E
-
Standards for Training
October 2010
Video Standards
flexiblelearning
.net.au
flexiblelearning.net.au
V1.1
E
-
standards for Training
May 2011
2011
Video Standards Report
E
-
standards for Training
-
Aust
ralian Flexible Learning Framework
Acknowledg
e
ment
s
The
E
-
standards for Training
business activity
, on behalf of the Australian Flexible Learning
Framework
(
Framework
)
,
wishes to acknowledge and thank participants from across the
Australian vocational education and training (VET) sector
,
as well as the following
key
contributors
:
Reference group
Helen Rysavy
Kym Schutz
Colin Simpson
Author
Rob Wellington
rob@tantamount.com.au
E
-
standards for Training
e
-
standards@flexiblelearning.net.au
Bronwyn Lapham (Project lead)
Kristena Gladman
Owen ONeill
Copyright in this work is owned by the Commonwealth of Australia
.
© Commonwealth of Australia 2011
Apart from any use as permitted under the
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, no part may be reproduced except under the licence below or
with prior written permission.
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–
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ummary of the scope of
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Requests and inquiries concerning other reproduction and r
ights should be directed in the first instance to the Director, VET
Technology, Policy and Projects, Department of Education, Employment and Workplace Relations, GPO Box 9880, Canberra,
ACT, 2601.
2011
Video Standards Report
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ralian Flexible Learning Framework
Table of Contents
1
Introduction
................................
................................
................................
..............
1
2
The changing digital environment
................................
................................
..........
2
2.1
National Broadband Network (NBN)
................................
................................
...................
2
2.2
Mobility
................................
................................
................................
................................
2
2.2.1
Remote and off
-
campus learning
................................
................................
..........................
2
2.3
Impacts
................................
................................
................................
...............................
2
3
Key considerations
................................
................................
................................
..
4
3.1
Considerations for VET
-
sector content developers
................................
............................
4
3.2
Technical considerations
................................
................................
................................
....
4
3.3
Social and educational considerations
................................
................................
...............
4
4
Video encoding
................................
................................
................................
........
5
4.1
Data rate
................................
................................
................................
.............................
5
4.2
Codecs
................................
................................
................................
................................
5
4.3
Players and plug
-
ins
................................
................................
................................
...........
5
4.4
Formats
................................
................................
................................
...............................
6
4.5
Player distribution
................................
................................
................................
...............
6
4.6
Compression
................................
................................
................................
.......................
7
4.6.1
Spatial vs temporal
................................
................................
................................
................
7
4.6.2
Lossless vs lossy
................................
................................
................................
...................
7
4.7
Audio
................................
................................
................................
................................
...
9
5
Video production for encoding
................................
................................
.............
10
5.1
Digital video process: shoot to media
................................
................................
...............
10
5.2
Digital video editing
................................
................................
................................
..........
11
5.3
Design for the codec
................................
................................
................................
.........
11
5.4
Five top tips
................................
................................
................................
......................
12
6
Encoding par
ameters
................................
................................
.............................
13
6.1
Data rate
................................
................................
................................
...........................
13
6.2
Variable bit rate
................................
................................
................................
.................
13
6.3
Key fra
mes
................................
................................
................................
........................
13
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6.4
Dimensions
................................
................................
................................
.......................
14
6.4.1
Non
-
square pixels
................................
................................
................................
...............
14
6.5
Screen r
esolutions
................................
................................
................................
............
15
6.5.1
Recommendations
................................
................................
................................
..............
15
6.6
Fields and frames
................................
................................
................................
.............
16
6.7
Frame rate
................................
................................
................................
........................
16
7
Players/Container formats
................................
................................
.....................
17
7.1
Windows Media Player
................................
................................
................................
.....
17
7.2
Flash video
................................
................................
................................
.......................
18
7.3
QuickTime
................................
................................
................................
.........................
19
7.4
VLC
................................
................................
................................
................................
...
20
7.5
WebM (On2 VP8 / Vorbis)
................................
................................
................................
21
7.6
Ogg (Vorbis / Theora)
................................
................................
................................
.......
21
7.7
Real Media
................................
................................
................................
........................
22
7.8
Silverlight
................................
................................
................................
..........................
23
7.9
AVI
................................
................................
................................
................................
....
23
8
Codecs
................................
................................
................................
....................
25
8.1
H.264 /
MPEG
-
4 AVC (.mp4)
................................
................................
...........................
25
8.2
MPEG
-
1
................................
................................
................................
............................
26
8.3
On2 (TrueMotion, VP3
–
8)
................................
................................
................................
26
8.4
Ogg Theora (On2 VP3)
................................
................................
................................
....
27
8.5
Windows Media Video (WMV)
................................
................................
..........................
27
8.6
Some comparisons
................................
................................
................................
...........
28
9
Streaming servers
................................
................................
................................
..
31
9.1
Server streaming
................................
................................
................................
..............
31
9.2
Transport protocols: RTP/RTSP/MMS
................................
................................
.............
31
9.2.1
Ports
................................
................................
................................
................................
....
31
9.2.2
Services
................................
................................
................................
..............................
31
9.3
Systems
................................
................................
................................
............................
32
9.3.1
QuickTime
................................
................................
................................
...........................
32
9.3.2
Real Media
................................
................................
................................
..........................
32
9.3.3
Windows Media Server
................................
................................
................................
.......
33
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9.3.4
Flash
................................
................................
................................
................................
...
33
9.3.5
FFmpeg
................................
................................
................................
...............................
33
9.3.6
Cherokee
................................
................................
................................
.............................
33
9.4
Alternatives to streaming servers
................................
................................
.....................
33
9.4.1
Flash
................................
................................
................................
................................
...
34
9.4.2
QuickTime reference movies
................................
................................
...............................
34
10
Screen recording and sharing
................................
................................
...............
36
10.1
Screen recorders
................................
................................
................................
..............
36
10.2
Screen sharing
................................
................................
................................
..................
36
11
Relevant findings
................................
................................
................................
...
37
11.1
Flash
................................
................................
................................
................................
.
37
11.2
HTML5 (and CSS3)
................................
................................
................................
..........
38
11.3
HTML5 and the video tag
................................
................................
................................
.
39
12
Recommendations
................................
................................
................................
.
40
12.1
Ap
plication video
................................
................................
................................
...............
40
12.2
HTML5, browsers and mobile devices
................................
................................
.............
40
12.3
HTML5 browser: device support
................................
................................
.......................
41
12.4
Streaming servers
................................
