greening’the’video’transcoding’ service’with’low6costhardware ... · 2019-12-18 ·...

Greening The Video Transcoding Service With Low-‐Cost Hardware

Transcoders Peng Liu, Jongwon Yoon, Lance Johnson,

Suman Banerjee University of Wisconsin-‐Madison

Video Streaming Service Is Popular

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Mobile Video Will Generate Three-‐Quarters of Mobile Data Traffic by 2020. Source: Cisco VNI Mobile, 2016

Wireless Live Video Streaming

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•  Challenges to stream live video to mobile devices

Glitch/JiUer InterrupVon Buffering

A TV Streaming Service On Campus •  We have a deployment based on UDP mulVcast

•  We developed a new system based on AdapVve BitRate (ABR) streaming over HTTP

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ABR Streaming Over HTTP

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Transcoder 3

Transcoder 2

Transcoder 1

Source Video Media Server

Index File

Video Player

…

…

…

…

Video chunks with the same content and duraVon but

different bitrates and qualiVes

HTTP

1200kbps

800kbps

600kbps

400kbps

2 seconds

Challenges Of Video Transcoding

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High power consumpVon

on GPP

High computaVonal complexity

High throughput does not help for live video

Video quality is criVcal

Goal A low-‐cost, highly efficient transcoder

cluster to provide reliable service for a live video streaming service.

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Outline •  Video transcoding overview •  Video decoder and encoder selecVon •  VideoCoreCluster architecture •  ImplementaVon •  EvaluaVon •  Deployment and summary

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Video Transcoder ImplementaVons

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H.264 Decoder

H.264 Encoder

VS

Flexible Efficient

✔

+

MoVon PredicVon

Entropy Decoding

Entropy Encoding

MoVon CompensaVon

Transform

MoVon EsVmaVon

…

CombinaVon of decoder and encoder Specialized H.264 to H.264 transcoder


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Available Video Decoder/Encoder Implementa)ons Advantages Disadvantages

Sojware on GPP Flexible, good video quality High power consumpVon

GPU-‐based Medium power consumpVon

Expensive, inflexible

FPGA-‐based Medium power consumpVon, flexible

Expensive

Hardware (ASIC or hardware IP in

SoCs)

Low power consumpVon Inflexible, medium video quality

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Decoder & Encoder In Our System •  The GPU (VideoCore IV) of BCM2835 has high performance hardware H.264 video encoder and decoder.

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BCM2835 Raspberry Pi


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VideoCoreCluster Architecture

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Cluster Manager

Transcoder

Dashboard

MQTT Broker

Transcoder Transcoder

Media Server

Player

MQTT

MQTT RTMP

HTTP

HTTP

. . . . .


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Media Server •  Receives RTMP pushes •  Cuts the video stream to chunks •  Generates the index files on the fly •  Supports both HLS and MPEG-‐DASH

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Cluster Manager

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Scheduler

task0 0 1

task1 task2 task3 task4 task5 task0 task1 task2 task3 task0 task1 task2 task3 task4

transcoder1

Task lists with different prioriVes

Transcoder List

Assign Job

Reclaim Job

transcoder2 transcoder3

Triggered by events

2

Transcoder Sojware Overview

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Cluster Agent

Transcoding Worker 1



MQTT

RTMP RTMP RTMP

Transcoding Worker ImplementaVon

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VideoCore IV GPU

Linux Kernel and Driver

OpenMAX IL

gst-‐omx plugins

Demux plugins

GStreamer Framework Mux

plugins RTMP plugins

Transcoding Worker

Ethernet Controller

ARM . . .

Transcoder SynchronizaVon

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….

….

Transcoder A

Transcoder B

Channel 1 (1.2Mbps)

IDR IDR

chunk

Chunk numbers are generated from frames’ Vmestamps

800kbps

600kbps

Transcoder Failure Handling

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994 995 996 0 1

Task migraVon

Rest RTMP connecVons to reset Vmestamps

…

…

…

…

ABC_1200kbps

ABC_800kbps

ABC_600kbps

ABC_400kbps

Chunk Number


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EvaluaVon Setup

Transcoding worker on Raspberry Pi Model B

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FFmpeg H.264 decoder + x264 H.264 encoder Intel i5 processor with all the CPU capabiliVes (MMX, SSE2, AVX etc.) enabled

vs.

Video Quality EvaluaVon

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30

32

34

36

38

40

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600 800 1000 1200 1400 1600 1800 2000 2200 2400

PSN

R (d

B)

Bitrate (kbps)

PSNR vs Bitrate

VideoCore IVx264-ultrafastx264-superfastx264-veryfastx264-mediumx264-veryslow

0.8 0.82 0.84 0.86 0.88 0.9

0.92 0.94 0.96 0.98

600 800 1000 1200 1400 1600 1800 2000 2200 2400

SSIM

Bitrate (kbps)

SSIM vs Bitrate

VideoCore IVx264-ultrafastx264-superfastx264-veryfastx264-mediumx264-veryslow

Source: An HD channel (1280x720, 30fps) with bitrate 4Mbps

Transcoding Speed And Efficiency EvaluaVon

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0 100 200 300 400 500 600 700 800

VideoCore IV

x264-superfast

x264-medium

Fram

erat

e (fp

s)

Transcoders

SD

120

690

229

HD

50

210

67

Video Sources: SD: 720x480, 30fps, 1.2Mbps HD: 1280x720, 30fps, 4Mbps

Speed(fps) Power Consump)on

(W)

Efficiency

VideoCore IV 120 2.5 7

x264-‐superfast

690 100 1

Transcoding Speed

Transcoding Efficiency EsVmaVon (SD)


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Deployment •  We are deploying VideoCoreCluster in a hybrid and incremental way

•  Currently 27 channels are being transcoded •  More than 4000 sessions and about 480 total watching hours in a month (April 2016)

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Summary •  A low-‐cost, highly efficient video transcoder cluster (VideoCoreCluster) for a live video streaming service

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Thanks! Q&A

greening’the’video’transcoding’ service’with’low6costhardware ... · 2019-12-18 ·...

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