Audio Test 4
Why does digital tape require proper handling?
Thinner, data densely packed. More susceptible to error.
The 2 most common computer interfaces that moves data from the computer to external devices are:
USB and Firewire
What is the default compression scheme for iTunes?
AAC, 256 kbps, 5:1 ratio
Tape used in digital recording is?
ADAT Digital Audio Tape
What digital format interface carries 8 channels of audio in both directions?
ADAT optical
The professional standard for 2 digital audio channels on a XLR connector is?
AES/EBU (Audio Engineering Society)
What type of digital tape format uses a 4mm cassette style tape?
Compact cassette, DAT
If error correction cannot be accomplished, what happens?
Audio will mute, stop, drop-out
What does DSP stand for?
Digital signal processing
What does DVD stand for?
Digital versatile disc
How would you describe lossless compression?
Reduces file w/o discarding data. Usually 2:1 ratio.
MPEG-4?
Facilitates streaming media
DTS was first used on what movie?
Jurassic Park
Standard for all CD masters 1982-1994?
Rotary head, 1st generation recorders
Lowering the sample rate will also lower?
The bandwidth of the recording; frequency response
How do I increase the resolution of digital audio?
increase the bit depth/word length
If I'm preparing a CD or EPK (electronic press kit) with full resolution audio plus pictures, videos, contact information with web links, what type of CD is needed?
blue book/enhanced CD
Which rainbow book is the SACD format standard found?
scarlet book
Which rainbow book does CD-R fall in?
orange
PCM is:
pulse code modulation- encoding and decoding binary. Decimation filter on recording, interpolation filter on playback. Developed early on at Bell Labs.
The resolution of a digital system is proportional to?
quantization/bit depth; affects dynamic range/level; length of word changes with resolution
How to find data rate?
resolution(word length) x sampling frequency x # of channels = bps Ex: 16 x 44,100 x 2 = 1,411,200 bps or 1.411 Mbps for CD
R-DAT
small 4mm cassette tape; second generation/semi-pro format
What is a plug-in?
software equivalent to hardware versions of processors, EQ, dynamics, effects, etc
What are the driving factors behind the development of compressed audio formats?
space and the internet
MDM recorders are distinguished by?
the type of tape used; VHS tape, 8 mm (Modular Digital Multitrack)
Blu-Ray
• 16-24 bits • 144 dynamic range • yes copyright, multi-channel, multi-media • 25GB/50GB • PCM encoding
SACD
• 2.8 Mhz • 1 bit • 120 dynamic range • yes copyright, multi-channel, not multi-media • 7.95 GB • DSD encoding
CD-audio
• 44.1 khz • 16 bits • 96 dynamic range • no copy protection, no multi-channel, no multi-media • 700 mb capacity • PCM encoding
Data rate for CD audio?
1.411 Mbps; 44.1 kHz
What is the tape width for DASH format open reel machine, specifically 24 & 48 track?
1/2 inch (Digital Audio Stationary Head- Sony's entry into the market)
One minute of uncompressed digital audio recorded at 44.1kHz/16 bit is how big?
10 MB
MP3s at 128 kbps use a compression ratio of? What about 256 kbps?
10:1; 5:1
What is the data rate for a CD quality lossy compressed file?
128 kbps
Quantization level for CD?
16 bit
When was the compact disc released in the US?
1982, Billy Joel
ORANGE BOOK
1990 CD-Recordable
When was DTS introduced?
1993, Jurassic Park
PCM F1
1st consumer/semi-professional format digital tape recorder
What is the sampling rate of the SACD?
2.8 Mhz or 64 x 44.1 kHz
A 20 bit recording yields approximately what dynamic range?
20 x 6db = 120 db 6db of dynamic range per bit
How many voltage levels are in an 8 bit word?
2^8 = 256
List the common sample rates for professional audio:
32, 44.1, 48, 88.2, 96, 176.4, 192 kHz (take 44.1 and 48 and double them)
How much data does a DVD-5 hold?
4.7GB
Sampling rate for CD?
44.1 kHz
What is the bandwidth of a 96 kHz digital recording?
48 kHz (HALF)
How many channels are there in Dolby surround?
6
How many audio channels/streams can you put on a DVD-V?
6 channels
The S/N ratio (dynamic range) is an A/D converter; how many dB per bit?
6 dB. The standard 16 bit CD has a S/N ratio of 6 x 16 or 96dB.
A 16 bit word uses approximately how much voltage and dynamic range?
65,536 voltage intervals to code amplitude; 96 db dynamic range in CD (16x6=96)
What is the maximum size of a CD (in MB)?
700 MB
Making an MP3 at 256kbps from a 40MB Wav file, the approximate size (in MB) would be? What about at 128kbps?
8 MB (5:1); 4MB (10:1)
Binary digits (bit) in a digital recording represent?
