedicated audio devices, e.g. audio drivers, interface to CODECs
• CPC Class Codes: H04L 2012/6481 Speech, voice
• CPC Class Codes: H04M 11/066 Telephone sets adapted for data transmision

Abstract

The present invention relates to a sound device (SD1), connected to a computer (P1), for handling of asynchronously transferred digital audio packets (5) on a network (LAN1). The computer has an interface (3) connected to a telephony application (1), a driver (D3) and a bus (4). The sound device (SD1) is connected (9) via the bus (4) and includes a software frame buffer (B2), codecs (C2) and an A/D-D/A converter (AD2), which is connected to in/out devices (10, 11, 12). The sound packets (5) are transferred asynchronously through the computer (P1), are buffered in the sound device frame buffer (B2), decoded in the codec (C2) and D/A converted into an analog signal for the in/out devices. Speech to the in devices (11, 12) is processed in a corresponding manner. Having the buffer (B2) close to the codec (C2) enables processing of the sound packets, e.g. with respect to the varying time delay in the computer (P1), restoring lost packets and producing replacement frames. The sound device (SD1) relieves the computer (P1) of the heavy workload of processing the sound packets (5).

Claims

1. A device for handling asynchronously transferred digital packets on a network, comprising:

a network connection for exchanging digital packets with the network and an associated personal computer (PC);

a control connection between the device and the PC for transferring control signals and for connecting

a telephony application, resident on the PC, to the device via the network connection wherein the device comprises;

a software frame buffer for buffering the digital packets;

a coder/decoder (codec) connected to the buffer for decoding the digital packets and

a digital-to-analog-analog-to-digital (D/A-A/D) converter connected to the codec, for converting the digital packets into an analog signal.

2. The device according to claim 1, wherein the codec and the frame buffer exchanges audio frames and the codec device includes an auxiliary codec for generating audio frames to be inserted in a stream of audio frames.

3. The device according to claim 2, wherein the auxiliary codec is arranged to predict audio frames and replace frames from lost audio packets with the predicted frames.

4. The device according to claim 2 wherein the codec device is a hardware device.

5. The device according to claim 2 wherein the D/A-A/D converter is a full duplex converter.

6. The device according to claim 2 wherein the buffer is arranged to receive a control signal on the control connection from the telephony application, which control signal determines the width of the buffer.

7. The device according to claim 2, the codec device has at least two codecs, wherein an appropriate one of the codecs can be selected by a control signal on the control connection from the telephony application.

8. A method for handling a digital audio signal with a personal computer (PC), the PC including a telephony application which is connected both to a network and to an audio device, the method including:

exchanging audio packets which are asynchronously transferred over the network;

transferring the audio packets asynchronously through the PC between the telephony application and the audio device;

buffering the audio packets in a frame buffer in the audio device;

decoding audio frames in the audio packets in a codec device; and

digital-to-analog (D/A) converting the decoded audio frames.

9. The method according to claim 8, wherein the codec device includes an auxiliary codec and the method includes:

following in the auxiliary codec a stream of audio frames;

generating audio frames in the auxiliary codec in dependence on the stream of audio frames; and

inserting the generated audio frames into the stream of audio frames.

10. The method according to claim 9 including:

predicting audio frames in dependence on the stream of audio frames; and

inserting predicted audio frames for frames in lost audio packets.

11. The method according to claim 9 including:

indicating whether the frame buffer is temporarily empty; and

inserting generated noise audio frames when the buffer is empty.

12. The method according to claim 8 including:

indicating whether the frame buffer is overfilled; and

speeding up the codec device when the buffer is overfilled.

13. The method according to claim 8, wherein the telephony application has a control connection to the audio device, the method including:

determining in the telephony application the width of the frame buffer; and

controlling the frame buffer width by a control signal on the control connection from the telephony application.

14. The method according to claim 8, wherein the telephony application has a control connection to the audio device and the codec device has at least two codecs, the method including selecting an appropriate one of the codecs by a control signal from the telephony application on the control connection.

17. The method of claim 8, wherein the audio device operates in full duplex.

15. A method for handling of a digital audio signal in connection with a personal computer PC, the PC including a telephony application which is connected both to a network and to an audio device, the method including:

A/D converting an analog audio signal into a digital audio signal in the audio device;

coding the digital audio signal and forming audio frames;

forming audio packets which are transferred asynchronously through the PC between the telephony application and the audio device.

16. The method according to claim 15, wherein the audio device operates in full duplex.