Upload
others
View
12
Download
0
Embed Size (px)
Citation preview
Avoiding zigzag quality switching in real contentadaptive video streaming
Wassim Ramadan, Eugen Dedu and Julien Bourgeois
Laboratoire d’Informatique de l’Universite de Franche-ComteMontbeliard, France
DICTAP21–23 June 2011
Wassim Ramadan, Eugen Dedu and Julien Bourgeois Avoiding zigzag quality switching 1 / 15
Introduction Zigzag avoidance Experiments Conclusions and perspectives
Goals of zigzag avoiding
Improve user video experience by minimizing unnecessaryquality switching
Optimise network resource usage by minimizing packet lossrate
Wassim Ramadan, Eugen Dedu and Julien Bourgeois Avoiding zigzag quality switching 2 / 15
Introduction Zigzag avoidance Experiments Conclusions and perspectives
Video adaptation and zigzag quality switching
Dynamic bandwidth vs static bitrates
0
0.5
1
1.5
2
2.5
3
3.5
0 20 40 60 80 100 120 140 160 180
Bitr
ate
(Mbi
t/s)
Time (s)
available bandwidthQ0
Q1Q2
Q3
Ideal bitrate
If bitrate<bw:non-optimised
If bitrate>bw: lost packets
Ideal: bitrate=bw
many zigzags occur
0
0.5
1
1.5
2
2.5
3
0 20 40 60 80 100 120 140 160 180
0
20
40
60
80
100
120
Bitr
ate
of tr
ansm
itted
vid
eo (
Mb/
s)
Time (s)
adapted video bitrate
Zigzag problem
Adaptation leads to:
many zigzags
poor quality
Wassim Ramadan, Eugen Dedu and Julien Bourgeois Avoiding zigzag quality switching 3 / 15
Introduction Zigzag avoidance Experiments Conclusions and perspectives
Video adaptation and zigzag quality switching
Dynamic bandwidth vs static bitrates
0
0.5
1
1.5
2
2.5
3
3.5
0 20 40 60 80 100 120 140 160 180
Bitr
ate
(Mbi
t/s)
Time (s)
available bandwidthQ0
Q1Q2
Q3
Ideal bitrate
If bitrate<bw:non-optimised
If bitrate>bw: lost packets
Ideal: bitrate=bw
many zigzags occur
0
0.5
1
1.5
2
2.5
3
0 20 40 60 80 100 120 140 160 180
0
20
40
60
80
100
120
Bitr
ate
of tr
ansm
itted
vid
eo (
Mb/
s)
Time (s)
adapted video bitrate
Zigzag problem
Adaptation leads to:
many zigzags
poor quality
Wassim Ramadan, Eugen Dedu and Julien Bourgeois Avoiding zigzag quality switching 3 / 15
Introduction Zigzag avoidance Experiments Conclusions and perspectives
Outline
1 Zigzag avoidance
2 Experiments
3 Conclusions and perspectives
Wassim Ramadan, Eugen Dedu and Julien Bourgeois Avoiding zigzag quality switching 4 / 15
Introduction Zigzag avoidance Experiments Conclusions and perspectives
Outline
1 Zigzag avoidanceZAAL (Zigzag Avoidance ALgorithm)
Wassim Ramadan, Eugen Dedu and Julien Bourgeois Avoiding zigzag quality switching 5 / 15
Introduction Zigzag avoidance Experiments Conclusions and perspectives
Overview of ZAAL
ZAAL Zigzag Avoidance ALgorithm
ZAAL maintains a successfulness value for each bitrate which:
is an arithmetic real value between 0 and 1
indicates the successfulness of the bitrate if used
uses a historic of the application last attempts to use thebitrate
is calculated at the end of an adaptation period
is obtained by applying an EWMAa algorithm on the bitratesuccessfulness historic
aEWMA: Exponential Weighted Moving Average
Wassim Ramadan, Eugen Dedu and Julien Bourgeois Avoiding zigzag quality switching 6 / 15
Introduction Zigzag avoidance Experiments Conclusions and perspectives
Details of ZAAL
ZAAL works as follows
at the beginning of a video transmission, all successfulnessvalues Si
a are set to 1
the application switches to a higher quality i + 1 only ifSi > β b
ZAAL uses the following general formula:Si = (1 − α/d)Si + s(α/d) c de
ai : bitrate indexbβ = 0.7 switching thresholdcif the bitrate succeeds s = 1 else s = 0dα = 0.3 degree of EWMA weighting increase/decreaseeand d = 1, 2 or 4 division factor
Wassim Ramadan, Eugen Dedu and Julien Bourgeois Avoiding zigzag quality switching 7 / 15
Introduction Zigzag avoidance Experiments Conclusions and perspectives
Formula of ZAAL
