Development and Evaluation of Robust HDTV Transmission System using FEC Tohru Kondo ( tkondo@hiroshima-u.ac.jp) Graduate School of Engineering, Hiroshima University
Introduction � Demand expansion of high-quality/definition picture transmission. � Growth the use of high definition TV technology � It is expected to be used in various fields. � Broadcast, Medial, Distance learning… � Applications that needed high-resolution. � The rapid spread of high bandwidth Internet connections. � The broadband Internet can provide a versatile application to users. 2 2004/10/14 18th APAN Meetings / HD session
Outline � Introduction � HDTV MPEG2 over IP Transmission System � Transmission System outline � FEC Gateway for FEC-incapable receivers � Performance Evaluation � The Effectiveness of FEC � Delay measurement � 3 point Multicast HD Transmission for distance seminar � Conclusions 3 2004/10/14 18th APAN Meetings / HD session
HDTV over IP Transmission System � System configuration ROBST system � Support IPv4/v6, IP Point-to-Multipoint / Multicast. � Use RS (Reed-Solomon) code as FEC Input Output � Support media format � MPEG2-TS (Transport Stream) Linux-PC Media packet � SD MPEG2-TS (4-8Mbps) De/capsulate � PCI Encoder/Decoder Card � HD MPEG2-TS (20-30Mbps) RTP � IEEE1394 input FEC processing � MPEG2 decoder output � DVB-ASI output media FEC media FEC � IP output (for Video LAN receiving) � DV (30Mbps) � IEEE1394 input/output IP Network IP Network 4 2004/10/14 18th APAN Meetings / HD session
HDTV over IP Transmission System � System configuration Software Decoding MPEG2 Without FEC MPEG2-TS MP@HL Encoding ( 19.7 Mbps, 720/30p) HDTV/MPEG2/RTP 20Mbps (without FEC). 22-30Mbps (with FEC). NIC Sender VideoLAN JVC HDcam (Windows or Linux) NIC Receivers Internet IEEE1394 Internet 1920x1080i 1440x1080i 1280x720i NIC 1280x720p 704x480i DVHS 704x480p MPEG2 Decoder Mediaglue PCI Card MGHDB3 PCI decoder (Linux) 5 2004/10/14 18th APAN Meetings / HD session
HDTV over IP Transmission System (contd.) � Packet loss recovery function using FEC. � RS (Reed-Solomon) coding based on RFC2733. � RFC2733 defines RTP payload format using parity code � Recovery function can apply to all RTP media streams. � Packet format FEC Recovery Unit Media packet K packet N packet IPv4 Media Packet UDP RTP Payload /v6 IPv4 Payload FEC UDP RTP FEC packet FEC Packet /v6 (N,K) coding Recoverable � FEC packet is sent as a separate stream. up to N-K packets � Backwards compatible with FEC-incapable receivers. 6 2004/10/14 18th APAN Meetings / HD session
Recovery performance of FEC FEC recovery performance ( X-axis: Before FEC, Y-axis : After FEC) Redundancy Increase in bandwidth (N,K) (15,13) 1.15 (15,12) 1.25 (15,11) 1.36 (15,10) 1.5 0.5 % → 3e-07 % (15,9) 1.67 1.0 % → 1.8e-07 % (15,8) 1.86 7 2004/10/14 18th APAN Meetings / HD session
Packet Interleaving � Methodology � shuffle the transmitting packet order. � disperse bursty packet losses on several FEC units. � have buffering delay on both end hosts. Unit (N) media packet (K) Interleave depth : d = 1 N-K − + ( N K )( d 1 ) Recover burst packet losses in the unit. 8 2004/10/14 18th APAN Meetings / HD session
FEC gateway for FEC-incapable receivers � The problems of the FEC. � FEC processing with low-spec PC or MPEG2 software decoding has higher risk. � It may be affect MPEG2 decoding process. � The advantage of FEC gateway � Applicable FEC function on Video LAN receiving. � Converting IP Unicast to IP Muiticast � We can construct flexible distribution network. Design and implement FEC gateway for FEC-incapable receivers 9 2004/10/14 18th APAN Meetings / HD session
FEC gateway for FEC-incapable receivers � System configuration FEC-capable HD Sender HD stream receiver with FEC Lossy network Lossy network Unicast Multicast FEC-incapable receivers FEC Gateway FEC Decoding 10 2004/10/14 18th APAN Meetings / HD session
Performance Evaluation of developed system � Performance evaluation was taken for � Tolerance against packet loss. � Impact on received picture. � Processing load. � Impact of FEC process to high-bandwidth stream � Transmission delay. � MPEG2 comp/decompression, FEC processing delay. 11 2004/10/14 18th APAN Meetings / HD session
Tolerance against packet loss � Demonstration environment � Sender sends MPEG2 HD (22.5Mbps) streams unidirectionally. � Intermediate host (loss generator) randomly drops the packet � In this experiment, set packet loss rate on 0.1%. � We recorded receiving picture with FEC / without FEC. DVHS Sender: Loss generator Sender Receiver DVHS (TT-D3000 ) Receiver: MGHDB3 HD decoder Packet loss!! 100base-TX 12 2004/10/14 18th APAN Meetings / HD session
