Transcript StreamScope MT-40 Version 4.3 DIP

StreamScope™
DTV Monitor & Analyzer
July 15 2009
SCTE Piedmont
Rakhi Modi
An LG Electronics Company
Copyright © 2008 Triveni Digital, Inc.
Overview
 MPEG Transport Stream Basics

Packet header
 PSI Tables metadata


PAT
PMT
 PSIP Tables metadata


Static tables
Dynamic tables
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 Elementary streams




Encoding
Buffering
Synchronization
IP monitoring &
synchronization
 Monitoring and
Troubleshooting streams


StreamScope architecture
Typical use case
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Page 2
DTV Broadcast Stream


Special case of MPEG-2 transport stream
May contain multiple virtual channels

Video channels




One or more audio streams
Possibly one or more data streams
Audio channels



A video stream
One or more audio streams
Possibly one or more data streams
Data-only channels

One or more data streams
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Page 3
MPEG-2 Transport Stream

Made up of 188-byte transport packets, each with 4
byte header & 184 byte payload

Each packet contains any ONE kind of information–
audio, video, data, PSI, …
One
Transport
(MPEG)
Packet
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Page 4
MPEG-2 Transport Stream (Contd.)

We say transport packets have multiple interleaved
elementary streams -- audio, video, data, PSI, ...

Packets belonging to the same elementary stream are
identified by packet id (PID) in packet header (same
color in our illustrations).
MPEG-2 Transport Stream
These three packets are the same color.
They have the same PID and belong to
the same Elementary stream.
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Page 5
MPEG-2 Transport Stream – Header Fields
Noteworthy fields:
1) Sync Byte – Find packet boundary
2) PID – Used while demultiplexing stream
3) Continuity Counter – Identify packet loss
4) PCR stamp in adaptation field – Clock sync
MPEG-2 Transport Stream
Header (4 Bytes)
Sync
Byte
PID
188 Bytes
Continuity
Counter
Adaptation
Adaptation
Field
Field
(Optional)
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PES 1
x
Or other Payload (Pat, PMT, PSIP,
etc)……………………………...
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Page 6
MPEG Header Fields: Sync Byte

When a decoder first tunes, all it sees are a stream of
0’s and 1’s

The decoder must first identify the beginning of
packets before it can interpret the stream

The decoder uses the Sync Byte field to do this
01010001111010010101101010001100011110010111000
MPEG Data Prior to
Packet Sync
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MPEG Header Fields: Sync Byte (Contd.)

The Sync Byte of a packet is always 0x47
(Hexadecimal) or 01000111 binary

The decoder looks for strings of zeros and ones which
match the pattern of the sync byte (see red below)
01010001111010010101101010001100011110010111000
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MPEG Header Fields: Sync Byte (Contd.)

Once the decoder finds a 0x47 in the stream, it looks 187 bytes
down the stream, and looks for another 0x47

If it finds three Sync Bytes in a row, then the Decoder has Found
Sync and assumes packet boundaries from then on

Each packet is tested for 0x47 as soon as it arrives. If a packet
arrives with an incorrect sync byte, the decoder starts over. This
is called SYNC LOSS
Found Sync
0x47
187 bytes
0x47
187 bytes
0x47
187 bytes
Packet 188 bytes
Sync Lost
Packet 188 bytes
Packet 188 bytes
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0x32
11010101010111011010101010001
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Page 9
MPEG Header Fields: Sync Byte (Contd.)

If you don’t have Packet Sync, the decoder cannot find
packet boundaries. You will not be able to decode at
all

Packet Sync problems typically occur in hardware at
packet boundaries during format converters, edge
devices, demodulators etc:



ASI to Gig-E
ASI to Microwave or QAM
Satellite to ASI
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Page 10
PIDs Defined


