Workshop_SMEast_2013_final

Transcription

Encoding for
Multiple Screen Delivery
Jan Ozer
www.streaminglearningcenter.com
@janozer
jozer@mindspring.com/
276-238-9135
Questions

Most information derived
from 0For more information,
check out the book
 http://bit.ly/Ozer_multi
 Published, April 2013
Copyright © 2013 Jan Ozer, All Rights Reserved
Agenda


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
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

Terms and terminology
Producing H.264
Finding the optimal video configuration
Introduction to adaptive streaming
Choosing a delivery technology
Producing for adaptive streaming
If you see red, pay attention
Terms and Terminology
Codec/compression
 Bandwidth
 Resolution
 Data rate
 Bitrate control
 Container formats, program and
transport streams

Compression/Codec

Compression


Used to shrink the size of video/audio still images
Common codecs

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Video - H.264/AVC, H.265/HEVC, WebM, MPEG-2
Audio - MP3, AAC, WMV
Still image - JPG, PNG, GIF
Codecs - all of the above

Any technology that COmpresses in the studio,
then DECompresses in the field
Why is Compression Important?
To achieve the target data rate, you
have to compress
 Compression is “lossy,” the more you
compress, the more you lose


This is immutable
About Bandwidth

What is bandwidth?


Viewer’s connection speed
Why is it important?


Controls your viewer’s ability to retrieve
and play video smoothly
Higher delivery bandwidths mean higher
data rates, which means better quality
Bandwidth - Where Are We?

Viewer’s connection speed to the Internet


Average download speeds per Akamai State of the
Internet:
 US - 7,611 kbps
 Canada - 6,607 kbps
 Mexico - 2,941 kbps
 UK - 6,470 kbps
 France - 4,804 kbps
So why does CNN max out at 1,200 kbps?
Paradigm Shift

Modem connection speeds (28.8/56 kbps)


Make the video fit
Broadband


Make it good enough
Make it affordable

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CNN is at 1,200 kbps; not to fit pipes, but because it’s
“good enough” and affordable
Cellular

Make it fit
About Resolution

What is it?

Actual pixels in the file
Resolutions That We Know
and Love



Acquisition
DV - 720x480
720p - 1280x720
1080i/p - 1920x1080

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
Distribution
DVD - 720x480
Streaming - 1080p or
smaller
iPod/iPhone/iPad 320x240 - 1080p
Why is Resolution Important



Most video starts life at 720p or higher
Streamed at 320x180 to 1080p
Resolution is key quality factor

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At a set bit rate, increasing resolution degrades
quality because you must compress more pixels
Can’t say that 1,200 kbps is “adequate” without
knowing resolution


For 640x360x25, it’s adequate
For 1080p, it’s not
What is Data Rate?


Amount of data per second of video
Largely determines video quality


At static resolution and frame rate, increasing bit
rate increases quality
Largely determines bandwidth costs
Constant vs Variable Bit Rate
800 kbps
VBR
500 kbps
CBR
300 kbps
Low Motion
Moderate Motion
Low
Motion
Moderate
Motion
High
Motion
VBR vs. CBR

Constant Bit Rate (CBR)
 One bit rate applied to entire video,
irrespective of content

Pros:



Computationally easy
Fast - one pass will do it
Cons: Doesn't optimize quality

Variable Bit Rate (VBR)
 Dynamic bit rate matches motion in video
Pros: Best quality
 Cons:
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Need two or more passes
Can produce stream with significant
variability
How do I Produce the Best
Quality CBR?

Use 2-pass CBR when available
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Scans file (like VBR), but packs data into a
consistent stream
Best of both worlds when available
1-pass of live or draft work
How Do I Produce the Optimal
VBR File?

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2 passes or more
Use “Constrained”

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Constrains to data rate to
specified max
Set Target and Max/Min

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Overall target – 500 kbps
Max/Peak bit rate – how
high rate can go when
varying

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Rule of thumb is 1.5 - 2X of
target
If minimum setting, use .5x
When Should I Use VBR/CBR?
VBR
Constrained VBR (usually
2X) for most streaming
applications


Broadband delivery can
handle spikes
Constrained VBR for
virtually all progressive
delivery
 Constrained VBR for
most cellular, though not
universal

CBR
 CBR for live, particularly
when limited outbound
bandwidth
 CBR or constrained VBR
for adaptive streaming
(more later)
Container Formats, Transport
Streams, Program Streams

Container format:

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
A meta-file format whose specification describes how
data and metadata are stored
Examples: MPG, MP4, MOV, F4V, WMV, FLV
Transport stream:

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Transport stream specifies a container format
encapsulating packetized elementary streams, with
error correction and stream synchronization features
for maintaining transmission integrity when the signal
is degraded (e.g. - broadcast)
Examples: .ts,
Why Do We Care?

