1. Ensuring High-quality
IPTV Services
Part 1

2. “Ensuring High Quality IPTV Services”
Why offer IPTV?
Economical solution that offers new business opportunities (revenue) for service providers.
New rates make it possible to easily integrate voice, video and data services over a phone line.
Simultaneously provide multiple standard and high definition television channels SDTV and HDTV to residences.
Provide specialized programming such as special events, movies, concerts only when requested by the user. (VoD)
“Ensuring High Quality IPTV Services”

3. IPTV Delivery– What’s the big deal?
Why can’t I just connect a 13” TV?
What’s so different from my old CATV?
Why can’t I just monitor dropped packets and % utilization?
“Ensuring High Quality IPTV Services”

4. TV – Traditional vs. IPTV
Traditional TV
All channels delivered to subscribers all the time
IPTV
Delivers a small number of channels to each subscriber
When a subscriber changes channels, a request is sent to an upstream server to:
- activate and deliver the new channels (Join)
- deactivate and stop delivering the old channels (Leave)
Subscriber can’t tell that all available channels are not present.
“Ensuring High Quality IPTV Services”

5. IPTV Delivery – Efficient yet Fragile
High speed
Low cost
Low latency
Fragile
Typically delivered over User Data Protocol (UDP)
depends on IP network bandwidth
depends on network components
depends on configuration
“Ensuring High Quality IPTV Services”

6. “Ensuring High Quality IPTV Services”
Customer Objections
Picture
Black
Frozen
Tiling or Blocking
Better picture quality
Distortion or pixelization
Loss of Resolution during motion
Audio
Dropout
Lip sync
Varying volume levels
Excessive time to change channel
“Ensuring High Quality IPTV Services”

7. “Ensuring High Quality IPTV Services”
IPTV General Delivery
Video service providers code and compress the video signal,
Create MPEG-2, MPEG-4 or WM9/VC-1 frames
Video frames are typically carried by streaming IP Packets using User Datagram Protocol (UDP) for its low latency.
At Subscriber’s house, the video stream is decoded by a set-top box (STB) and plays on the TV.
“Ensuring High Quality IPTV Services”

8. UDP – Delivering on hope
“Dropped packets are preferable to delayed packets”
A good IPTV analyzer needs to provide statistics for dropped packets.
“Ensuring High Quality IPTV Services”

9. “Ensuring High Quality IPTV Services”
MPEG Compression
Relies on the eye's inability to resolve high frequency color changes
Relies on the fact that there’s a lot of redundancy with and between frames.
Predicts the value of pixels in a frame, from the information in adjacent frames. (motion)
Relies on the fact that, high power tones tend to blot out lower power adjacent tones. So if you can't hear it, don't transmit it.
Same principal as a *.zip file
A good IPTV analyzer needs to detect and indicate the compression type – MPEG-2, MPEG4, H.264 etc. Increasing compression decreases the bandwidth but also decreases the quality of the video.
“Ensuring High Quality IPTV Services”

10. Introducing I, P and B Frames
Compressing Video Frames
Start with complete still image (I Frame)
Partial frames (P and B Frames) set brightness, color, motion vectors etc and are much smaller than I Frames.
P Frames are forward predictors and are partially compressed.
B Frames are both forward and backward predictors and are heavily compressed.
Less data is sent using this method
“Ensuring High Quality IPTV Services”

11. MPEG-2: Group of Pictures
Group of Pictures (GOP) – Sequence of frames
Successive pictures within a coded video stream
Defines how many I, P and B frames in each GOP
M=3, N=12, GOP structure is IBBPBBPBBPBBI
Less data is sent using GOP
Only need to update the macro blocks that change or move
A good IPTV analyzer needs to identify the GOP type, structure and min/avg/max length. This defines the time to recover from errors.
“Ensuring High Quality IPTV Services”

12. “Ensuring High Quality IPTV Services”
MPEG-2 Error Recovery
I Frames are typically once every 15 frames (1/2 second), then the next GOP starts.
Higher levels of compression may cause errors to last longer
Quantization and motion estimation ensure that errors propagate quickly
A good IPTV analyzer needs to keep statistics for I,P and B frames received vs. packets that are lost, discarded or impaired.
“Ensuring High Quality IPTV Services”

13. “Ensuring High Quality IPTV Services”
Packet and Frame Loss
Blurred Motion
Single B-frame lost
1 frame affected
Tiling or Blocking
Single I-frame lost
14 frames affected
A good IPTV analyzer needs to detect excessive problems like blurring and tiling and report the degradation factors contributing to the root cause.
“Ensuring High Quality IPTV Services”

