A brief explanation of digital signal processing, compression, encryption and file translation
It happens to many people have no idea what that means, the digital signal processing, even if you do not hear more often these words today. Given the name, Digital Signal Processing, thinking people to conduct this process deals with digital signals. No, Digital Signal Processing is a method for improving the quality of analog signals only. In fact, the name used (DSP) is considered inadequate, because it refers to all types of digitalTransformation. The methods and techniques in DSP-action only with the transformation of the signals that are used by analogy in nature. In the case of digital signals, we can only compress, encrypt, and translates them into other digital formats (the other) procedures do not require DSP techniques. The DSP-name when it comes to digital signals leads to confusion.
That each of them one step after another, and with some practical examples. Suppose you have an old vinylwe want to protect and record the analog signal to be better than a digital copy on CD, which is taken – CD a lot of reliable information to maintain the same over time. This means that we are to convert the analog signal into digital format, and the best way to do this is through the techniques of DSP, as described below. First, we need to convert an analog / digital hardware module to the analog signal into digital format – this is usually a codec "- then select a specificSampling frequency, in order to fulfill this task. Because we use frequencies from 40 kHz audio sampling of work should be sufficient.
Please note: the sample rate should be at least twice the maximum frequency of the original analog signal – the analog audio signals have frequencies from 10 Hz to 16 kHz. After scanning, we have a copy of analog recording, expressed in digital data as a series of digital values to integersbinary.
Unfortunately, our record is pretty old and has a lot of noise about it, the noise is the digital copy, and must be filtered before burning the CD digitally. The next step is to take the digital copy – please note: The digital copy is still the analog signal – and we to them, a mathematical function transformation: in this way, change the digital time-domain "for"Frequency-domain". This will be done gradually, by changing the data in digital images of 512, 1024 or 4096 numbers in the size, and the transformation of an image at a time. Once we have the data in the frequency domain, it is easy to filter, noise, and select / check only audio frequencies we want. We use digital filters firmware or software, which in reality are well-known mathematical algorithms.
Once the disk is properly filtered, we need to changeBack in the time domain, and we do it using a second transform function. Now we are able to listen to our records, the (all noise) filtering. If we are satisfied with the quality of the image, we can burn the CD, otherwise you could repeat the above process until the results are exactly what we have for them. Digital Signal Processing expects to end up here.
Now we have a CD to a digital signal processing – a sound file in this case. May happen, our digital audioByte file takes too much memory store, and we can not afford that much. We want our digital files to use the minimum amount of memory so that we can quickly transfer files over the Internet, you do not want to save as many records as we do in a small MP3 player, for example. For this we need a "compression" technique, and, implicitly, a cryptography ".
There are a lot of compression / encryption methods available, and many of them are developedFuture. Basically, the digital signal is in fact a series of numbers – an integer is 2 bytes, one byte of 8 bits, each bit is 0 or 1 – and each number represents a mathematical value in the range from 0 to 65,535. Now we have all the numbers range from 0 to 65,535 note is repeated several times throughout the digital audio file. This information is very important because it helps us, our series of numbers into a mathematical structure encoded by a transformationSoftware compression / encryption "key". Instead of using, for example, the number of 23,501 for 1522 times in our digital audio file, you use only information on numbers, which means that only store the value in 1522, only once, based on the number 23,501.
The compression / keys – that is, in fact, a mathematical algorithm – is the adoption of the first digital files and broke under the entire responsibility for the replacement of each facilitywith the number of transit is used for storing and reconstructing the code was the first set of numbers that work, the original digital audio file. Often the key with a special structure of memory called a "binary tree". In this binary tree is the position of each number, how many times throughout an entire file (or a frame), and also applies to the information necessary to restore the structure and hence the entire audio-digital File.
Once the digital audio file format binary tree, its size is considerably smaller – it's packed – and we can do to conserve memory, or use to transfer files faster. In this form of binary tree data is also encrypted, in addition to being packed, and we need to reconstruct the compression-key to the first digital signal, otherwise there is no way we could make out, "the track – tree.
Well, what else can we do for our> Digital Audio Files? Well, there are many audio formats, and we can change our digital audio file from one format to another. The simplest form of audio file contains the data as a sequence of bits 0 and 1 Another type can display the data in small packets are grouped into a series of bytes, integers or doubles. This type of grouping of data compression allows a different level of information, but to get from one format to another, we need to changeRead the hardware, firmware, software or data read / write driver. Change the file format is called "translation" or "conversion" and that it is much easier to implement.
Basically that's all we do for analog and digital signals. As you can see there are a lot of math involved, but the good news, all the standard math routines and algorithms. A developer does not need a lot of math to know to complete its task quite well. TheseStandard mathematical algorithms were developed and optimized by a team of engineers and programmers, and we all use them. However, if you plan to develop proprietary algorithms, to achieve spectacular effects, it must be very good for learning DSP, compression / encryption, and translation techniques. For more information please visit my site at home, and find other related articles I've written in various publications on the Internet to find out.
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