When producing for single file or adaptive
delivery, you must choose the right container
format/transport stream for your application

Streaming
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Flash - MP4, FLV, F4V, MOV - H.264
HTML5 - MP4 - H.264, WebM - VP8
iDevices - MP4, MOV - H.264
Adaptive - HTTP Live Streaming - .ts
Questions on Terms and
Terminology?

Should be 9:25
Download presentation handouts
At www.streaminglearningcenter.com
Producing H.264


Introduction to H.264
H.264 encoding parameters
Introduction to H.264
The MPEG-4 specification
 The MPEG-4 codec
 MPEG-4 spec audio options
 The H.264 codec
 H.264 Basics

Preload http://www.doceo.com/rethink2/Main.html
MPEG-4 Specification


Introduced in 1998 by ISO/IEC Moving
Picture Experts Group
28 “Parts” within specification
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Part 2 - MPEG video codec (the MPEG-4 codec)
Part 3 - MPEG-4 audio (AAC, etc)
Part 10 - Advanced Video Coding (AVC/H.264)
Part 14 - container format (MP4)
The MPEG-4 Video Codec

Used only for low power
devices: Two profiles:


Simple Profile - very low
power, low bandwidth
applications
Advanced Simple Profile Simple plus:
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Support for "MPEG"-style
quantization
Support for B pictures (a.k.a.
B-frames)
Motion compensation
Check specs on target devices
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Will refer to MPEG-4 encoding
only in mobile segments
Never use for computer
playback
MPEG-4 Audio

AAC-Low Complexity (AAC-LC)
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High Efficiency AAC (2003)
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The most basic and most broadly
compatible
In my tests, indistinguishable from
HE AAC/HE AACv2
Also called AAC+ and aacPlus
High Efficiency AACv2 (2006)

Also called enhanced AAC+,
aacPlus v2 and eAAC+
MPEG-4 Audio Summary

Recommendations

Usage dictated by specs of target device
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When producing for multiple devices, use lowest
common denominator
When in doubt, choose AAC-LC
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Most compatible on the playback side
Universally available on MPEG-4/H.264 encoders
What is H.264?

Adapted by ISO and
ITU
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Telephony/cellular
TV - consumer
electronics
Computer electronics
Only codec adopted by
top three streaming
providers (Apple,
Adobe, Microsoft)
Streamcrest Associates
http://www.streamcrest.com/SDF%20Final1.pdf
What's MPEG-4/H.264 Cost?

For free Internet video (e.g. no subscription
or pay per view), free in perpetuity
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Thank you Google (WebM)
Still technically an obligation to sign a license, but
there are no teeth and no motivation to enforce
For subscription or PPV, there may be a
royalty obligation
Check www.mpeg-la.com
The Many Wrappers of H.264
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.MP4 - official MPEG-4
wrapper
.M4V - Apple’s variant for
iTunes and devices
.MOV - H.264 file for editing
or QuickTime delivery
.F4V - H.264 for Flash
.3GP - (not shown) - phone
.MPG - H.264 in MPEG-2
transport stream
H.264 Encoding Parameters

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The basics
I, B and P-frames
Search-related options
Miscellaneous options
H.264 Encoding - Basics


Profiles and Levels
Entropy encoding
What are H.264 Profiles?
“Define a set of coding tools or algorithms
that can be used in generating a bitstream”

Profiles and Playback
Compatibility
PreiPhone 4
Android
3.0
Software
Android
Hardware
iPad 1
iPhone 45
iPad 2/3
Flash/
HTML5
Baseline
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Main
No
No
?
Yes
Yes
Yes
Yes
High
No
No
?
No
Yes
Yes
Yes
Profile


Using the wrong profile results in a file incompatible
with your target
Need to know profile of target device and choose
appropriate profile

Some interesting decisions to make when encoding for
multiple device delivery
Quality-Related Expectations

Baseline profile - fewest advanced
algorithms:
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Lowest quality stream
Easiest to encode and particularly decode
High profile – most advanced algorithms


Highest quality stream
Hardest to encode/decode
Why Do Profiles Exist?


