igrigorik + audio   85

Sam Saccone: Recreating a dialup modem in javascript | JSConf US 2015 - YouTube
- baud: single character via keyboard instead of typing out the bit-pattern
audio  history  javascript  video  w:2 
october 2015 by igrigorik
Can’t You Just Turn Up the Volume? — Medium
- hearing loss is due to loss in the dynamic range (or particular frequency ranges)
sounds  audio  health  hearingloss 
january 2015 by igrigorik
Archimago's Musings: 24-Bit vs. 16-Bit Audio Test - Part II: RESULTS & CONCLUSIONS
In a naturalistic survey of 140 respondents using high quality musical samples sourced from high-resolution 24/96 digital audio collected over 2 months, there was no evidence that 24-bit audio could be appreciably differentiated from the same music dithered down to 16-bits using a basic algorithm (Adobe Audition 3, flat triangular dither, 0.5 bits).
audio  codec  bitrate  study 
december 2014 by igrigorik
HTML5DevConf: Jordan Santell, "Browser Dance Party: Visualizing Audio with the Web Audio API" - YouTube
- audio processors allows you to specify the size of the buffer to pass to analyzer
- frequency domain is much easier to interpret (for humans)
- sample rate and bit-depth are the two major quality factors
audio  html5  visualization  w:1 
may 2014 by igrigorik
Digital Audio Fundamentals - Online Training Course for Developers
- Nyquist rate: lower bound on the sample rate for alias-free signal sampling
- many libraries use 32-bit numbers to encode samples just for simplicity (no 24-bit primites)
- channels are typically interleaved in the data format
- PCM > WAV - no compression, although technically WAV is a container...
- Different codecs offer different bit-depth / dynamic range, sampling rate -> bitrate
- Opus uses multiple different codecs depending on type of signal
- Playback rate: resample the signal at higher/lower sampling rate (simple strategy)
- Resampling at different rate will result in a pitch shift, which needs to be adjusted for
- Signal chains -> middleware
- Spectrum analyzer is an example of FFT in action: decomposing signal into different waves
audio  course  video  w:8 
december 2013 by igrigorik
The Emperor’s New Sampling Rate -- Are CDs Actually Good Enough?
Later in the paper, Moorer noted that humans can distinguish time delays — when they involve the difference between their two ears — of 15 microseconds or less.
audio  sound  sampling 
december 2013 by igrigorik
Audio Fundamentals Course - YouTube
- three domains: acoustic (air pressure), analog (waves), digital (bitrate)
- all sound is composed of one or more sine waves, each wave has an amplicate and frequency
- you always go through acoustic > analog > digital conversion, even if analog is just within the ciruit
- digital bitrate determines the quantization of the sine wave: 96KHz is common, 144KHz often used in editing
- EQ allows you target specific frequency ranges: you end up affecting all waves
- "envelopes" allow you to define sound behavior: attack, gain, sustain, fadeout
- dB's are relative units and measure different things in each domain
- microphone and speaker work in same way: magnets that emit sound waves, or reverse (mic can be a speaker)
- digital audio is sampled at defined PCM rate - e.g. 44KHz
- bit-depth (8,16,24,32) affects the granularity of the captured amplitude at a point in time (24 is enough)
- you can extract specific components by phase-shifting the wave: cancel out the individual components
- spectral analyzer shows you the individual components
- noise gate silences all sound beyond specified threshold (as opposed to just multiplying the wave)
audio  course  video  w:10 
december 2013 by igrigorik
Mark Boas: Hyperaudio - Making Audio a First Class Citizen of the Web on Vimeo
- synchronizing text and audio is the obvious starting point
- combining text search + audio: skip track of debate
- remixes with full embedded programs (don't cut the video, script it)
- media fragments will (hopefully) allow smart fetch in the future
- IE8 is the new "6" for audio
audio  web  video  w:3 
july 2013 by igrigorik
Xiph.Org Video Presentations: A Digital Media Primer for Geeks
awesome introduction to audio and video encoding / decoding
audio  video  encoding  codec  w:5 
november 2011 by igrigorik
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