PID stands for Packet ID
Each Packet has a PID (indicated by color). Packets
belonging to the same source of information have the
same PID (same color).
MPEG-2 Transport Stream
These three packets are the same color.
They have the same PID and belong to
the same Elementary stream.
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Page 11
PIDs Defined - ATSC Bitstream
PSIP Tables
PSIP Generator
Video
PAT
Audio
PMT
Data channel
Data Server
Data
Null
PSIP
Dataenhanced
Audio/Video
channel
Audio/Video
channel
Data Server
Audio Encoder
Multiplexer
Video Encoder
Audio Encoder
Video Encoder
MPEG-2 Transport Stream
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PIDs Defined - Digital Cable Bitstream
Video/Audio
channel
Video/Audio
channel
Video/Audio
channel
Video/Audio
channel
Audio Encoder
PAT
Video Encoder
PMT
Audio Encoder
CAT
Video Encoder
Audio Encoder
Null
Video
Audio
Video
Audio
Video
Audio
Video
Audio
Multiplexer
Video Encoder
Audio Encoder
Video Encoder
MPEG-2 Transport Stream
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Page 13
Transport Stream Demultiplexing

When a set top box first receives a Transport Stream, it
demultiplexes that stream based on PID.
set top box
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Metadata


Data about included data is metadata

There are two kinds of Metadata
Metadata tells the decoder which kinds of information
are contained in each PID, and which PID’s go
together.

Program Specific Information (PSI) - Tables in the stream
defined in the MPEG standards

Program and System Information Protocol (PSIP) -Tables
defined in ATSC A/65
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PSI Tables (MPEG-2 Tables)

PAT - Program Association Table


Appears in PID 0x0000

The PAT is on PID 0x00. This is the first PID or ‘Base PID’ a
MPEG decoder looks for
Identifies MPEG-2 programs in transport stream and gives
PIDs for their PMTs

PMT - Program Map Table
Identifies elementary streams in program (virtual
channel), and gives their PIDs.


CAT - Conditional Access Table
NIT - Network Information Table
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MPEG-2 PSI Tables (Contd.)
PMT 1
Video PID 0x31
Audio PID 0x34
Audio PID 0x35
PCR_PID 0x31
PAT (always on PID 0x0)
Station TSID
PMT 2
PID 0x40
PMT 1 -> On PID 0x30
PMT 2 -> On PID 0x40
PMT 3 -> On PID 0x50
Video PID 0x41
Audio PID 0x44
Audio PID 0x45
PCR_PID 0x41
PMT 3
Video PID 0x51
Audio PID 0x54
Audio PID 0x55
PCR_PID 0x51
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MPEG-2 PSI Tables (Contd.)
Set top Box
“WXXX Channel Video”
PID 0x31
“WXXX Channel Audio”
PID 0x34
PSI
PID assignments
These PIDS go together
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Page 18
PSIP Tables (ATSC Tables)

Branding – Station call letters and Channel number

Signaling – V-Chip data, information about audio and
Video PID’s

Announcement – Program Guide
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ATSC PSIP Tables

MGT - Master Guide Table
- Appears in PID 0x1FFB.
- Gives PIDs, sizes, and version numbers of other PSIP
tables (except STT).

STT - System Time Table
- Appears in PID 0x1FFB
- Gives current UTC time.

VCT - Virtual Channel Table
- Identifies and describes virtual channels.
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Page 20
ATSC PSIP Tables (Contd.)
 RRT - Rating Region Table
- Describes content advisory system(s) being used to
rate events.

EIT - Event Information Table
- Gives titles, start times, durations, content advisory
ratings of events (TV programs).

ETT - Extended Text Table
- Gives extended textual descriptions of virtual
channels and events.
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Page 21
PSIP and PSI Link
Table Information for a
Television Broadcast Stream
PAT
(On PID 0x0)
PMT 1
(On PID 0x30)
Station TSID
Video PID 0x31
Audio PID 0x34
PCR_PID 0x31
PMT 1 -> On PID 0x30
PAT and PMT Tables
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VCT
On Pid 0x1FFB
4-1
WXXX
Video PID 0x31
Audio PID 0x34
PSIP table
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Page 22
Table Intervals

Metadata is transmitted periodically in the transport
stream

Each table in the system, MPEG or PSIP, has a defined
repetition rate. e.g. the Program Association Table
(PAT) must appear in the transport stream every
100ms

If the table does not appear frequently enough in the
stream, it can cause minor problems while decoding

If the table is MISSING all together then larger
decoding problems begin to occur
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Page 23
Electronic Program Guide

Receiver periodically scans all channels and caches
program info from EITs and ETTs.