................................
................................
.............
41
12.5
More information
................................
................................
................................
...............
41
Appendix 1: Standards recommendation
................................
................................
........
42
Appendix 2: Players/container formats and codecs
................................
.......................
43
Appendix 3: Video codec table
................................
................................
........................
45
Appendix 4: Bit rates
................................
................................
................................
........
47
Appendix 5: Screen resolutions
................................
................................
.......................
50
Appendix 6: Video accessibility
................................
................................
.......................
51
More Information
................................
................................
................................
...............
52
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1
1
Introduction
The
purpose
of th
e
Video Standards Report
–
2011
is
to provide information to
help
e
-
learning content developers make informed
decision
s
about the use of video formats,
codecs and delivery systems for e
-
learning video content.
The report is intended to be used in conjunction with the c
urrent VET standards
, which are
available at
:
http://e
-
standards.flexiblelearning.net.au/technical_standards/content_formats.php
Where possible, t
h
is
report
aims
to ensure that
VET
video standards support current and
future needs of VET e
-
learning practitioner
s
,
particularly given the
fast
-
changing
digital
media
landscape
.
It acknowledges
that
content items need to:
have a long life span
operate across
a broad range of potential platforms and applications
run on
a wide range of devices
, including portable med
ia
-
browsing devices
.
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2
The changing digital environment
While it
i
s difficult to predict
details about our technological
future
,
we know
that three
things
will happen
:
The National Broadband Network
(NBN)
will be built
, so data transfer speeds will
incre
ase.
Mobile devices will continue to gain momentum in the market.
Devices will continue to improve in specification and affordability.
2.1
National Broadband Network (NBN)
The
NBN
promises to offer a high standard of
i
nternet access for the entire country.
A
DSL,
which is currently the most common form of
residential broadband
in Australia
,
has a
data transfer speed of
512
kbit/s
(
kilobits per second
), or
512
,000
bits per second. The
FibreLAN
-
based NBN
will
offer 1
Gbit/s (giga
bit per second)
, which is
2000 ti
mes faster
than
ADSL
.
O
ne of the most obvious benefits
of the NBN will be
a
n
increase
in the distribution of video
content
of a high technical quality across the internet
.
South
Korea has become an international leader in
i
nternet
-
based technologies
. I
n 2
009
,
the
South
Korea
n government
announced
plans to increase
its wireless broadband
transfer
speed
from 1
Mbit/s
(
megabit per second
)
to 10
Mbit/s
.
Australia is
following
South Korea’s
lead with the NBN.
2.2
Mobility
Wireless telephony and miniaturi
s
ation cont
inue to dramatically
impact our everyday lives
.
Recent ‘smart’ phones, for example,
outperform desktop computers
that were
built
a few
years earlier, and v
ideo can be delivered to an increasingly broad range of devices.
Furthermore, the speed of m
obile net
works
continues to
improve. The 4G standard
, for
example,
supports rates
of
up to 100
Mbit/s
.
Mobile devices
will increasingly offer
a great
opportunity for delivering
e
-
learning content
,
including video,
to learners
.
2.2.1
Remote and off
-
campus learning
Mobil
e
-
networked devices also
allow
workers and students to send text, sound, images and
video back to a base, enabling educators and supervisors to provide students and staff with
informed
,
timely
direction.
First aid training is a
good
example of the use of m
ultimedia
information for on
-
demand delivery in
-
situ.
A swathe of new Android tablets will join the iPad in the market
in 2011
. (
Like Safari on the
iPad, the default
Android
web browser
also uses WebKit.)
The advent of these tablets
provides enormous
oppor
tunit
ies
for e
-
learning
purposes
.
2.3
Impacts
The following list outlines k
ey features
and developments
that
will
have a direct impact on
the future of mobile e
-
learning and video for e
-
learning:
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3
high
-
resolution touch screens
high
-
quality video and audio play
back
cheap and easy access to a large catalogue of content (video, audio, books, multimedia,
games)
3D rendering
HTML rendering
h
igh
-
speed
i
nternet access (3G, 4G and wireless LAN)
open development environments
that support free sharing of information
prof
itable distribution channels for
content
developers
media capture, editing and delivery (upload)
multimedia telephony
IP telephony
geolocation services
b
lue
t
ooth and WiFi
3
-
axis accelerometer, compass (magnetometer), proximity and light sensors
.
Most of th
ese features are popular with consumers
,
and app developers are coming up with
exciting new ways to use them.
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3
Key considerations
In recent times, the
demand for rich
multimedia
content
has increased rapidly
and
the
improved capabilities of
mobile devices
have continued to
expand the possibilities for
content delivery and interactivity. As a result, t
here have been a number of key
developments in video technology
. The associated considerations are outlined below.
The rest of the report provides more detail
ed information about these considerations,
especially those listed in Sections 3.1 and 3.2.
3.1
Considerations for VET
-
sector content developers
In 2011, the k
ey considerations
for content developers in the VET sector are
:
software
(What software, ideally ope
n
-
source or freely available software, is
available for
use by authors with varying levels of technical ability
?)
mobile devices
(Which devices,
includ
ing
MP3 players and phones with video playback
capability
, are
commonly used by VET learners, teachers an
d trainers
?)
licensing
(What are the licensing considerations and requirements?)
3.2
Technical considerations
The h
igh
-
level technical considerations include:
file size/data rate v
ersu
s quality
of
image and sound
infrastructure requirements
–
for example,
spec
ific hardware or software to author
and/
or
deliver the format (streaming)
bandwidth constraints
interoperability
–
the multiple
formats and
multiple operating systems in common use in
the VET sector (
R
efer to
http://e
-
standards.flexiblelearning.net.au/technical_standards/desktop_platforms.php
for
supported systems
.
)
tools for encoding, transcoding and streaming
.
3.3
Social and educational considerations
In addi
tion, there are s
ocial and educational challenges
surrounding the development and
delivery of video content.
They include:
cost barriers for
some
end
users
accessibility for end
users with disabilities, bearing in mind the
f
ederal
g
overnment’s
adoption of
the
W
eb
C
ontent
A
ccessibility
G
uidelines version
2.0
(WCAG 2.0)
.
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4
Video encoding
Video, like film,
consists of
a series of still images
,
which
are displayed so quickly
that
they
give the illusion of movement. Australian
television
displays 25
fps (
frames
per second)
,
synchronised to our 50
Hz power system.
(Our system
is based on the British system PAL
,
which is also
used across most of Europe.