Amplitude, dynamic range/level/resolution
What is actually sampled when we record a sound?
Amplitude; value or set of values at a point in time and/or space
What happens in anti-aliasing?
Any of a number of techniques to combat the problems of aliasing in a sampled signal such as a digital image or digital audio recording; aliasing is caused by the sample rate not being high enough to accurately recreate the wave; anti-aliasing is the fixing of mysterious harmonies or frequencies in digital audio.
Lossless examples:
Apple lossless, WMA, FLAC , aif, MP3-HD, WAV
YELLOW BOOK
CD-ROM/data disc 1985. More robust error correction.
What version of DVD is being used when I have to turn the DVD over to view the Widescreen version?
DVD 10
What version of DVD is being used when I see a pause in the middle of the movie?
DVD 9
Where would you most likely find multiple camera angle disc?
DVD video
What was the first (unsuccessful) compressed format?
Dolby
What is the most widely used digital audio technology in theaters?
Dolby surround 7.1; Batman Returns 1st film in theaters 1992
Why is DVD-A and SACD appealing?
Gives us a high resolution product. More space and higher capacity/better audio quality. Multi-channel, multi-media, has copy protection built in.
Positions of a 5.1 surround sound system:
L, C, R, LS, RS, subwoofer
Lossy examples:
MP3, MP4, AAC, M4a, WMA, dts, mpg, au, dolby digital
Which MPEG compression scheme is used for DVD-V?
MPEG 2
An MP3 is part of what MPEG technology?
MPEG-1, layer 3. Lossy compression.
Are all lossy formats compatible?
No
What is PD?
ProDigi Mitsubishi (Otari); 32 tracks on 1 inch tape (Nashville largest market)
The dynamic range and S/N ratio in digital recording is proportional to?
Quantization rate
The protocol or format standard for an audio CD is contained in what book?
Redbook
Lossy codec?
Reduces file size by discarding data, anywhere from 12:1-5:1 ratio.
The ADAT uses what type of tape compared to the TASCAM MDM?
S-WHS vs. 8 mm tape
Recording digitally, the #of measurements taken per second is called the?
Sample rate
Harry Nyquist discovered?
Sampling rate must be 2x the highest frequency at even intervals. 1928. Working for AT&T and then Bell Labs.
The consumer standard for 2 digital audio channels on an unbalanced connector is?
Sony Phillips digital interface (SPdif/RCA connector)
Who developed the compact disc?
Sony and Phillips
What is the primary drawback to a Host Based DAW?
The CPU must do all the work. Needs external interfaces for analog inputs. Less capabilities (fewer inputs/outputs, fewer tracks, latency, etc)
Quantization represents?
The level component (amplitude/resolution). Converting a waveform that is infinitely variable into a finite series of discrete levels in the form of bits. Voltage off=0, voltage on=1 Word length = bit depth = resolution
Sampling represents?
The time component (frequency). Must be TWICE that of the needed frequency response. Ex: 96 kHz sample rate to get 48 kHz range of frequencies/bandwidth. Ex 2: 48 kHz sample rate means 24,000 Hz max frequency response
What tape machine category do MDM's fall into?
They are rotary head technology, not stationary. Digital tape recorders.
Time & Level in Analog
Time: frequency Level: amplitude FA
Time & Level in Digital
Time: sampling Level: resolution SR
A white book CD is?
Video CD MPEG-1
What is the industry standard audio file format?
WAV
The most revolutionary aspect of digital recording is?
We can create a recording that can potentially last forever
Problem we face?
We don't have working hardware to transcribe all the recordings we have from the past; incompatible with today's systems. One solution: translate entire catalogs to .wav as soon as possible
MP3s use what type of compression?
lossy
What file format is used on a red book cd?
none, no files in a red book CD
Where would I find helical scanning technology?
video tape machine
I'm providing a data disc with wav files, mp3 files, and Word Docs. What type of CD should I make?
yellow
List as many digital audio interfaces as you can?
• AES/EBU (standard digital audio connection interface) • S/PDif (Sony/Phillips - AES variation for consumer gear) • ADAT (Optical, proprietary digital connection from Alesis) • TDIF (Tascam Digital Interface Format) • MADI (Multi-channel audio digital interface, up to 64 channels, 1 coaxial cable) • SCSI (small computer systems interface for hard drives/some peripherals) • Firewire (IEEE1394) • USB (universal serial buss)
RED BOOK
• CD Audio (US Release Billy Joel 1982) • Plays 79.8 minutes, 99 tracks
BLUE BOOK
• CD Plus/enhanced CD • Audio (red) recorded first, then data (yellow) • text, graphics, video, audio, html, flash data, etc...
DVD
• up to 192 kHz • 16-24 bits • 144 dynamic range • yes copyright protection, multi-channel, multi-media • up to 10 GB capacity • PCM encoding