Receiver displays:





Channel, program title, etc., on channel change.
Detailed info on current program on request.
On-screen, interactive program guide on request.
Detailed info on future programs on request.
Note: Closed Captioning information NOT in this
location
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Page 24
MPEG Header: Continuity Counter

The continuity counter is a 4 bit field in the header
which increments by 1 each time a packet comes out
on a specific PID:
All Packets PID 0x52
0
1
2
3
4
5
6
7
…
8
14 15
0
1
 When a PID ‘skips’ one value of the continuity Counter,
we call it a ‘Continuity Error.’ This means one or more
packets were lost.
Continuity
Error Here
All Packets PID 0x54
0
1
2
3
7
8
9
10
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11
…
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MPEG Header: Continuity Counter (Contd.)
Identifies WHEN we lose
Packets, but not HOW MANY!

Packet loss causes many other kinds of analysis to ‘reset’ or give
bogus results.

Any analysis based on an average over many packets will
automatically reset when it encounters continuity problems.

Since a continuity error mean ‘some packets’ have been lost,
frequent continuity errors should be one of the FIRST things you
look for when debugging.
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Three Things to Remember

Three main monitoring and troubleshooting lessons:

Fix Continuity Problems first




Continuity errors create bogus alarms in other areas.
Until you resolve the continuity problems, it will be very hard to
determine if you have other problems in your stream
TBD
TBD
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Video Formats

ATSC supports 18 different MPEG-2 video formats:

HDTV




1080x1920 pixels; 60i, 30p, 24p; 16:9 aspect
720x1280 pixels; 60p, 30p, 24p; 16:9 aspect
SDTV


480x704 pixels; 60p, 60i, 30p, 24p; 16:9, 4:3 aspect
480x640 pixels; 60p, 60i, 30p, 24p; 4:3 aspect
SCTE supports more video formats

SDTV


480x528 pixels; 60i, 24p; 4:3 aspect
480x352 Pixels; 60i, 24p; 4:3 aspect
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MPEG-2 Video Encoding


Video is sequence of frames.
Each frame is encoded in one of three ways:

I-picture: intra-picture encoding, similar to jpeg encoding

B-picture: bi-directional encoding, using motion adjusted

P-picture: predictive encoding, using motion adjusted deltas
(exploiting spatial redundancy).
deltas from a previous and a future frame (exploiting temporal
redundancy).
from a previous reference frame (exploiting temporal
redundancy).
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MPEG-2 Video Encoding (Contd.)
Example 1. Panning Camera
I-picture
B-picture
I-picture
B-picture
I-picture
Example 2. Moving Object
I-picture
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MPEG-2 Video Encoding (Contd.)



Encoder emits sequence of encoded frames.

PES packets are packed into MPEG-2 transport packets.
(All packets for single video stream have same PID
value.)


Overall compression ratio is 50:1 or more.
Sizes of encoded frames vary.
Encoded frames are packed into packetized
elementary stream (PES) packets.
Closed captioning associated with video frame is
encoded here
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ATSC/SCTE Audio Formats

ATSC uses AC-3 audio encoding, with up to 6 audio
channels: left, right, center, left surround, right
surround, low frequency enhancement.



The full set is often called 5.1 audio.
The sampling rate is always 48 kHz.
The encoded bit rate may be up to 384 kbps.
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AC-3 Audio Encoding

Audio frames, each 32 milliseconds in length, are
encoded.


Encoded frame size depends only on bitrate.

PES packets are packed into MPEG-2 transport packets.
(All packets for single audio stream have same PID
value.)
Encoded frames are packed into packetized
elementary stream (PES) packets.
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Audio-Video Synchronization

Audio, video are encoded independently, must be
synchronized during play.

