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Networked Video Media Lab., Kyughee University 서 덕 영

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Presentation on theme: "Networked Video Media Lab., Kyughee University 서 덕 영"— Presentation transcript:

1 Networked Video Media Lab., Kyughee University 서 덕 영

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

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

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

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

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

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

8 Networked Video Coding efficiency Tempere CIF 30Hz Bit-rate [kbit/s] Quality Y-PSNR [dB] MPEG-2 H.263 MPEG-4 JVT/H.264/AVC H.264MPEG-2

9 QoS in video layer? QoS (bandwidth, loss_rate, delay) Bandwidth  coding efficiency Delay  low delay 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 MPEG 심층 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)

12 MPEG 심층 Error Resilient Tools(2) The error resilience syntax features supported with 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 in a few minutes 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, this is just a list of syntax features - it ignores non-normative things 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 have a lot of loss robustness in our design. Best Regards, Gary Sullivan

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

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 Networked Video 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...

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

17 Networked Video scalability adaptive to variable bandwidth Available Bandwidth Non-Scalable R [bps] Scalable Time Medium Low High Why Scalable? (1) 건국대학교 임창훈 교수 R Adaptation to time-varying channel condition

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

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

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

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

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

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

24 Networked Video Scalable coding : tradeoff Bitrate Normal100% Spatial100+α Temporal100+α SNR150+α Complexity Normal100% Spatial125+α Temporal105 SNR110 Base : totalin bitrate Spatial1:4 Temporal2:3 SNR1:2

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

26 Networked Video 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

27 Networked Video 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


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