Systems of digital music (Part 1)

Digital music is becoming a popular hobby for over 10 years with the popularity of computers and personal music players. Same to that the development of these kinds of headphones – headphones that access to “enjoy” the music becomes a lot easier.

CDs, Vinyl shrinking market, but still serve a certain number of customers. “Crime Map” to the throne when the music on the Internet is no shortage of music store, store digital music distributor.

However, there is still much controversy, the misconceptions about digital music, music CD, vinyl music, which over the public. Hopefully the article “music system” will help you understand what parts of the basics of digital audio, as well as better understanding the nature of the device DAC, amplifier … in a music system .

Musical numbers – definition of digital music – The nature of digital music

Back a bit of knowledge of Physics; I know the sound is an alliance of many continuous waveform oscillator. The vibrations emitted by the instrument, or the singer’s voice.

In the recording system “classic”, the sound is emanating from the instrument – singer recorded “completely in the waveform” surface storage devices (tapes, disks Vinyl). When played, the tape – Vinyl disc impulses generated as “original impulse” recording time, called the electromagnetic signal – waveform – or known as analog signals.

Back to the knowledge of the computer, we know that the data is written in binary 0 and 1. townhouse Similarly, with a complex digital audio tracks, signals are encoded by the human 0 and 1. Signal 0, 1 from digital music file is called a digital signal (digital signal).

The human ear can only receive signals “waveform” sinusoidal (ie Analog signal). Thus to “decode” the music signal, should have a “decoder” is called DAC (Digital to Analog). A question was posed, “music” and “music CD” really differently? Why do many people think that “music CD” or more “music”?

With CDs, it is a kind of optical disc (Optical Disk), and type of disc is used to “store binary data” (0 ​​and 1). Thus, a song, a song stored on a CD – optical discs, it is the collection of data 0 and 1 are encoded. Thus, we can say “music CD” is “a form of music”! More by “CD” and “music” that ordinary people understand, that’s the difference in the nature of the format used to encode digital signal (sound of music formats) and storage methods (used optical disc or hard drive). Saying that “music CD or more” or vice versa is very difficult, because I do have a reference system to be “normalized”. This will be clarified in the next post.

Some kind of digital music formats, Lossless and Lossy, standard format of music CD, music concept High resolution

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For players unfamiliar photographers make no concept of RAW, and the need to process RAW image processing, but RAW has a large capacity. For digital photos with smaller capacity, we again use other formats like JPG, JPEG … using compression algorithms.

Going into surface data, a data is always divided into “two types”: a kind of “original data – not lose – well preserved”, and a “data compression – loss” (thanks algorithm handle). Thus, RAW image can “deemed Lossless” and JPG can “deemed Lossy”.

Same with digital music, lossless data storage format is “not lose – is preserved” (with the standard of music stored on the CD), and Lossy compression is a form of music storage (have lost the original data) .

Some lossless music player – music typical high resolution

Lossless or Lossy formats for digital music can tell a lot. But here are some commonly used formats.

Lossless: WAV, FLAC, APE, ALAC ….
Lossy: mp3, wma, aac ….
Standards of music CD is stored in the format CD – DA (Compact Disk Digital Audio – consult Wikipedia), encoded 2-channel LPCM signal at 16 bits (1411 kbps bit rate), the sampling frequency is 44100 Hz.

WAV is a lossless format typical, it accurately records data in the standard 16 bits, 44100 Hz from a CD, but the drawback is the large capacity and not managing the data tag, metadata. So formats like FLAC, APE, ALAC launched to cover imperfections on: it uses compression algorithms (but optimized data and preserve the original), more intermediate information, easy to storage and management.

Lossless narrow sense as “no loss compared to standard CD”: 16-bit, 44.1 kHz. But in a broad sense, there are many standards for lossless format. Currently, there are higher standards than standard CD format is very much (24 bits / 96 kHz, 24-bit / 192 kHz). This standard is often called the “studio standard” or high resolution music, and is also distributed, storage formats such as FLAC, APE, ALAC … This form usually rarer, larger capacity , and requires a digital signal decoders (DAC) must also correspond to decipher.

With Lossy audio formats, the most common is mp3, and here mp3 also taken a good example for Lossy music. Mp3 with the sampling frequency of 44.1 kHz (like CD), but a lower bit rate (64, 128, 192, 256, 320 kbps) instead of 1411 kbps. The higher the bit rate the better the quality, and closer than the CD.

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