Method and structure to output four-channel analog signal using two channel audio hardware

Method and architecture for outputting four-channel analog signal by two-channel audio hardware

<p>Sound effect program. . . 100</p><p>Operating system core program. . . 110</p><p>Sound hardware driver. . . 120</p><p>PCI sound card. . . 130</p><p>Multi-channel PCI sound hardware. . . 140</p><p>Multi-channel digital analog converter. . . 150</p><p>Multi-channel analog signal. . . 160</p><p>The motherboard South Bridge has built-in two-channel audio hardware. . . 230</p><p>Two-channel digital analog converter AC97 CODEC. . . 240</p><p>Two-channel analog signal. . . 250</p><p>Sound effect program. . . 300</p><p>The core program of the operating system. . . 310</p><p>Four-channel-two-channel conversion function means. . 3.20</p><p>Software frequency converter. . . 330</p><p>Identify the tag generator or means (genes for generating tag). . . 340</p><p>Data reformer or means for formatting. . . 350.</p><p>The motherboard South Bridge has built-in two-channel audio hardware. . . 360</p><p>Codec device (CODEC). . . 370</p><p>Data tag converter or functional means. . . 380</p><p>Hardware frequency converter. . . 390</p><p>Four-channel digital analog converter. . . 400</p><p>Four-channel analog signal. . . 410</p>

The preferred embodiment of the present invention will be explained in more detail in the following description with the following figures:

Figure 1 shows the traditional PCI high-order multi-channel audio software and hardware processing architecture.

Figure 2 shows the built-in two-channel software and hardware processing architecture of the traditional motherboard south bridge.

FIG. 3 shows the four-channel enhanced sound effect software and hardware processing architecture of the present invention.

Figure 4 shows the architecture of the Windows-based operating system of the present invention.

Field of invention:

The present invention relates to a method and architecture for multi-channel audio output, and more particularly to an analog sound effect that can be used to output a two-channel audio effect of a two-channel audio output.

Background of the invention:

With the continuous expansion of the information and computer market, electronic products are driven by the trend of thin, short, and versatile. Personal computers have become the standard for performing homework and entertainment. With the development of integrated technology and peripheral devices, the DVD multi-channel home theater playback system, which is constantly improving the effects of entertainment and computing, and based on the PC, is based on the innovation of the industry and expands the scope of the market and services. In addition, in recent years, computer games on PCs have begun to add 3D positioning sound effects, so that the original screen is very attractive, the game has increased the ability to listen to the sound, and also because of the popularity of DVDROM, most PCs are already equipped with DVD playback. The ability to multi-channel movies also puts the PC's sound into a multi-channel system. At present, 3D positioning technology generally includes HRTF (Head Related Transfer Function) and Panning. The HRTF mainly uses the model of the human ear to find out the way the brain judges the orientation, and then uses the DSP to copy the sound that can deceive the brain. The three elements of sound localization include the difference in the amplitude of the IAD-ear two ears, the time difference between the ITD and the ears, and the frequency response allows the brain to produce a sense of height and rear.

In theory, a good HRTF Library plus a superior crosstalk cancellation circuit (TCC) to add a sweet spot (Sweet Spot) should be the ideal 3D positioning system, and as long as two speakers can produce up/down, Pre/post effect. In general, the system is not as ideal, because the crosstalk cancellation circuit is also measured by the dummy head HRTF The formula derived by Library, and the dummy head is not the same as the real head (each person's head is not exactly the same), so it is impossible to completely eliminate the crosstalk between the speakers, so that the brain can be carefully calculated. The sound field. In addition, the speaker frequency response of a general PC is not ideal. There is no way to send a distortion-free waveform. The pre-prepared crosstalk cancellation signal successfully pushes the air through the horn to the person's ear. In particular, some high-frequency signals are more difficult to pass through the speaker to the ear. At this time, the sound that should have formed an audio image at the rear will appear in the front. This is of course also because the resulting front speakers are closer to themselves. Unfortunately, the high-frequency component is the element that the brain uses to judge the top and bottom. Therefore, if the speaker distortion is more serious, the effect of the 3D sound field will not be too good. Fortunately, the improved four-channel HRTF system can solve this problem. If the front and rear channels use the HRTF to generate the sound field, the most difficult rear sound field is generated by the human brain and the structure of the ear shell. In this way, we only need to deal with the height and other directions, and the four channels improved by the two-channel HRTF Library can successfully demonstrate the advantages of HRTF. The sense of height and horizontal plane is quite smooth and four channels. The sweet spot will also be relatively large so that more users can enjoy the three-dimensional sound effect from all directions.

