Hardware for processing digital audio
An important part of the conversation about sound has to do with hardware.
There are many different devices for audio processing and input / output. With regard to an ordinary personal computer, one should dwell on sound cards in more detail. Sound cards can be divided into sound, music and zvukomuzykalnye. By design, all sound cards can be divided into two groups: main (installed on the computer motherboard and providing audio data input and output) and daughter (they have a fundamental structural difference from main boards ; most of the time they are connected to a special connector located on the main board). Daughter cards are most often used to provide or extend the capabilities of a MIDI synthesizer.
Sound, music and sound cards are created in the form of devices inserted into the motherboard slot (or already integrated from scratch). Visually, they usually have two analog inputs: line and microphone, and several analog outputs: line outputs and a headphone output. Recently, the cards have also been equipped with a digital input and output, which provides audio transmission between digital devices. The analog inputs and outputs usually have connectors similar to the headphone jacks (1/8 ”). Generally, the sound card has a little more than two inputs: analog CD, MIDI, and other inputs. Unlike the mic and line inputs, they are not located on the back panel of the sound card, but on the card itself; there may be other inputs, for example to connect a voice modem. The digital inputs and outputs are usually S / PDIF (digital signal transfer interface) with a corresponding connector (S / PDIF stands for Sony / Panasonic Digital Interface – Sony / Panasonic digital interface). S / PDIF is a “home” version of the more complex professional standard AES / EBU (Audio Engineering Society / European Broadcast Union). The S / PDIF signal is used to digitally transmit (encode) 16-bit stereo data at any sample rate. In addition to the above, sound-music cards have a MIDI interface with connectors for connecting MIDI devices and joysticks, as well as for connecting a daughter music card (although recently the ability to connect the latter has become a rarity). Some sound card models are equipped with a front panel for user convenience,
Let’s define several basic blocks that make up the sound and sound-music boards.
1. Digital signal processing block (codec). This block is used for analog-to-digital and digital-to-analog conversions (ADC and DAC). This block determines the characteristics of the card, such as the maximum sample rate for recording and playback of a signal, the maximum quantization level, and the maximum number of processed channels (mono or stereo). To a large extent, the characteristics of noise also depend on the quality and complexity of the components of this block.
2. Synth Block. Present on musical cards. Made on the basis of FM or WT synthesis, or both at the same time. It can work both under the control of its own processor, and under the control of a special controller.
3. Interface block. Provides data transfer over various interfaces (eg S / PDIF). A purely sound card often lacks this block.
4. Mixing unit. On sound cards, the u
