Title:
Karaoke system with built-in camera
Kind Code:
A1


Abstract:
A karaoke system with built-in camera includes a decoder, a camera system, and a video selector. The decoder (e.g., a CDG decoder) receives data from a disc and provides a first video signal having graphics, e.g., for lyrics of a selected song. The camera system captures an image of a live scene and provides a second video signal. The video selector combines the first and second video signals to obtain a third video signal and can provide the first, second, or third video signal (e.g., based on user control) as an output video signal. A color eliminator can filter out a designated frequency (e.g., for a designated color such as blue) in the first video signal to provide a better output image for the third video signal. The decoder and camera system are synchronized with a common vertical timing signal and further use a common oscillator signal.



Inventors:
Lau, Kwok Piu (Nt, HK)
So, Kin San (Nt, HK)
Application Number:
10/966073
Publication Date:
04/21/2005
Filing Date:
10/15/2004
Assignee:
The Singing Machine Company, Inc. (Coconut Creek, FL, US)
Primary Class:
Other Classes:
84/610
International Classes:
A61K31/4709; A61K31/498; A61K31/502; A61K31/517; C07D401/12; C07D401/14; G10H7/00; (IPC1-7): G10H7/00
View Patent Images:



Primary Examiner:
THAI, XUAN MARIAN
Attorney, Agent or Firm:
Truong Dinh;Dinh & Associates (2506 Ash Street, Palo Alto, CA, 94306, US)
Claims:
1. A karaoke system comprising: a decoder operative to receive data from a disc and provide a first video signal having graphics defined by the data; a camera system operative to capture an image of a live scene and provide a second video signal; and a video selector operative to combine the first and second video signals to obtain a third video signal and to provide the third video signal as an output video signal.

2. The karaoke system of claim 1, wherein the video selector is operative to provide the first, second, or third video signal as the output video signal based on a control signal.

3. The karaoke system of claim 1, further comprising: a color eliminator operative to receive the first video signal, filter out a designated frequency, and provide a filtered first video signal, and wherein the video selector is operative to combine the filtered first video signal with the second video signal to obtain the third video signal.

4. The karaoke system of claim 3, wherein the designated frequency corresponds to a designated color.

5. The karaoke system of claim 4, wherein the designated color is blue.

6. The karaoke system of claim 1, wherein the decoder and the camera system are synchronized based on a common frame synchronization input signal that provides vertical timing for the first and second video signals.

7. The karaoke system of claim 1, wherein the decoder and the camera system use a common oscillator signal to generate color subcarriers for the first and second video signals.

8. The karaoke system of claim 1, further comprising: a control unit operative to enable the camera system to adjust white balance of the image and disable the camera system from adjusting the brightness of the image.

9. The karaoke system of claim 8, wherein the control unit enables the camera system to adjust the white balance of the image when the karaoke system is powered on and not playing a CDG disc.

10. The karaoke system of claim 1, further comprising: a first amplifier operative to amplify the first video signal and provide an amplified first video signal; and a second amplifier operative to amplify the second video signal and provide an amplified second video signal, and wherein the video selector is operative to combine the amplified first and second video signals to obtain the third video signal.

11. The karaoke system of claim 1, wherein the camera system is implemented on a CMOS (complementary metal oxide semiconductor) integrated circuit.

12. The karaoke system of claim 1, wherein the graphics on the first video signal if for lyrics of a song.

13. The karaoke system of claim 1, wherein the graphics on the first video signal are for graphics, pictures, symbols, or any combination thereof.

14. The karaoke system of claim 2, wherein the control signal is indicative of user-selection for the first, second, or third video signal as the output video signal.

15. The karaoke system of claim 1, wherein the disc is a CDG (compact disc+graphics) disc.

16. A method of providing an output video signal from a karaoke system, comprising: processing data from a disc to obtain a first video signal having graphics defined by the data; capturing an image of a live scene with a camera system to obtain a second video signal; combining the first and second video signals to obtain a third video signal; and providing the third video signal as the output video signal.

17. The method of claim 16, further comprising: filtering out a designated frequency from the first video signal to obtain a filtered first video signal, and wherein the filtered first video signal is combined with the second video signal to obtain the third video signal.

