Project Presentation

Reminder 13th November 1 – 5pm Read your s/Visit web sites for more information (later)

Reminder Please check your project title Please check your grades

Reviews Categories 4 categories No submission Did not demonstrate understanding Understand and summarize Understand, think and summarize

What I Hope You Have Learned How to read papers? How to evaluate papers? Think critically about what you read

Recent Papers from conferences

Sessions Session 1: Movies and Music Session 2: Peer-to-Peer Streaming Session 3: Power-Friendly

Movies and Music Session 1

Characterizing DVD Wu-Chi Feng et. al. Packet Video 2003

Motivations Lots of DVD videos available How are they encoded? What is the implications to our research?

DVD data 107 video streams 140 hours 80 DVDs

Bit-rates Maximum DVD bit rates 10 Mbps Found on DVD 3.3 – 7.8 Mbps VBR Quantization values change over time (only Spy Kids is CBR)

GOPs and Sequences Each GOP was encoded into a different sequence GOP sizes: around 12 frames

NUS.SOC.CS5248 OOI Wei Tsang Sequence sequence header: width height frame rate bit rate :

NUS.SOC.CS5248 OOI Wei Tsang GOP: Group of Picture gop header: time :

NUS.SOC.CS5248 OOI Wei Tsang Picture pic header: number type (I,P,B) :

Frame Patterns Most videos have varying Number of frames within a GOP Frame patterns (ID4 has 134 unique GOP patterns)

Frame Pattern Scene Change Detection used extensively IPPPPPPP quite common!

Implication to Research Cannot assume fixed frame pattern Cannot always drop B frames

Network Musical Performances UC Berkeley NOSSDAV 2001

Goal Show that networked musical performances (NMP) can be done

Observation Stanford – Berkeley (40 miles) RTT ~4 ms 0.72 meters Berkeley – Caltech (375 miles) RTT ~28 ms 4.88 meters

Observation Musical instruments have long production latency

Observation Don’t send audio, send command Keeps “states” of the current music performance

Example NoteOn(channel, note, velocity) NoteOff(channel, note)

Packet Loss Recovery Lost/Late NoteOn skipped Lost/Late NoteOff executed

Packet Loss Recovery Guard packets Recovery journals

Bandwidth 20 MIDI command per seconds 640 bps With recovery journals ~7 kbps

Experience Lost/Late NoteOn/NoteOff But musician can adjust and play fluidly

Peer-to-Peer Session 2

P2Cast Yang Guo et. al. WWW 2003

NUS.SOC.CS5248 OOI WEI TSANG Patching Time Client Request mcast unicast

NUS.SOC.CS5248 OOI WEI TSANG Patching Time Client Request Patching Window: W mcast

Problem with VOD IP Multicast usually assumed Patching still requires unicast connections

P2Cast

New Session

Existing Session + Patch ? ? Fat Pipe First

Patch Server Selection

Patching Stream patching stream base stream

Tree Example

Failure Recovery X

What if Patch server failed? Base server failed?

PROMISE Mohamed Hafeeda et. al. ACM MM 2003

Problem P2P with streaming One peer may not have enough bandwidth Need to aggregate multiple peers

Architecture B/2 B/4 CollectCast

Select sending peers Monitor network Assign streaming rates and data segments Decide when to change peers

PROMISE Operations I want to watch LOTR:T2T

PROMISE Operations These are the candidate s..

PROMISE Operations Max expected goodness Subject to rate constraints

PROMISE Operations Here are your peers!

PROMISE Operations Send these..

PROMISE Operations Should I switch?

PALS Reza Rejaie et. al. NOSSDAV 2003

Problem P2P with streaming One peer may not have enough bandwidth Need to aggregate multiple peers Using layered coding With congestion control

Sliding Window playout time window

Packet Assignment playout time S1S2

Sending Mechanism Request packets in priority order Sender must send in order Next request overwrites previous one

Power-Friendly Session 3

GRACE-OS Wanghong Yuan SOSP 2003

Motivation Mobile devices run on battery How to save battery?

Dynamic Voltage Scaling Example: AMD Athlon 4 PowerOn {300, 500, 600, 700, 800, 1000}MHz Energy  V 2

CPU Scheduler When to execute a task How long to execute it How fast to execute it

NUS.SOC.CS5248 OOI WEI TSANG CPU Reservation “I need C units of time, out of every T units.”

Probability Distribution cycles Cum. Prob.

CPU Requirements “I need C units of time, out of every T units.”

Speed Schedule speed time

Finding Speed Schedule Let task execute at speed v x during cycle x execution time: power: average power:

Optimize This Minimize: Subjected to:

Implementation Linux Kernel AMD Athlon lines of code

Findings Probability distribution is quite stable Able to meet deadlines with bounded miss ratio Save energy by 7 – 72%

Proxy Assisted Streaming Prashant Shenoy et. al. MMCN 2003

Motivation Power-aware streaming to mobile device save energy in decoding frames save energy in receiving packets

Architecture server/proxyclient Here’s my energy budget for decoding + network reception and max resolution

Architecture server/proxyclient OK, what should I send?

Information Needed Map stream properties to energy requirement Need to know decoding time of a frame

Frame Decoding Time

Estimating Frame Decoding Time

Transcoding If current stream would exceed client decoding energy budget Need to transcode by reducing quality

Transcode to what? E = estimated energy needed while E > energy budget reduce quality by ε E = estimate energy needed

Transcoded Streams server/proxyclient

Reducing NIC Energy NIC has two modes : active/sleep Client can activate NIC only when packets are expected.

Burst Transmission I will start transmitting at 10:12:54.86 pm

Evaluations Decoding Time Frame Number

Evaluations NIC Idle Uptime: 2 – 20%