digital audio monitoring set2008 v3
TRANSCRIPT
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Presented by Ing. Jess V. Osorio Lpez
Digital Audio Monitoring
SET2008
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Back to basics
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Distortions
THD+N (Total Harmonic Distortion + Noise) IN=f
OUT=2f, 3f,.nf
IMD (Inter modulation distortion) IN=f1 & f2 OUT= f1+f2, f1-f2, f1*f2
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If Sound Phase SameBetween Speakers
Phantom Source specific spot In Phase - Correlation is +1
If Sound Phase DifferentBetween Speakers
Phantom Source not specific,rather is smeared
Sounds origin over an area
More difference in phase, thewider the area
180 degrees out of phase,Correlation is -1
Phantom
Source
PhantomSource
Phase Differences and Correlation
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Loudness
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Basic Monitoring
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Amplitude, Phase and Correlation Monitoring Similar to analog, a need exists to monitor phasing of two or more digital
stereo pairs
Left display is in phase
Right display is out of phase
Monitoring
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Meter Ballistics VU (Volume Unit) Meter
Shows average volume level Symmetric rise and fall times
Based on oldest analog dials
Peak Program Meter
Displays quasi-peak levels
Fast rise and slow fall time True Peak Meter
Displays actual peaks
Nearly instantaneous rise andfall times
Monitoring
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Meter Scale dBFS
Decibels Full Scale where0dBFS is a sample of all1s
This is the default selection
Peak Program Level Default -8dBFS
User can change
Test Level Default -18dBFS
User can change
Monitoring
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Monitoring
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Monitoring
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Monitoring Levels Monitoring with Bars
Meter Ballistics
Amplitude Levels
Clip (all 1s)
Over (-8dBFS)
Silence (-70dBFS)
Mute (all 0s) In Bar Displays
Unlocked
AES CRC Error
Silence
AES V Bit Mute
Monitoring
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Surround SoundMonitoring
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Surround Sound Display
Allows visualization of interaction between multiple channels Left (L), Right (R), Center (C), Left Surround (Ls), Right Surround (Rs)
Show Dominant Sound
Correlation between channels
Phantom Phase Indicators
Linear or A Weighting Filters
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Basics of the Surround Display
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Phantom Source Indicators
Associated with each channelpair
Provides indication on thelocalization of the sound
White tic mark indicatescorrelated sound (+1)
Slightly Correlated (
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Basic Display
Linear (RMS) Filter Linear relationship
between amplitude of
sound and display
A Weighting Filter Amplitude modulated by
frequency of sound relatedto human auditory
response
Correlation Bend outwards In-Phase
Straight Line 0 Correlation
Bend inwards Out-Phase
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Example Displays
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MetadataMonitoring
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Metadata Parameters 3Ds DialNorm
DialNorm Dialogue Normalization Uniform dialogue levels when decoding a Dolby stream.
Conveyed once per block (5ms)
Valid Range 1 to 31
Volume
SPL67dB
DialNorm25dB
Volume
SPL92dB
DialogueLevel
SPL 67dB
Program 1High Quality
Entertainment Program
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Metadata Parameters 3Ds DialNorm
DialNorm Dialogue Normalization Uniform dialogue levels when decoding a Dolby stream.
Conveyed once per block (5ms)
Valid Range 1 to 31
Volume
SPL67dB
Volume
SPL82dB
DialogueLevel
SPL 67dB
Program 2Commercial
Message
DialNorm15dB
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Metadata Parameters 3Ds Dynrng Example
DialNorm25dB
Full ScalePeak Level
0dB
Quiet Sound
Loud Sound
50dB BelowDialogue Level
(-75dB)
Dynrng -15dB
Dynrng +20dB
-75dB
0dB
-55dB
-15dB
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Metadata Parameters 3Ds DownMix
Ability to hear all L C R Ls Rs in a stereo mix
(Lo Ro) Stereo DownMix
-3/-4.5/
-6 dB
-3/-6/0 dB
-3/-6/0 dB
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Metadata Parameters 3Ds DownMix
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Audio structureReview
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One Block = 192 Frames
One Frame = 2 Subframes
Start of Block indicated by Z Preamble
AES/EBU Data Structure (Review)
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32 Bits/subframe
4 Preamble Bits, 24 Data Bits, 1 Validity,1 User, 1Channel Status & 1 Parity
Subframe
X Y
Frame
AES/EBU Frames & Subframes (Review)
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Ancillary Data Format (Review)
SMPTE 291M Ancillary Data Packet and Space Formatting ADF Ancillary Data Flag (ADF) is a three-word header 000h 3FFh 3FFh
DID Data ID identifies the type of data packet DBN Data Block Number optional counter determines missing data
DC Data Count (DC) word indicating the size of data packet
Checksum Simple error detection
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HD Audio Control Packet (Review)
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Channel Status Mapping WFM7120
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LoudnessMonitoring
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What is Loudness ?
Loudness is a subjective measure Different people perceive loudness differently
Loudness is primarily a psychological correlation of the physicalintensity of the audio signal.
Different techniques have been used to provide correlation ofthe overall loudness of the signal.
Different filters are used to adjust the models to perceivedloudness of the human ear.
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Loudness Measurements Standards
IEC 61672-1 Electroacoustics Sound Level Meters
ITU 1770 Algorithms to measure audio program loudness and true-peak audio level
ITU 1771 Requirements of loudness and true-peak indicating meters
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Configuring Loudness Measurement
Select Weighting Filter Linear, A Weighted, RLB
Select Duration Select Start & Stop Time
Leq, LAeq or L(RLB)
measurements Individual Channel Channel Pairs
Selected Channels
10 second Short Average
Infinite duration of Session Program Average
True Peak
Audio Level
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Audio Vide DelayMonitoring
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Summary
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Summary FlexVu@Channel Status
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Summary FlexVu@Error Status
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