Loudness measurement monitoring
Download
1 / 39

Loudness Measurement & Monitoring - PowerPoint PPT Presentation


  • 116 Views
  • Uploaded on

Loudness Measurement & Monitoring. Yannick LE DREAU. Agenda. What is Loudness ?. Loudness Standards. Measurement Method. Demonstration. What is Loudness?. Loudness is a subjective measure Different people perceive loudness differently

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Loudness Measurement & Monitoring' - maik


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

Loudness measurement monitoring

Agenda

What is Loudness ?

Loudness Standards

Measurement Method

Demonstration

Loudness Measurement & Monitoring


What is loudness
What is Loudness?

  • Loudness is a subjective measure

    • Different people perceive loudness differently

  • Loudness is primarily a psychological correlation of the physical intensity of the audio signal.

  • Different techniques have been used to provide correlation of the overall loudness of the signal.

  • Different filters are used to adjust the models to perceived loudness of the human ear.

  • Necessary to measure perceived Loudness

    • Radio & Television broadcasts

    • Music, Speech & Sound Effects

Loudness Measurement & Monitoring


Loudness standards
Loudness Standards

  • IEC 61672-1

    • Electroacoustics Sound Level Meters

  • ITU-R.BS 1770

    • Algorithms to measure audio program loudness and true-peak audio level

  • ITU –R.BS 1771

    • Requirements of loudness and true-peak indicating meters

  • ATSC A/85 RP

    • Techniques for Establishing and Maintaining Audio Loudness for Digital Television

  • P/Loud Working Group

    • http://wiki.ebu.ch/loud/Main_Page

    • Gating Measurement

    • Inclusion of LFE

Loudness Measurement & Monitoring


Introduction to the standard itu r bs 1770
Introduction to the Standard ITU-R BS 1770

  • ITU-R Monophonic Loudness

    • Measured Leq(RLB) K-weighted means square

    • Low computational complexity of algorithm

    • Leq(RLB) provides best performance of all meters tested

    • Simple energy-based loudness as robust as more complex models

  • Design of Leq(K) algorithm

    • High Pass Filter

    • Summation of energy over time

  • Design of Multi-Channel Loudness algorithm

    • Simple building blocks

    • Scalable from 1 to N

Loudness Measurement & Monitoring


Measuring loudness
Measuring Loudness

  • Uses RLB Filter

    • Simpler to implement

    • It should be noted that BS.1770 ended up NOT incorporating Leq(RLB), BUT Leq(R2LB), now formally known as Leq(K)

  • Pre Filter

    • Accounts acoustic effects of the head

  • ITU-R.BS 1770 Algorithms for audio programme loudness

Loudness Measurement & Monitoring


True peak metering
True Peak Metering

  • Audio Meters use 4x oversampling

  • Allows True Peak Measurement

  • Other types of meter may under report audio level.

    • Especially at high frequencies

  • ITU-R BS 1770-1 provides method for measurement of True Peak.

VID-11 Loudness Measurement & Monitoring


Loudness measurement lkfs
Loudness Measurement (LKFS)

  • Definitions

    • L, C ,R, Ls, Rs & N which is total number of channels

    • y Input signal filtered by pre-filter and RLB weighting curve

    • z Weighted Mean Square level

    • G Channel weighting

    • Pre-filter and RLB weighting curve defined as K-Weighting

(LKFS)

i

i

i

i

VID-11 Loudness Measurement & Monitoring



Ebu p loud r128
EBU P/Loud R128

The following slides draw heavily from EBU Technical documents 3341/2/3.

There are two ways to achieve loudness normalisation in the home:

the actual normalisation of the source itself, so that the programmes are equally loud by design

the use of loudness metadata that describe how loud a programme is.

Within the EBU R128 loudness levelling the first solution is encouraged due to the advantages:

simplicity

potential quality gain at the source


Ebu p loud r1281
EBU P/Loud R128

Definitions:

‘LUFS’ is equivalent to ‘LKFS’ (which is used in ITU-R BS.1770-1). An input document to change the nomenclature to ‘LUFS’ (which is compliant with international naming conventions) has been submitted to the ITU.

A programme is an individual, self-contained audio-visual or audio-only item to be presented in Radio, Television or other electronic media - this includes commercials, trailers, promos, interstitials and similar items

Programme Loudness is the integrated loudness over the duration of a programme

Loudness Range (LRA) describes the distribution of loudness within a programme

Maximum True Peak Level is the maximum value of the audio signal waveform of a programme in the continuous time domain


Ebu p loud r1282
EBU P/Loud R128

The Recommendations are:

that the descriptors Programme Loudness, Loudness Range and Maximum True Peak Level shall be used to characterise an audio signal;

that the Programme Loudness Level shall be normalised to a Target Level of -23 LUFS with a permitted deviation of +/-1 LU for programmes where an exact normalisation to Target Level is not achievable practically (for example live programmes)

that the audio signal shall be measured in its entirety, without emphasis on specific elements such as voice, music or sound effects

that the measurement shall be made with a loudness meter compliant with both ITU-R BS.1770 and EBU Technical Document 3341