MPEG has to allow for great distances between the
Encoder and Decoder, and still allow for Correct Decode
of the transport stream
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The Encoder and Decoder Clock

The MPEG encoder and MPEG decoder use a 27Mhz
‘clock’ to encode/decode incoming audio and video

The clock is actually a ‘counter’ which advances every
1/27000000 seconds
Encoder
Decoder
27Mhz Clock
27Mhz Clock
1,2,3,4…..
1,2,3,4…..
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Decode Time Stamp - DTS

Each Frame is marked with a DTS – “Decode Time
Stamp” – a positive number

The value of the DTS is set to the value of the Encoder
Clock when the frame is encoded
Encoder
27Mhz Clock
MPEG Packets
1,2,3,4…..
F1
DTS
500
F2
DTS
950
Packetizer
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Packets Assigned to Decode Buffer

As packets flow into the Decoder, a space in memory is
set aside for them, one buffer for each PID.
Decoder
27Mhz Clock
MPEG Packets
1,2,3,4…..
Buffer 1 Pid 0x31 Video
Buffer 2 Pid 0x34 Audio
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Reconstruction of Frames From Buffer

Packets form Video and Audio Frames in the buffer
Decoder
27Mhz Clock
MPEG Packets
1,2,3,4…..
Buffer 1 Pid 0x31 Video
F1
DTS
500
F2
DTS
675
F3
DTS
950
Buffer 2 Pid 0x34 Audio
F1
DTS
200
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F2
DTS
990
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The Magic of Decode

When the value of the Decode clock MATCHES the DTS
on the frame, that frame is sent to the decode
hardware
Decoder
Decode
Hardware
27Mhz Clock
MPEG Packets
F1
DTS
200
= 200
Buffer 1 Pid 0x31 Video
F1
DTS
500
F2
DTS
675
F3
DTS
950
Buffer 2 Pid 0x34 Audio
F2
DTS
990
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Another Frame Goes to Decode Hardware

Next Frame
Decoder
Decode
Hardware
27Mhz Clock
MPEG Packets
F1
DTS
500
= 500
Buffer 1 Pid 0x31 Video
F2
DTS
675
F3
DTS
950
Buffer 2 Pid 0x34 Audio
F2
DTS
990
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One More Frame Heads to Decode

And the next frame…
Decoder
Decode
Hardware
27Mhz Clock
MPEG Packets
F2
DTS
675
= 675
Buffer 1 Pid 0x31 Video
F3
DTS
950
Buffer 2 Pid 0x34 Audio
F2
DTS
990
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Page 41
Audio and Video Buffers

Receiver must buffer audio and video frame data until
presentation time.

If data appears too late in the transport stream, buffer
underflow results.

If data appears too early in the transport stream, buffer
overflow results.

Either condition results in garbled play or incorrect
synchronization.

Different set top boxes may respond differently to the
same underlying buffer violations
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Page 42
How to Assure Audio/Video Sync?

In order for the audio and video Elementary Streams to
remain in Sync, the Encoder Clock and the Decoder
Clock must remain in sync

The next few slides will demonstrate how this happens
and what components to check when it fails…
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Page 43
Encoder Inserts PCR

When the encoder streams creates packets, it embeds
the current value of it’s 27 MHz clock into the stream

This time reference is called the PCR: Program Clock
Reference

MPEG demands that one PCR packet appear in the
stream every 100ms
Encoder
27Mhz Clock
MPEG Packets
MPEG
Packet with
PCR Stamp
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Decoder Consumes PCR

When the decoder gets a packet containing a PCR
timestamp, it adjusts it’s 27Mhz clock accordingly
Decoder
27Mhz Clock
MPEG Packets
Adjusts value of
counter based on
incoming PCR Packet
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Page 45
PCR Timestamp Issue


What could conceptually cause PCR timestamps to go
awry?

Encoder possibly time stamped incorrectly

Decoder possibly failed to consume time stamps

PCR packet was accidentally lost in transmission
When PCR time stamps go awry, we have “PCR jitter”
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PCR Jitter
PCR Jitter is:
 Difference between
the Actual Value of the PCR time stamped by
encoder
and
the expected value of the PCR as calculated by
decoder based on the clock rate and the time
at which the PCR value is received.
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PCR Rate (Frequency) Offset
PCR Frequency Offset is:
 Difference between
the clock frequency calculated at decoder
based on actual PCR values received
and
an “ideal” 27 MHz clock, which is the clock rate
dictated by the MPEG-2 standard
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PCR Intervals, Jitter and Rate



Transmit interval: 100 ms

Most streams seen in the field are compliant, but every
now and then extreme jitter shows up.
Jitter: no more than 500 ns
Rate: 27 MHz +/- 810 Hz
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Page 49
PCR Timestamp Issue (Contd.)