Meeting point for hardware
vendor and video producer
Example: Original video
capable iPod is baseline only:
why?

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Lower power (cheaper) CPU
Less power consumption
Video producer: to produce
that will play on iPod, use
Baseline profile
Rule Number 1

Don’t exceed profile of target device


Exclusively a concern with mobile
Computers and OTT devices can play High
profile (any level)
Required Profiles for iDevices
Original iPod
(to-5g)
iPhone 4
/iPod touch 4/
iPad 1&2
iPhone 4S
IPhone 5/
New iPad
Max video data rate
H.264
Baseline to
Level 1.3
768 kbps
iPod nano/
classic/ iPod
touch/iPhone
to V4
H.264
Baseline to
Level 3.0
2.5 Mbps
H.264
Main to Level
3.1
14 Mbps
H.264
High to Level
4.1
50 Mbps
Max video resolution
Frame rate
Audio codec
Max audio data rate
Audio params
320x240
30 fps
AAC-LC
160 kbps
48 kHz, stereo
640x480
30 fps
AAC-LC
160 kbps
48 kHz, stereo
720p
30 fps
AAC-LC
160 kbps
48 kHz, stereo
1080p
30 fps
AAC-LC
160 kbps
48 kHz, stereo
H.264
High to Level
4.1
62.5 mbps for
level
108p
30 fps
AAC-LC
160 kbps
48 kHz, stereo
Video codec
Profile/level


Four playback classes
Must configure video appropriately to
play on target
Required Profiles for Android
http://developer.android.com/guide/appendix/media-formats.html

These recommendations are least common
denominator software-only playback


Most devices probably more capable (no table
because too many manufacturers)
For 100% compatibility, use these
Required Profiles for Windows
8 Phones


H.264-encoded video
in MP4 container
Files s/not exceed
params for 7x27a
CPU.
http://msdn.microsoft.com/en-us/library/windowsphone/develop/ff462087%28v=vs.105%29.aspx
Profiles and Playback
Compatibility
PreiPhone
4
Android
3.0
Software
Android
Hardwar
e
iPad 1
iPhone
4-5
Win 8
Phone
iPad
2/3
PCs/
note
books
OTT
Baseline
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Main
No
No
?
Yes
Yes
Yes
Yes
Yes
Yes
High
No
No
?
No
Yes
Yes
Yes
Yes
Yes
Profile


Using the wrong profile produces a file
incompatible with your target
Need to know profile of target device and
choose appropriate profile
Big Decision #1

One set of files – all Baseline – that plays
everywhere?


Cheapest, easiest
Separate files:




Baseline – Very old iOS and Android
Main – Old iOS and Android
High – new iOS, computers and OTT
Optimal quality, but more encoding, storage
and administrative
What is the Quality Difference?

Consulting project – questions



“Is it worth creating two sets of files, one for mobile
(with Baseline and Main), the other for Desktop
(High)?
“How much difference quality?
Ran comparisons at aggressive data rates:



720p@800 kbps (Burberry is at 3 mbps)
640x480 @ 500 kbps (CNN is at 1200 kbps)
640x360 @ 240 kbps
http://bit.ly/h264profile
Does Profile Matter?



http://www.streaminglearningcenter.com/articles/h264-in-a-mobile-world-adios-tothe-main-and-high-profiles.html
http://www.doceo.com/rethink/Main.html
http://www.doceo.com/rethink2/Main.html
Does Profile Matter?
http://bit.ly/h264profiles
The Bottom Line

At 640x360@240
kbps:

Some noticeable
differences appear at
these extreme
encoding parameters
The Bottom Line

Key takeaway:


The quality difference may be less than you
would expect
Two sets of files, one for mobile, one
for desktop/OTT?


Test quality difference at most extreme rates
and see if the quality difference warrants it
This client used all Baseline
What are H.264 Levels?

