Audio effects (2)

This articleArticleThis section describes several mainstream audio effects:

I. Microsoft playfx sound technology

Microsoft's playfx sound technology includes 3D headphone, pure bass, and auto volume to immerse audiences in the 3D music world, enjoy a dynamic and thrilling experience and a sound experience with consistent volume. This sound effect instantly improves the sound quality of this new product and brings new music experiences to consumers.

First, we need to learn about playfx sound technology theoretically. Microsoft developed a playfx technology that integrates the best listening experience with rich knowledge in the field of human perception. The result is a complete set of signal processing with easy deployment.AlgorithmAudio technology that combines efficiency with sound quality. The features provided by the playfx technical suite are as follows:

● Autovolume creates a pleasant and consistent listening experience by providing consistent volume levels during the music playlist process.

● Pure bass is designed specifically to improve the dull and powerless bass effect in other ways. The proprietary pure bass algorithm provides a clear and powerful low-end frequency that listeners expect from high-quality speakers.

● The 3D surround speaker provides an immersive audio experience in the home media room, as if sitting in the front row of a live concert. The 3D speaker designed for the multi-channel home theater Environment draws on the main advantages of dual-channel stereo music and extends it to the center, rear and side speakers, to create a realistic environment like a concert hall.

● 3D surround headphones provide a complete three-dimensional sound field through headphones and ear plugs.

● Room calibration optimizes the audio experience of home speakers to adjust any location. The user selects a point in the room. through several quick measurements, the indoor calibration function can compensate for speaker placement and indoor sound effects, this accurately balances the frequency response, volume, and latency of each speaker at the listening position.

● Bass management is designed for the home theater environment. The bass management function allows listeners to control which speakers play low-frequency content.
According to the products we have obtained, the original MP3 app of Microsoft playfx is mainly reflected in: 3D surround, pure bass, and volume balancing, in addition, indoor calibration and bass management are mainly used in home cinema equipment and are not used in portable media players.

(I have tried a player with this special effect. Some of the effects are not as good as described in publicity. When a special effect is enabled, the original audio quality will be affected)

Ii. SRS sound effects (this effect is applied to Zhuhai moments and sigmtal decoding chips)

The birth of an SRS

SRS is the abbreviation of the sound retrieval system, which means the audio restoration circuit, can reproduce the real three-dimensional sense of the scene. It is the latest audio technology patent of the SRS lab in the United States. The main direction of SRS is dual-channel surround, AND SrS () is its registration mark.

The inventor of SRS technology is Arnold Klayman ). He is an audio enthusiast. When he was engaged in psychological acoustics research, he found that the positioning of the sound source in three-dimensional space by the human auditory system always led to the prototype of SRS technology. You can do an experiment, rub your fingers on the forehead, and then slowly shift your fingers back to the side of your head, so that your fingers are equal to your forehead and ears, you will notice that the volume is increased, medium, and high. In the experiment, rubbing your fingers is equivalent to generating a stable volume. Your ears have the same sound of hearing and different instructions on the brain, depending on whether the sound comes from the front or the side, the sound from the side is loud, which is caused by the ear chamber.

When the sound comes from the front, the ear Chamber reflects many frequency elements from the ear canal, and the side of the sound is different from the reflection. In this way, the sound intensity from the side is high and the arrival time is short, and the ear transmits the information to the brain, which is called brain-related transmission function. Because this propagation is determined by the volume and direction of the sound, sound waves are always changing during the propagation, and the details of the changes must be provided to your brain so that you can know what you are listening, in what direction.

Traditional dual-channel stereo sound cannot create a three-dimensional surround sound field, not because only two speakers are used, but because the microphone in the dual-channel recording has no ears, therefore, when recording a microphone, the sound on the side cannot be the same as that on the human ears, no matter how many microphones are used. The SRS system takes into account these changing transmission functions, so that the listener can hear more similar to the original performance.