What in your network facility could cause PCR
timestamps to go awry?

Three of the most common are:



It can happen at the source encoding (rare except for
broadcast streams!)

It can happen on any IP link – due to network lag
It can happen any time you MUX streams
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Page 50
PCR Packet Spacing Before Muxing

Note the Number of Packets between each PCR packet
in each Input Stream
Video 0x31
PID
Packet
Spacing
Video 0x41
Transport
Stream
Multiplexer
Video 0x51
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0x31
2 Packets
0x41
1 Packet
0x51
0 Packets
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Page 51
PCR Packet Spacing After Muxing

Note that the PCR packet spacing has changed!
Video 0x31
Video 0x41
Video 0x51
Transport
Stream
Multiplexer
PID
Old Spacing
New Spacing
0x31
2 Packets
8 Packets
0x41
1 Packet
5 Packets
0x51
0 Packets
2 Packets
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Page 52
Muxing Causes PCR Jitter

When we MUX multiple streams together, the
spacing between the PCR packets in each
stream CHANGES

The physical shift results in a TEMPORAL shift
as well, throwing the time stamps off

The TEMPORAL shift in PCR values is referred
to as “PCR jitter”
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Muxing Causes PCR Jitter (Contd.)

The MUX has to RESTAMP all the PCR values
to correct for the change in the packet
spacing – THIS IS VERY HARD TO DO

The more services on the output, the harder it is to
restamp

The fewer ‘null’ packets at the output, the harder it
is to restamp
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Page 54
PCR Timestamp Issue (Contd.)

What in your network facility could cause PCR
timestamps to go awry?

Three of the most common are:

It can happen any time you MUX streams


It can happen at the source encoding (rare
except for broadcast streams!)

It can happen on any IP link – due to network lag
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PCR Jitter From Incorrect Encoding

If the MPEG encoder’s parameters are set up
incorrectly, you can introduce jitter at the source

This is relatively rare

If HBO sent it’s stream up to the bird with jitter in it, a LOT of
people would complain!

Local broadcast streams are more likely to have this problem
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Page 56
PCR Timestamp Issue (Contd.)

What in your network facility could cause PCR
timestamps to go awry?

Three of the most common are:

It can happen any time you MUX streams

It can happen at the source encoding (rare except for
broadcast streams!)


lag
It can happen on any IP link – due to network
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Page 57
PCR Jitter Due to IP Carriage

Network lag can conceal MPEG jitter problems on an IP
link. The network jitter is usually so much larger than
the PCR jitter that the PCR jitter is ‘lost in the noise.’

Hopefully, the IP-ASI or IP-QAM edge device will
provide buffering and use ‘high level math’ to smooth
out the network lag.

MT-40 provides a way to separate the Network Lag
from PCR Jitter.
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Page 58
IP Encapsulation of MPEG Packets

When MPEG packets are carried over Gig-E, they are
‘Encapsulated’ inside IP packets.

An IP header is wrapped around the MPEG packets, so
that the MPEG data can be routed through an IP
network

Typically, other intermediate encapsulations involved
are UDP, RTP, VLAN tags
An IP packet
Up to 7
MPEG
packets
IP Packet
Header
IP data section
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Page 59
Multicast IP Basics

Network edge devices forward packets to hosts based
on the packet’s IP address
Packets with destination
Address of 134.2.4.3
Enter the network here
NETWORK
Packets routed to
Host with matching IP
Host 1
IP 134.2.4.1
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Host 2
IP 134.2.4.2
Host 3
IP 134.2.4.3
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Page 60
Multicast IP Basics (Contd.)

There is a reserved range of IP addresses which go to
ALL hosts on the network!

