Apparatus and method of automatically compensating an audio volume in response to channel change

• US 20060018493A1
• Filed: 04/28/2005
• Published: 01/26/2006
• Est. Priority Date: 07/24/2004
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kim, Seoung-hun, Oh, Yoon-hark
• Granted Patent: US 8,107,643 B2
• Time in Patent Office: Days
• US Class Current: 381/107
• CPC Class Codes: H03G 11/008 of digital or coded signals
• CPC Class Codes: H03G 3/301 the gain being continuously variable
• CPC Class Codes: H03G 7/007 of digital or coded signals
• CPC Class Codes: H04H 40/18 Arrangements characterised by circuits or components specially adapted for receiving
• CPC Class Codes: H04H 60/43 for identifying broadcast channels
• CPC Class Codes: H04N 21/439 Processing of audio elementary streams
• CPC Class Codes: H04N 21/44016 involving splicing one content stream with another content stream, e.g. for substituting a video clip
• CPC Class Codes: H04N 5/602 for digital sound signals
• CPC Class Codes: H04R 3/00 Circuits for transducers , loudspeakers or microphones

Abstract

An apparatus and method of automatically compensating audio volume in response to a channel change. The method includes generating a gain value to adjust a level of an input audio signal by comparing an average level of the input audio signal with a predetermined input/output level curve, adjusting an audio volume of the input audio signal by applying the generated gain value to the level of the input audio signal, and adjusting a dynamic range of the audio signal having the adjusted audio volume.

Claims

1. A method of automatically compensating audio volume, the method comprising:

generating a gain value to adjust a level of an input audio signal by comparing an average level of the input audio signal with a predetermined input/output level curve;

adjusting an audio volume of the input audio signal by applying the generated gain value to the level of the input audio signal; and

adjusting a dynamic range of the input audio signal having the adjusted audio volume.

2. The method of claim 1, further comprising:

initializing the level of the input audio signal to a predetermined level when a broadcast channel is changed.

3. The method of claim 2, wherein the initializing of the level of the input audio signal comprises initializing the level of the input audio signal to an intermediate level between a maximum level and a minimum level.

4. The method of claim 1, wherein the generating of the gain value comprises:

calculating the average level of the input audio signal in a predetermined range; and

generating the gain value by comparing the calculated average level of the input audio signal with the input/output level curve based on a predetermined input/output equation and mapping the average level of the input audio signal in the predetermined range to a predetermined level of the input/output level curve.

5. The method of claim 4, wherein the generating of the gain value comprises adjusting the average level of the input audio signal to a first level of an intermediate audio volume when the input audio signal has a high audio volume, and adjusting the average level of the input audio signal to a second level of the intermediate audio volume when the input audio signal has a low audio volume.

6. The method of claim 1, wherein the adjusting of the audio volume of the input audio signal comprises adjusting the input audio signal to an intermediate level between a maximum level and a minimum level.

7. The method of claim 1, wherein the adjusting of the dynamic range of the audio signal comprises:

calculating an average envelope value of the input audio signal in a predetermined range;

comparing the calculated average envelope value of the input audio signal with a level curve based on a predetermined input/output equation and mapping the calculated average envelope value of the input audio signal to a level defined by the input/output level curve; and

adjusting the dynamic range of the input audio signal by multiplying the input audio signal by the mapped level.

8. A method of controlling an audio volume, comprising:

adjusting a volume level and a dynamic range of an input audio signal according to a global gain value and a final gain value of the input audio signal so that an audio volume is maintained constant regardless of a channel change.

9. The method of claim 8, wherein the adjusting of the volume level and the dynamic range of the input audio signal comprises:

adjusting the volume level of the input audio signal; and

adjusting the dynamic range of the input audio signal having the adjusted volume level.

10. The method of claim 8, wherein the adjusting of the volume level and the dynamic range of the input audio signal comprises:

adjusting the volume level according to the global gain value and static level curve zones; and

adjusting the dynamic range according to the final gain value and the static level curve zones.

11. The method of claim 8, wherein the adjusting of the volume level comprises:

measuring average levels of the input audio signals in a predetermined range to generate a global RMS value;

comparing the global RMS value with a level of a static level curve to generate a gain level value; and

calculating the global gain value according to the gain level value and a previous gain level value of the input audio signal.

