AN2011-03 Inserting VO into Dolby-E.pdf

Inserting Voice Over into Dolby-E

GEP100 - HEP100

An application example of how to insert 3Gb/s, HD, SD embedded domain Dolby Ea tovoice PCM over into decoder Dolby-E with encoded Program 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 AUDIO INSERTING A VOICE PROCESSING OVER INTO DOLBY-E

Introduction Traditionally TV channel playout signal paths contained a Presentation Mixer to switch between sources and to add branding, such as graphics, and voice-overs (V/O) to the original programme material, the mixers frequently contained, or had the option to install, the processing necessary to handle Dolby-E encoded material. With the rapid increase in channels and the deployment of fully automated workflows it is less common to install mixers in every channel.

same V/O being inserted into the 5.1 surround sound and stereo PCM signals.

Control of the mix levels are pre-set and the mix could be initiated by an external trigger such as a GPI or Ethernet based control message originating from the automation or channel-in-a-box system.

An alternative approach is to utilise a mixer which

The introduction of a single device that fulfils both media origination and branding, so called channel-in-a-box solutions, means that all of the Presentation functionality is determined by the software supplied by a specific manufacturer which may not provide the processing required to insert a V/O into a Dolby-E bit-stream.

The diagram below shows the stages required to insert a V/O into a Dolby-E encoded bitstream embedded in a SDI signal. The processing should provide the option to mix the V/O with just the centre audio channel or, additionally, with the left and right channels.

Many playout systems are configured to output both a stereo and 5.1 mix, the diagram shows the

PROGRAM

DEEMBEDDER

DOLBY-E BITSTREAM

detects the presence of audio on the voice-over input line and in response drips the programme audio to a pre-set level.

VIDEO DELAY

DOLBY-E DECODER

EMBEDDER

L

+

R

+

C

+

LFE

DOLBY-E ENCODER

DOLBY-E BITSTREAM WITH V/O

Ls Rs PCM STEREO

VOICE-OVER

+

PCM STEREO WITH V/O

PROGRAM WITH V/O

EMBEDDED AUDIO INSERTING A VOICE PROCESSING OVER INTO DOLBY-E

Synapse Solution Utilising three Synapse cards a fully self-contained audio mixing and insertion system can be assembled, providing simultaneous V/O processing in a 5.1 Dolby-E encoded bit-stream, voice-over mixing into a PCM Stereo audio pair and also be accomplished with the addition of another simple audio I/O card.

The processing latency of Dolby-E encoding and decoding is at least 1 video frame for each process, Synapse re-embedder cards have sufficient inbuilt delay to accommodate this ensuring correct lip-sync is maintained through the system.

The diagram on page 5 shows the three Synapse cards, G/HRB100 provides deembedding, the video delay to compensate for the Dolby-E decoding and subsequent encoding, it also embeds the Dolby-E stream following V/O insertion. The DBD18 decodes the Dolby-E stream and provides an automatic audio ducker which detects audio presence on the V/O input and reduces the programme level and mixes the V/O audio into it on the user configured channels, LCR or just C. By adopting this process

there is no requirement for external control of the Synapse cards to initiate the V/O insertion, greatly simplifying the integration with a wide range of systems. However the mixing process can also be triggered by an external GPI if required.

Connection between the G/ HRB100 and the DBD18 is achieved using the bi-directional AddOn Quad Speed Audio Bus, which also provides the Master clock references derived from the de-embedder.

Dolby-E encoding is undertaken by the DBE08 card which utilises a local AES input on the DBD18 card as an input port to the Output Quad Speed Bus which is used to transport the bitstream to the embedder on the G/HRB100 card.

If the system also needs to mix V/O into a PCM stereo programme, the DBD18 has addition routing a mixing facilities to achieve this.

New Metadata is generated in the Dolby-E encoder following the V/O insertion and this is passed to the embedder to be included in the SDI output signal.