The other is called Panning technology. Generally speaking, HRTF technology will involve the issue of authorization of rights. Therefore, in order to save the license fee of using foreign HRTFLibrary, some audio chips use Panning technology. Panning technology, in fact, also uses the positioning system of the two factors of IAD and ITD, using the rear speakers to make up for the lack of sound field. The effect of such a four-channel sound system at the level is acceptable.

With the current CPU computing power, you can play SoftwareDVD smoothly and provide AC35.1 audio field output. AC3's audio track is divided into: left front, right front, left rear, right rear, center speaker, super bass and other six channels. If it is expressed by four speakers, the sound in four directions will be directly sent to the four speakers of the PC, and the sound of the center speaker will be synthesized by the front left and right speakers. That is to say, the middle sound is as long as the average of the two horns in front of the brain will naturally feel an audio image in front. Since the wavelength of the acoustic wave received by the brain exceeds the diameter of the head, there is no way to resolve the orientation. Therefore, the long-wave woofer can only be designed with one good effect. In the four-channel system of the PC, the 4.1D speaker specification is designed in the industry, that is, the design of four channels plus a subwoofer. The source of the subwoofer's sound is to filter out the non-directional low-frequency components with a low-pass filter in the front two-channel material, and then send it to the mono bass amplifier to drive the speaker. Therefore, the AC3's subwoofer data uses this architecture to add the bass component to the two speakers in the front channel. After that, it is automatically separated by an external filter. From the above description, we can know that the four-channel core 3D positioning sound technology can greatly improve the limitation of the two speaker sound fields by using the newly added satellite speakers. It has become a must-have playing environment for small home theaters. Therefore, after 1999, the high-end PCI sound card is almost all 4 channels of sound effects for sales focus, but the price-oriented motherboard is the hope to balance the price and function.

Figure 1 shows the traditional PCI high-order multi-channel audio software and hardware processing architecture. In block 100, the sound effect application in the application software processes the sound effect information or signals to the operating system core program 110 in the operating system through the high-level interface. The above application software includes 3D games, CDs, MP3 players or DVD multi-channel home theater playback software. In addition, the operating system referred to herein is known to those skilled in the art and includes Microsoft's Windows series, Linux, and Beos. One of the functions of the operating system involves the creation of a standard sound interface that allows application software to play on any hardware platform.

Then, in block 120, the processed data or signal can be used to convert the multi-channel data transmitted by the upper layer into a hard-acceptable multi-channel DMA (directmemory access) through the low-level interface via the audio hardware driver. Delivery format. Then, the hardware-receivable data multi-channel digital sound or signal is transmitted to the hardware through the PCIDMA interface, such as the PCI sound card 130. The PCI sound card 130 described above includes a multi-channel PCI sound hardware 140 and a multi-channel digital analog converter (Code and Decode; CODEC) 150. Therefore, the data or signal processed by the multi-channel PCI audio hardware 140 is processed by PCI integrated single chip or AC-LINK, and then transmitted through the multi-channel digital analog converter 150 to soften the digital sound to the adult ear. The actual sound that can be heard. A digital analog converter is required for each channel. Finally, the above-mentioned digital analog data or signal 160 is generally outputted through a multi-channel analog signal via an output device (generally a speaker or a headphone).

The disadvantage of this prior art is that the high-order sound processing device is relatively expensive, and it is difficult to popularize the sound system built in the motherboard.

Figure 2 shows the built-in two-channel software and hardware processing architecture of the traditional motherboard south bridge. That is, the processing before the hardware level is similar to the previous conventional PCI multi-channel audio processing, and the signal data is fed to the operating system core program 110 by the high-level interface. The multi-channel data transmitted by the upper layer is converted into a hardware-acceptable multi-channel DMA transfer format by the low-level interface via the audio hardware driver.

Then, the hardware-receivable data is transmitted to the motherboard south bridge to build a two-channel audio hardware 230. The above-mentioned motherboard South Bridge built-in two-channel audio hardware 230 includes a built-in digital circuit that provides a DMA interface and an AC-LINK format conversion circuit to transfer digital data to the two-channel digital analog converter AC97CODEC 240. In general, the AC97 CODEC 240 can be installed directly on the motherboard or through the AMR/CNR expansion slot card developed by Intel. The two-channel analog signal 250 processed by the above digital analog conversion is outputted by the output device in two-channel audio.

The above-mentioned two-channel digital analog converter output class uses a two-channel digital analog converter as a two-channel signal. The disadvantage is that it cannot provide a high-order four-channel effect, and cannot satisfy the necessary playback environment of a small home theater.

In view of the above disadvantages, the present invention will provide a solution that can provide high-order four-channel audio effects under the existing two-channel south bridge architecture.

Purpose and overview of the invention

The main object of the present invention is to make a hardware capable of outputting two-channel sound effects by using the method and architecture of the present invention, and the four-channel analog sound can be output by the present invention.

