Transcript Overiew of ATSC data broadcasting specification

OVERVIEW OF THE
ATSC DATA BROADCAST SERVICE
SPECIFICATION
Version 1.0
Don Newell, Intel Corporation
Regis J. Crinon, Sharp Labs of America Inc.
R
R
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
1
®
PRESENTATION OVERVIEW
MANDATE OF THE ATSC T3S13 WORKING GROUP
A/V/D SERVICES
DATA SERVICES SIGNALING
• ANNOUNCEMENT, DISCOVERY, BINDING
• ADVANTAGES (for broadcast, interactive services)
LAYERS AND PROTOCOLS
• PACKETIZATION, SYNCHRONIZATION , PROTECTION LAYERS
• DOWNLOAD, IP PROTOCOLS
• ADVANTAGES
TRANSPORT SYTEM TARGET DATA RECEIVER MODEL
• DATA SERVICE PROFILES
• BUFFER MODEL
• DATA SERVICES LEVELS
CONCLUSION
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
2
R
R
®
ATSC T3S13 MANDATE
• Define how data associated with a television program is carried,
scheduled and announced.
• Define how data not associated with a program is carried, scheduled
and announced.
• Build a foundation for new services (e.g. interactive services).
• Define transport mechanisms to support a wide variety of data
services:
 Asynchronous/Synchronous/Synchronized data
 Multiprotocol data
 Fixed bandwidth data
 Opportunistic data.
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
3
R
R
®
THANK YOU!
• T3 members for recognizing importance of data
services and starting T3S13
• T3 members trying to promote our work
• Active participation of experts from other WGs
• Companies who have hosted meetings
• MPEG for endorsement of some new aspects of
transmission
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
4
R
R
®
A/V/D SERVICES
R
R
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
5
®
DTV = VIDEO + AUDIO + DATA
MPEG-2 Transport Streams carrying multiplexed:
• Service Information (ATSC PSIP + MPEG-2 SI)
• Audio, video and data elementary streams
R
R
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
6
®
GENERAL PICTURE
* Television Programs
* A/V
* PSIP/System Info
*Associated data such as
- HTML-based
-New media/graphics
Stand-alone Data Services
* Subscription Services
- Magazines, Music
- Targeted info services
* Streaming Data
(DSM-CC, IP)
Broadcast
Multiplex
MPEG
Transport
Stream
R
R
Opportunistic data services
* Business data services
* IP router in the sky
*Targeted info services
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
7
®
ATSC T3S13 BENEFITS
•Richer presentation model for advertisers/content producers
Media object delivery
(HTML, JAVA applets, Rich Graphics)
•New incremental capabilities based on data
•Support for widespread existing data protocols
•Basic data services
File download
Integration with Web content
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
R
R
8
®
DATA SERVICES SIGNALING
R
R
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
9
®
•ANNOUNCEMENT : PSIP + DIT
• DISCOVERY
• BINDING
SDF
R
R
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
10
®
ANNOUNCEMENT (SCHEDULE)
Data Services associated with an A/V event:
value of service_type is 0x02 or 0x03
Use either
> PSIP EIT(s) for a data services sharing same schedule and
same title as A/V event OR
> DIT(s) for a data service having a separate schedule or title
A/V events
data service 1
data service 2
Data Services NOT associated with an A/V event:
value of service_type is 0x04
Use DIT(s)
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
11
R
R
®
ANNOUNCEMENT (SCHEDULE)
In the descriptor loop of every A/V/D or D event:
A Data Broadcast Descriptor is present.
service_profile
service_level
Fields may be used by data receiver to determine whether it
can proceed with acquisition of data service or not
A PID Count Descriptor is optionally present:
total # of PIDs
minimum # of PIDs
Fields may be used by data receiver to determine whether it
can acquire full or “minimal” data service
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
12
R
R
®
ANNOUNCEMENT (SCHEDULE)
Only one data service per virtual channel
Possibly multiple data services in a single
MPEG-2 Transport Stream
(in this case SDF must be on distinct PIDs)
R
R
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
13
®
DISCOVERY AND BINDING:
SERVICE DESCRIPTION FRAMEWORK
SDF:
• Describes a data service as an aggregation of
applications (discovery)
• Provides information for associating an application
with broadcast or remote data components (binding)
• Is designed based on MPEG-2 DSM-CC mechanisms
(Association Tag descriptor, Tap structure).