“Constrains key parameters in the bitstream”
H.264 Levels-Devices

Critical not to exceed level of target device


Devices won’t load file encoded beyond max
supported level
So, make sure encoding parameters don’t exceed
level (most templates do this)
H.264 Levels – Desktops

Flash/HTML5 players will load and attempt to play all
profiles/all levels


Exceeding a certain level won’t kick the file out like devices
If resolution too large, file won’t play smoothly


Up to 848x480 will play smoothly on most computers
720p may not play on some older/slower computers

Don’t use 720p and higher unless you’re offering adaptive (or
otherwise multiple) streams
Entropy Encoding

CABAC (Context-adaptive binary arithmetic coding)



More efficient (e.g. better quality), but harder to decode
Main/High profile only
CAVLC (Context-adaptive variable-length coding)

Less efficient, easier to decode
What Would YouTube Do?


High Profile
CABAC
I-, B- and P-frames

Caveats:


Presented differently by each encoding tool
Will only cover most important and most
common parameters
What are I, B and P Frames?



I-Frame - encoded
without reference to
other frames (also
called Key Frames)
P - looks backward to
I and P frames
(predictive)
B - looks forward and backward to previous I and P
frames (Bi-directional interpolated)

No frames refer to B-Frame (most of the time)
Configuring Key Frames
Least efficient – so largest (which is bad)
But, key frames enhance interactivity






All playback starts on a key frame
When seeking to random frame, must
start playback at key frame
Maximum interval should be 5-10
seconds
Key frames "reset" quality:


Useful at scene changes
Enable natural key frames or key frames
at scene changes
Configuring Key Frames

Rules change completely when encoding a
group of files for adaptive streaming


Shorter key frame interval
Disable scene change detection
Configuring B Frames?


Main/High profiles only
The most “efficient” frame


So improves quality (comparisons to come)
Hardest to decode


Decoder has to have all referenced frames
in memory to decode B-frame
Frame usually delivered out of order, which
also complicates playback
Typical B-Frame Encoding
Parameters

Number is number of B frames between I
and P-Frames; (IBBBPBBBPBBBPBBBP)


3 is recommended
Reference frames (both P and B-frames)


Number of frames searched for redundancies
5 is recommended setting
Do B-Frames Matter?
YouTube does NOT use Bframes with many H.264 files it
produces


Though they are used with
some encodes
My tests in Episode with 0, 1,
3 and 5 B-frames



640x480@468 kbps
1280x720@800 kbps
Showed very, very little
difference (and then only in HD
clip)
HD Comparisons
Do B-Frames Matter?
Do B-Frames Matter?
B-Frame Bottom Line


3 B-frames/5 reference frames is a good
general purpose recommendation
Don’t spend a lot of time worrying about
“optimal” B-frame settings, because for
most videos, it probably wouldn’t make
that much of a difference
Advanced Frame Options

IDR frames


Two kinds of key frames
 IDR key frame – no frame can reference frame
before key frame
 Non-IDR key frames – B- and P-frames can
reference frames before key frame
All key frames should be IDR key frames in
streaming files
Advanced Frame Options

Adaptive B-frames – adapt frame type to improve
quality


Reference B-pictures – Allows P-frames to reference
B-frames


Always enable
Enable for optimal quality
Pyramid B-frame – allows B-frames to reference
other B-frames

Enable for optimal quality
Search Related Options

Searching for redundancies; multiple factors



Search shape (8x8/16x16) – size of shape used
for searching (smaller is more accurate
Sub-pixel mode – (full/half/quarter pixel) – smaller
is more accurate
Fast - trades encoding speed for quality
Slices
Divides frame into segments to
speed encoding
 Assign a CPU to each slice
But: Search for redundancies
occurs within each slice
 If lots of inter-slice motion,
encoder won’t find these
redundancies
Using slices can reduce quality
Set to lowest value (either 0 or
1)




Reflections on the Utility of
H.264 Tweaking
Less is more
 Many high-end hardware
encoders offer minimal
H.264 config options



Elemental (right)
Envivio
Make most configuration
decisions for you
As We’ve Seen


Profile matters very little
B-frames matters very little
Where to Focus Your Attention?

Get the config right



Rez/data rate/key frames
Choose the right H.264
codec (x264 > MC >
Apple)
You’ve captured 98%
of potential quality
Does it all Matter
Tweaking Relevance
As data rates
increase, the
impact of H.264related tweaking
goes down
Low
Data Rate
High
Synthesis
Focus heavily on finding the optimal
configuration for your video
 Don’t mess up anything else





De-interlacing
Aspect ratio
Bitrate control
Then, if you have the time, worry about
tweaking to get the last 1-5%
Questions on H.264

Should be 10:20
Finding the Optimal
Configuration
Understanding bits/pixel
 Applying bits/per pixel

Why Bits/Pixel is Relevant


Which of these firms would you take videorelated configuration advice from?
Kind of tough to compare, isn’t it?