Ii. Basic Principles

RS is recorded in the left and right audio channels according to the surround sound (reflection and reverb sound) that can reflect the field sense in the stereo signal, add the R and l signals to produce a total signal (R + l), and then subtract the two signals to generate two differential signals (R-L) and (L-R ), the total signal, differential signal, and surrounding environment information (reflected sound field and reverb sound field) after SRS processing are provided to the human ears system. For microphones and conventional stereo sound, because of the "L-R" and "R-L" differential signal microphone "can not hear", stereo sound system can not copy, therefore, there is no sense of space during replay. SRS processes the differential and total signals. The final sound conforms to the human auditory system and the spatial information is restored. In this way, the restoration of the real playing environment enhances the stereo image, so that people can intuitively feel the spatial orientation and distribution of the audio and video.

Three applications 

SRS has an amazing effect on live recordings (concerts, movies. If the program source itself does not have an on-site environment sound, such as the multi-channel pre-recording and post-synthesis cdns, or computer synthesis, the effect is not as obvious as the live concert. SRS can play normal stereo program sources, Dolby Surround Sound encoding programs, and process single-channel signal sources, using stereo amplifiers and two speakers to create a three-dimensional surround sound field with a sense of space.

There is no limit on the speaker placement and listening position of SRS. Even if the two speakers are very close or move around in the room, you can hear three-dimensional surround sound with a strong sense of space. SRS can be combined with a variety of existing stereo sound to form a set of three-dimensional surround sound. Practice shows that the higher the audio class, the more we can reflect the style of SRS. In my opinion, a couple of hundreds of Yuan better source integrated speaker with SRS can become a very cost-effective SRS home theater audio system, absolutely in line with the principle of personal consumption.

SRS has been protected by U.S. patents and has obtained 17 patent rights abroad, and 45 other patents are pending worldwide. Existing authorized companies include SONY, RCA, and NEC.

SRS 5250s is developed and licensed by SRS labs. It is a three-dimensional audio processor for the execution of SRS sound replication systems, produced by seponx.

There are already some processors on the market that claim to have the SRS function. When purchasing the software, you should first pay attention to the presence or absence of registered trademarks of the SRS lab. Secondly, specifies whether the SRS-specific center Adjustment Center and space control potentiometer are available.

When SRS 5250s is used, it must be connected between the audio source and the Power Amplifier. If there is a frequency balancer or tone circuit before the power amplifier, SRS 5250s should be connected to the frequency balancer.

Iv. Comparison with Dolby decoding surround sound system 

Let's talk about the results of comparison between the Dolby decoder surround sound system (Dolby prologic) of SRS surround sound system: Use two identical speakers and switch SRS and Dolby multiple times, when using SRS, professionals often check whether the rear speaker is working. In fact, SRS is the front speaker working. SRS sound definition is higher than Dolby logic, and the ring sound is a continuous Three-dimensional Sound Field, full of space; while Dolby ring sound is from five speakers, the listener feels a plane two-dimensional sound field.

If SRS is placed in the front of Dolby, the original flat two-dimensional sound field changes to a three-dimensional sound field with a sense of space continuity, which makes people feel a real sense of monitoring. The SRS surround sound makes people feel that each sound source is distributed in the whole three-dimensional space. The speaker is no longer a source point, the masking effect between each sound source is much weaker than that of a traditional multi-channel system with only a few "points", so the SRS definition is higher than that of multi-channel surround. The background noise is replayed from two speakers (two points). The noise is concentrated on two points, while the noise is distributed throughout the space during the SRS system, compared with the centralized noise of a general stereo system, the background noise of SRS has little effect on the signal interference of sound, therefore, SRS are superior to stereo sound in terms of sound restoration, sound definition, and noise reduction.

(Note: This kind of International Audio special effect also has related software. You can try it, but the trial version can only achieve several effects, and there is a time limit)

3. Bee sound effects

We understand that bbe technology originated in 1985, but now, bbe technology has evolved through several generations, it has evolved from the patented power amplifier technology to AV audio-visual, Walkman, broadcast, CD, and digital audio technology.