)
T
he
US
system
, which is also used in Japan, is
called NTSC.
It
displays 30
fps.
4.1
Data rate
Even short s
equence
s
of digital video and sound produce large files. Video codecs
are used
to
reduce the data rate (bits per second) so that it is manageable by
a
computer and/or
network. This
process
is often called ‘compression’.
For further information, see Section 4.6
(
Com
pression
)
.
4.2
Codecs
Digital video uses codecs (encoders
and d
ecoders) to convert a stream of sound and
images into a stream of data (ones and zeros). The data streams are stored in a file format
such as a .MOV or .AVI.
Audio is synchronised with the video,
but it is a separate stream of information.
Video and
audio are encoded using different codecs. Players decode the video and audio streams
simultaneously
. For more information, see Section 4.3 (Players and plug
-
ins).
Not so long ago
,
encoding hardware conv
erted analogue sound and images into digital data.
Nowadays,
video is recorded digitally
.
T
he video
is
converted and encoded
i
n the camera
and stored with encoded audio on
a
tape, disk, optical disk or memory chip.
F
or most of this
report
, when we refer to
‘
encoding
’,
we actually
mean
‘
transcoding
’
–
that is,
converting from one codec to another or re
-
encoding in the same codec to reduce data rate
.
For example, converting from the camera’s codec to the edit codec, and then to the MPEG
codec for subsequent D
VD creation.
4.3
Players and plug
-
ins
To watch encoded video
,
you must have a player (decoder) installed. The browser version of
the player is
usually
called a ‘plug
-
in’. Plug
-
ins are used by an application, typically a
browser, to access decoders stored in th
e system by a player. Plug
-
ins are often installed
with a matching player.
Players are stand
-
alone applications that include a suite of decoders
.
A player
‘play
s
’ video
and audio of its own
format
, and sometimes other
formats.
Common players
include
the
Wi
ndows Media Player, Flash Player, QuickTime Player and Real Player. Applications
such
as
VLC play many video formats
,
including DVDs. Some players support
a range of
codecs
;
others
,
such as
Flash, only support a few. Players can be built into applications
.
F
or
example
,
Adobe’s Director Shockwave plug
-
in supports Flash, Real and QuickTime formats.
PC and Mac computers
have
Windows Media and QuickTime players
included as part of
their
system installation. Installed browsers often include Flash
, as well as
som
e
other plug
-
ins.
If you wish to use a video format
that is
not supported by
a
mainstream player
,
you must
en
sure
it is permissible to install
th
e particular
player or plug
-
in
on
the target platform
.
(
This
permissions aspect can be
an issue in educational
institutions and corporations
.
) Distributing
a player with educational material is usually free
.
Some players, however,
may have
special
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licensing
conditions
associated with their use
.
Luckily
,
the
mainstream players, which are
preinstalled on most comput
ers, support a range of
good codecs.
4.4
Formats
The term ‘container format’ describes the file that holds the various data types that make up
a video file. A digital video file is usually made up of
two
data
streams created with
two
codecs
–
one for audio and
one for video. Other data such as metadata and text, and
sometimes animation
s, transitions and 3D tracks
can be added in some formats.
Formats have one or more player applications, usually with matching web plug
-
ins, that play
them (
player to format is wh
at
Word is to .doc). Some players can work with a variety of
formats and other media.
Figure 1: A digital video format contains encoded video and audio,
plus
other data
.
For more detailed information, see
Section 7 (
Players/Container formats
)
.
4.5
Player dis
tribution
Players and plug
-
ins may be
pre
installed
on
the user
’
s system. Players are usually free and
are
often
distributed with content on CD
-
ROM
s
and
DVD
-
ROM
s
.
WARNING:
Players distributed with commercial products
may
be subject to a licen
c
e.
In
additio
n,
a codec used by a player
may
have its own licensing requirements.
If you can assume that
the target audience
has
internet access,
it
may
be best to provide
links to player downloads
,
which will
ensure
that
users get the best version of the player for
t
heir system.
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URLs can change.
So, if a
link
is provided o
n
a
fixed
-
media
format, such as
a CD
-
ROM
,
there
should
be
an intermediary site
that provides
up
-
to
-
date links. This requires an on
-
going
maintenance
commitment
by the content provider.
New player v
ersions are
no
t always backwards compatible
, so
a
new version of a player
may cause problems with older, unsupported codecs. Ideally, an application should have
the
required player
,
plug
-
in
and
extension packaged with it.
Flash
, for example,
can use its o
wn video content. The functionality of Director and
Authorware can be extended with ‘Xtras’ such as support for video formats. Flash,
QuickTime and Real
Media are supported by Director and Authorware.
The b
est practice is to test for the availability of a
player in the initialisation phase of a
multimedia application or web page. If the test fails to find the required player
, you should do
one of the following
:
For
a browser
-
based application, offer a link to the player download page
.
For
a CD
-
ROM or
DVD
-
R
OM
, l
aunch the player installer.
4.6
Compression
Compression settings
can be adjusted to achieve a balance between data size and quality.
The
goal i
n video encoding is to reduce the data rate while maintaining
optimal
image and
audio quality.
4.6.1
Spatial vs tempor
al
Video compression works in two fundamental ways
:
spatial and temporal.
Spatial compression averages out areas of similar colour in individual images. It takes
advantage of the fact that the human eye
does not
identify
small differences in colo
u
r as
re
adily
as it
detects
changes in brightness. JPEG and other still
-
image codecs reduce the
data of an image by looking for blocks of the same colour
–
for example, blocks of sky. In
this way, they replace the same 24
-
bit (RGB) value for every pixel with one R
GB value and
the position of the rectangle.
Temporal compression compares frames and ignores duplicated data,
such as
a
stationa
ry
background behind a subject.
4.6.2
Lossless vs lossy
Lossless compression keeps all the data and simply loses redundant information
–
f
or
example
,
using spatial compression such as JPEG at the highest setting.
Lossy compression throws away some data to achieve the desired data rate. The lower the
data rate
,
the
greater the likelihood
that codec ‘artefacts’ will appear
. (V
isible flaws
created
by spatial and/or temporal compression
are examples of artefacts
.
)
So,
l
ossy
compression
results in
loss of quality and/or detail.
In both lossy and lossless compression, information redundancy is reduced
by u
sing
methods such as coding, pattern re
cognition and linear prediction to reduce the
amount of
data.
V
ideo compression
a
rtefacts
, such as
‘blockiness’ and chunks of frame staying on screen
(
‘
lag
’
),
are visible signs of a lossy codec at work
.
