9415319
Description
Flashcards by Robin Batman, updated more than 1 year ago
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Created by Robin Batman
about 7 years ago
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| Question | Answer |
| AUDIO SYLLABUS | sound waves: – analogue and digital wave patterns – volume – frequency • mono/stereo/surround sound • converting analogue to digital sound • sampling: – sample rate – sample size – 8-bit – 16-bit • relationship to file size: file compression • file formats: – WAV – AIFF – MP3 – WMA – MIDI |
| lossless compression | Uncompressed data; does not minimize the data at all à larger file size, original data, better quality |
| lossy compression | Compressed data; removes data outside human perception e.g. white spaces, frequencies the human ear can’t hear à some loss of quality is acceptable, smaller file size. |
| Outline factors that can affect sound quality when creating a video | Large sampling rates per second of captured sound will result in higher quality sound captured for the video. Also, the bit depth of 8 bit sound will not produce the quality of 16 bit sound as the number of bits of information recorded in each audio sample is greater in 16 bit sound. - Sampling rate for audio capture - Quality of microphone use for capturing sound - Sample depth (bit depth) 8 bit sound to 16 bit sound - The file type used to store captured sounds may affect the quality as some files, such as MP3 files, are compressed resulting in some sound frequencies being removed. |
| What is a sound wave? | IS the pattern of disturbance caused by the movement of energy travelling through medium (such as air, water or any other liquid or solid matter) as it propagates away from the source of the sound. |
| Two main properties of a regular vibration | Amplitude and frequency -> affect the way the way it sounds |
| Amplitude | Is the size of the vibration and determines how loud the sound is. - Amplitude is important when balancing and controlling the loudness of sounds, such as with the volume control on your CD player. It is also the origin of the word amplifier, a device which increases the amplitude of a waveform. |
| Frequency | - Frequency is the speed of the vibration, and this determines the pitch of the sound. It only useful or meaningful for musical sounds, where there is a strongly regular waveform - Frequency is measure d as the number of wave cycles that occur in one second. The unit of frequency measurement is Hertz (Hz for short) - A frequency of 1 hz means one wave cycle per second. A frequency of 10 Hz means ten wave cycles per second, where the cycles are much short and closer together. |
| Common audio file formats | WAV, MP3, AIFF, WMA, MIDI, |
| Analogue Wave patterns | Analog refers to audio recorded using methods that replicate the original sound waves such as vinly records and cassette tapes. Analog sound wave replicates the original sound wave . |
| Digital Sound Wave Patterns | Digital audio is recorded by taking samples of the original sound wave at a specified rate. Examples of digital mediums is CD and Mp3 files. Digital sound wave only replicates the sampled sections of the original sound wave. |
| How do you convert analogue signals into digital data? | An ADC (analogue to digital converter) chip is used to convert the continuous analogue signal into the 0s and 1s of the binary system. The process is called digitising, the analogue sound is digitised by (1) taking samples of the analogue signal at regular intervals (called the sample rate), then (2) measuring the volume (amplitude) of each sampled sound and assigning it a ‘value’, and then (3) converting this ‘value’ into a digital format (1s and 0s). Depending on the accuracy (and hence quality) required for the audio the digital data can be represented by with an 8-bit or a 16-bit digital number (referred to as the sample size). |
| Audio Sampling | this involves capturing small ‘slices’ of a sound and representing them digitally. The quicker the sampling rate and the more digits (1s and 0s) used (the sample size), the closer the digitised sound will be to the original (source) signal. |
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