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104.01 A Digital Audio
Transcript of 104.01 A Digital Audio
What is audio streaming?
Transmitting audio files that can begin playing
over the Internet as the remaining data is still
-Creates little to no wait time to begin hearing
the audio file
The Sound Wave
What is sound?
vibrations that travel through the air or another medium and can be heard when they reach a person's or animal's ear. AKA compression waves
The sample rate is the number of "snapshots" of audio that are sampled every second. The continuous audio stream is digitally encoded in a similar way to a movie camera capturing motion by recording an image frame many times per second. The higher the sample rate (and bit depth), the more accurately the original sound can be represented. The following diagram helps to illustrate this point. The curve can be thought of as being the original sound whereas the columns can be thought of as digital data trying to represent the original sound.
This seems to suggest that you should always record at higher sample rates, but again there are costs and you need to decide the most appropriate rate for your project. 44.1k refers to 44.1 thousand sample per second and you will find that 44.1k, 48k and 96k are the most common sample rates although 192k is now becoming more popular. 44.1k is the standard for CDs, 48k is common in video
How do we record sound? (or Analog v. Digital)
Analog recording methods store signals as a continual wave in or on the media. The wave might be stored as a physical texture on a phonograph record, or a fluctuation in the field strength of a magnetic recording. Think about examples of analog recordings as vinyl records or cassette tapes
In digital recording, digital audio is recorded as a series of changes in air pressure (sound) over time. The shape of the recording is a series of steps. Each step represents an individual recording at a specific time. That shape is remembered by computers as a series of numbers.
Analog audio in red
Digital recording in black
Digital Audio Quality
These are coded and decoded by computer programs or "codecs"
Amplitude = loudness
Pitch = frequency of waves
(the more close together=higher pitch)
measured in hertz or hz, mhz, khz
interesting fact that the older you get, the less you can hear high pitch
measured in decibels or dB
mono v. stereo jacks
mono= one ring
stereo = 2 rings
3 rings = you guess!
Mono, Stereo and Surround sound
Channel Number- The amount of individual audio channels used during playback
- Monaural (Mono)--all sources of audio play out of one single channel
- Stereophonic (Stereo)-- audio sources can be separated into two different channels (left and right)
listen to this with
close your eyes
Example websites that use streaming audio
technology include Pandora, Spotify, iTunes Radio, etc.
Multiple audio channels; usually 5-7 separate channels
more channels= more realistic
Sometimes with digital audio, no new sounds need to be created
Sampling is a digital way to select fragments of other recorded sounds and create a new compositon with the sampled digital files
Common things to make in class using digital audio
Record new foley for a video clip (sound effects)
Record a podcast about something you are passionate about
"Mash-up" two songs
Record a song/rap set to instrumental track
Making a whole track with garage band
Haunted surround sound