Successfulness value can change in three cases
Application increasesthe bitrate
Application maintainsthe bitrate
Application decreasesthe bitrate
s=1d=1
S j : ji=1−α S jα S i=1−α S i
s=0d=1
S j : ji=1−α S jα
s=1d=1
s=1d=4
s=1d=2
S i=1−α /2 S iα /2
S i1=1−α / 4S jα / 4
(a) (b)Wassim Ramadan, Eugen Dedu and Julien Bourgeois Avoiding zigzag quality switching 8 / 15
Introduction Zigzag avoidance Experiments Conclusions and perspectives
Outline
2 ExperimentsNetwork topologyZigzag avoidance checking
Wassim Ramadan, Eugen Dedu and Julien Bourgeois Avoiding zigzag quality switching 9 / 15
Introduction Zigzag avoidance Experiments Conclusions and perspectives
Network used in experiments
Network parameters
Parameter name Parameter value
Experiments place In buildingPacket size 1024 bytesPC1 (sender): Wired card, 100Mb/sPC2 (shaper machine): Wireless card, 802.11b/g 54Mb/sPC2 (shaper machine): Wired card, 100Mb/sPC3 (receiver): Wired card, 100Mb/sPC1,2&3 OS Linux (Ubuntu 64bits)PC1,2&3 OS kernel 2.6.35 genericDCCP Included in the kernelDistance (AP ↔ PC2) 50cm
Wassim Ramadan, Eugen Dedu and Julien Bourgeois Avoiding zigzag quality switching 10 / 15
Introduction Zigzag avoidance Experiments Conclusions and perspectives
Zigzag avoidance, ex. of one flow in (case of) traffic shaping
0
0.5
1
1.5
2
2.5
3
0 20 40 60 80 100 120 140 160 180
0
20
40
60
80
100
120
Bitr
ate
of tr
ansm
itted
vid
eo (
Mb/
s)
Time (s)
adapted video bitrate
(c) without ZAAL: many zigzags occur
0
0.5
1
1.5
2
2.5
3
0 20 40 60 80 100 120 140 160 180
0
20
40
60
80
100
120
Bitr
ate
of tr
ansm
itted
vid
eo (
Mb/
s)
Time (s)
adapted video bitrate
(d) with ZAAL: few zigzag occur
Wassim Ramadan, Eugen Dedu and Julien Bourgeois Avoiding zigzag quality switching 11 / 15
Introduction Zigzag avoidance Experiments Conclusions and perspectives
Performance comparisonTwo experiments: one flow and ten concurrent flows
Traffic shaping 10 concurrent flowsMethod Sent pkts Received pkts Lost pkts Sent pkts Received pkts Lost pktsWithout ZAAL 47795 42043 5752 (12%) 41191 32307 8884 (21%)With ZAAL 43548 39865 3683 ( 8%) 36713 32477 4236 (11%)
Number of sent and received packets (average of all flows) with and without ZAAL
in the first experiment, ZAAL has less sent and receivedpackets than without ZAAL, but using ZAAL is more usefulbecause it avoids the zigzag and leads to 30% fewer packetlosses
in the second experiment, ZAAL is better in terms of sent andreceived packets, avoiding the zigzag in the same time
Wassim Ramadan, Eugen Dedu and Julien Bourgeois Avoiding zigzag quality switching 12 / 15
Introduction Zigzag avoidance Experiments Conclusions and perspectives
Outline
3 Conclusions and perspectives
Wassim Ramadan, Eugen Dedu and Julien Bourgeois Avoiding zigzag quality switching 13 / 15
Introduction Zigzag avoidance Experiments Conclusions and perspectives
Conclusions
ZAAL is a general solution, since it can be integrated to anyadaptation method
ZAAL avoids the undesirable constant switching in quality(the zigzag problem)
Perspectives
working on a hybrid solution, which uses a bandwidthestimation method together with ZAAL
Wassim Ramadan, Eugen Dedu and Julien Bourgeois Avoiding zigzag quality switching 14 / 15
Introduction Zigzag avoidance Experiments Conclusions and perspectives
Conclusions
ZAAL is a general solution, since it can be integrated to anyadaptation method
ZAAL avoids the undesirable constant switching in quality(the zigzag problem)
Perspectives
working on a hybrid solution, which uses a bandwidthestimation method together with ZAAL
Wassim Ramadan, Eugen Dedu and Julien Bourgeois Avoiding zigzag quality switching 14 / 15
Introduction Zigzag avoidance Experiments Conclusions and perspectives
Questions?
Wassim Ramadan, Eugen Dedu and Julien Bourgeois Avoiding zigzag quality switching 15 / 15