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Figure 2: Spatial artefacts
–
blockiness
Figure
3: Temporal artefacts
–
lag
2011
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T
o avoid
artefacts
, implement any of the following actions or combinations of actions:
increase the data rate
reduce the image size
remove noise (unnecessary information).
Designing for the encoding phase will
also
help
to
reduce the likelihood of
artefacts
.
For
further information, see
Section 5 (
Video production for encoding
)
.
4.7
Audio
Specific
c
odecs
have been
designed for
different
sound types such as voice and music.
Since
the data rate is reduced
,
a
udio compression
can ma
ke
the
sound
quality more muffled
and metallic
.
Medium compression
, for example,
may
remind the listener of FM radio
quality
.
Excessive audio compression sounds like AM radio or a Skype call on a poor
i
nternet
connection.
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5
Video production for encoding
To
achieve the
best
final results
, you should plan
to create footage that will
cut together well
and
compress well.
T
echnology
can only do so much. It is
very hard
for the codec to
maintain quality and a low data rate if the original video continually change
s
or
is noisy
.
Your planning should
therefore
include
the entire
video production
process
, not forgetting
how you will address access to your information
for
users
with disabilities
(see Appendix 6:
Video accessibility)
.
Even very
experienced producers
f
ollow
a
process
, en
sur
ing
a
video is well scripted
(
often
with a storyboard
)
and
well
planned before
any
shot
s
are
taken.
A ‘
We’ll fix it in post
’
attitude
inevitably
leads to
an
overrun schedule
and budget.
5.1
Digital video process: shoot to media
Figure 4
shows the digital video process. Specific parts
of the process are discuss
ed in the
following
sections.
Figure 4: The digital video process
,
from camera
shoot
to
final
media
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5.2
Digital video editing
Once the footage is ‘in the can’ (recorded)
,
it can be e
dited. Today
,
video is edited on
computers in almost all circumstances, even
footage for
feature films.
Digital video editing uses a variety of computer
-
, camera
-
, device
-
and broadcast
-
based
codecs.
It is important to c
hoos
e
the
most appropriate
editing c
odec
, as it
can make a big
difference to
the
editing time and
output
quality
of the video
. Ideally
,
to reduce render times
or the need for transcoding
,
the footage
should be
edited using the codec
it
was shot in.
Where possible, i
t is best to edit in the
highest quality codec of the source footage. For
example
,
if the best footage was shot in 1080p HD
(high definition),
then
any
lower quality
footage should be upgraded. To speed workflow
,
any upgrading
should be done before the
edit
,
so that editing can pr
oceed without
needing to
continually render
and then
transcod
e
.
There is an argument for ‘upscaling’
(
transcoding
)
to a lossless codec
to avoid the risk of
producing artefacts during the editing process
. If a lot of image processing is anticipated
,
it
can
be useful to have more ‘headroom’
(the margin between the pure uncompressed video
and the compressed end result). If you r
ender transitions and effects in codecs designed for
capturing live video
, it
can
result in
artefacts in the master edit.
Ideally
,
the
final edit
should
be rendered in the edit codec to a master file, which can be
transcoded with multiple data rates and codecs as required.
Exporting from an editor can be
technically
difficult, so it is
important
to
research
a tool’s
useability
before cho
osing an editing package.
5.3
Design for the codec
Getting the best out of a codec requires a combination of techniques beyond simply using
the best codec and the best tool.
You should also plan and design for the codec.
Here are some points you should conside
r:
Flat backgrounds,
such as
a blue sky,
enable
enormous spatial compression without
artefacts.
Video of s
tatic talking heads compress
es
easily
,
as very little chang
es
from frame to
frame.
As a result,
temporal compression
can
block out large chunks of th
e frame and
use more data for details such as the moving mouth and head.
Chroma key (blue/green screen) of the subject over a static image enables the
background to stay largely unchanged
,
allowing for higher temporal compression with
less
loss of
image qu
ality.
Cross
-
dissolves are the enemy of video compression
.
In this type of dissolve
, every pixel
typically
chang
es
from the start frame to the end frame of the transition.
So, if the cross
-
dissolve is maintained,
the file size will be large
. This is a big
pay
-
off for a shot that probably
doesn’t add
to the message
of the video
.
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5.4
Five top tips
Get in close
Digital video is often less than half the original picture size, so you need to take close shots.
Although close shots accentuate what is changing in the
image (and therefore increase data
size), the content should always take precedence over technical considerations. What is the
point of good technical quality if you can’t see the subject?
Use a tripod
Static shots suit temporal compression
. U
nnecessary ca
mera movement chokes data rate
,
so use a tripod.
Avoid ‘noise’
Do no
t add unnecessary visual effects.
Remember, p
oor
-
quality
‘
noisy’ source
s
, such as
VHS or S
-
Video
,
will always return poor results.
In addition, f
ile sizes will be larger because
a codec ca
nnot distinguish between noise and content.
Avoid transitions
W
here possible
,
avoid transitions
and use wipes rather than dissolves. (In a dissolve
,
the
entire
image is changing in each frame
, which
mak
es
temporal compression impossible.)
Consider quality
vs bandwidth
How important is the image quality? Sometimes it is worth making the user wait
in order
to
maintain
video
quality or dimensions. But
,
even the most patient user has
a time
limit.
Sometimes immediacy is important and the message can be deliver
ed effectively with a
substandard video image.
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6
Encoding parameters
Most tools offer
a number of parameters that allow the developer to get the best from the
codec.
The parameters are discussed in this section.
6.1
Data rate
Imagine you are pumping petrol int
o your car’s tank. If it pumps too fast
,
it will not go through
the pipe fast enough
, so it
overflow
s
. Petrol pumps should pump no faster than the thinnest
petrol tank pipe can handle.
To use this analogy, d
ata (video and audio) is
the
petrol
.
T
he
pump spe
ed is the rate and the data rate must suit the user with the slowest pipe
–
within
reason.
The
d
ata
r
ate
,
or
b
it
r
ate parameter
,
sets how many bits per second the encoder will aim
to
achieve
. Higher data rates achieve higher quality video. Lower data rates
work better
with
slower networks and media.
Streaming servers encode specifically for the typically variable data rate of a network. (Not to
be confused with
v
ariable
b
it
r
ate encoding
–
see below
.
)
QuickTime
r
eference
m
ovies deliver a compressed video fi
le
that
suit
s
the user’s connection.
