Notes

Outline

Active Transcoding High Performance Team #5 Demo Javed I. Khan ACTIVENET Demo DEC 2000 Atlanta Networking and Media Communications Research Lab Dept of Math & Computer Science Kent State University Sponsor: DARPA/ITO

MPEG-2 Transcoding The digital video standard for DTV/HDTV. Compression performance for high-end video Combines co-efficient transform+predictive coding+ motion estimation. Extremely computation intensive: Current state-of-the art in video compression technology requires custom chipset to obtain real-time performance in MPEG-2 encoding. Roughly speaking, something close to CIF video (CCIR 4:2:0 CIF=352x240 at 30 frames/second or 352 x288 at 25 frames/second) can be decoded in software satisfactorily. It requires processing of 69,300 blocks per second. In comparison, a broadcast quality video (CIR-601 4:2:2: 720x480 at 30 frames/second or 352x576 at 25 frames/second) requires processing of 405,000 blocks per second. a production or medical quality video  (MPEG-2 HIGH@HIGH-1440 profile=1920x1152x 60 frames/second) will require processing of 5,184,000 blocks per second. A full logic xcoder is encoder+decoder!

Network Adaptation

3 Way Tradeoff

Adaptation Services Link Capacity Adaptation splices wide-band links with low capacity links. application aware rate adaptation greater down-scalability range (4/5th vs. 1/100th) Perceptual encoding Much sophisticated perceptual control over where and how quality is compromised Node Capacity Adaptation allows network junction nodes with unequal CPUs to perform rate adaptation. auto-configuration by motion vector bypass Reuses motion vector and saves computation for  quality Cycle sweeping (network spread) If one node is not enough it spreads the computation upstream and sweeps additional cycles from active nodes.

Application Level Adaptation: Active Transcoding

RATE SCALABILITY

Full Cascade Adaptation

MPEG-2  Rate Control

Slide 10

REGION OF INTEREST ADAPTATION

ROI Encoding (Uniform)

ROI Encoding (Focus)

Slide 14

Slide 15

SELF-CONFIGURATION

Resource Impact Active Node CPU Cycle Parameter bypass DCT domain transcoding MV optimization Memory I,P,B frame buffer Instruction foot-print Disk Access GOP buffer Auxiliary data storage

Time Profile on PIII-450MHz

Xcoder States

Motion Vector Bypass

3-way Tradeoff

CYCLE SWEEPING

Active Netwide Computing

Flow: “Single Stream Multiple Form”

Mapping

MPEG-2 DEMO

Today’s Demo Link Capacity Adaptation splices wide-band links with low capacity links. application aware rate adaptation greater down-scalability range (4/5th vs. 1/100th) perceptual encoding Much sophisticated perceptual control over where and how quality is compromised Node Capacity Adaptation allows network junction nodes with unequal CPUs to perform rate adaptation. auto-configuration by motion vector bypass Reuses motion vector and saves computation for  quality Cycle sweeping (network spread) If one node is not enough it spreads the computation upstream and sweeps additional cycles from active nodes.

Parallel XCoding

Adaptive MPEG-2 XCoding

Comments on Performance Self-reconfiguration signaling At any given time, there will be nodes with unequal capacities. It will be critical to build self-configuring middle box which can withstand the variation. Self-reconfiguration signaling can be permanent part. Cycle sweep technology Sweeping cycles from active network neighborhood will be one of the key means for real-time stream processing. Support should be built in any realistic ANET architecture.  FPGA (architecture+ application level) Atleast some high performance ANET router should have more esoteric mean for booting application performance.

Comments on Systems Engineering Multiprocessing & multithread capsules Few node OS/EE seems to lack support for complex application execution model. But, our experience is that for the middle-box model, such models are indispensable (MPEG-2 decode/ reencode threads) Event driven model? Few OS/EE have been modeled as 100% event driven model. However, a mixed model perhaps is desirable. After all a continuous data stream can cause havoc in performance in event driven I/O. Cost of structural conversion? Have active network community thought about legacy applications? ANTS and few others requires middle-box to cast in a specific program forma. It will be nice to have an automatic tool which will reengineer a middle box written in legacy forma to  that forma.

Team From front left (anti-clockwise): Wansik, Yang, Darsan, Zhong, Oleg & Patrck, missing: Gu, and Sharif