224.x.x.x to 239.x.x.x
NETWORK
Packets with destination
Address of 239.4.4.2
Enter the network here
Packets routed to
ALL hosts!
Host 1
IP 134.2.4.1
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Host 2
IP 134.2.4.2
Host 3
IP 134.2.4.3
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Multicast IP Basics (Contd.)

Sending packets to all hosts on a network is NOT
desirable.



Not appropriate for services such as VOD
Requires MASSIVE amounts of network resources and
bandwidth.
That’s why most cable networks only route multicast
packets when they are REQUESTED with IGMP
(Internet Group Management Protocol) message!
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Multicast IP Basics (Contd.)

In this case, the multicast packet comes into the
network, but doesn’t go out to a host until an IGMP
‘join’ request comes in
Packets with destination
Address of 239.4.4.2
Enter the network here
NETWORK
IGMP Join
From Host
IGMP Join
From Host
Packets
To Host
Host 1
IP 134.2.4.1
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Packets
To Host
Host 2
IP 134.2.4.2
Host 3
IP 134.2.4.3
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Page 63
Multicast IP Basics (Contd.)

In order to monitor multicast Gig-E packets at an edge
switch, one must first generate IGMP requests from the
Host. In this case, the analyzer is the host.
IGMP Message
NETWORK
Stream
Scope
Packets for Analysis
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Page 64
GigE Monitoring Point-to-Point (Non-IGMP)

This method is much simpler. Plug the Monitor card
directly into the Switch under test.
Monitor GIG-E
Card
MT-40
Analyzer
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Switch
under
test
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Page 65
More IGMP Info Later

There is a step-by-step example of IGMP setup in this
packet while on StreamScope
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Page 66
Overall Jitter versus MPEG Jitter

Use ‘Overall’ or ‘MPEG’ jitter settings when measuring
from constant bit rate sources like ASI

Use ‘MPEG’ jitter setting when measuring jitter on ‘GigE’ links to exclude the network associated jitter from
the jitter calculation.

Use ‘Overall’ jitter setting when measuring jitter on
‘Gig-E’ links if you want to see the total jitter due to
network lag AND MPEG issues (requires Gig-E w/PCR
option)
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Page 67
Overall Jitter versus MPEG Jitter (Contd.)

Gigabyte Ethernet offers specific difficulties when
monitoring PCR related issues


The network delay on a typical UDP network is usually orders
of magnitude greater than the PCR Jitter detected on the
network
Be sure to use the appropriate setting for ‘MPEG’ or
‘Overall’ jitter when measuring PCR on Gigabyte
Ethernet networks (see previous slide)
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Page 68
How to Assure Audio/Video Sync? (Contd.)

PCR values help the Encoder Clock and the Decoder
Clock to remain in sync

PCR jitter can cause synchronization problems for
elementary streams

Ensure




PCR jitter and frequency offsets are within standard limits
Elementary stream buffers limits are NOT violated
Large PCR jitter values can cause “Lip sync” error
Buffer over- or underflow problems may cause “tiling”,
“pixelization”/”macroblocking” errors
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Page 69
Three Things to Remember

Three main monitoring and troubleshooting lessons:

Fix Continuity Problems first



Until you resolve the continuity problems, it will be very hard to
determine if you have other problems in your stream
Check for PCR jitter



Continuity errors create bogus alarms in other areas
PCR jitter can cause packet over- or underflow problems
Lip synch errors may also be result of PCR jitter
TBD
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Page 70
Why Transport Stream Analyzer?

With analog transmission, if audio/video did not have
any anomalies on a TV set up in the studio, it would
show up intact on the end user’s TV

For digital transmission, this assumption is NOT valid
as digital signals rely on the decoder’s



Firmware implementation
Buffer sizes
Software decoding capability
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Page 71
Why Transport Stream Analyzer? (Contd.)

The transition to digital has introduced some specific
challenges for broadcast engineers
• Not all Set top boxes will respond the same way to the same
underlying problem
• Standards violations in digital Transport Streams may show up on a
receiver only intermittently

The only streams which will consistently decode are
those which are compliant

The best way to assure compliance is with a Transport
stream Analyzer/Monitor
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Page 72
MT-40: Collaborative Mode Debugging

Two or more technicians use MT-40 to examine the
same input.