18. The method of claim 16, further comprising: enabling the camera system to adjust white balance of the image for a particular operating scenario; and disabling the camera system from adjusting the white balance of the image after the particular operating scenario.

19. The method of claim 16, further comprising: receiving a user-selection for the first, second, or third video signal; and providing the first, second, or third video signal as the output video signal based on the user-selection.

20. An apparatus comprising: means for processing data from a disc to obtain a first video signal having graphics defined by the data; means for capturing an image of a live scene to obtain a second video signal; means for combining the first and second video signals to obtain a third video signal; and means for providing the third video signal as an output video signal.

21. The apparatus of claim 20, further comprising: means for filtering out a designated frequency from the first video signal to obtain a filtered first video signal, and wherein the filtered first video signal is combined with the second video signal to obtain the third video signal.

22. The apparatus of claim 20, further comprising: means for enabling the camera system to adjust brightness of the image for a particular operating scenario; and means for disabling the camera system from adjusting the brightness of the image after the particular operating scenario.

Description:

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the benefit of provisional U.S. application Ser. No. 60/511,851, entitled “Karaoke System with Built-in Camera,” filed Oct. 15, 2003, which is incorporated herein by reference in its entirety for all purposes.

BACKGROUND

The present invention relates generally to consumer electronics, and more specifically to a karaoke system.

Karaoke singing has become a popular entertainment activity in homes and commercial establishments throughout the world. A karaoke system generates background music for a user-selected song from a disc and allows one or more users to sing along with the music via one or more microphones. The karaoke system mixes the vocals from the users with the background music and provides an output audio signal that contains a mixture of the user vocals and the music. The output audio signal is typically played via a speaker for listening pleasure of the users as well as any audience that may have gathered for karaoke.

The karaoke system normally also has a video unit as well as the audio unit. The video unit generates lyrics for the user-selected song and displays the lyrics on a screen. This allows the users to sing along, even if the users do not know the words to the song, by scrolling the lyrics across the screen. The lyrics are often highlighted in a manner to cue the users as to when each word of the lyrics should be sung. The video unit may also receive or generate pre-recorded graphics, video images, and/or video for display along with the lyrics.

Since karaoke singing is a form of entertainment, it is highly desirable to capture the excitement and enhance the experience of users and audience gathered together for karaoke.

SUMMARY

A karaoke system with built-in camera is described herein. This karaoke system can capture the excitement of a live scene with the camera to enhance the experience of those gathered for karaoke.

In a specific embodiment, the karaoke system comprises a decoder, a camera system, and a video selector. The decoder (e.g., a CDG decoder) receives data from a disc and provides a first video signal having graphics defined by the data. This graphics can be for lyrics of a song selected by a user. The camera system, which may be implemented on a Complementary Metal Oxide Semiconductor (CMOS) integrated circuit (IC), captures an image of a live scene and provides a second video signal. The video selector combines the first and second video signals to obtain a third video signal and can provide the first, second, or third video signal (e.g., based on user control) as an output video signal. The decoder and camera system are synchronized based on a common frame synchronization input signal that provides vertical timing for the first and second video signals. The decoder and camera system further use a common oscillator signal to generate color subcarriers for their video signals.

The karaoke system may further include a color eliminator, amplifiers, and a control unit. The color eliminator receives the first video signal, filters out a designated frequency (e.g., for a designated color such as blue), and provides a filtered first video signal. The amplifiers amplify the filtered first video signal and the second video signal and provide amplified video signals, which are combined by the video selector to obtain the third video signal. The control unit provides various controls for video and audio units within the karaoke system. For example, the control unit may enable the camera system to adjust the brightness of the image under certain conditions and otherwise disables the camera system from adjusting the brightness.

Various aspects, embodiments, and features of the invention are described in further detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of a karaoke system with built-in camera;

FIG. 2 shows a functional block diagram of the karaoke system;

FIG. 3 shows a schematic diagram of a noise filter and amplifier and a color eliminator;

FIG. 4 shows a block diagram of a camera system;

FIG. 5 shows a schematic diagram of video buffers and a video selector; and

FIG. 6 shows horizontal timing for a video signal generated by the karaoke system.

DETAILED DESCRIPTION

The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any embodiment or design described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments or designs.