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
14
R
R
®
SERVICE DISCOVERY
• Main element is the Data Service Table identifying
the applications making up a data service
• The transmission of a Data Services Table is mandatory for
any ATSC Data Service
•
Data Service Table follows MPEG-2 System section
format
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
15
R
R
®
DATA SERVICE TABLE
dataServiceTable(){
for (applications count) {
compatibility descriptor
application identifier
for (tapsCount){
protocol_ encapsulation
Tap()
} // end tapsCount
application parameters
descriptors
application private information
} // end applications count
service private information
}
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
MPEG-2
packetization,
synchronization,
protection layers
+
protocol
“pointer”
to data
element
16
R
R
®
BINDING TO A COMMUNICATION
CHANNEL
APP
ApplicationCode()
{
open( TapId )
}
TAP IN DST
TapId
use
associationTag
selectorLength
for(j=0;j<selectorLength; j++){
selectorByte
}
}
}
R
R
associationTag
in associationTag descriptor in PMT
OR
in Network Resource Descriptor
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
17
®
SERVICE BINDING
• Main elements are the Network Resources Table and the
Association Tag descriptor(s) in the PMT
• The Network Resources Table announces any external
communication channels used by a data service.
• The transmission of a Network Resources Table is optional
for any ATSC Data Service
R
R
• Network Resources Table follows MPEG-2 section
format
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
18
®
NETWORK RESOURCES TABLE
networkResourceTable(){
compatibility descriptor
dsmccResourceDescriptor
private information
}
The internet address
of a server in an
interactive service
OR
a remote data
elementary stream
in another MPEG-2
Transport Stream
R
R
includes an association tag
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
19
®
SERVICE BINDING
Multiple Taps of one or several applications can reference
the same Network Resource !!!
AT2
NRT
App1
Tap1
Tap2
Tap3
App2
Tap1
Tap2
AT1
PMT
DST
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
20
R
R
®
SDF: GENERAL PICTURE
Tap1
Tap 1
(AT1)
Application 1
Tap2
Tap 2
(AT4)
Network Resources Table
Program Map Table
Connection 1
(AT1)
Matching AT
PID 4
ATdescriptor
AT 4
Connection 2
(AT2)
Connection 3
(AT3)
PIDx
PIDx
PIDx
PIDx
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
PIDy
PIDy
PID4
PID4
21
INTERACTIVE DATA
Matching AT
BROADCAST DATA
COMMUNICATION LAYER
APPLICATION LAYER
Data Service Table
WEB
SERVER
R
R
®
SDF ADVANTAGES
• promotes responsible usage of bandwidth
• flexibility to determine how frequently it is transmitted
(impact on accessibility)
• designed for broadcast and interactive services
• based on basic MPEG section parsing.
• direct access to association tags so they can
be managed easily in emission station
• uses new resource descriptors for broadcast and
interactive services (amendment 2 to DSM-CC)
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
22
R
R
®
LAYERS AND PROTOCOLS
R
R
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
23
®
PACKETIZATION, SYNCHRONIZATION, PROTECTION
LAYERS
Non-flow
data
controlled carousel
DSM-CC
download
IP
SDF PSIP
LLC/SNAP
checksum
CRC32
checksum
MPEG-2
PTS
checksum
CRC32
MPEG-2 addressable
sections sections
DSM-CC
sections
A V
LLC/
SNAP
MPEG-2 PTS
PES packets
MPEG-2 Transport Stream
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
IP
24
Data
Piping
R
R
®
PES Packets
• Carry A/V data
• Carry data synchronized with A/V
• Carries data synchronized with other PES streams
• Carries synchronous data
A V
LLC/
SNAP
IP
MPEG-2 PTS
R
R
PES packets
MPEG-2 T.S.
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
25
®
PES PACKETS
• Synchronous data streaming harmonized with
SCTE DVS132
• Synchronized data streaming harmonized with DVB
• Each type has a defined header
• Headers are not the same for Synchronous and
Synchronized data elementary streams
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
26
R
R
®
EXAMPLE OF SYNCHRONOUS DATA
SERVICES
• Video Games based on 2D/3D graphics and image rendering
• Infomercial based on animated computer graphics
R
R
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
27
®
DSM-CC SECTIONS
• carousel scenario = periodic re-transmission of
data module (for increased accessibility)
• non-flow controlled scenario = one time download
of a data module
• Download protocol follows amendment 1 to DSM-CC
for directory message numbering
• The synchronized download protocol offers capability
to transmit non-streaming, error-protected,
synchronized data
Non-flow
data
controlled carousel
DSM-CC
download
MPEG-2
PTS
checksum
CRC32
R
R
DSM-CC
sections
MPEG-2 T.S.
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
28
®
EXAMPLES OF ASYNCHRONOUS DATA
SERVICES
• Stock tickers
• sports statistics
• weather reports
• music downloads,...