Evaluation of tolerance against packet loss � Comparison of receiving picture. � MPEG2 MP@HL (22Mbps, 1080/60i) packet loss rate : 0.1 % Without FEC With FEC: (15,13)coding 13 2004/10/14 18th APAN Meetings / HD session
Measurement of processing load by FEC � Methodology � Sender generates streaming data (4-40Mbps), applies FEC, and sends to loss generator. � Intermediate host (loss generator) randomly drops the packet � In this experiment, set packet loss rate on 0-10%. � Receiver recovers lost packets by FEC decoding. � We investigate CPU processing load at receiver. Loss generator Sender Receiver Packet loss!! 14 2004/10/14 18th APAN Meetings / HD session 100base-TX
Measurement of processing load by FEC � Relation between bandwidth and processing load � Decoding processing with packet loss: (15,13)condig 15 2004/10/14 18th APAN Meetings / HD session
Delay measurement of HD transmission � System configuration � Measuring method � Compare two images (source and receive images) side-by-side. FEC gateway Sender Receiver � Record by using Digital Video Camera. � Calculate frame difference Source Receive image (1frame : 1/30 second) image between source and receive VideoLAN images (by comparing SMPTE time-code) It is not strict measurement JVC JY-HD10 16 2004/10/14 18th APAN Meetings / HD session
Delay measurement of HD transmission � System configuration � Measuring method � Compare two images (source and receive images) PCI HD Decoder (MGHDB3) side-by-side. approx. 18 frames: 600msec FEC gateway Sender Receiver � Record by using Digital Video Camera. � Calculate frame difference Source Receive image (1frame : 1/30 second) image between source and receive VideoLAN images (by comparing SMPTE time-code) It is not strict measurement JVC JY-HD10 17 2004/10/14 18th APAN Meetings / HD session
Delay measurement of HD transmission � System configuration � Measuring method � Compare two images (source and receive images) Video LAN side-by-side. FEC gateway approx. 22 frames: 740msec Sender Receiver � Record by using Digital Video Camera. � Calculate frame difference Source Receive image (1frame : 1/30 second) image between source and receive VideoLAN images (by comparing SMPTE time-code) It is not strict measurement JVC JY-HD10 18 2004/10/14 18th APAN Meetings / HD session
Delay measurement of HD transmission � System configuration � Measuring method � Compare two images Video LAN (loss 1.0% 、 through FEC gateway) (source and receive images) approx. 22 frames: 740msec Video LAN side-by-side. FEC gateway approx. 22 frames: 740msec Sender Receiver � Record by using Digital Video Camera. � Calculate frame difference Source Receive image (1frame : 1/30 second) image between source and receive VideoLAN images (by comparing SMPTE time-code) It is not strict measurement JVC JY-HD10 19 2004/10/14 18th APAN Meetings / HD session
Summary � Influence of delay � The system constantly produces hundreds more delay. � MPEG2 (de)compression delay � It is fatal impact for applications that needs interaction communication. � It is important that using various tools as situation demands. � For distance learning... � Discussion, Interaction ： low-delay application (H.264 etc) Uncompressed HDTV � Transmission of document and black board ： MPEG2 HDTV 20 2004/10/14 18th APAN Meetings / HD session
3-point HD Multicasting Seminar � We have been performing the student seminar using HD transmission system. � 3-point native IPv6 Multicasting � Hiroshima Univ., Hiroshima City Univ., Saga Univ., every week. Hiroshima City Univ. Hiroshima Univ. Saga Univ. 21 2004/10/14 18th APAN Meetings / HD session
3-point HD Multicasting Seminar � System configuration � We transmit HD video and audio separately. � Audio: MRAT (Multipurpose RAT) � http://lab.ipc.hiroshima-cu.ac.jp/mrat/ 400Km JGNv6 Saga Hiroshima Kyushu Hiroshima Univ. Saga Univ. Okayama (Saga) (Higashi Hiroshima) 45Km Hiroshima City Univ. VideoLAN 22 2004/10/14 (Hiroshima City)
3-point HD Multicasting Seminar Transmission Delay (one-way) � � MPEG2-HD : 600msec � MRAT : 130msec Voice can be transmitted with the low delay � by separating video and audio. � Although the system can not synchronize video and audio, it is not affected from a practical standpoint 23 2004/10/14 18th APAN Meetings / HD session
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