Ebu p loud r1283
EBU P/Loud R128

Further recommendations:

that this measurement shall include a gating method with a relative threshold of 8 LU below the ungated LUFS loudness level as specified in EBU Technical Document 3341

that Loudness Range shall be measured with a meter compliant with EBU Technical Document 3342

that the Maximum Permitted True Peak Level of a programme during production shall be -1 dBTP (dB True Peak), measured with a meter compliant with both ITU-R BS.1770 and EBU Technical Document 3341

that loudness metadata shall be set to indicate -23 LUFS for each programme which has been loudness normalised to the Target Level of -23 LUFS

that loudness metadata shall always correctly indicate the actual programme loudness, even if for any reason a programme may not be loudness normalised to -23 LUFS



Lkfs meter target loudness
LKFS Meter & Target Loudness

  • Audio Meter Scale in LKFS

  • Settings

    • Number of Channels

    • Duration of Average

    • Gating

    • Threshold settings

  • EBU R128 standard -23 LKFS with deviation of +/-1 LKFS

  • User Defined Limits

N

Loudness = - 0.691 +10 log ∑ G . z (LKFS)

i

i

10

i

Too Loud

User Defined

EBU

Target Loudness

-23LKFS

(+/- 1)

User Defined

Too Quiet

User Defined

Loudness Measurement & Monitoring


Wfm7120 loudness configuration
WFM7120 Loudness Configuration

  • Press Config button

  • Navigate to Loudness Settings

  • Enter sub menu and select Loudness Preset EBU R128

  • Yellow text indicates changing of settings

Loudness Measurement & Monitoring


Wfm7120 elements of loudness monitoring
WFM7120 Elements of Loudness Monitoring

Loudness Measurements

ShortInfinite

True Peak

Dialnorm

Run Time

Loudness Meter

Program Loudness

Green Audio Labels

Channels Summed into Loudness Measurement

Loudness Measurement & Monitoring


Wfm7120 elements of loudness monitoring1
WFM7120 Elements of Loudness Monitoring

Too Loud

User Defined

EBU R128

-23LKFS

(+/- 1)

User Defined

Too Quiet

User Defined

In-Bar Message

LOUD, QUIET, GATED

Loudness Measurement & Monitoring


Wfm7120 audio session
WFM7120 Audio Session

  • Summary of Audio

  • Clips, Over, Mute, Silence, Peak/ High Level

    • Loudness MeasurementPer ChannelPer PairInfinite LoudnessShort Loudness

    • Loudness InformationDuration of Short PeriodChannel Used in summation

    • Loud Alarm

    • Run Time of Session

Loudness Measurement & Monitoring


Wfm7120 loudness session
WFM7120 Loudness Session

  • Loudness Chart

  • Logs Loudness value every second

  • Trend Chart

  • 90 Seconds

  • 180 Seconds

  • Bar Chart

  • 9 minutes to 6 hours

  • Save Loudness value to USB or via network.

Loudness Measurement & Monitoring


Wfm7120 loudness session1
WFM7120 Loudness Session

  • Loudness Chart

  • Bar Chart

  • From 9 minutes to 6 hours

  • LKFS Short

  • LKFS Infinite

  • Dialnorm

  • True Peak

  • Max / Min Value LKFS

  • Summary Information

  • Channel Summation Short Period Target Loudness

  • Save Loudness Session to USB or via network.

Loudness Measurement & Monitoring


Wfm7120 loudness session export
WFM7120 Loudness Session Export

Loudness Measurement & Monitoring


Wfm7120 loudness session export1
WFM7120 Loudness Session Export

Loudness Measurement & Monitoring


Loudness measurement monitoring

Multichannel Audio & Distribution Systems


Dolby metadata
Dolby Metadata

  • AC-3 Metadata includes 28 parameters

    • Informational

      • Seven optional parameter

      • No effect on audio decoding

    • Basic

      • Nineteen parameter

      • Dynamic Range, Downmix

      • Optimize the listening experience

    • Critical

      • Required for proper encoding and decoding

      • Channel Mode (acmod)

        • Describes channel format

      • Dialog Level (dialnorm)

        • Sets dialog level

Loudness Measurement & Monitoring


Dolby metadata management
Dolby Metadata Management

  • Requirements for accurate Metadata

    • Methods

    • Fixed Method

      • AC-3 encoder Dialog Level Is “fixed” to a single value

    • Preset Metadata

      • AC-3 encoder “presets” are programmed, each with different dialnorm

    • Agile Metadata

      • AC-3 encoder is configured to receive external metadata

Loudness Measurement & Monitoring


Fixed metadata
Fixed Metadata

ATSC

Distribution

Source 1

Audio

  • Simply “Fix” AC-3 Encoder dialnorm setting

    • Measure long term loudness and set dialnorm to this value

    • Content Delivery specification should set Target Loudness of ingest material

    • Non-conforming content needs to be measured and offset applied

  • Poses mininal risk to content. Simplifies system requirements

Process,

Storage

Distribution

and

Switching

AC-3

Encoder

Audio

Consumer

AC-3

Decoder

Internal

Metadata

Values

Audio

Source n

Audio

Loudness Measurement & Monitoring


Preset metadata
Preset Metadata

ATSC

Distribution

Source 1

Audio

  • Change between preset metadata values via external control

    • Preset are loaded into AC-3 encoder based on known differences in content loudness

    • Automation system used to recall presets based on content and channel modes

    • AC-3 Framesync some encoders disrupt audio bit stream when preset is changed.

