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Digital audio
This document discusses key concepts in digital audio including sampling, quantization, digital recording, and disk-based audio systems. It explains that sampling is taking parts of an existing music piece to create a new production. Quantization refers to capturing amplitude values during sampling. The document also discusses sample rates, bit depths, lossy and lossless audio formats like MP3, WAV, and FLAC. Common sample rates used in the industry like 44.1 kHz and 48 kHz are also outlined.
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Digital audio
- 1. Digital Audio & TechnologyApplication Sampling Quantization Digital Recording Reproduction Process Disk Based Audio System By Azmawati Binti Mohd Lazim | azmawati@mmu.edu.my
- 2. Learning Objective • LO1- To execute audio recording sessions in a proper studio environment. • LO2 - To operate the features found in a digital audio workstation and essentially use it as a tool for multimedia production.
- 3. What is sampling? whichis taking 'samples' (or parts) of an existing music- piece and using that to create a new music production.
- 5. Real life situation Ifwe sample a 20 KHz frequency with a samplerate of 20KHz, we only have one sample per cycle. To capture the +ve and -ve side of the cycle we will need to have a sampling rate that is double the frequency that we’re sampling. In other words : To capture a 20 KHz frequency, we’ll need to have a samplerate of at least 40KHz.
- 6. Nyquist Theory • FS= 2 x FN • FS=Sampling frequency • FN=Nyquist frequency
- 7. What is quantisation? Samplingis capturing an amplitude value in time. This value is captured in a process called quantisation
- 8. • As wellas with the time axis, digital systems have a certain resolution on the amplitude axis • The higher this resolution is, the more accurate the digital representation of the waveform’s amplitudes.
- 9. Reproduction Process The higherthe bit-depth, the more dynamic range can be captured. So a 24 bits system has a higher resolution than a 16 bits system.
- 10. You can imaginethat mixing with audio that has a 24 bit resolution is much easier and pleasant to mix with since we literally have more values on the amplitude axis.
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- 12. Disk-based Audio System This sample-rate standarddates back to the days of videocasettes. Digital audio was stored in the scans of a videoframe and a samplerate of 44.1KHz could fit in both systems. It was mathematically compatible with both European PAL as the United States standard NTSC film systems.
- 13. Does Bitrate ReallyMake a Difference In My Music? Lossy • MP3 • WMA Lossless • WAV • AIFF
- 14. Digital Audio Format: LossyFormat Both WAV & AIFF file are uncompressed formats They are exact copies of the original source audio. The same quality; they just store the data a bit differently.
- 15. AIFF vs WAV AIFFis made by Apple, so you may see it a bit more often in Apple products WAV is pretty much universal. However, since they're uncompressed, they take up a lot of unnecessary space. Unless you're editing the audio, you don't need to store the audio in these formats.
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- 17. MP3, FLAC, MWA MPEGAudio Layer III, or MP3 for short, is the most common lossy format around. So much so that it's become synonymous with downloaded music.MP3 isn't the most efficient format of them all, but its definitely the most well- supported, making it our #1 choice for lossy audio.
- 18. MP3, FLAC, MWA FLACis Free Lossless Audio Codec with high audio quality and smaller file size. Therefore, it is quite popular with storing FLAC files with less space and better quality and many people have FLAC files. The popularity of Apple devices like iTunes, iPhone, iPod, Apple Watch
- 19. MP3, FLAC, MWA WindowsMedia Audio (WMA) is an audio data compression technology developed by Microsoft. The name can be used to refer to its audio file format orits audio codecs. It is a proprietary technology that forms part of the Windows Media framework.
- 20. Real Life Situation •Originally, Microsoft claimed that WMA files had the same quality as MP3 files with half the size
- 21. Real Life Situation •Independent testing has disputed this claim, but WMA may still have slightly better quality than MP3. So why convert WMA files to MP3?
- 22. It is aboutcompatibility • The most important is compatibility. • Even though WMA is popular in Windows programs, there are still many multimedia programs and MP3 players that are incompatible with this format. • MP3, on the other hand, is so ubiquitous that almost any program or device will play it. • Another reason to convert WMA to MP3 is if the file will be used on Mac-based software.
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- 24. So why not40 KHz you ask?
- 25. Good Tips! Working onhigher sample-rates. There’s a number of reasons why we could chose to work with higher sample-rates and bit-depths when recording and mixing. • The first would be the better quality and more dynamic range given at these higher sample-rates and bit-depths. This is much more pleasing to work with during mixing. KHz for surround material.
- 26. Good Tips! Working onhigher sample-rates. • Processing is much more accurate on higher resolution material. Equalizing, reverbs, filters, etc. • All sounds much better on higher sample-rate material. This is the reason why many plugins use so called ‘upsampling’ techniques to internally work at higher samplerates when processing audio. • When you’re producing sound for DVD’s, which can handle samplerate’s up to 192 KHz on stereo material, and 96
- 27. Here is alist of most common sample-rates found in the industry. Samplerate Usage 44.100 hertz Audio cd quality. 48.000 hertz Pro video, Dat audio, sampling rate of a lot of professional audio gear. 88.200 hertz Not often used doubling of the cd-quality, can sometimes be found. 96.000 hertz DVD audio quality supporting stereo-mixes up 5.1-surround-mixes. 192.000 hertz DVD audio quality supporting stereo-mixes.
- 28. References McGuire, Sam, andRoy Pritts. Audio Sampling: A Practical Guide. Burlington, MA: Focal Press, 2008. Thompson, Daniel M. Understanding Audio: Getting the Most out of Your Project or Professional Recording Studio. Boston: Berklee Press, 2005. Winer, Ethan. The Audio Expert: Everything You Need to Know about Audio. Waltham, MA: Focal Press, 2013. Stanley, R Audio in Media 10th Edition. : Michael Rosenberg 2014 Audio Engineering Society (AES): www.aes.org Audio Publishers Association (APA): www.audiopub.org audio-tutorials/season-3-mixing/Episode-7-Digital-Audio-Sample-Rate-Bit- Depth.html
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Editor's Notes
- #13 Digital audio was stored in the scans of a videoframe and a samplerate of 44.1KHz could fit in both systems. The 44.1 KHz samplerate with a 16 bit bit-dept was also adopted as the audio-quality for the standard audio-cd. So this samplerate has been relevant for years, and actually still is!