Both are companding techniques used in telephone systems. The system of a law is mainly used in countries like Europe, etc. The main reason for using this particular system is that it is most convenient when it comes to compensating international signals. U-Law, μ-Law or Mu-Law is a standard signal compression in digital telecommunications. It is one of two standard versions of the G.711. This companding algorithm is used in telecommunications in North America and Japan to optimize the dynamic range of an analog audio signal before it is digitized. A-law is used throughout Europe as a competition standard recommended by the CCITT. By limiting the linear value of the sample, which is equal to 12 bits, we can obtain an A-law equation as mentioned below. Here, A is known as a compression parameter and its value is about 87.7 in Europe, while x is the normalized integer that needs to be compressed. In companding, we convert the signal non-linearly into a digital domain to achieve compression. The Î1/4 and A-law companding standards use logarithm-based functions to encode audio examples of Integrated Services Digital Network (ISDN) telephone services using nonlinear quantization.
The μ-law algorithm (sometimes spelled mu-law, often approximated as u-law) is a companding algorithm primarily used in 8-bit digital PCM telecommunications systems in North America and Japan. It is one of two versions of ITU-T Standard G.711, the other version being the similar A Act. A-law is used in regions where digital telecommunications signals are transmitted to E-1 circuits, such as Europe. From Nuvoton`s Archived Speech Codec FAQ: « μ-law and A-law are audio compression schemes defined by ITU-T Recommendation G.711 that compress 16-bit linear data into 8-bit logarithmic data. The coding process (called logarithmic companding) breaks down linear data into segments, doubling the size of each progressively higher segment. This ensures that low amplitude signals (where most of the information takes place in speech) receive the highest binary resolution while providing sufficient dynamic range to encode high amplitude signals. Although this method does not offer a very high compression ratio (about 2:1), it does not require much processing power to decode. In countries such as the United States and Japan, u Law is used as a composite system that is helping to radically change the digitization of signals on the Internet. The result of step a. is multiplied by 2SC, where SC is the segment code.
A) It reverses the P bit and the even bits of the code. 8-bit code = sgn(x) (lnâ¡[1+Î1/4|x|]) /(lnâ¡[1+Î1/4]). Because the encoder receives the 14-bit x signed input probe, the input range is (-8192, +8191). A-Law Compander is used in European telephone networks. A) Determine the position of the most significant bit in the input. In such cases, there is a need for a specific system with which these digitized signals can be optimized. Discover our key features with a free trial of LiveAgent and discover what it`s like to offer professional services with our solution. This special system ensures that when transmitting calls, the channels forwarding these calls do not have negative experiences during the process. μ encoding effectively reduces the dynamic range of the signal, thereby increasing the encoding efficiency while distorting the signal in a way that results in a higher signal-to-distortion ratio than that obtained by linear coding for a given number of bits. In other words, by using this particular channel, international calls can be easily optimized in order to avoid the negative effects that may be found there.
This code word is then scaled to (-256, 255) using the following format recommended by G.711. The most important function of this particular system is to reduce the dynamic range of a particular signal so that the expected quality levels can be achieved without distorting the actual signal. The encoder determines the segment code by adding a deviation of 33 to the absolute value of the input sample. In other words, some signals with a higher dynamic range can also be optimized with this particular system, and it is precisely this feature that makes u Law`s system unique in itself. B) If such a position is found, the segment code becomes the position determined in step a. minus 4, otherwise it becomes 0. Switching algorithms reduce the dynamic range of an audio signal. In analog systems, this can increase the signal-to-noise ratio (SNR) achieved during transmission; In the digital domain, it can reduce quantization error (and thus increase the signal-quantization-noise ratio). These SNR increases can be replaced by equivalent SNRs for reduced bandwidth.
Another reason for the popularity of this particular system is that it can cover not only regular calls, but also calls that have a wider dynamic range. Two of these systems are a distribution algorithm and a u-distribution algorithm. Although the two appear to be very similar and interdependent, there is a very thick line of distinction between these two particular algorithms. The u-law algorithm is used in both older analog and newer digital systems. In analog systems, it is used after sound is received by a digital computer system. This modification is performed using a nonlinear gain amplifier. Compression and expansion according to the A-distribution equation are shown in Figure 2. This is also known as compander and A-Law extension because of the encoding and decoding process. The range of the signed input is (-4096, +4095) and this sample input x is normalized to an interval (-1, 1) using a logarithmic expression. Since the day digitization conquered the world, various types of assistive technologies have been used around the world to facilitate acceptance and trust in digitization. When digitized signals are transmitted from one place to another, the main problem is that these signals collide with each other and can have adverse effects on the transmission channels. For example, this particular system is relatively popular in countries like the United States and Japan, and people there believe in this system so much.
But to the great dissatisfaction of customers, this system also has a particular drawback. Is this simply a battle of political sophistication between two standards organizations, or is there a compelling technical reason to choose one over the other (I can`t help but notice that different telecommunications organizations tied to different countries seem to be making efforts for « hegemony » at the expense of simplicity and interoperability)? Î1/4 Law Encoder enters 14-bit samples and generates 8-bit code words. It can be very confusing for some people to distinguish between these two terms. Therefore, it is very important to know where and how these two systems should be used to achieve the greatest possible efficiency. It can be said that the field of application or industry of these two systems is similar, but the actual field of operation of these two systems is very different from each other. The discrete form is defined in ITU-T Recommendation G.711. [2] If the signal is already digital, it does not need to be further compressed, as an 8-bit data file size is the ideal size for a digital file and is recognized by the icon size of most computers. μ extension of the distribution is then given by the inverse equation:[1] C) The 4-bit QC is defined on the 4 bits that follow the position of the bit determined in step a.
