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Networked Video

Networked Video. Media Lab., Kyughee University 서 덕 영 suh@khu.ac.kr http://newmedia.khu.ac.kr. Service Classes in UMTS. “Our task is to satisfy different request of users.” Connection for a service = [routing, QoS]. UMTS(universal mobile telecommunication system) : 3GPP

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Networked Video

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  1. Networked Video Media Lab., Kyughee University 서 덕 영 suh@khu.ac.kr http://newmedia.khu.ac.kr Networked Video

  2. Service Classes in UMTS “Our task is to satisfy different request of users.” Connection for a service = [routing, QoS] UMTS(universal mobile telecommunication system) : 3GPP QoS(quality of service) Networked Video

  3. QoS (quality of service) loss delay 1% 100ms 5% 1sec 10sec 20% 100kbps 1Mbps 10Mbps bandwidth VOD videophone • Network QoS • Bandwidth • Delay, jitter • Loss • Priority • Security • Media QoS • PSNR • Continuity • Initial delay • Security Networked Video

  4. Tradeoff of bandwidth/delay/loss Bandwidth=15 I P 0.5sec Bandwidth=3.5 I I • Delivery of video traffic Bandwidth  Delay  Bandwidth Delay  • Retransmission or FEC Bandwidth LossDelay • Encryption SecurityDelay Networked Video

  5. QoS control for networked video Upper Layers (Video Layer) Error resilience/concealment, scalability coding End-to-end UDP/RTP&RTCP, FEC, retransmission Transport Layer IP TOS, RSVP, intServ Network Layer FEC, retransmission, MAC Data Link Layer Power control Physical Layer Networked Video

  6. Network-aware video coding • Bandwidth : coding efficiency • VBR/CBR • Error propagation • Scalable coding Networked Video

  7. Video coding, trends 2010 Coding Efficiency 2005 HDTV SVC AVC 2003 Mobile TV MPEG4 1999 Hand PC Video Conferencing H.263 Mobile Phone MPEG2 1994 1992 MPEG1 Year • Highercompression ratio • More network-friendly HVC : High Performance(2009~) MVC : Multi-view (~2008) Dr. C.H. Lim in Konkuk Univ.

  8. Coding efficiency Tempere CIF 30Hz 38 H.264 MPEG-2 37 36 35 34 33 Quality Y-PSNR [dB] 32 31 30 JVT/H.264/AVC 29 MPEG-4 28 MPEG-2 27 H.263 26 25 0 500 1000 1500 2000 2500 3000 3500 Bit-rate [kbit/s] Networked Video

  9. QoS in video layer? • QoS (bandwidth, loss_rate, delay) • Bandwidth  coding efficiency • Delay  lowdelay mode (OK) • Loss_rate  ? • ‘Loss’ is a problem of several dBs. • Too large to hand over to non-video-experts Networked Video

  10. Loss protection in video codec • Let’s include loss adaptation • If you have ‘loss resilient video codec,’ you can program a video application just by writing Encode_video(allowable_bitrate, allowable_delay, current_lossrate); • If you do not have loss resilient video codec, Encode_video(allowable_bitrate, allowable_delay); // loss rate adaptation in the application layer Networked Video

  11. Error Resilient Tools(1) • Limit error propagation • Intra placement • Picture Segmentation into slices : RM in MPEG-4 • Reordering in terms of importance • Data Partitioning • FMO and ASO • Increase redundancy • With feedback : • Reference Picture Selection (SP, SI), NEW_PRED in MPEG-4 • LARDO (AIR in MPEG-4) • FEC (forward error correction) for low delay (vs RTT), multicast • Redundant picture (RP) MPEG 심층 2006

  12. Error Resilient Tools(2) The error resilience syntax featuressupportedwith every profile: 1) sequence parameter set repetition capability, 2) picture parameter set repetition capability and the associated lack of any loss-vulnerable "picture header", 3) slice-structured coding capability, with slice decoding processes independent of each other within each picture, 4) constrained intra prediction, 5) start code resynchronization markers, 6) the frame_num design, 7) the POC design robustness aspects, 8) multiple reference picture buffering (allowing encoders to avoid referencing erroneous reference pictures in a NEWPRED fashion, for example), 9) the ability to mark some pictures as non-reference pictures (not found in H.261, for example), 10) intra and IDR pictures, 11) IDR picture IDs, 12) explicit-mode reference picture marking, 13) recovery point SEI messages, 14) sub-sequence SEI messages, 15) reference picture marking repetition SEI messages, 16) the ability to turn off deblocking filtering across slice boundaries. That is just the quick list of things that spring to my mind ina fewminutes of thought without looking through the spec or any other reference material. I'm sure there are others. Probably twice that many or more. Also, thisis just a list of syntax features - it ignores non-normativethings that encoders can do like intelligent intra refreshing and error tracking and intelligent alignment of packets with slices, and also ignores non-normative things that decoders can do like error concealment, and also ignores things that can be in system designs like FEC, ARQ, etc. Look up some papers on the subject - such as ones authored or co-authored by Thomas Stockhammer or Stefan Wenger. We havea lot of loss robustness inour design. Best Regards, Gary Sullivan MPEG 심층 2006

