HTTP-based Video Streaming - Stanford University · 2013. 4. 10. · Serve the video with quality...
Transcript of HTTP-based Video Streaming - Stanford University · 2013. 4. 10. · Serve the video with quality...
HTTP-based Video Streaming
Confused, Timid, and Unstable: Picking a Video Streaming Rate is HardTe-Yuan Huang, Nikhil Handigol, Brandon Heller, Nick McKeown, Ramesh Johari
Experimental Setup
The$Internet$
Video Client
The$Internet$
Bandwidth$Controller$
CDN$1$
CDN$2$
CDN$3$
Content$Distribu9on$Networks$
CDN A
Get File 1 (1750kb/s), Chunk 1
Serve the video with quality 1750kb/s
Playout Buffer Standardized, commoditized HTTP servers
Videos are pre-encoded and deployed in CDNs
Rate selection logic resides at the client side
File%1:%
File%2:%
1750% 1750%
1050% 1050%
Problem
0 100 200 300 400 500 600 700 800 900Time (s)
235375560750
105014001750
2500
3000
4000
5000
kb/s
Avai
labl
e Vi
deo
Rat
e
Video Flow Throughput
Competing Flow Throughput
Video Rate
Fair Share
In the presence of a completing flow, video quality steps down all the way to the lowest
Why? Here is the answer!
Download and
MeasurePick a Rate
Initial Bitrate
BandwidthEstimation
Video Rate for the Next Chunk
Bandwidth Under-estimation: The ON-OFF traffic pattern periodically resets TCP congestion window.Pick a Rate Conservatively: Since the estimated bandwidth typically is not equal to the actual bandwidth, video clients tend to pick a rate conservatively.Lower Rate means Smaller Chunk: Requesting a smaller chunk means a lower probability to obtain fair share. More information? Read our paper!
http://www.stanford.edu/~huangty/IMC.pdfRecipient of IETF/IRTF Applied Network Research Prize
BandwidthUnder-estimation Conservatively
Request for a smaller chunk
Video Client
Competing Flow Generator