This adds some data, but how do they really
compare compression-wise?


How about now?
Accenture’s bits/pixel is almost 7 times higher
Bits Per Pixel


How much data
applied to each
pixel in video file
To calculate:


Data rate/(fps*pixels)
Or, get MediaInfo

Calculates for you,
plus lots of other file
details
mediainfo.sourceforge.net/en
Bits Per Pixel

In general


At 640x360 or smaller, values above .2
almost clearly a waste
 CNN is about .121 for low motion
 ESPN maxes at .201, but that’s for sports
Values drop as videos get larger (codecs
work more efficiently at higher resolutions)
What’s the Magic Number?
Corporate – Ultra Conservative
Corporate - Conservative
Corporate - SD
Corporate – Aggressive
Corporate Summary
Bottom Line
 You
should know the bits/pixel for
each video that you produce
If too low – quality suffers
 If too high, may not stream smoothly
and bandwidth costs (if a factor) may
be unnecessarily high

Bottom Line
 You
should know the bits/pixel for
each video that you produce
If too low – quality suffers
 If too high, may not stream smoothly
and bandwidth costs (if a factor) may
be unnecessarily high

Questions on Bits Per Pixel

Should be 10:35
Introduction to Adaptive
Streaming


What it is
How the various alternatives work




RTMP (server-based)
HTTP (no server)
ID existing technologies
Transmuxing
What is Adaptive Streaming?


One stream in, multiple streams out
Streams switched transparently to adapt to
factors like:


Changing delivery bandwidths (avoid hard stops)
CPU utilization at client (avoid frame drops)
Key Benefits

Match stream quality to connection and
playback platform used by viewer
Mobile
Desktop
OTT
Technology Overview

Two types of systems


Server-based (Flash, RTMP)
HTTP




HTTP Live Streaming (HLS)
Smooth Streaming
HTTP-based Dynamic Streaming (HDS)
Dynamic Adaptive Streaming over HTTP (DASH)
RTMP Flash - Overview
1. Uses standard
MP4/F4V files
as encoded (no
chunking)
2. Persistent
connection
between player
and server
3. Player monitors:
-
Buffer
-
CPU utilization
4. Requests
different stream
when needed
5. Server sends
different stream
Issues with RTMP

Server required:




RTMP packets can get blocked by Firewalls
RTMP packets do not take advantage of HTTP
caching mechanisms


May increase cost (because servers cost $$)
May limit scalability (if not enough servers for all
viewers)
Less efficient for popular videos
Some CDNs are dropping support for RTMP
In Contrast, HTTP
Technologies

Don’t require a streaming server




Better scalability
Lower cost
Ubiquitous CDN support
Use HTTP protocol so:


No firewall issues
Will leverage standard HTTP caching
structures

More efficient for popular videos
Bottom Line


RTMP-based Dynamic Streaming has been
most popular technology
Market is moving towards HTTP
Apple HTTP Live Streaming
(HLS)

Encoder creates:



Chunked video files
Index file (M3U8)
Sends to HTTP Server

Player



Retrieves index
Monitors buffer
Changes streams as
necessary
The Manifest File Structure
Perspective

All HTTP Technologies work the same way




Create chunked data files (or segments within longer
file)
Create index files (also called manifest)
Placed on HTTP server
Player side



Monitors playback buffer and (sometimes) CPU use
Changes streams as necessary
Uses index files to find the right files
Adobe HTTP Dynamic Streaming
(HDS)
MP4

.F4F
Media file chunks
.F4M
Manifest files that tell
player where to find
file chunks
Into
Packager
Player driven system


Player monitors heuristics
Retrieves different stream as necessary
Smooth Streaming – How
It Works
Manifest file
(.ism)
Chunked content file (ismv)
Dynamic Adaptive Streaming
over HTTP (DASH)

Like all HTTP-based technologies, it
has



Fragmented video chunks (or single file
with segments)
Manifest files
Supports multiple codecs, container
formats and manifest file formats
Where is DASH?

Lots of smoke, but no real fire



No native support on any platform
Plug-ins available on most platforms
Microsoft/Google working on browser support
Where is DASH?

