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Ready to supercharge your mixing? Sign up for more knowledge bombs, mixing and mastering mastery, productivity tips and offers. Sign Up Here. These can also sometimes be referenced as slopes in dB per second instead of times. Typically, release time should be set as short as possible without producing a "pumping" effect, which is caused by cyclic activation and deactivation of compression.
For example, if the release time is set too short and the compressor is cycling between active and non-active, your dominant signal — usually the bass guitar and bass drum — will also modulate your noise floor, resulting in a distinct "breathing" effect. Compression ratio specifies the amount of attenuation applied to the signal.
You will find a wide range of ratios available depending on the type and manufacturer of the compressor you are using. These compression ratios are expressed in decibels, so that a ratio of indicates that a signal exceeding the threshold by 2 dB will be attenuated down to 1 dB above the threshold, or a signal exceeding the threshold by 8 dB will be attenuated down to 4 dB above it, etc.
Although we perceive compressed signals as being louder, compression-induced attenuation actually lowers the output. The type of compressor you choose will also play a large role in the overall sound of the effect. This is a list of the four most famous compression types and a brief description of how they differ. Tube Probably the oldest type of compression is tube compression.
Tube compressors tend to have a slower response — slower attack and release — than other forms of compression. Because of this, tube compressors exhibit a distinct coloration or "vintage" sound that is nearly impossible to achieve with other compressor types. Optical Optical compressors affect the dynamics of an audio signal via a light element and an optical cell. As the amplitude of an audio signal increases, the light element emits more light, which causes the optical cell to attenuate the amplitude of the output signal.
They are fast, clean, and reliable. The is perfect for vocals, bass, guitar and more. It's also a popular choice for bringing out excitement in room mics. Robinson and C. It was first used to reduce transmission bandwidth of analog television signals.
This concept is still used in digital video today. With the advent of the 70s came the introduction of digital video. It was sent using the same techniques as were used for telecommunications - pulse-code modulation PCM. You might recognize this term from a little bit earlier when we talked about DPCM. PCM is used to digitally represent a sampled analog signal. It's a standard for audio and in the 70s it was used to convert to digital video. It required high bitrates and wasn't a very efficient way to transmit video, but it worked.
It's an image processing technique where you split images into parts composed of different frequencies. During a process called quantization, some of the frequencies are dropped. The more important frequencies are saved and used for image reconstruction later.
Because some frequencies are dropped, the image won't be exactly the same, but it's often good enough that you will not notice a lot of difference. Nasir Ahmed worked with T. Natarajan and K. Rao at the University of Texas to shape the DCT concept into a working algorithm for image compression. The results of their work were published in As we went over earlier, predictive coding is about guessing what will come before or after a current image. Habibi's algorithm worked within each image intraframe rather than predicting across images interframe.
John A. Roesse and Guner S. Robinson developed Habibi's algorithm further, making it usable across frames interframe. They experimented with many different ways of doing this and found that Ahmed's DCT technique was the most efficient to combine with predictive coding. Smith and S. Anil K. Jain and Jaswant R. Jain continued developing motion-compensated DCT video compression. This kind of development continued, with Wen-Hsiung Chen using their work to create a video compression algorithm combining all the research.
Work on motion-compensated DCT led to this becoming the standard compression technique used from the s until now. All of the previous research finally let to the first video compression standard - H. This standard was great with individual images but didn't do as well when it came to preserving quality from frame to frame. Later revised in , this standard was the first international standard for video compression.
Its main use was for videoconferencing. While this was a great first effort, many inefficiencies led to various companies experimenting with ways to improve the standard.
The first in the series of codecs you've probably seen or used is H. It's the first digital video compression algorithm that efficiently uses intraframe and interframe compression techniques.
It was used around the world for video conferencing and is responsible for introducing hybrid block-based video coding, which is still used in many video standards today MPEG-1 Part 2, H.
The way people collaborated to build this standard is also still widely used. Knee — sets how the compressor reacts to signals once the threshold is passed. Hard Knee settings mean it clamps the signal straight away, and Soft Knee means the compression kicks in more gently as the signal goes further past the threshold. Make-Up Gain — allows you to boost the compressed signal, as compression often reduces the signal significantly.
Output — allows you to boost or decrease the level of the signal output from the compressor. Cnet cnet. Completely uncompressed music would sound lifeless and boring to most listeners.
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