FIG. 1 shows a perspective view of an embodiment of a karaoke system 100 with a built-in camera. Karaoke system 100 is encapsulated in a casing that is dimensioned to be of a convenient size and shape for ease of transport and placement. This allows karaoke system 100 to be placed, for example, on top of a home television, next to a computer monitor, in an entertainment system, and so on. In general, karaoke system 100 may be of any form factor, size, and shape.

Karaoke system 100 includes a CDG system 120 that can read a CD (compact disc) disc or a CDG (CD+graphics) disc. A CD disc contains only music. A CDG disc contains music as well as graphics, which may be for lyrics of the songs contained in the CDG disc. The lyrics may be read from the CDG disc and displayed on a blue (or any other color) background in synchronization with the music. The lyrics are also often highlighted in a manner to signal when the words should be sung. A CDG disc, however, contains no moving video in the background.

Karaoke system 100 further includes a camera system 130 that can capture an image of a live scene. This live scene may be of a person singing in front of the karaoke system, a gathering of people in a room where the karaoke system is located, and so on. Camera system 130 may be implemented in various manners. For the embodiment shown in FIG. 1, camera system 130 is encapsulated in a unit that may be flipped up to activate the camera system and flipped down to hide and protect the camera system. Camera system 130 may also be mounted in other manners, and this is within the scope of the invention. For example, camera system 130 may be mounted (1) on a swivel so that the camera can be rotated to capture scenes around the room or (2) on a ball joint so that the camera can be pointed in any direction.

Karaoke system 100 has easily accessible knobs 142 for various audio and video controls such as audio volume control, left/right balance control, and so on. A display 146 provides a simple display of the track number of the CD or CDG being played. Input and output jacks 148 are provided on the side, in the back, and possibly in the front (not shown in FIG. 1) for input and output audio signals and input and output video signals. For example, two microphone inputs may be provided on the side, and output audio/video signals may be provided in the back.

FIG. 2 shows a functional block diagram of an embodiment of karaoke system 100 with built-in camera. A controller 210 receives various inputs (e.g., from knobs 142 and buttons 144) and provides various controls for the processing units within karaoke system 100. A memory unit 212 provides storage for code and data used by controller 210 and possibly other processing units within karaoke system 100.

Within CDG system 120, a CD mechanism 220 reads data from a CD disc or a CDG disc via a CD lens and provides disc data to a CD servo system 222. CD servo system 222 processes the disc data and provides various signals to other circuit blocks. For example, CD servo system 222 provides CDG sub-code data to a CDG decoder 224. The CDG sub-code data may include (1) a clock signal used by CDG decoder 224 for decoding/decompression, (2) data for graphics in a video signal, and (3) an SFSY signal that contains control data and other information used for decoding/decompression. CD servo system 222 also provides left and right audio signals, ALcdg and ARcgd, to an auto voice control (AVC) mute circuit 276.

CDG decoder 224 receives the CDG sub-code data from CD servo system 222, decodes the CDG sub-code data, and generates a graphics video signal, Vcdg. The graphics video signal may contain, for example, lyrics for a song in the CDG disc. In an embodiment, CDG decoder 224 is implemented with integrated circuit (IC) chips and additional circuitry. For example, these IC chips may include Toshiba TC-9411F and Oki 514256C IC chips, which are commercially available.

A noise filter and amplifier (Amp) 240 receives the Vcdg video signal from CDG decoder 224 and provides a filtered and amplified graphics video signal, Vlpf. The noise filter removes digital noise in the Vcdg video signal, which may be generated by CDG decoder 224. The amplifier enhances the filtered graphics video signal, which is reduced in amplitude after the noise filtering.

A color eliminator 242 receives the Vlpf video signal and, when enabled by a CEenb control signal, removes (i.e., suppresses or eliminates) a designated color (e.g., blue) in the Vlpf video signal and provides a color-eliminated graphics video signal, Vce. The Vce video signal has most of the designated color removed. The Vce video signal is subsequently merged with a camera video signal, Vcam, from camera system 130 to obtain a composite video signal, Vcomp, as described below. Removing the designated color from the Vce video signal results in a better output image on a television screen for the composite video signal. Color eliminator 242 provides a buffered version of the Vlpf video signal if it is not enabled by the CEenb control signal. Thus, color eliminator 242 provides a Vce/lpf video signal, which may be either the Vce video signal (with the designated color removed) or the Vlpf video signal (without the designated color removed) depending on the CEenb control signal.