Process,

Storage

Distribution

and

Switching

AC-3

Encoder

Audio

Consumer

AC-3

Decoder

Internal

Metadata

Values

Audio

Source n

Audio

External

Control

Auto-

mation

Loudness Measurement & Monitoring


Agile metadata
Agile Metadata

Source 1

Audio

  • Setting different dialnorm values for different content

    • Embed the metadata parameters within the SDI ANC data

    • De-Embed metadata just prior to AC-3 Encoder

    • Dialnorm settings change appropriately on boundaries of content

    • Needs to be employed throughout the whole system

ATSC

Distribution

Process,

Storage

Distribution

and

Switching

Embed

Process,

Storage

Distribution

and

Switching

Audio

AC-3

Encoder

Meta-

Data

Values

De-

Embed

Internal

Metadata

Values

Source n

Audio

Consumer

AC-3

Decoder

Embed

Audio

Loudness Measurement & Monitoring


Agile metadata1
Agile Metadata

  • Complex System

  • Requires full Loudness measurement of each piece of content

  • Loss of metadata could result in an audio discrepancy

    • AC-3 encoder will revert to units metadata settings

  • Requires an agile infrastructure throughout Broadcast plant

  • Equipment deployed at all input, output and monitoring locations

  • Agile systems provide the greatest flexibility for the content provider

    • Does not impose creative limitations

Loudness Measurement & Monitoring


Fixed agile hybrid
Fixed Agile Hybrid

HD-SDI

With

SMPTE 2020

  • Broadcast Example

  • Live productions

    • Metadata delivered via Dolby E

  • Broadcast Center infrastructure

    • Metadata extracted from Dolby E signal

    • Inserted into HDSDI VANC line 9

  • Routed through plant

    • To Distribution system

VANCInserter

IRD

HD-SDI

To Facility

HD Router

L-Band

MUX

Ch 1/2 L/R

ASI

Dolby E

Dolby E

Decoder

Ch 3/4 C/Lfe

Ch 5/6 Ls/Rs

Ch 7/8 Lt/Rt

BB Reference

Loudness Measurement & Monitoring


Fixed agile hybrid network distribution

ASI

Fixed Agile Hybrid – Network Distribution

HD-SDI

With

SMPTE 2020

  • Broadcast Center Signal Flow

  • Multiple Sources

  • Signals Routed to Transmission

    • Dolby E encoding

    • Audio Metadata In VANC

  • Metadata Extracted from VANC and delivered to Dolby E encoder

  • Also extracted by transmission encoder

  • Delivered to Network as private MPEG data service

HD

Router

VANCDecoder

HD-SDI

HD

Master

Control

MPEG

Encoder

D

E

M

U

X

Ch 1/2 L/R

Ch 3/4 C/Lfe

Metadata

Ch 5/6 Ls/Rs

Dolby E

Encoder

Ch 7/8 Lt/Rt

Dolby E

BB Ref.

Stereo

Downmix

AES

L/tRt

Stereo

Loudness Measurement & Monitoring


Effectively control of program to interstitial loudness
Effectively control of program-to-interstitial loudness

  • Fixed dialnorm

    • Ensure all content meets Target Loudness

    • Long term loudness matches dialnorm

    • File based use a scaling device to match long term loudness

    • Real-time loudness processing device to match loudness

  • Agile dialnorm

    • Measure all program content

    • Dialnorm must match actual calculated loudness

    • Filebased set dialnorm to measured loudness of specific content

    • Real-time process to match content specific loudness and set dialnorm based on this loudness value

Loudness Measurement & Monitoring


Dynamic range control
Dynamic Range Control

  • DRC calculations based on the indicated loudness

  • Dialnorm need to accurately reflect loudness

  • Profession Encoding profiles for DRC

    • Music Light

    • Music Standard

    • Film Light

    • Film Standard

    • Speech

  • Dolby Digital (AC-3) modes

    • Line Mode

    • RF Mode

  • DRC – “None”

    • Inhibits Generation of DRC profiles

    • Prevents viewer selection

    • Protection Limiting will not be available

    • Recommend profile other than “None”

Loudness Measurement & Monitoring


Dynamic range control monitoring
Dynamic Range Control Monitoring

  • Dynamic range values shown in Dolby Status display.

  • Monitoring function allows dynamic range parameters to be applied

    • Selection for:-

    • Line Mode

    • RF Mode

Loudness Measurement & Monitoring


Conclusion
Conclusion

  • Audio Loudness is becoming a critical measurement

  • ITU-R BS 1770/1 and ATSC A/85 have been adopted by broadcasters

  • We expect EBU R128 will be adopted by EBU member broadcasters

  • New Audio measurement tools are needed

  • New work practices need to be adhere by program producers and broadcasters

VID-11 Loudness Measurement & Monitoring