A further object of the present invention is to provide a reinforced audio hardware driving function, which facilitates the transmission of the encoded four-channel data by the hardware of the two-channel 48KHZ and 16bits formats.

It is still another object of the present invention to provide an enhanced four-channel encoding and decoding function for facilitating the output of a four-channel analog signal.

The invention discloses a method for outputting a four-channel analog signal by a two-channel audio hardware, comprising: an audio application transmitting information to a core program of a working system through a multi-channel sound interface; and an operating system core program receiving multi-channel sound information The software converter reduces the four-channel frequency to half to save bandwidth; establishes the identification labels of the front and rear channels to avoid the loss of the above four-channel data in the transmission; re-forms the above four-channel format to two channels Information, so that the hardware can smoothly transmit the encoded four-channel data; the re-formed information is transmitted to the two-channel audio hardware; the data label is converted to facilitate the hardware to distinguish the front and rear channels for correctly separating the four channels. Data; the hardware frequency converter is converted to a four-channel analog signal by frequency doubling to reduce distortion due to data compression.

The architecture of the present invention enables a two-channel audio hardware to output a four-channel analog signal, and includes a sound effect program for processing multi-channel sound information of the application software. The operating system core program receives multi-channel sound information transmitted by the above-mentioned sound effect program through a multi-tone to sound interface. Means for transforming afour-channel signal to two-channel signal, coupled to the operating system core program to convert four channels of information transmitted by the low-order interface into two sounds The information output of the road. Two-channel audio hardware, coupled with the above four-channel-two-channel conversion function. The codec is coupled to the two-channel audio hardware for converting the information of the two channels into a four-channel analog signal.

The above four-channel-two-channel conversion function means: a software frequency converter, which reduces the above four-channel frequency to half to save bandwidth. A tag generator or means (meanS for generatingtag) is used to establish an identification tag to prevent the above four-channel data from being lost in transmission.

A data reformer or means for formatting, which is used to reform the data format so that the hardware can smoothly transmit the encoded four-channel data.

The above codec comprises: a data tag converter or a functional means, and the above identification tag is used to facilitate the hardware to distinguish the front and rear channels for correctly separating the four channels of data. The frequency converter is processed by frequency doubling to reduce distortion due to data compression. A four-channel digital analog converter that converts digital information into the above four-channel analog information.

Detailed description of the invention

The present invention discloses and provides a method for the two-channel south bridge chip to cooperate with the enhanced sound effect hardware driving function provided by the present invention, so as to facilitate the two-channel audio hardware processing of the encoded four-channel data. Used to achieve the output analog analogy of four-channel sound. Therefore, the present invention provides an enhanced sound-driven hardware driving function for converting a four-channel, 48K, and 16-bit format into a two-channel 48K, 16-bit format to facilitate the transmission of encoded information. Furthermore, the present invention provides an enhanced four-channel encoding and decoding function to facilitate output of a four-channel analog signal.

The present invention is described in detail below. The preferred embodiment is not intended to limit the present invention. FIG. 3 is a functional architecture diagram of an embodiment of the present invention. The software user hierarchy of the present invention includes a sound effect application. 300. The user can execute the application software, and the sound effect program transmits the sound information or signal to the core program 310 of the operating system through the high-level interface and multi-channel sound interface. The above application software includes but is not limited to 3D games, CDs, MP3 players or DVD multi-channel home theater playback software. In addition, the operating system referred to herein is known to those skilled in the art, including but not limited to Microsoft's Windows series, LinuX, BeOS. One of the functions of the operating system involves the creation of a standard sound interface that allows application software to play on any hardware platform. In the present invention, the enhanced four-channel architecture has four-channel processing capability, so the lower driver will report the hardware playback capability to four channels. Therefore, the operating system converts multiple channels into four-channel signals. Or information.

After that, the information of the operating system conversion, including four-channel 48K, 16-bit information format, is transmitted to the four-channel to two-channel converter through the low-order interface or defined as four-channel - two sounds The processing is performed in a mean S for transforming a four-channel signal to two-channel signal. Through the above-mentioned four-channel-two-channel conversion function means 320, the input four-channel 48K, 16-bit information can be converted into two-channel 48K, 16-bit information output.

In a preferred embodiment, the four-channel-two-channel conversion function means 320 is an enhanced audio hardware driver. A software frequency converter 330, an identification tag generator or a mean tag for generating tag 340, and a data reformer or means for formatting 350 are included.

In this driver hierarchy, the enhanced audio hardware driver will return four channels of playback, so the upper layer (operating system level) will transmit 48KHZ of four channels of data to the driver. The frequency is down-converted to 24 kHz through the software frequency converter 330 to save half the bandwidth.