A video buffer 244 receives the Vce/lpf video signal from color eliminator 242, amplifies the Vce/lpf video signal to obtain the proper signal level, and further buffers the amplified video signal to provide the proper signal drive and impedance level for a conventional television. Video buffer 244 also provides isolation and prevents video signals from flowing backward. More specifically, when a first video signal is combined with a second video signal, the video buffer for the first video signal prevents the second video signal from flowing back to the source of the first video signal, and vice versa. Video buffer 244 provides to a video selector 246 an amplified graphic video signal, Vbuf, which may or may not have the designated color removed depending on the CEenb control signal.

A buffer 226 receives an oscillator (OSC) signal and a frame synchronization input (FSI) signal from CDG decoder 224. The OSC signal is the clock signal used by CDG decoder 224 to generate the color subcarrier and color bursts for the graphics video signal, Vcdg. The FSI signal is a vertical timing signal used by CDG decoder 224 to generate the vertical video lines for the graphics video signal. Since the graphics video signal from CDG decoder 224 and the camera video signal from camera system 130 are subsequently combined into one video signal, these two units should be synchronized with the same color carrier phase and line timing so that the color and lines from these two units are aligned. For the embodiment shown in FIG. 2, CDG decoder 224 is the master unit and its OSC and FSI signals are also used by camera system 130 for synchronization with CDG decoder 224. Buffer 226 amplifies each signal to obtain the proper signal level, buffers each amplified signal, and provides the buffered FSI and OSC signals, FSI′ and OSC′, to camera system 130. In alternative embodiments, camera system 130 may be the master unit and CDG decoder 224 may be slaved to camera system 130, or another master unit may drive both CDG decoder 224 and camera system 130.

When the camera is enabled, an automatic (auto) white balance adjustment algorithm 230 within camera system 130 automatically adjusts the white balance of the image in the Vcam video signal generated by camera system 130. The auto white balance adjustment may also be referred to as brightness adjustment, intensity adjustment, and so on. This auto white balance adjustment may be desirable if the camera video signal is displayed by itself. However, the camera video signal may subsequently be merged with the graphics video signal. If the auto white balance adjustment is not disabled, then camera system 130 will perform the auto white balance adjustment continuously. In that case, when the color of the graphics video signal changes, the white balance of the image on the television screen will also change and may cause the screen to become unstable. Since users are normally annoyed by fluctuation in the intensity on the screen, the auto white balance adjustment is disabled, for example, once the karaoke system starts playing the CDG tracks.

A control unit 228 receives a CDG signal from CDG decoder 224 and controls the operation of color eliminator 242 and camera system 130. The CDG signal indicates whether or not CDG decoder 224 is reading a CDG disc. CDG decoder 224 sets the CDG signal to a low amplitude when CDG servo system 222 is reading a CDG disc and to a high amplitude otherwise. If control unit 228 receives a low CDG signal, indicating that a CDG disc is being read, then control unit 228 allows buffer 226 to provide the FSI signal to camera system 130, disables the auto white balance function of camera system 130, and enables color eliminator 242 to remove the designated color from the Vcdg video signal. If control unit 228 receives a high CDG signal, indicating that a CD disc or no disc is being read, then control unit 228 prevents buffer 226 from providing the FSI signal to camera system 130, enables the auto white balance function of camera system 130, and disables color eliminator 242 so that the designated color is not removed from the Vcdg video signal. When reading a CD disc that contains no graphics, the camera output is provided as the video output and is not superimposed on any graphics. When reading a CDG disc, the camera output is superimposed with the graphics from the CDG disc, and the auto white balance adjustment is disabled to prevent the screen from changing rapidly and/or becoming too light or too dark. The auto white balance adjustment function is enabled when karaoke system 100 is first turned on until and unless a CDG disc is read.