Bbe sound has always had very strict quality control over bbe technology. To put it simply, although bbe technology is very cost-effective, it is not that easy to obtain bbe authorization. After the partner submits an application to bbe sound, bbe sound will first send someone to investigate the partner. After the company's strength is recognized, it will be authorized by BbE, in the product design process using bbe technology, bbe sound will be involved in the design of sound effects. After the final sound quality is recognized, the product can be added with the trademark of bbe sound. This rigorous operation method also makes the bbe trademark a symbol of superb quality in the audio industry. Unfortunately, bbe sound does not directly grant algorithm authorization to Chinese enterprises due to its distrust of intellectual property rights in China. Therefore, most Chinese enterprises are indirectly authorized by bbe sound by purchasing chips from third-party countries.

The bbe technology improves the sound quality, mainly because the whole audio domain seems to be much wider than the original sound, and the level of the high and low sounds has become very clear, this experience is significantly different from the effect of the traditional EQ. Which method does bbe use to improve the sound quality?

It should be noted that the bbe technology is generally referred to as a general term. In fact, bbe technology has different branches for different applications, while bbe is the most basic one, it also includes:

Bbe-the most basic algorithm. All other branches are based on BbE.
Bbe mach3bass-bass lifting algorithm, widely used
Bbe viva-bbe 3D effect, applicable to stereo TV, portable single sound, etc.
Bbe MP-compression compensation algorithm, suitable for MP3, MD, and other products that use lossy compression music formats
Bbe OPTIMA-Simplified bbe-related algorithms, removing the bbe algorithm of adjustment items
Bbe K3/K1-compression/restriction/automatic gain control for professional program recording
Bbe T2/T2R/t2c/t2m-bbe telephone technology, comprehensive use of bbe MP and bbe K3 technology to achieve high-quality phone call results

The bbe technology used for MP3 mainly includes:

Bbe mach3bass: this algorithm is based on bbe and used to improve the low-frequency capability. It is different from the simple increase of the general EQ method. Because of the error correction, therefore, when it improves the low frequency, it does not make others feel the attenuation of other frequencies, especially the intermediate frequency (VOICE.

Bbe MP: this algorithm is very important for those of us who often play MP3, because it was born to make up for this type of lossy compression (including MP3, MD, Ogg, WMA, etc) the loss. Generally, such compression algorithms discard the weak parts of the music signal, because in terms of auditory theory, that part of the audio cannot be heard by human ears. But in reality, that part of the sound may contain some eye-catching details. Therefore, the music after this part of compensation, will make people feel more delicate, after the BBE-MP processing of the music package contains more details.

In terms of the actual listening effect, the sound effects implemented by bbe have almost no loss in the intermediate frequency, while SRS is not perfect in this aspect, but SRS is better than bbe in the sense of presence.

Because of the strict requirements for bbe admission, it is difficult for us to see bbe in popular devices. Currently, only several iaudio MP3 players have bbe sound effects, therefore, we can see that digital products are beginning to notice the charm of BbE. I believe that with the increasing popularity of bbe, there will be more and more MP3 players with bbe sound effects.

Advantage: The bbe effect makes the sound more clear and transparent, and it is not easy to get bored for a long time, and the sound is quite audible.

Bbe MP plays back the sound of lossy compression files such as MP3 and carries out frequency Regeneration. For files with high bit rates, it can be similar to MD. Bbe M3B stresses, elasticity is good, and ears are not easy to hurt. The bbe 3D surround effect is similar to SRs and Xtreme 3D. In fact, almost all 3D sound effects are relatively close. The difference is not big.

Disadvantage: bbe M3B does not have deep stress dive.

Overall Evaluation: bbe sound effects are more suitable for playing popular rock games. Clear and audible.
(This special effect is widely used in MP3 or MP4 decoding chips from South Korea ).

 

I have collected all the content in this article on the Internet during the study of audio special effects. I will reference it here.