The video is encoded at different data rates and then linked into the
r
eference
m
ovie.
Web pages and players can be programmed to use a suitably encoded video stream.
Sometimes users are offered choices such as ‘low’,
‘medium’ and ‘high’ (quality/data rate).
6.2
Variable bit rate
Many codecs and tools support variable bit rate
(VBR)
encoding.
With V
BR, as opposed to
constant bit rate (CBR), the encoder produce
s
an average bit
rate or target file size, but
it
is
free to vary
the data rate for different
sequences
within the video file. This means more data
can be used for complex sequences and less for simpler scenes
.
This approach
tends to
produce a better result
,
but
it
takes more time as the encoder needs to look ahead to k
now
how to vary the data rate.
VBR
is unusable for streaming video
,
which sets the data rate to
the connection speed and does
n
o
t have the time to look ahead.
See
Appendix 4 (
Bit rates
)
for further information.
6.3
Key frames
Key frames are frames in the video
where the codec stores the entire frame
,
ignoring
previous temporal compression data. Temporal compression saves a lot of data
.
However,
if
the user jump
s
around in the video timeline
,
they might go to a frame that needs data from
previous frames. This wi
ll give unexpected results,
such as
a corruption of the video image,
until the temporal compression is ‘refreshed’ and fills in the image.
Key frame o
ptions are
:
regular intervals
–
for example,
every second
automatic, which creates new key frames whenever
a significant percentage of the
image changes from one frame to the next.
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6.4
D
imensions
Digital video can
use
any dimensions
(width and height in pixels) on screen.
It is possible to
have a vertical format (
for example,
for a phone), to crop a percentage fr
om the source
,
and
to
matte a video (
use a custom alpha channel or mask
).
In
some
applications, players and web pages the dimensions can be specifie
d
.
In these
contexts,
i
t is common to halve video dimensions and ‘pixel double’
on playback.
(Pixel
doublin
g doubles the dimensions of the image and smoothes the image slightly.)
Halving the
dimensions saves a lot of data
,
but pixel doubling can ‘soften’ the image
,
mak
ing
it look
slightly out of focus.
T
his
outcome
is
often
perfectly acceptable and unnoticeable
when
displayed on a
television
.
N
eat halving or quartering of
the
dimensions render
s
sharper results than
using
odd
fractions
.
For example
, if the original dimensions are 1024 x 768, halving the dimensions to
512 x 384 will give sharper results than 676 x
507 (two
-
thirds) because there is no need to
round up or down to a whole pixel.
T
he ‘natural’ numbers of computers are divisible by 8 (8
bit, 16
bit, 32
bit, 64
bit, 256
bit, etc)
–
a byte is 8 bits.
C
odecs work
more effectively
when the dimensions of a v
ideo are divisible
by 8. The factor of 8 usually matches the dimensions of video formats
,
but sometimes it is
necessary to crop pixels from the image
,
especially after a reduction in dimensions.
6.4.1
Non
-
square pixels
The pixels on a c
omputer screen are square.
Video CD,
Super Video CD (
SVCD
)
and some
HD formats use non
-
square pixels. Most encoding tools allow you to output the video at
custom proportions and set the pixel aspect
ratio
from square to
HD (
16:9).
Stretching pixels
allows
you to have a larger image
from a
file of
smaller dimension
s
,
which
sav
es
data rate.
Figure 5: Example of geometry parameters (Apple’s Compressor)
:
Crop
ping
, Dimensions
(including
Pixel
a
spect
)
and Padding
Some players allow you to change the dimensions of a vi
deo file
–
for example
,
to stretch
them
from
s
tandard
definition
(4:3) to
h
igh
d
efinition (16:9).
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6.5
Screen resolutions
The screens on N
okia phones come in many sizes
, including
128 x 160, 176 x 208,
208 x 208, 240 x 320 and 352 x 416
.
T
he first three genera
tions of the iPhone have a
screen
resolution of 320 x 480 (HVGA) at
163
ppi (pixels per inch)
, while the display on the iPhone 4 has a
screen
resolution of 640 x
960 at 326 ppi.
The forthcoming
Android
-
based tablets
have
a variety of
dimensions
,
such as 1
024
x
600,
854
x
480
and
800 x 400. Unfortunately
,
manufacturers are pulling the standard
size
in
different directions. The iPad is
1024
x
768
pixels
,
which is good for full
-
screen HD
video
playback
,
but
some
upcoming tablets support 1080p. Hopefully, like
mobile phones, tablet
screen sizes will
evolve
in
to one or
two
standards.
For an overview of tablet m
odel
s, see
:
http://en.wikipedia.org/wiki/Comparison_of_tablet_PCs#Slate
Alt
h
ough mobile phone manufacturers have created phones with a plethora of dimensions
,
the practicalities of manufacture and necessities of content have created a trend towards
common screen sizes. Currently
,
32
0 x
24
0 (called QVGA) is the most popular mobile
phone
screen size. (Note
that
320 x 240 is exactly half of 640 x 480
,
and
it is
divisible by 8.)
Figure
6
: The most significant screen sizes, from smallest to largest
,
with upcoming phones as dotted
lines.
Note
the
trend in higher resolution (
p
ixels
p
er
i
nch)
.
6.5.1
Recommendations
A screen size of
640 x 480 is still a good standard for SD (4:3) video.
For HD video, the dimensions
512 x 288
are
a good size
.
This screen size is
half the PAL
HD standard of 1024 x 576 (
which is
good for pixel doubling)
.
The dime
nsions 512 x 288 are
good for a web page
,
but
they are
a little too big for mobile phones.
T
he most common screen
size for mobile phones is 320 x 240 (QVGA).
See Appendix 5 (Screen resolutions) for an overview.
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6.6
Fields and frames
Video can be interlaced
or progressive.
The use of interlacing helps to achieve good visual
quality in narrow bandwidth contexts.
Fields are alternating half frames that are horizontally
‘interlaced’ (odd and even) lines of the image. This approach was developed as a solution to
the issue of the duration of phosphor glow with television cathode ray tubes. Footage shot
with interlacing can appear to have a ‘comb’ effect on a computer screen when there is quick
horizontal movement. If this effect is evident, make sure the video mast
er is rendered with a
deinterlacing filter.
Abbreviated video resolution specifications may include an ‘
i
’ or a ‘
p
’. For example, ‘
1080i
’
refers to
1080 horizontal lines interlaced
(
drawn odd
and
then even
), whereas ‘
1080p
’
means the lines are progressive
(
drawn from 1 to 1080
)
.