Auto white balance adjustment algorithm 230 adjusts and calibrates the image device sensitivity on the primary (RGB) colors to match the color cast of the light source. The auto white balance adjustment is one of the built-in function of the CMOS IC for camera system 130. The auto white balance adjustment algorithm operates as follows. After karaoke system 100 is turned on or is reset, the CMOS IC performs the auto white balance until it reaches balance level. The CMOS IC continues to perform the auto white balance when it is powered on and adjusts to changes in the light level of the ambient area. The auto white balance function is disabled if a CDG disc is played. If control unit 228 receives a low CDG signal from CDG decoder 224, then control unit 228 sends the appropriate control to disable the auto white balance function within the CMOS IC. On the other word, when karaoke system 100 is turned on and before a user starts to play a CDG disc, the auto white balance function is enabled. Once the user starts to play a CDG disc, the auto white balance function is disabled. When the user stop to play the CDG disc, the auto white balance is enabled again.

Camera system 130 includes a built-in camera and associated video processing circuitry. The built-in camera has a lens that captures an image of the scene in front of the camera. The video processing circuitry then processes the image and provides the Vcam video signal, which contains the image captured by the built-in camera. The Vcam video signal is a composite video signal with just the image captured by the built-in camera. Camera system 130 may be implemented with a camera CMOS IC such as, for example, an OV7910 or an OV7930 color CMOS analog camera chip from Omni Vision (™). The use of a CMOS camera chip for camera system 130 provides various benefits such as low cost, smaller area, greater reliability, less power consumption, and so on.

A video buffer 234 receives and buffers the camera video signal from camera system 130 and provides an amplified camera video signal, V′cam. Video buffers 234 and 244 also provide isolation between the Vcam video signal and the Vce/lpf video signal so that (1) the Vce/lpf video signal does not feed through to the Vcam video signal, when these two signals are combined by video selector 246, and bleed into a Camera Out output, and (2) vice versa.

A video selector 246 receives the Vbuf video signal from video buffer 244 and the V′cam video signal from video buffer 234. Video selector 246 provides an output video signal (Vout or Video Out) which may be (1) the graphics video signal with the lyrics (i.e., the Vbuf video signal), (2) the camera video signal with the image captured by built-in camera 130 (i.e., the V′cam video signal), or (3) the composite video signal with both the lyrics and image (i.e., a Vcomp video signal). The Vcomp video signal is generated by merging the Vbuf and V′cam video signals. The determination of which video signal to provide as the output video signal may be determined by a user, by pre-configuration, and so on. Depending on a video selection control signal, Csel, the output video signal may be relatively static or may jump dynamically from video signal to video signal.

The output video signal is typically connected to a television so that the user can see on the television screen what has been selected (e.g., lyrics, image, or both lyrics and image). The camera video signal (or Camera Out) may also be provided to a VCR (or DVD recorder) and used to record the image without the lyrics.

Karaoke system 100 can superimpose the graphics video signal from CDG decoder 224 on top of the camera video signal from camera system 130. This allows the lyrics from a CDG disc to be displayed on the image captured by camera system 130. The camera video signal can capture the excitement of users and audience gathered within a room for karaoke. Showing this captured image on a television screen can enhance the experience of those in the gathering. Superimposing the lyrics over the camera image can (1) allow the singer(s) to see how he/she/they perform without missing the lyrics, (2) allow the singer to read the lyrics and the audience to see the live scene on the same screen at the same time, which can bring extra fun to the karaoke experience.

The video and audio portions of karaoke system 100 is described below. The video processing units within karaoke system 100 may be implemented in various manners. Exemplary designs for these units are described below.

FIG. 3 shows a schematic diagram of an embodiment of noise filter and amplifier 240 and color eliminator 242. Noise filter and amplifier 240 includes an input buffer 310, a noise filter 320, and an amplifier 350. The graphics video signal, Vcdg, is provided to the base of an NPN transistor 312. Noise filter 320 is implemented with resistors 322 and 330, capacitors 324 and 328, and an inductor 326, as shown in FIG. 3. Noise filter 320 removes digital noise generated by CDG decoder 224. Two-stage amplifier 350 is implemented with an NPN transistor 352, a PNP transistor 362, and resistors 354, 356, 358, 364 and 366, which are coupled as shown in FIG. 3. The first stage has a gain determined by the ratio of resistors 354 to 356. The second stage has a gain determined by the ratio of resistors 366 to 364. Resistor 358 provides feedback for the two stages to improve linearity.

