Presentation on theme: "Ensuring High-quality IPTV Services Part 1. Ensuring High Quality IPTV Services Why offer IPTV? Economical solution that offers new business opportunities."— Presentation transcript:
Ensuring High-quality IPTV Services Part 1
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 IPTV Delivery– Whats the big deal? Why cant I just connect a 13 TV?Why cant I just connect a 13 TV? Whats so different from my old CATV?Whats so different from my old CATV? Why cant I just monitor dropped packets and % utilization?Why cant I just monitor dropped packets and % utilization?
Ensuring High Quality IPTV Services 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 cant tell that all available channels are not present.
Ensuring High Quality IPTV Services IPTV Delivery – Efficient yet Fragile Efficient 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 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 Customer Objections
Ensuring High Quality IPTV Services 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 Subscribers house, the video stream is decoded by a set-top box (STB) and plays on the TV. IPTV General Delivery
Ensuring High Quality IPTV Services UDP – Delivering on hope A good IPTV analyzer needs to provide statistics for dropped packets. Dropped packets are preferable to delayed packets
Ensuring High Quality IPTV Services Relies on the eye's inability to resolve high frequency color changes Relies on the fact that theres 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 MPEG Compression 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 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 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 MPEG-2: Group of Pictures 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 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 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.
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Ensuring High-quality IPTV Services Part 2
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 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 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 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 Key Factors affecting Zap Time Encoding Network Set top Box (leave and joins) Zap Time (channel change time) A good IPTV analyzer needs to measure channel change latency (zap time).
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 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) Checkpoints Affecting IPTV Quality A good IPTV analyzer needs to measure IP bandwidth. Standard definition (SD) video typically uses 3-6 Mbps but high definition (HD) can use Mbps.
Ensuring High Quality IPTV Services 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 customers STB. Limited Bandwidth Ultimately determined by customers 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.Cant 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 Summary: Factors Affecting IPTV Quality
Ensuring High Quality IPTV Services 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 Introducing Turn your PC into a Powerful IPTV Analyzer
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