6.7
Frame rate
Video can
consist of
25 (PAL), 30 (NTSC) or 60 (HD) f
ps
. Halving the frame rate can reduce
the data rate without loss of image
quality
.
PAL
, for example,
can be reduced to 12.5 fps,
although at 12 f
ps
motion
may begin to
look a little jerky.
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7
Players/Container formats
This section provides a list of common players and plug
-
ins, along with some information on
associated licences, tools, severs and platforms. A final recommendation is provided for
each player/plug
-
in
.
Infor
mation on supported codecs can be found in Appendix 1
(Standards recommendation) and Appendix 2 (Player
s/container formats and codecs
).
An overview of available players can be found
at
:
http
://en.wikipedia.org/wiki/List_of_media_players
R
emember, the licence for a
player
only pertains to
the
distr
ibution of the player software.
A
publisher is constrained by the licen
sing requirements of any
codecs used by content
,
regardless of the player li
cen
c
e.
7.1
Windows Media Player
.wmv
Windows Media Player is a media player developed by Microsoft
. It is
i
ns
talled by default on
Windows machines.
The player
features a number of proprietary codecs
,
developed by
Microsoft, Sorenson, Adobe and Sony.
Licence
Wi
ndows Media Player is proprietary. Content produced in the WM format is free to
distribute
,
but the content is
subject to the licensing
requirements
of
any
included codecs.
Tools
Windows
-
based video
-
editing tools offer Windows Media Player formatting
,
usua
lly via a
plug
-
in.
Windows Media Plug
-
in for Adobe Premiere 6.5 (Beta)
can be downloaded from
:
http://www.microsoft.com/downloads
/en/details.aspx?FamilyID=fbcd4987
-
86c6
-
4fe0
-
8a6d
-
f19ddf89217e&displaylang=en
Sony Vegas Pro 10 supports Windows Media 9 HD
.
Microsoft Expression includes a number of applications bundled into various suites
,
which
offer similar functionality to Flash
,
in
cluding a video encoder that creates WMV and
Silverlight plug
-
in files.
Microsoft Expression
is available in a variety of editions, including
a free edition
,
a commercial Pro edition
,
a
nd
the Studio 4 Ultimate and Web Professional editions
.
See:
http://www.microsoft.com/expression/
Server
Section 9.3.3 (
Windows Media Server
).
Platform
U
nfortunately
,
t
his is complicated. Platform support has evolved with Windows Media Player
versions. The latest version
(12) is
only
compatible with Windows Server 2008 R2 and
Windows 7.
See:
http://en.wikipedia.org/wiki/Windows_media_player#Release_history
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It is recommended that user
s
ar
e provided with
a link to the Microsoft site
,
so they
can
get
the
most appropriate
version for their OS:
http://windows.microsoft.com/en
-
US/windows/downloads/windows
-
m
edia
-
player
Flip4Mac is a WMV QuickTime component that provides WMV playback on Mac OS X 10.4
and later
,
using QuickTime 7 and later.
Recommendation
While Windows Media Player
i
s always available on Windows machine
s,
the complicated
breadth of versions, a
nd the fact that it only supports Microsoft’s version of MPEG
-
4 make it
complicated to
use to
produce cross
-
platform content.
The WMV format includes its own Digital Rights Management
(DRM)
, which has been
subject to much criticism.
N
ote that
Windows 7 shi
ps with an H.264 decoder (licen
c
e included in OS fee).
7.2
Flash video
.flv, .f4v, .f4p, .f4a, .f4b
Adobe’s Flash is a popular, web
-
pervasive, multimedia application, which has its own video
container format
known as
FLV. Most audio and video on the net is FLV
. Flash has a
huge
developer
community, plus t
here are many pre
-
made players and scripts
.
Video content can be played using a custom
-
built
interface
or the Flash player
.
Flash has
no support for built
-
in text tracks
(subtitles). However, like QuickTime,
F
lash can
be programmed to
use
features such as
multi
-
language support
and
graphics layers
.
Use of
these features
requir
es
experience in Flash development.
Licence
The
licence
is free,
but there are some restrictions.
S
ee:
http://www.adobe.com/products/players/fpsh_distribution1.html
Tools
Flash Media Encoder is proprietary
.
It is
bundled with the Adobe Creative Suite Web and
Master editions.
A f
ree ‘Lite’ encoder
is available at
:
http://www.adobe.com/products/flashmediaserver/flashmediaencoder/
Server
See
Section 9.3.4 (
Flash
).
Platforms
Windows
LINUX
Solaris
Mac OS X
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Recommendation
Flash may lose g
round as HTML5 becomes more popular
,
but it
currently
has
an
enormous
installed base
.
It
can be used in concert with HTML5.
7.3
QuickTime
.mov, .moov, .mp4, .mp3, etc.
QuickTime
is a cross
-
platform player
,
developed by Apple
.
It
supports a broad range of
code
cs (largely legacy)
. U
ntil recently,
it also supported
Flash. On Apple computers,
QuickTime is built into the operating system, which enables video and audio to be supported
in
-
application. (For example
,
you can play a video in an email or a Word doc.)
MOV
s (the main QuickTime file format) combine layers of data. Multiple text and audio
tracks can be added to a video track for multi
-
language support, accessibility and other
purposes.
T
ransitions,
3D,
image, vector and other data streams can be used, but the
tools
to add these data streams are often rudimentary.
QuickTime has an enormous library of commands
.
In addition,
Apple offer
s
free
programming tools
,
which
make it possible to do everything from building simple players to
advanced editors.
The QuickTi
me file format offers a succinct suite of user interface options.
To deliver video to users on a variety of
i
nternet connection speeds
,
QuickTime has
‘reference movies’. Reference movies are .movs that point to two or more versions of the
same movie
,
each
with
a
different data rate. The QuickTime player
on the
user’s
computer
tells the reference movie to send the version with the desired data rate.
QuickTime X (the version of QuickTime installed with OSX 10.6) features a screen recorder,
video and audio cap
ture, live streaming and
many more features
. Version 7 includes useful
features
such as the ability to
add tracks
. M
ost Mac videographers have both versions.
For further information on QuickTime, see:
http://developer.apple.com/library/mac/#documentation/QuickTime/RM/Fundamentals/QTOv
erview/QTOverview_AIntro/Introduction.html
Licence
QuickTime is proprietary. Co
ntent produced in QuickTime format is free to distribute
, but the
content is
subject to the licensing
requirements
of
any
included codecs.