R
R
SONICS 102 PACERS 90 FINAL ...
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
29
®
EXAMPLES OF NON-STREAMING
SYNCHRONIZED SERVICES
Just-in-Time transmission of data synchronized
with video and/or audio
•
•
•
•
Pop-up videos
Hot-spots, URL links in commercials and documentaries
Evening games
Triggers
born
in 1962
R
R
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
30
®
ADDRESSABLE SECTIONS
• For tunneling of Internet Protocol
• Include a 6-byte MAC address
• Default mapping is 28-bit IP multicast
address to 23-bit Ethernet MAC multicast
address
• Agree with Amendment 1 to DSM-CC
• checksum protection only for backward
compatibility with MPEG section parsers
IP
LLC/SNAP
checksum
R
R
• Note: We need protocols to manage
ATSC IP Network (urgent) !!!
addressable
sections
MPEG-2 TS
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
31
®
EXAMPLES OF ADDRESSABLE SECTION
-BASED SERVICES
Personalized services:
• Download of software at night
• Subscription to newspaper service
Scalable services:
• platform-dependent downloads
R
R
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
32
®
TRANSPORT SYSTEM TARGET
DATA RECEIVER MODEL
R
R
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
33
®
DATA SERVICE PROFILES
Purpose is:
• To represent maximum bandwidth allocated to a
data service.
• Multiple services can be bundled together into the
same profile
R
R
• A data service may use less than the transmission
bandwidth allowed by the profile
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
34
®
DATA SERVICE PROFILES
G1
Guaranteed bandwidth up to 384 kpbs
G2
Guaranteed bandwidth up to 3.84 Mbps
G3
Guaranteed bandwidth up to 19.39 Mbps
R
R
A1
Opportunistic up to 19.39 Mbps
( NTSC VBI-based Data Services: 180 kbits/sec max )
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
35
®
OPPORTUNISTIC DATA SERVICES
Opportunistic data service = A data service for which
no transmission bandwidth has been provisioned in the
emission station. Data packets are inserted into the
multiplex upon request from multiplexer (see IS DIWG)
Opportunistic data services make use of instantaneous
bandwidth available in a transport stream. Profile
to be used in connection with VBR video encoders .
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
36
R
R
®
T-STD BUFFER MODEL
The T-STD buffer model embodies the timely
and controlled delivery of data. Its purpose:
• To provide multiplexers with tool to implement
synchronization of data with video or audio
in a reliable manner.
• To define bounds on size of data to be acquired
by data receivers
• To define bounds on throughput required in data
receivers.
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
37
R
R
®
T-STD BUFFER MODEL FOR
ASYNCHRONOUS SERVICES
Leak
rate
specified
by
sb_leak_rate
Data transfer
rate specified
by RXn
Transport
buffer
TBn
Smoothing
buffer
SBn
512 Bytes
R
R
Size determined
by sb_size
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
38
®
T-STD FOR SYNCHRONIZED SERVICES
Data transfer
rate specified
by RXn
Transport
buffer
Smoothing
TBn
buffer
SBn
512 Bytes
Leak
rate
specified
by
sb_leak_rate
Size determined
by sb_size
Data
Access Unit
(DAU) taken out at
time specified
by MPEG-2
PTS associated
with DAU,
assuming
instantaneous
decoding
Data
Elementary
buffer
DEBn
R
R
Size determined
by SDEBn
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
39
®
DATA SERVICE LEVELS
1
4
16
DEBSn = 120120 bytes
DEBSn = 480480 bytes
DEBSn = 1921920 bytes
R
R
64
DEBSn = 7687680 bytes
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
40
®
DATA SERVICE LEVELS
Purpose to provide reference points for memory and
throughput requirements in data receivers
DEBn buffer is split uniformly among all data elementary
streams so applications of a same service can be run
concurrently in a data receiver
Nominal Data Access Unit (DAU) size is 40040 bytes
= 19.2 Mbits/sec * 1001 / (8 * 60 * 1000)
R
R
DAUs must at least 5.561111 msec apart (172.8 Mbits/sec
throughput for level 1 services )
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
41
®
CONCLUSION
• ATSC Data Broadcast Service specification is the result of
more than 2 years of successful collaboration between CE,
PC and head-end equipment manufacturers.
• It has been recorded as DVS 161 by SCTE
• The specification opens up new business opportunities
(opportunistic data, data service devices, IEEE 1394,
personalization,...)
• The specification will help accelerate deployment of DTV
services.
May 6, 1999
SHARP LABORATORIES OF AMERICA, INC.
42
R
R
®