Thereafter, the down-converted information is created using an identification tag generator or means for generating tag 340. The main purpose is to prevent accidental loss of four-channel data during transmission, resulting in unrecognizable data before and after. In an embodiment, the identification tag can be added to the resolution of any bit of any of the preceding and following channels. For an embodiment, the identification tag can be added to the resolution of any last bit of any channel before and after, so that the Enhanced Ac97 Tag decoding circuit can distinguish the front and rear channels. The invention utilizes the sacrifice of one bit as the identification tag, and the quality of the sound will be reduced from the theoretical value of 96db to 90db. However, the environment required by a general PC is about 85db or more, so the sound quality of 90db still meets its requirements.

After the identification tag is created, the data format is reformed using a data resizer or means for formatting 350. That is, the 24 KHz, four-channel, 15-bit audio and 1-bit tag data format package is converted into a two-channel, 48 KHz, 16-bit format. The hardware can smoothly transmit the encoded four-channel data, that is, 2CH, 48KHz, 16bits DMA format.

After the above-mentioned coded information is input into the hard-level hardware, in one embodiment, the two-channel audio hardware 360 included in the south bridge of the motherboard may be used.

The two-channel signals described above are decoded by a codec (CODEC) 370. For a preferred implementation, it is possible to include, but is not limited to, a reinforced four-channel AC97. The AC97 CODEC acts as a codec (CODEC) 37 and can be built directly into the motherboard or via the AMR/CNR expansion slot card developed by InteL.

In the codec 370, the data tag is first used by the data tag converter or the function means 380 to identify the front and rear channels by using the label of the tag bit to correctly separate the four channels of data. In other words, it is converted to the front and rear channels, 24KHz, 16-bit format.

Thereafter, the hardware frequency converter 390 is used to perform hardware frequency multiplication processing to reduce distortion due to data compression. That is, the hardware frequency converter 390 converts the frequency from 24 kHz to 48 kHz.

The frequency-converted information is converted into four-channel analog information by a four-channel digital analog converter 400 built into a codec (CODEC) 370, and output through an output device (generally a headphone or a speaker). The four-channel analog signal 410 is output in two-channel hardware.

Based on the above, the data frequency is converted from 48 KHz to 24 KHz, which is limited by the limitation of the two-channel hardware DMA transfer bandwidth. It is necessary to step down the data to obtain the four-channel playback capability, which is generally acceptable. Since most of the personal computer 3D games use a sound file format of only 22 KHz, 24 KHz processing power is sufficient. Moreover, the hardware will eventually convert 24K Hz back to 48 KHz to minimize distortion.

FIG. 4 shows an embodiment in which the present invention is implanted in the above operating system by taking a window operating system as an example. It is not intended to limit the invention, and those skilled in the art can apply to other operating systems in accordance with this embodiment without departing from the scope of the invention. The enhanced WDM driver 320 of the present invention is coupled to the adaPter driver of the Windows operating system. The enhanced audio hardware driver 320 is also coupled to the two-channel south bridge, allowing the hardware to transmit encoded four-channel information. The AC97 CODEC 370 decodes the above two-channel signals to output a four-channel analog signal. The AC97 CODEC can be built directly into the motherboard or via the AMR/CNR expansion slot card developed by Intel.

The present invention is described in the above preferred embodiments, and those skilled in the art can make some modifications and modifications in the scope of the invention without departing from the spirit and scope of the invention. Depending on the field.

Simple illustration

The preferred embodiment of the present invention will be explained in more detail in the following description with the following figures:

Figure 1 shows the traditional PCI high-order multi-channel audio software and hardware processing architecture.

Figure 2 shows the built-in two-channel software and hardware processing architecture of the traditional motherboard south bridge.

FIG. 3 shows the four-channel enhanced sound effect software and hardware processing architecture of the present invention.

Figure 4 shows the architecture of the Windows-based operating system of the present invention.

Main component symbol description

Sound effect program. . . 100

Operating system core program. . . 110

Sound hardware driver. . . 120

PCI sound card. . . 130

Multi-channel PCI sound hardware. . . 140

Multi-channel digital analog converter. . . 150

Multi-channel analog signal. . . 160

The motherboard South Bridge has built-in two-channel audio hardware. . . 230

Two-channel digital analog converter AC97 CODEC. . . 240

Two-channel analog signal. . . 250

Sound effect program. . . 300

The core program of the operating system. . . 310

Four-channel-two-channel conversion function means. . 3.20

Software frequency converter. . . 330

Identify the tag generator or means (genes for generating tag). . . 340

Data reformer or means for formatting. . . 350.

The motherboard South Bridge has built-in two-channel audio hardware. . . 360

Codec device (CODEC). . . 370

Data tag converter or functional means. . . 380

Hardware frequency converter. . . 390

Four-channel digital analog converter. . . 400

Four-channel analog signal. . . 410