Distribution of the player is also free
,
but
it is
subject to some restrictions. See:
http://developer.apple.com/softwarelicensing/agreements/quicktime.html
Tools
Most tools support the QuickTime format
,
which is integrated with all major digital video
-
editing tools.
Compressor, bundl
ed with Final Cut Studio Pro, is
an
ideal batch
-
encoding tool
.
I
t is very
fast, enables a large number of files to be set up for encoding,
allow
s multiple encodings of
the same file, offers access to every parameter and enables the user to save suites of
s
ettings.
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Flash is no longer supported by the QuickTime format
, but
the QuickTime format
support
s
the same codecs
as
Flash
(
H.264, On2 VP6 and Sorenson Spark
)
.
As a result,
an encoding
tool is likely to be able to output identical video to both formats.
Ser
ver
See
Section 9.3.1 (
QuickTime
).
Platforms
Windows XP or later
Mac System 7 or later
Mac OS X Leopard or earlier
Recommendation
QuickTime offers broad codec support and can be confidently installed on PCs. The plug
-
in
supports H.264 in browsers without n
ative support
,
for example
Internet Explorer
(
pre
-
9
)
.
7.4
VLC
VLC
is
a
cross
-
platform multimedia player, server and framework.
(It is not a format.) It
plays
most multimedia files
,
as well as DVD, Audio CD, VCD and various streaming protocols.
VLC is
free and
open
source
.
See:
http://www.videolan.org/
The VLC
p
lug
-
in can be used to play files in web pages.
Go to:
http://wiki.videolan.org/Documentation:WebPl
ugin
Licence
VLC is free to distribute.
Tools
VLC plays
most
media
formats,
regardless of which
tool
was used to create them
.
Server
VLC media player can be used as a server to stream and receive network streams. VLC is
able to stream
all of the file form
ats
that it
supports
.
Pros: supports a large number of audio, video and streaming formats
;
not memory
-
intensive
;
simple to use
;
platform
independent
.
Cons: poor
H
elp documentation
.
Platforms
Mac OS X
Windows
BeOS
GNU/Linux
FreeBSD
WinCE
Recommendation
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VLC
is h
ighly recommended as a powerful
,
free video tool.
In addition, it
is an open
-
source,
cross
-
platform, all
-
purpose video player. VLC can transcode to popular formats and play
regionali
s
ed DVDs.
The VLC plug
-
in supports H.263 in browsers without native
support.
Also see
Section 11.3
(
HTML5 and the video tag
)
.
7.5
WebM (On2 VP8 / Vorbis)
WebM is a format without its own player
.
Even so,
the Matroska
-
based WebM container is
widely supported.
Google’s implementation of On2 uses the Matroska media container (for
mat) with the Vorbis
audio codec.
See:
http://www.webmproject.org/
WebM is v
ery close to the technical quality of H.264
.
It
is being used for YouTube’s HTML5
experiment.
Licence
All versions of On2 are open sourc
e
. However,
On2
shares some code
with H.264, so On2
may
infringe
H.264’s
patent and copyright.
At the time of writing, this issue was
untested
from a legal standpoint
, so
On2
may need to be completely rewritten before it can be
considered truly
‘
free
’
.
To
ols
The tools are f
ree. There are patches for FFmpeg and MPlayer
,
which extend the tools to
support On2 VP8.
Encoding is slow, and the codec has been
describ
ed as buggy
.
T
he encoder and decoder
shar
e
buggy code.
Server
See
Section 9.3.6 (
Cherokee
).
Platfor
ms
Mozilla Firefox 4 and later, Opera, Google Chrome 6
QuickTime, Media Player Classic, Moovida Core, VLC, Winamp and XBMC.
Recommendation
It is difficult to recommend WebM due to the p
otential technical and licensing issues
,
plus its
uneven support
(desp
ite
Google’s backing
)
.
7.6
Ogg (Vorbis / Theora)
Ogg is a
free
,
open
-
source container format for
use with
Theora and Vorbis codecs. Used by
several Web browsers for their new HTML5 media elements
,
Ogg supports text tracks
(subtitles) and metadata
,
as well as
audio codecs
such as
Speex, FLAC
and
OggPCM.
For additional information, see
http://www.xiph.org/
Theora, the video codec, is inferior to H.26
4. The file size/quality balance is not as good.
Licence
2011
Video Standards Report
E
-
standards for Training
-
Australian Flexible Learning Framework
Page
22
Open
-
s
ource
licenc
e.
Tools
A variety of third
-
party tools can be found
at
:
http://www.vorbis.com/software/
The codecs are open source, so they are often included in common tool suites.
C
heck
before you buy anything new.
Serve
r
VLC, Icecaste, FreeCast and Flumotion.
Platforms
Windows
OS X
LINUX
Recommendation
In comparison to H.264, Ogg
’
s file size/quality balance is inferior.
This format is unlikely to
become a broad standard.
7.7
Real Media
.rm
Real Media is a
proprietary multime
dia container format that supports a broad range of
popular, contemporary and legacy codecs.
It
is the container for RealVideo and RealAudio
.
It
requires installation of the RealPlayer.
Primarily designed to work with streaming servers, Real supports WMV
(
prior to Real Player
v
11)
and
QuickTime
formats.
See:
http://
www.
real
.com
http://en.wikipedia.org/wiki/RealMedia
Licence
The player is free.
Tools
Free tools
are
a
vailable from Real and
some third
parties.
Server
See
Section 9.3.2 (Real Media).
Platforms
The latest version (RealPlayer SP) is supported on
:
Windows XP to Windows 7
Mac OS X 10.4.11
and
later
.
Recommendation
2011
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E
-
standards for Training
-
Australian Flexible Learning Framework
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23
As RealNetwork’s influence continues to wane,
its future
is
unclear
. I
t is difficult to
recommend this format with any confidence. However, as a media
-
streaming solution,
it has a strong track record.
7.8
Silverlight
Microsoft Silverlight is a new web application framework that integrates multimedia,
gr
aphics, animation and interactivity into a single runtime environment.
It was i
nitially
released as a video
-
streaming plug
-
in
.
L
ater versions
have
additional interactivity features
,
as well as
support for CLI languages and development tools.
V
ersion 4
,
rel
eased in April
2010
, is the latest version at the time of writing this report
.
S
ilverlight
’s features
are similar to
those
available
in Adobe Flash.
Licence
Silverlight is free to install from the Microsoft site.