Color eliminator 242 eliminates or suppresses the designated color (e.g., blue) from the graphics video signal so that a clearer picture with both the lyrics and image is displayed on the television screen for the composite video signal, Vcomp. Color eliminator 242 is implemented with an inductor 378 and capacitors 380 and 382, which are coupled as shown in FIG. 3. Inductor 378 and capacitors 380 and 382 form a trap filter having a very low impedance (almost ground) for certain frequency (e.g., the designated color) and a nominal impedance for other frequencies (other colors). The designated color may be blue or some other color which may either be pre-set or adjusted by the user. The resonant frequency of the trap filter is determined by the values of inductor 378 and capacitors 380 and 382 and may be adjusted with variable capacitor 380. The trap filter may be enabled by closing a switch 376 and disabled by opening the switch with the CEenb control signal. NPN transistor 372 and resistor 374 also provide buffering for the Vce/lpf video signal, which may or may not have the designated color removed.

FIG. 4 shows a block diagram of an embodiment of camera system 130. A 2-dimensinonal array 410 of photodiodes converts incoming light into charge. A row decoder 412 selects one row of photodiodes at a time based on a control signal from a clock/timing generator 440. Column sense amplifiers 414 convert the charges in the selected photodiodes into voltages. An analog processing unit 420 processes the signals from sense amplifiers 414 and provides component signals. For example, analog processing unit 420 may perform color separation, automatic gain control (AGC), gamma correction, black level calibration, aperture correction, luminance and chrominance processing, filtering, and so on. A video encoder 430 converts the component signals from analog processing unit 420 into a composite video signal, which is provided as the camera video signal, Vcam.

Clock/timing generator 440 receives the buffered OSC and FSI signals from buffer 226 and generates various controls for row decoder 412, analog processing unit 420, and video encoder 430. A control unit 450 receives the auto white control signal Cabc and possibly other input control signals and controls the operation of analog processing unit 420 and video encoder 430. Control unit 450 implements auto white balance adjustment algorithm 230 and adjusts the white balance under the specific IC pin setting. As noted above, camera system 130 may be implemented with a CMOS camera chip.

FIG. 6 shows the horizontal timing for a video signal generated by karaoke system 100. In general, the video signal may be an NTSC or PAL signal. For an NTSC signal, each horizontal line of active video has the timing shown in FIG. 6. The vertical timing for the video lines in the video signals from CDG decoder 224 and camera system 130 is determined by the FSI signal. The color subcarrier and color bursts are generated from the OSC signal and has a frequency that is one quarter of the frequency of OSC signal.

FIG. 5 shows a schematic diagram of an embodiment of video buffers 234 and 244. Video buffer 234 is implemented with a PNP transistor 522, resistors 512, 514, 524, and 528, and a capacitor 526, which are coupled as shown in FIG. 5. Resistor 514 provides termination for the camera video signal from camera system 130, which is designed to drive a standard television or video monitor. PNP transistor 522 and resistor 524 implement an emitter follower that buffers the camera video signal and drives subsequent circuitry. Since the emitter of PNP transistor 522 is a low impedance source, the Vbuf video signal is prevented from flowing backward and affecting the Vcam video signal. Capacitor 526 and resistor 528 provides a source impedance for video buffer 234.

Video buffer 244 is implemented with a PNP transistor 552, capacitors 542 and 556, and resistors 544, 554, and 558, which are coupled as shown in FIG. 5. Capacitors 542 and 556 provide AC coupling. PNP transistor 552 and resistor 554 implement an emitter follower that buffers the input video signal and drives subsequent circuitry. Since the emitter of PNP transistor 552 is a low impedance source, the V′cam video signal is prevented from flowing backward and affecting the Vce/lpf video signal. Resistor 558 provides a source impedance for video buffer 540.

