AN2011-07 Signal legalization.pdf

Video and audio legalization

GEP100 - HEP100

Automatic correction of Gamut, and 3Gb/s, HD, SD embedded domainVideo DolbyLevel E to PCM Audio Loudness decoder with audio shuffler A

A

®

® product application note

Quad speed

Upgradable to

3Gb/s Embedded

Metadata S2020

COPYRIGHT©2011 AXON DIGITAL DESIGN B.V. ALL RIGHTS RESERVED NO PART OF THIS DOCUMENT MAY BE REPRODUCED IN ANY FORM WITHOUT THE PERMISSION OF AXON DIGITAL DESIGN B.V.

EMBEDDED VIDEO AND AUDIO AUDIO PROCESSING LEGALIZATION

Introduction Material intended for transmission may have come from a wide range of sources and undergone a number of differing processes during its passage through a broadcast facility this may result in some uncertainty regarding its compliance with level and color-space requirements. Add to this the well-known issue of audio level variations between differing material types, the so-called “loud commercial problem” or that the program requires both a surround sound and stereo mix and there could be a range of issues that require rectifying prior to the signal leaving the broadcast facility and passing to the transmitter or satellite.

Ideally this rectification should be undertaken in a seamless way that is not apparent to the viewer and involve no manual intervention.

The Axon Synapse range of modular interfacing products includes advanced video legalization and audio loudness correction modules which can be used singularly or in combination to provide a total solution to issues such as:

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Audio loudness variation between programs Overall video level is too high Color information not conforming to the correct standard, a situation that can arise when a program has been up- or down-converted without the necessary color-space correction being applied Missing surround sound or stereo audio mix No Dolby-E Metadata for downstream encoding processes

Synapse Video Legalization and Audio Loudness Solution

VIDEO + EMBEDDED AUDIO / DOLBY-E

SOURCE PROGRAM

DE-EMBEDDED AUDIO TO /FROM LOUDNESS CORRECTION VIA QUAD SPEED BUS

VIDEO LEGALIZATION AND AUDIO LOUDNESS CONTROL VIDEO LEGALISATION GDL/HDL200

TRANSMISSION

AUDIO LOUDNESS CORRECTION DLA44

The GDL/HDL200 is a dual-standard legalizer for digital video signals, automatically detecting HD (3G with GDL version) or SD input and operating in the appropriate color space standard. It legalizes 3G and HD streams in the RGB domain within 709 color space and SD signals in 601 color space.

various pieces of material being transmitted on the same channel. The variation can be caused by a number of factors such as the type of material (speech/music/sport) being transmitted and how heavily the audio has been processed by devices such as compressors, limiters etc.

It also has a preview output with a highlight function that indicates to the operator the areas that are being processed.

This audio level variation is termed loudness and in some territories broadcasters are mandated to ensure that the variation in measured loudness between all of the material on a channel is keep within strict limits an example of this being the Commercial Advertisement Loudness Mitigation (CALM) Act in the USA.

Broadcasters specify the nominal audio operating level to which a program should be mixed, however this does not prevent a viewer experiencing differences in perceived audio level between the

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EMBEDDED VIDEO AND AUDIO AUDIO PROCESSING LEGALIZATION Processors can be used to adjust the level of the audio using pre-defined algorithms, these are commonly installed in the media reception and Ingest area to ensure all stored material is corrected before transmission. However material could be delivered as complete files or the channel might carry live broadcasts both of which may need adjustment as part of the playout process.

The GDL/HDL200 card is equipped with the Quad Speed Audio bus which enables the building of a complete video and audio legalization platform with the addition of a card from the DLA series, such as the DLA44, without the requirement for external connections.

algorithm, to produce a consistent audio loudness across all transmitted material, protecting viewers from perceived loudness shifts.

The DLA42 can process 4 PCM audio pairs simultaneously and the DLA43/44 can be configured to process 3 PCM pairs grouped for 5.1 surround sound and a fourth PCM pair used for a stereo mix.

The DLA44 card can also automatically provide a 5.1 upmix from the stereo source material, using the UPMAX algorithm should the program source not contain any surround sound audio.

DLA cards can be configured to generate Dolby-E Metadata for use in subsequent encoding processes.

All cards in the DLA series utilize industry tried and tested algorithms, such as the popular AEROMAX

System Configuration By use of the Quad-Speed Multiplex Audio Bus and the Synapse Bus within the Synapse frame the majority of the audio connections, which would traditionally require external cables, are handled internally. In the system shown above the only installed cable would be the Dolby-E metadata inter-connection, if required (not including those from the source and to the transmission system).

A number of Synapse cards can store multiple configurations in on-board pre-sets which can be recalled by either GPI or via Ethernet commands.

By employing this functionality the configuration of the processors could be dynamically controlled by the Playout Automation system. For instance, this could be used to change the overall audio level or the maximum level of the RGB signals on a program by program basis.

Video Legalization and Audio Loudness Control - Details The example on the next page shows the combination of GDL200 and DLA44 modules. The GDL200 detects the video standard and selects the appropriate legalizer standard, manual adjustment of video and color levels are possible.

The de-embedded audio from the GDL200 is placed on (up to) the first 16-channels of the Quad Speed Multiplexing Audio Bus. By positioning the DLA44 card in the succeeding numbered slot (N+1 etc.) it is possible to configure the cards to select the audio input from the Quad Speed Bus, process it as required and return it to the Bus for other cards to utilize.

All audio channels are corrected for normalized audio level by the DLA44 card which can also produce a 5.1 upmix from a source of stereo audio if the native 5.1 is not available.

The output of the DLA44 is also placed on a second Quad Speed Multiplexing Audio Bus which returns the outputs of the “Add-on� card back to the GDL200 where it can be re-embedded into the legalized video stream.