  13. VBR Video • Encoded audio and speech are CBR. • Constant quality video is VBR. (CQ-VBR) • VBR video over VBR channel is ideal. Bitrate (Mbps) Quality p r bad good too good Min Mean Max Bitrate, R Time (GOP) Networked Video

  14. CBR Transmission of VBR Video? • Naturally compressed video is VBR. • VBR traffic is better suited to VBR channel. • Double Leaky Bucket • Peak bitrate (p, bp) • Guaranteed bitrate (r, b)

  15. Error propagation (1) : Temporal correlation • Every audio packet is independent of each other. • I:P:B = 8:3:2 in bitrate. • Intra refresh to cut error propagation. Order (GOP=12) : 1, -2, -1, 4, 2, 3, 7, 5, 6, 10, 8, 9, 13, 11, 12... Networked Video

  16. Error Propagation (2): Spatial Correlation • Picture > Slice > macroblock • DC, MV : DPCM based coding • Transform coefficients : variable length coding Slice #0 Slice Group #0 Slice #1 Slice Group #1 Slice #2 Slice Group #2 • Resynchronization : Every slice is decodable independently of other slices in a picture. Networked Video

  17. Why Scalable? (1) • Adaptation to time-varying channel condition R Time Low Medium High 건국대학교 임창훈 교수 Networked Video

  18. Enh 2 Decoder LAN ADSL Enh 1 Decoder Server Proxy Wireless Internet Base only Decoder Why SVC? (2) • Adaptation to heterogeneous • network, device, and user preference Networked Video

  19. Spatial Scalable Decoding Enhancement Video Clipping VLD IQ IDCT Enhancement Bitstream + + Upsampling Base layer Bitstream VLD IQ IDCT Clipping Base layer Video Motion Compensation Frame Memory • Scalable spatial resolution • QCIF<CIF<4CIF Networked Video

  20. Enhancement Layer Enhancement Frame Enhancement Frame Enhancement Frame Base Frame Base Frame Base Frame Base Frame Base Layer Temporal Scalable Coding • Scalable temporal resolution • 7.5Hz < 15Hz < 30Hz Networked Video

  21. SNR Scalable Decoding Enhancement Bitstream VLD IQ + + Video output Base Bitstream VLD IQ IDCT Clipping Motion Compensation Frame Memory Networked Video

  22. + + Fine Granular Scalable (FGS) Encoding/Decoding Input Video Base Layer Compressed Bit-stream DCT Q VLC IQ Enhancement Compressed Bit-stream Bitplane Shift Find Max. Bitplane VLC Base Layer Compressed Bit-stream Base Layer Decoded Video VLD IQ IDCT Enhancement Compressed Bit-stream Enhanced Decoded Video Bitplane VLD Bitplane Shift IDCT Networked Video

  23. RD (Rate-Distortion) e.g.) Rate : 0.3Mbps~3Mbps, PSNR 31dB~40dB . RD curve Networked Video

  24. Scalable coding : tradeoff Networked Video

  25. Back signaling • Error Resilience in MPEG-4 and H.264 Networked Video

  26. Feedback/Retransmission (draft) • Against burst loss (Internet, wireless) • Unicast or (small) multicast • real-time applications with relaxed delay bounds (e.g. 2-3 sec in streaming) • RTP/AVPF 0: unassigned 1: Picture Loss Indication (PLI) 2: Slice Lost Indication (SLI) 3: Reference Picture Selection Indication (RPSI) ………….. • Internet draft, yet Networked Video

  27. RFC 3984 : RTP Payload Format for H.264 Video • RTP header + NAL header + slice header + coded slice • RTP header • V(2)+P(1)+X(1)+CC(4)+PT(7)+SN(16)+TS(32)+SSRC(32)+SCRC • MANE (Media Aware Network Element) with NAL header • F(1) + NRI (2) + NAL Type (5) • Packetization • 1. A single NALU, 2. Aggregation, 3. Fragmentation • Order of packets • FEC with RFC 2733 (1999) • An RTP Payload Format for Generic Forward Error Correction Networked Video

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