Card Settings The following tables give examples of the configuration options required to successfully decode the Dolby-E stream, insert a V/O into it, encode the mix as a Dolby-E stream and embed the stream into the original SDI signal. Please note that the cards have considerably more settings than shown here and these should be set to match the user’s individual requirements.

GRB100 Settings 1. Frame Delay = 4 Frames, and Vertical Delay = 562 Lines; the card is configured to compensate for the total audio delay through the audio processing stages (4.5 Frames).

Delay Status = On, enables the delay processing.

2. The Metadata for this system is carried in the Dolby-E stream so no S2020 data is required.

EMBEDDED AUDIO INSERTING A VOICE PROCESSING OVER INTO DOLBY-E GRB100 Settings (continued) The card is configured to embedded Quad Speed AddOn Bus channels 1 and 2 into SDI Group 1. The signal on these channels is the Dolby-E stream that originated from the DBE08 Dobly-E Encoder module and uses the DBD18 card to insert the Dolby stream on to the Quad Speed AddOn Bus.

DBD18 Settings 1. Lock Mode = Ref1, the card is configured to be referenced to the same external source as the DBE08 Dolby-E Encoder module 2. Dolby E Input = Master and Dolby E Input Channel = 1/2, the module’s Dolby decoder’s input is from the Master Card (GRB100) on channels 1 and 2 via the Quad Speed AddOn Bus (QSB).

The DBD18 module can use a PCM stereo pair as a back-up if no Dolby-E is detected, this is shown configured to use channels 3 and 4 from the Master Card.

Internally the DBD18 module has 16 channels.

Channels 1 – 8 are used as the source to local outputs from the Master Bus, Dolby-E decoder of local inputs, Channels 9 -16 can be used for routing of audio from the Dolby decoder, or local inputs to either the output AddOn QSB or to local AES outputs.

The configuration shown here routes the discrete 5.1 channels from the Dolby decoder to channels 1 – 6 which are also the local AES outputs and will be used as the source to the Dolby encoder module.

EMBEDDED AUDIO INSERTING A VOICE PROCESSING OVER INTO DOLBY-E DBD18 Settings (continued) The Local Inputs 7 and 8 are routed to channels 9 and 10, these carry the Dolby-E stream from the DBE08 module to the Output QSB (see diagram on page 5 for more detail).

The Master Inputs 3 and 4 are routed to channels 11 and 12, these carry the PCM Stereo mix with V/O back to the embedder via the Output QSB (see diagram on page 5 for more detail).

Slot 1/2 = Out9/10, the module is routing internal channels 9 and 10 (Dolby Encoded audio with V/O mix) to the Output AddOn Quad Speed Bus which will be used by the GRB100 Master Card as the source for its embedder.

Slot 3/4 = Out11/12, the module is routing internal channels 11 and 12 (PCM Stereo mix + V/O) to the Output AddOn Quad Speed Bus which will be used by the GRB100 Master Card as the source for its embedder.

EMBEDDED AUDIO INSERTING A VOICE PROCESSING OVER INTO DOLBY-E DBD18 Settings (continued)

1. Voice Over = Local and Channel Select = 1, selects the AES channel 1 input on the module as the source of the audio to be used as the Voice Over.

2. Trigger = Auto and Trigger Level = -40dBFS, the card is configure to mix the Voice Over source into the channels selected by (3) when the level is over -40dBFS for more than 256mS. The Voice Over mix can also be triggered by an external GPI. 3. Channel Effected = Channel 1 -3 and 11 & 12, pervious settings have configured the module such that L/R/C/LFE/Sl/Sr are on channels 1 to 6. This setting mixes the Voice Over audio with channels 1 – 3 (Left, Right and Centre). It is easily possible to mix the Voice Over with just the Centre channel (Channel 11) if required. The setting also mixes the Voice Over with the PCM Stereo Audio on channel 11 and 12.

DBE08 Settings 1. Lock Mode = Reference and Ref-Input = Ref1, references the encoding processes to the same external reference as the DBD18 module 2. Program Config should be configured to suit the user’s requirements (shown here for 5.1 surround sound). The letter refers to the Metadata configuration chosen (see item 4).