Customers leverage subject matter experts from many
different geographical locations
Head End
Tech Operations Center
LAN
WAN
LAN
MT-40
IRD
MUX
Encoder
Modulator
Equipment Room
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MT-40: Multi- Channel Fleet Monitoring
Local DTV Station or Headend
Chief Engineer’s Office
Remote location with MT-40
MT-40 Visualization
Client viewing all
sources, all channels
simultaneously
Network
Equipment Room
Remote location with MT-40
MT-40
Monitoring
local channel
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Page 74
Troubleshooting Example – Audio Outage
• Customer calls into station – audio dropping out on their set
• In station set top boxes do not have any problems
• How serious is this problem? Are other Customers seeing it?
PSIP
Generator
QPSK
ASI
MUX
Satellite
Receiver
SMPTE 310
Transmitter
8VSB
ASI
Satellite
Dish
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Page 75
Troubleshooting Example (Contd.)
PSIP
Generator
QPSK
ASI
MUX
Satellite
Receiver
SMPTE 310
Transmitter
8VSB
ASI
Satellite
Dish
Transport
Stream Analyzer
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Page 76
Troubleshooting Example (Contd.)

Standards violation has occurred
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Troubleshooting Example (Contd.)

Move backwards in your set up
PSIP
Generator
QPSK
ASI
MUX
Satellite
Receiver
SMPTE 310
Transmitter
8VSB
ASI
Satellite
Dish
Transport
Stream Analyzer
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Troubleshooting Example (Contd.)

Standards violation is still present
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Troubleshooting Example (Contd.)

Move backwards further in your set up
PSIP
Generator
QPSK
ASI
MUX
Satellite
Receiver
SMPTE 310
Transmitter
8VSB
ASI
Satellite
Dish
Transport
Stream Analyzer
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Page 80
Troubleshooting Example (Contd.)

And further…
PSIP
Generator
QPSK
ASI
MUX
Satellite
Receiver
SMPTE 310
Transmitter
8VSB
ASI
Satellite
Dish
QPSK
Transport
Stream Analyzer
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Page 81
Troubleshooting Example (Contd.)

Using recording capability to collect data
QPSK
Satellite
Receiver
Groomer
and/or
Splicer
Gig-E
Or
ASI
Modulator and
Upconverter
(RF or Fiber)
QAM
Satellite
Dish
Record from
These points
Transport Stream
Analyzer
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Page 82
MPEG Monitoring Over the Long Term
PSIP
Generator
QPSK
ASI
MUX
Satellite
Receiver
SMPTE 310
Transmitter
8VSB
ASI
Satellite
Dish
QPSK
Transport Stream
Analyzer
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Page 83
On Error – Do something!
PSIP
Generator
QPSK
ASI
MUX
Satellite
Receiver
SMPTE 310
Transmitter
8VSB
ASI
Satellite
Dish
QPSK
Transport Stream Analyzer
Error Detected!
Email, SNMP, Contact Closure etc.
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Page 84
Three Things to Remember

Three main monitoring and troubleshooting lessons:

Fix Continuity Problems first



Until you resolve the continuity problems, it will be very hard to
determine if you have other problems in your stream
Check for PCR jitter



Continuity errors create bogus alarms in other areas
PCR jitter can cause packet over- or underflow problems
Lip synch errors may also be result of PCR jitter
Move Backward through your network as you debug

Isolate the offending device first, then go for detailed problem
solving steps (recording a file, etc.)
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Page 85
References

Information Technology -- Generic Coding of Moving Pictures and
Associated Audio Information: Systems (MPEG-2 Systems
standard), ISO/IEC 13818-1.


ATSC Digital Television Standard, ATSC Doc. A/53.


ATSC Data Broadcast Standard, ATSC Doc. A/90.
Program and System Information Protocol for Terrestrial Broadcast
and Cable, ATSC Doc. A/65 (with corrigenda and amendments).
Measurement Guidelines for DVB Systems, ETSI Technical Report
ETR 290.
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Page 86