14. Ensuring High-Quality IPTV Services - Part 2
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Ensuring High-Quality IPTV Services - Part 2
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“Ensuring High Quality IPTV Services”

15. Ensuring High-quality
IPTV Services
Part 2

16. “Ensuring High Quality IPTV Services”
IPTV Protocol Stack
A good IPTV analyzer needs to provide performance statistics at all levels of the protocol stack to isolate a problem layer.
“Ensuring High Quality IPTV Services”

17. MPEG-2 Transport Stream
Fixed Length packets, multiplexes many PES packets.
Program Identifier (PID) contains information to find, identify and reconstruct program contents
Continuity Counter (CC) – 4 bit counter to detect loss or out of sequence packets
Program Clock Reference (PCR) – clock reference to time sync the video and audio
Sync byte set the start of a TS packet and allows synchronization
Transport Error Indicator indicates a TS packet error
A good IPTV analyzer needs to detect Sync byte, PID and CC errors to determine the quality of a transport stream.
“Ensuring High Quality IPTV Services”

18. MPEG-2 - Program Clock Reference
PCR – Clock recovery mechanism for MPEG
42 bits – 33 bits for 90Khz and 9 bits for 27MHz.
Inserted in Transport Stream no less than every 100 msec
Excessive PCR jitter can make it impossible to decode programs.
A good IPTV analyzer must measure PCR jitter.
“Ensuring High Quality IPTV Services”

19. “Ensuring High Quality IPTV Services”
PSI Tables
PAT list all programs available in the transport stream with their program ID (PID).
Each program has a PMT that lists the elementary streams for that program.
A good IPTV analyzer needs to detect PMT, PAT and CAT errors.
“Ensuring High Quality IPTV Services”

20. Zap Time (channel change time)
Key Factors affecting Zap Time
Encoding
Network
Set top Box (leave and joins)
A good IPTV analyzer needs to measure channel change latency (zap time).
“Ensuring High Quality IPTV Services”

21. “Ensuring High Quality IPTV Services”
User QoE
A good IPTV analyzer needs to provide a video preview and a suite of QoE perceptual quality metrics including a MOS score so that the technician knows exactly what the subscriber can expect to see.
“Ensuring High Quality IPTV Services”

22. Checkpoints Affecting IPTV Quality
Video Stream (coding, compression)
IP Core network layer (bandwidth, congestion, integrity etc.)
ATM payload (XDSL network)
ADSL2+/VDSL2 (copper loop, modem, impulse noise, rates)
Fiber (power level, modem, rates)
Set-top Box (decoding, cable/connections)
Interaction of layers (xDSL, ATM, IP and Video Transport)
A good IPTV analyzer needs to measure IP bandwidth. Standard definition (SD) video typically uses 3-6 Mbps but high definition (HD) can use 8-10 Mbps.
“Ensuring High Quality IPTV Services”

23. Summary: Factors Affecting IPTV Quality
Encoding and Compression
Trade off between quality and compression level
Determines information per IP packet
Affect error recovery time
Jitter
Short term variation in packet arrival time
May affect the transport stream carrying the PCR
Direct impact on the decoding process of the customer’s STB.
Limited Bandwidth
Ultimately determined by customer’s access rate (xDSL or Fiber)
Packet are discarded when maximum bandwidth is exceeded
Packet Loss
Bandwidth limitations, network congestion
Range from single, unnoticeable, missing point of video sequence to long periods of degraded, pixilated or unavailable images.
Transmission Errors .Can’t recover packets sent with UDP
Lost I frame , there is a good chance of losing the video for a short period
Lost B/P/Si/Sp frames, impact less severe but could lead to poor image quality
Lost MPEG bytes (Sync Bite, PID, Continuity Counter, PSI Tables
“Ensuring High Quality IPTV Services”

24. “Ensuring High Quality IPTV Services”
Introducing
Turn your PC into a Powerful IPTV Analyzer
Attractive price
Automatically tests all channels with pass/fail results
Complete Set Top Box (STB) emulation
Full Motion Picture video preview
Accurate audio and video MOS scores and QoE/QoS metrics
Comprehensive Video and Transport Stream statistics
Drill into detail to determine root cause of problems
Generate detailed and summary pdf reports
Detects degrading conditions that simple TV viewing would fail to detect
Correlate dropped packets with other events to determine root cause
“Ensuring High Quality IPTV Services”

25. “Ensuring High Quality IPTV Services”
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“Ensuring High Quality IPTV Services”