12. The method of claim 8, wherein the adjusting of the dynamic range comprises:

measuring an average envelope value of the input audio signal in a predetermined range;

comparing the average envelope value with a static level curve to generate a gain level value; and

calculating the final gain value according to the gain level value and a previous gain level value of the input audio signal.

13. The method of claim 8, wherein the adjusting of the volume level and the dynamic range comprises:

adjusting the volume level to an intermediate volume when a channel is changed having one of a high volume and a low volume; and

adjusting the dynamic range according to a dynamic range control process.

14. The method of claim 13, wherein the adjusting of the volume level of the input audio signal comprises:

initializing a global root mean square (RMS) of the input audio signal when a current channel is changed;

calculating a global gain according to

Global_—

g(n)=Global_—

g(n−

1)·

0.5+G(n)·

0.5

where Global_g(n) is the global gain value, Global_g(n−

1) is a previous global gain value, and G(n) is a first gain level mapped from a value of the input audio signal to a first predetermined gain level curve; and

adjusting the volume level of the input audio signal according to the global gain value.

15. The method of claim 14, wherein the first predetermined gain level curve decreases a high volume level by a first predetermined decibel level and increases a low volume level by a second predetermined decibel level.

16. The method of claim 15, wherein the high volume level corresponds to a Bturn zone of the first predetermined gain level curve and the low volume level corresponds to an Sturn zone of the first predetermined gain level curve.

17. The method of claim 13, wherein the adjusting of the dynamic range of the input audio signal comprises:

determining an average envelope value of the volume adjusted input audio signal;

comparing the average envelope value with a second predetermined gain level curve to determine a second gain level; and

calculating the final gain value according to the second gain level and a previous final gain value; and

adjusting the dynamic range of the input audio signal by applying the final gain value to the volume adjusted input audio signal.

18. The method of claim 17, wherein the average envelope information is determined according to:

X_RMS(n)=a|X(n)|+(1−

a)·

X_RMS (n−

1),

where X_RMS(n) is a root mean square value of the input audio signal, a is one of a decay time coefficient and an attack time coefficient, |X(n)| is an absolute value of the input audio signal, and X_RMS(n-1) is a previous root mean square value of the input audio signal.

19. The method of claim 17, wherein the final gain value is positive when the input audio signal has a low volume and the final gain value is negative when the input audio signal has a high volume.

20. The method of claim 13, further comprising:

changing a channel of the input audio signal to a channel having a different corresponding volume level.

21. An apparatus to control an audio volume, comprising:

an audio volume compensator to adjust a volume level and a dynamic range of an input audio signal according to a global gain value and a final gain value of the input audio signal so that an audio volume is maintained constant regardless of a channel change.

22. The apparatus of claim 21, wherein the audio volume compensator adjusts the volume level and the dynamic range of the input audio signal by adjusting the volume level of the input audio signal, and adjusting the dynamic range of the input audio signal having the adjusted volume level.

23. The apparatus of claim 21, wherein the audio volume compensator adjusts the volume level and the dynamic range of the input audio signal by adjusting the volume level according to the global gain value and static level curve zones, and adjusting the dynamic range according to the final gain value and the static level curve zones.

24. The apparatus of claim 21, wherein the audio volume compensator adjusts the volume level of the input audio signal by measuring average levels of the input audio signals in a predetermined range to generate a global RMS value, comparing the global RMS value with a level of a static level curve to generate a gain level value, and calculating the global gain value according to the gain level value and a previous gain level value of the input audio signal.

25. The apparatus of claim 21, wherein the audio volume compensator adjusts the dynamic range of the input audio signal by measuring an average envelope value of the input audio signal in a predetermined range, comparing the average envelope value with a static level curve to generate a gain level value, and calculating the final gain value according to the gain level value and a previous gain level value of the input audio signal.

26. The apparatus of claim 21, wherein the audio volume compensator adjusts the volume level and the dynamic range of the input audio signal by adjusting the volume level to an intermediate volume when a channel is changed having one of a high volume and a low volume, and adjusting the dynamic range according to a dynamic range control process.