3. Selects the Metadata set to be edited, Sets are used by the Program Config (see item 2).

4. Audio Coding Mode = 3/2 and LFE Enable = checked, configures the encoding format in the metadata used by subsequent decoders, this example it configured for 5.1.

Dolby-E Encoded Audio fed to embedder via Quad Speed Bus

AES/EBU IN 11/12

AES/EBU IN 9/10

AES/EBU IN 7/8

AES/EBU IN 5/6

AES/EBU IN 3/4

AES/EBU IN 1/2

3Gb/s, HD, SD IN 2

32 CHANNEL

SRC

SRC

SRC

SRC

SRC

SRC

DBD18

1

2Ch

2Ch

2Ch

2Ch

2Ch

2Ch

2Ch

2Ch

DECODER

52x17 INPUT MUX

REFERENCE INPUTS

PLL

S2020 READER

16 CHANNEL DE-EMBEDDER SDI IN 2

16 CHANNEL DE-EMBEDDER SDI IN 1

METADATA

Eq

DELAY DELAY DELAY DELAY DELAY

GAIN

GAIN

GAIN

GAIN

32CH IN

VO MIXER

+

+

+

+

+

+

+

+

MUX

Rack controller

2Ch

2Ch

2Ch

32CH IN

ΜP

RACK CONTROLLER

AES/EBU OUT 7/8

2Ch

METADATA

AES/EBU OUT 5/6

2Ch

METADATA PROC

AES/EBU OUT 3/4

2Ch

AES/EBU OUT 1/2

GPI/O

METADATA IN/OUT

3Gb/s, HD, SD OUT 2

3Gb/s, HD, SD OUT 1

2Ch

INTERNAL SYNAPSE BUS

32CH OUT

µP

METADATA HANDLING METADATA

META DATA

[QUAD SPEED AUDIO BUS]

16 CHANNEL EMBEDDER

2Ch

DELAY GAIN PHASE

16 CHANNEL

S2020 INSERT

[QUAD SPEED AUDIO BUS]

OPTIONAL READD-ON EMBED MULTIPLEXING INSERTING OF 8 X 2-CHANNELS INTO 32 PROCESSED AUDIO

DELAY

DELAY

GAIN

VOX DETECT

Ch Ch Ch Ch

INTERNAL SYNAPSE BUS

GAIN

GAIN

4 4 4 4

QUAD SPEED MULTIPLEXING AUDIO BUS

32CH IN

TDM DE-MUX

32 Ch

32 QUAD SPEED

DELAY

DELAY

64X16 MUX

ADJUSTABLE OFFSET DELAY 0-500ms

16 DE-EMBED 1 16 DE-EMBED 2

GAIN

LOSS OF ‘E’ FAIL SWITCH

2

TDM MUX

32CH OUT

16 Ch

16 Ch

AUTO MUX

2x1

FROM MASTER

Eq

FROM ADD-ON

3Gb/s, HD, SD IN 1

TO ADD-ON TO NEXT ADD-ON

Video with Dolby-E Audio

TO MASTER

GRB100 - HRB100

Delay set to 4.5 Frames to compensate for Dolby processing latency

System Schematic

INSERTING A VOICE OVER INTO DOLBY-E

FROM NEXT ADD-ON

METADATA

GPI

AES 7/8

AES 5/6

AES 3/4

AES 1/2

1

DBE08

Video with Dolby-E Audio + V/O

2

SRC

SRC

SRC

SRC

GENERATOR

GAIN CONTROL

CHANNEL SWAP

1

2

3

4

3

2

BY-PASS DELAY

DARS GENERATOR

ENCODER

INTERNAL SYNAPSE BUS

Audio in/outputs To/from Synapse bus

PLL

DELAY

DELAY

DELAY

DELAY

1

µP

Rack controller

+

CHANNEL 3/4 [AUX] SELECTION

AES/EBU FORMAT

AES/EBU FORMAT

MAIN OUTPUT SELECTION

AUX OUT

DOLBY E OUTPUT