FIG. 5 also shows an embodiment of video selector 246. Video selector 246 receives the Vbuf video signal from video buffer 244 and the V′cam video signal from video buffer 234. Within video selector 246, a summer 562 combines (or merges) the Vbuf and V′cam video signals to obtain the composite video signal, Vcomp. The Vbuf and V′cam video signals may also be combined in other manners. For example, the Vbuf video signal may be multiplexed as the output video signal for certain video lines and the V′cam video signal may be multiplexed as the output video signal for other video lines. A multiplexer 564 receives the Vbuf, Vcomp, and V′cam video signals and the Csel video selection control signal from controller 210. Based on the Csel control signal, multiplexer 564 provides one of the three video signals as the output video signal, Vout.

Referring back to FIG. 2, karaoke system 100 also includes an audio portion. A microphone amplifier 270 receives input audio signals from two microphones, Am1 and Am2, amplifies each input microphone signal, combines the two amplified microphone signals, and provides a combined microphone signal, Am. Microphone amplifier 270 may also be designed to receive one input audio microphone signal, or to receive and combine more than two input audio signals.

An echo system 272 simulates echo effect in the combined microphone signal. This may be achieved by (1) delaying the combined microphone signal by different amounts of delay to obtain different delayed versions of the combined microphone signal, (2) scaling the different delayed versions by different gains (e.g., lower gain for greater amount of delay) to obtain scaled and delayed versions of the combined microphone signal, and (3) combining the scaled and delayed versions to obtain an echo signal, Ae. Echo system 272 provides the echo signal having echo effect. The echo effect may be turned off or reduced by getting the gains for greater delays to zero or low values.

An AVC system 274 controls the combining of the combined microphone signal, Am, from microphone amplifier 270 with the left audio signals, ARcdg, from CD servo system 222. When AVC system 274 is activated and a microphone signal is received, AVC system 276 mutes (partial mute, depended on the VR knob) the right audio signal from CD servo system 222 so that the combined microphone signal can be provided on the right audio channel. The user can control the amount of muting by turning a knob (e.g., one of knobs 142 in FIG. 1). AVC system 274 provides a mute control signal, Cavc, for muting the right audio channel for AVC.

AVC mute circuit 276 receives the echo signal, Ae, from echo system 272 and the left and right audio signals, ALcdg and ARcdg, from CD servo system 222. AVC mute circuit 276 combines the echo signal with each of the left and right audio signals and further mutes the right audio channel if directed by the mute control signal. AVC mute circuit 276 provides ALl and ARl audio signals.

A volume balance unit 278 receives the ALl and ARl audio signals, adjusts the amplitude of each of the two audio signals based on a balance control signal, Cbal, and provides adjusted left and right audio signals, ALb and ARb. The user may manipulate the balance control signal (e.g., with one of knobs 142 in FIG. 1) so that the left/right balance is suitably adjusted.

A system mute circuit 280 receives the ALb and ARb audio signals from volume balance unit 278 and mutes both audio channels if indicated by a reset control signal, Creset. For example, the audio signals may be temporarily muted when karaoke system 100 is first powered on or reset. Mute circuit 280 provides final right and left audio signals, ALf and ARf.

An audio buffer 282 receives and buffers the final left and right audio signal from mute circuit 280 and provides an output audio signal, Aux Out, for the left and right channels. A power amplifier 284 also receives and amplifies the final left and right audio signal from mute circuit 280 and provides a speaker output signal, Speaker Out, for a speaker and an output audio signal, Headphone, for a headphone jack. The amplification may be in accordance with a loudness setting that may be adjusted by the user.

The karaoke system described herein may be used with various disc formats such as CD, CDG, SCDG, MP-3, DVD, and so on. Different disc formats may be supported through the use of different decoders. The other video processing units within karaoke system 100 (e.g., noise filter and amplifier 240, color eliminator 242, buffers 234 and 244, and video selector 246) can perform the same processing to provide the desired output video signal, regardless of the disc format.

The karaoke system described herein may be implemented by various means. For example, the video and audio processing units for the karaoke system may be implemented in hardware, software, or a combination thereof. For a hardware implementation, the processing units may be implemented within one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, micro-controllers, microprocessors, other electronic units designed to perform the functions described herein, or a combination thereof.

Portions of the karaoke system may also be implemented in software. For example, the controls for various processing units may be implemented with modules (e.g., procedures, functions, and so on) that perform the functions described herein. The software codes may be stored in a memory unit (e.g., memory unit 212 in FIG. 2) and executed by a processor (e.g., controller 210).

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.