No information on licensing could be found
at the time of writing this report. It is assumed that licensing is codec specific
, like
it is for
other players.
Tools
Microsoft Expression includes a number of applications bundled into various suites that offer
similar functionality to Flash
,
including
a video encoder that creates WMV and Silverlight
plug
-
in files.
There are various editions of
Microsoft Expression
, including
a free edition
,
a commercial
Pro edition
,
and
the Studio 4 Ultimate and Web Professional editions
. See:
http://www.microsoft.com/expression/
Server
Silverlight is new
. T
he only way to stream it is to use the
free
Windows Media Services add
-
on for the highly regarded Windows Server 2008 (
which must be purchased
).
Silverlight will no
t ‘cross
-
scheme’
,
which means you can
not
stream via Real Time Streaming
Protocol
(RTSP
) into HTTP.
Platforms
Most current versions of Windows browsers,
and
some Mac browsers
. At the time of writing,
support was
not yet available on Windows Phone 7
.
Microso
ft is gradually increasing support for other platforms. F
or a current platform overview
,
refer to
:
http://www.silverlight.net/getstarted/overview.aspx
Recommendation
Silverlight is new,
it
has not been
tested and
uptake is still limited.
I
t is
therefore
impossible
to recommend
Silverlight
at the time of
writing
this report.
7.9
AVI
Audio Video Interleave
, known by its acronym AVI, is
Microsoft’s ‘ancient’ Windows video
format
. While it
is unive
rsal
,
it does not officially support features of more recent container
formats
such as
embedded metadata or, more importantly,
the
most
up
-
to
-
date
video and
audio codecs. Some companies have tried to extend
AVI
in generally incompatible ways.
It is still
the default container format for popular encoders such as MEncoder.
2011
Video Standards Report
E
-
standards for Training
-
Australian Flexible Learning Framework
Page
24
Recommendation
The AVI container should probably be phased out
.
It
is not recommended.
2011
Video Standards Report
E
-
standards for Training
-
Australian Flexible Learning Framework
Page
25
8
Codecs
This section gives an overview of the main codecs
, including information on associated
licenc
es, tools and platforms. See Appendix 1 (Standards recommendation) for a table
summary of this information. For
an overview of lossy video codecs
, see Appendix 3 (Video
codec
table
).
8.1
H.264 / MPEG
-
4 AVC (.mp4)
Well known as the .mp4 format
,
H.264 (MPEG
-
4 AV
C) is a high
-
quality codec for data rate
with broad applications and support. H.264 is ideal for multimedia, web and broadcast
applications. YouTube recommends this format and many online publishers use it. H.264 is
supported by Flash, WebKit’s HTML5, iOS,
OS X and QuickTime.
MPEG
-
4 files use the AAC audio codec and typically use the .mp4 codec.
See:
http://en.wikipedia.org/wiki/MPEG_4
http://mpeg.chiariglione.org
Containers
MP4, MOV, DivX and FLV
.
Licen
ce
H.264 MPEG
-
4 (mp4) is owned by MPEG LA
,
‘
the world’s leading packager of patent pools
for standards and other technology platforms
’
. They
license and
own patents on MPEG
-
2,
ATSC, ACVC/H.264, VC
-
1, MPEG4
-
Visual and various other technologies related to s
atellite
and digital broadcasts
,
and set
-
top and digital video devices.
If the H.264 codec is used for commercial purposes
,
a licence fee
must be paid
. For the
purposes of e
-
learning
,
it is unlikely that the fee would be prohibitive.
Tools
The codec has br
oad support
.
E
ncoders include Flash Video Encoder and QuickTime.
X264
is a free encoder with a command line interface and API
. It is
used by many ‘front
-
ends’ on all platforms
. Examples
include
:
VLC:
http://www.videolan.org/
HandBrake:
http://handbrake.fr/
Squared 5:
http://www.squared5.com/
VLC is highly recommended as an all
-
purpose pl
ayer that can transcode to H.264 and other
codecs.
Apple’s
Compressor
application provides advanced features
bundled with Final Cut Pro
Studio.
Commercial developers offer suites of transcodin
g software that will convert from DVD or
any other digital video file to H.264 for iOS devices and other purposes.
CoreAVC
is a very fast proprietary H.264 software encoder for Windows.
2011
Video Standards Report
E
-
standards for Training
-
Australian Flexible Learning Framework
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26
Platforms
All major platforms a
re supported with a variety of players such as QuickTime, DivX,
Windows Media Player and other software implementations
.
VLC, which is free, is t
he most
popular
and
flexible.
http://www.videolan.org/
The QuickTime 7
Player is free
.
It is
the highest version for Windows and
Mac
OS 7 to 9
(also available for OS X). The Pro version enables additional features such as the ability to
add tracks.
http://www.apple.com/q
uicktime/download/
H.264 is also built into WebKit (Safari, Chrome)
,
as well as Android and iOS.
When publishing for
HTML5
,
you
will
get the widest compatibility
i
f you use H.264 and
fallback to VP3 and then FLV in the <video> tag code.
8.2
MPEG
-
1
While
it
is
not the best quality codec
,
the .MPG format has the largest installed base.
Licence
Patents have expired
,
and there are no licen
c
e fees.
Tools
All general video tools and players support MPEG
-
1.
Platforms
Windows
OS X
LINUX
8.3
On2 (True
M
otion, VP3
–
8)
O
n
2 i
s an open
-
source codec
, which is
now owned by Google.
http://www.on2.com/
http://en.wikipedia.org/wiki/On2_Technologies
On2 promotes
its codec
as a cheaper a
nd better quality alternative to H.264
–
this is
disputed by H.264 supporters.
Licence
Free for commercial and non
-
commercial use. Note
that
WebM uses VP8.
Alt
hough Microsoft, Mozilla, Opera and Google are behind this format
,
there is real concern
that MP
EG LA will be able to bring it to a grinding halt
. On2
is understood to include sections
of vital code taken directly from H.264.
Note that Google own
s
both On2 (the VP series) and YouTube. Also
,
YouTube announced
in May 2010 that the video service is movi
ng from Flash to WebM (VP8 with the Ogg audio
codec).
2011
Video Standards Report
E
-
standards for Training
-
Australian Flexible Learning Framework
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27
Tools
The On2 Flix Engine, a video
-
encoding SDK, is used by many leading sites (and supports
H.264). Flix Engine currently supports WebM, VP6
-
E and VP6
-
S video for Adobe Flash
Player
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