All processing latencies can be accounted for in this combination with the appropriate amount of delay being applied to the video signal in the GDL200 module to maintain absolute lip-sync.

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EMBEDDED VIDEO AND AUDIO AUDIO PROCESSING LEGALIZATION GDL200 and DLA44

GDL200 – HDL200

SOURCE PROGRAMMING

3Gb/s, HD, SD IN 1

3Gb/s, HD, SD IN 2

3Gb/s, HD, SD OUT 1

MANUAL OR AUTOMATIC

EQ

COLOR CORR.

OFFSET DELAY

FRAME SYNC

INPUT SELECTION

EQ

RGB (709 AND 601) LEGALIZER

LEGALIZED AND LOUDNESS CORRECTED PROGRAMMING

3Gb/s, HD, SD OUT 2

EMB

3Gb/s, HD, SD OUT 3

16 CHANNEL DE-EMBED PREVIEW WITH HIGHLIGHT

PREVIEW OUT

GPI IN

QUAD SPEED MODE

PLL

32CH OUT

1

TO ADD-ON

QUAD SPEED MULTIPLEXING AUDIO BUS 2

FROM ADD-ON

REFERENCE INPUTS

µP

4CH 4CH 4CH 4CH IN IN IN IN

32CH IN

OR

RACK CONTROLLER 1

2

3

4

INTERNAL SYNAPSE BUS

DLA44 – DLA43 – DLA41

AES/EBU IN 1/2 LfRf

SRC

GAIN PHASE & DELAY

SRC

GAIN PHASE & DELAY

5.1 AES/EBU IN 3/4 C/LFE

AEROMAX 5.1 PARAM. EQ

MUX

AES/EBU IN 5/6 LsRs

AES/EBU IN 7/8

SRC

GAIN PHASE & DELAY

SRC

GAIN PHASE & DELAY

LOUDNESS CONTROL

AUTOMAX-II (AUTO SWITCH) UPMIXING

DLA44 DLA43

DLA44 DLA41

5.1 AES/EBU OUT 3/4 C/LFE

OUTPUT MUX AES/EBU OUT 5/6 LsRs

c PAR EQ

Lt/Rt Downmix

AEROMAX 2.0

Loudness corrected audio

AES/EBU OUT 7/8 Lt/Rt

LOUDNESS CONTROL

METADATA INPUT

METADATA OUTPUT

32CH IN

REFERENCE INPUTS

1

2

MUX

32CH OUT

ADD-ON MULTIPLEXING 8 CHANNELS INTO 32

32CH IN

32CH OUT TO MASTER

PLL

FROM NEXT ADD-ON

GPI INPUT

OPTIONAL REINSERTING OF PROCESSED AUDIO

TO NEXT ADD-ON

ADD-ON DE-EMBED SELECTOR 8 CHANNELS OUT OF 32

FROM MASTER

Deembedded audio from G/HDL200 video legaliser card

AES/EBU OUT 1/2 LfRf

UPMIX SOURCE SELECT

QUAD SPEED MULTIPLEXING AUDIO BUS

ΜP

RACK CONTROLLER

INTERNAL SYNAPSE BUS

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EMBEDDED VIDEO AND AUDIO AUDIO PROCESSING LEGALIZATION

Configuration examples The following tables and Cortex screenshots give examples of the configuration options required to successfully legalize the video, de-embed the audio, correct for audio loudness, provide an upmix if required and re-embed the resultant audio into the original SDI stream. Please note that the cards have considerably more settings than shown here and these should be set to match the user’s individual requirements.

GDL200 settings 1. Frame Delay = ? Frames, the card should be configured to compensate for the total audio delay through the processing stages.

2. Delay Status = On, enables the delay processing.

3. Control = Manual, the card can either be configured with a setup that is manually changed as required (Manual) or it can be configured to change predefined presets depending on the detected input video format (Auto-Format).

The card is configured to embed Quad Speed Add-On Buss channels 1 to 4 into SDI Group 1 and channels 5 to 8 into Group 2.

In this configuration Group 1 carries four of the six surround sound channel (Left, Right, Center and Low Frequncy Effects), Group 2 carries the other two (Surroudn Left and Surround Right) and the stereo mix.

The audio on these channels originated from the DLA44Audio Loudness Control card via the Quad Speed (Add-On) Bus.

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EMBEDDED VIDEO AND AUDIO AUDIO PROCESSING LEGALIZATION DLA44 settings 1. The card has been configured to use channels 1 to 8 from the Quad Speed Bus as the source to the 5.1 loudness control (internal channels 1 to 6) and upmixer (internal channels 7 to 8).

Quad Speed Bus channels 1 to 8 originate from the GDL200 card (see settings above).

2. The card’s clock are referenced to the GDL200 MasterCard via the Quad Speed Bus.

The configuration for the source for the DLA44’s internal buses is achieved by selecting the Master button, the drop down dialogue box changes to a list of the 32-channels available on the Quad Speed Master Bus. Highlight the relevant channel from the list for each of the 8 processing channels.

Channels 1-6 can grouped surround sound processing.

for

5.1

Note: It is necessary to individually select the audio source for each leg of a PCM audio pair.

The Upmixer Input is configured to use Internal Channels 7 and 8, the configuration above has determined that these are being fed from the Quad Speed Bus. Up Mix Mode configures which algorithm to use to produce surround sound from a stereo source, in this example is it configured to use the Linear Acoustic AutomaxII algorithm.

5.1 -> PCM Speed and PCM -> 5.1 Speed selects how quickly upmix processing is enabled in event of no 5.1 being detected and how fast the card will revert to 5.1 input when it becomes available again.

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