DASH2M: Exploring HTTP/2 for Internet Streaming to Mobile Devices Mengbai Xiao1, Viswanathan swaminathan2, sheng wei2,3, songqing chen1 1george mason university 2adobe research 3University of nebraska-lincoln

Streaming to Mobile Devices

HTTP Streaming HTTP streaming is the most prevalent streaming method over Internet The well-known implementations: Apple HLS, Adobe HDS and MPEG DASH Qlty#1 Qlty#2 Qlty#3 Qlty#4 Video HTTP request (Qlty#1) Video segment (Qlty#1)

HTTP/2 HTTP/2 is the new HTTP protocol, featuring couples of advanced techniques Server-initiated push Stream termination Etc. HTTP/2 is replacing HTTP/1.1 and is expected to eventually fully replace its predecessor Can HTTP streaming benefit from the protocol evolution?

Existing Schemes Most pioneering studies investigating HTTP/2 for Internet streaming exploit the server-initiated push mechanism Improve the user experience in HTTP streaming Live latency [Wei et al. 2014, Huysegems et al. 2015] Fast start [Cherif et al. 2015] Not consider the power efficiency Improve the power efficiency in HTTP streaming [Wei et al. 2015] Fixed push number Over-push video segments

Push Mechanism in HTTP/2 Streaming K-push is an effective means to improve HTTP streaming performance Client Server Client Server req seg 1 req seg 1 Request overhead elimination Aggregated network transmissions Degraded network adaptability Over-pushed content seg 1 seg 1 Push cycle req seg 2 … seg k seg 2 req seg k+1 … … (a) No-Push (b) K-Push

DASH2M Design DASH2M directs how to operate for the push cycles in a video streaming session Push number determination per cycle Playback Stop watching here Waste of power

Watching Energy per Segment Watching energy per segment indicates the power efficiency in a push cycle Achieve the lowest watching energy per segment Calculate the expectation of the watching energy per segment for every K K is constrained by current network condition K=5 1 J watched not watched 1 J 2.5 J

Bitrate Selection per Segment Objective: Maximize the cumulative bitrate of all involved segments in a push cycle Integer linear programming problem 1080p 720p 360p bandwidth Playback K=5

Linear Programming Constraints Continuous playback: the playback buffer should not be consumed up during the time of segment retrievals Smooth playback: the quality switch should not be abrupt Maximum buffer size: the playback buffer should not overflow ✔️ ✖️ ✖️

Bandwidth Prediction and Push Cycle Termination DASH2M predicts future bandwidth from two sources Local measurement: weighted by the time distance Server support (optional): allocated bandwidth on the server side Terminate all upcoming transmissions of pushed segments If the consumed network resources have significantly exceeded the predicted available network resources Send the RST_STREAM to terminate all active pushing transmissions

Linear Programming Evaluation Setup Experimental parameters Bandwidth candidates (kbps): 60, 200, 600, 800 Bandwidth changing interval (s): 10 Video quality (kbps): 49, 217, 504, 752 Segment duration (s): 2 Streaming session duration (s): 40 Solver exit time (s): 0.5 m, the quality duration: 2, 3, 4 Maximum K: 5, 10, 15, 20 Average quality distance The average bitrate level difference from the selected bitrate to the optimal bitrate

Linear Programming Performance

Rate Adaptation Evaluation Setup An example video is selected to perform real streaming experiments Video quality (kbps): 49, 217, 504, 752 Segment duration (s): 2 Compare with x-push schemes and the regular DASH scheme (HTTP/1.1) x-push stands for the k-push scheme when K is set as x The x candidates: 2, 5, 10, 20 Bandwidth candidates (kbps): 400, 600, 800, 1600

Rate Adaptation Performance 572 kbps 440 kbps 485 kbps 434 kbps 489 kbps 293 kbps

Push Termination Performance 647 kbps 561 kbps 586 kbps 512 kbps 644 kbps 357 kbps

Power Efficiency Evaluation Setup Dataset: Apple HLS trace collected at the client side from Vuclip ~ 12 million video sessions: the session duration and the watched duration

Power Efficiency Evaluation Setup (Cont.) The dataset is divided into two halves One half is used to build the user watching portion distribution in the client The other half is fed as the input of the simulation A perl simulator is implemented to calculate the energy wasted by the over-push The ratio of bandwidth to video quality: 10:1, 10:4, 10:7

Power Efficiency DASH2M DASH2M Ratio of bandwidth to segment bitrate 10:1 Ratio of bandwidth to segment bitrate 10:7

Conclusion We design and implement the DASH2M, which are based on the server-initiated push technique in HTTP/2, to improves the streaming experience in terms of power efficiency and user QoE DASH2M is able to switch the video quality even inside a push cycle in a gentle manner without buffer starvation and buffer overflow DASH2M approaches the most power efficient solution no matter how the bandwidth changes

Thank you!