DASH committee working on H.264-only subspec that Adobe/MS will endorse




Apple/Google (Android) have not announced support
Royalty picture not cleared
DASH for computers/mobile is very much a work
in process
Likely will find native support in OTT platforms
first (because closed system), but HLS is very
entrenched
DASH Alternative? HLS

Several pre-fab video players (JW Player)
are adding HLS support


(As you’ll see) this makes HLS available on
computers, mobile and OTT
If these become pervasive, HLS could
become the dominant format over DASH
Transmuxing Technologies

Perspective: most producers serve multiple clients




In the past, that meant two separate encoding and
delivery workflows


Desktop - Flash (or Silverlight or DASH) AND
Mobile - HLS for iOS/Android (maybe)
OTT - HLS
Separate encoder for each target
Now, multiple streaming that:


Input one set of streams, and
“Transmux” to create second set for different target
Transmuxing Technologies

Options

Technology providers - Wowza, Real,
Microsoft, Adobe
Transmuxing

Not re-encoding




“re-wrapping” file into a different
container format
Creating necessary manifest files
Delivering files to HTTP server
All in real time
Perspective

Key point: If serving multiple targets, you
must produce using lowest common
denominator H.264 encoding parameters
 Must be all baseline for streams
targeted for mobile
 If so, can use one set of files to deliver
to all three groups

Bottom line: If serving multiple
targets, must consider transmuxing
Questions on ABR?

Should be 11:10
at www.streaminglearningcenter.com
Choosing a Delivery
Technology – Two Scenarios

Single video file, no DRM, live or captioning


HTML5 with Flash fallback should work for
browser-based playback and OTT
If you need adaptive, live, DRM or captions,
choosing a path is much more challenging
Distributing Single Files

Desktop


Mobile


Flash/HTML5/
100% playback of HTML5/H.264
OTT

Each service has own delivery structure, typically
MP4 files are recommended
When Producing for Flash
Flash Player
Playback Specifications
Video codec
H.264 ONLY, not MPEG-4
Profiles
Baseline, Main, High
Audio codec
AAC, AAC-LC, HE-AAC
Container formats
MP4 (preferred), F4V, M4V, M4A,
MOV, 3GP
Understanding the HTML5
Playback Environment
HTML5 introduction
 HTML5 penetration - desktop
 HTML5 codec support

HTML5 Overview

HTML5’s key benefit
Death to plug-ins everywhere (Particularly
Flash)


How it works
Instead of obtaining decoders for H.264 and
other codecs in plug-ins
Browsers supply players and decoders



Use <Video> tag in HTML to call player
HTML5 Operation
For video tag to work:

1.
2.
Browser must be HTML5 compatible
Browser must supply appropriate
decoder
Two key markets



Desktop
Mobile
Penetration of HTML5-compatible
Browsers on Desktops
Not
HTML5
Comp+

So, at best, HTML5 is 69% of the market on desktops
http://www.netmarketshare.com/browser-market-share.aspx?qprid=2&qpcustomd=0
HTML5 Codec Support

H.264 Camp – IE, Safari, Chrome


Google announced plans to remove H.264 1/2011, hasn’t yet
WebM camp


Native – Firefox, Chrome, Opera
Via plug-ins – IE 9/Safari
http://diveintohtml5.info/video.html
HTML5 and H.264
Flash Player
Playback Specifications
Video codec
H.264 ONLY, not MPEG-4
Profiles
Baseline, Main, High
Audio codec
AAC, AAC-LC, HE-AAC, HE-AACv2
Container formats
MP4 (otherwise, may call a different
player)
Desktop Analysis


HTML5 can access 69% of desktops (maximum)
To access, you must produce two file versions


H.264 – Chrome, Safari, IE9
 Chrome leaving? In 1/2011, Google said Chrome would
drop H.264; it hasn’t yet
 Firefox coming? Mozilla adding support for Android
Firefox 17, so H.264 may be coming to Firefox soon (at
least of OSs with H.264 support, which doesn’t include
Windows XP)
Web M – Firefox post 3.6, Opera post 10.6, Chrome
Distributing to Mobile


HTML5 - 100% support in iOS, Android,
Windows 8 phones and tablets
H.264 - 100% support, though, as seen,
profiles and levels differ
Distributing to OTT


Channel schema varies by device (HTML5
isn’t relevant)
All devices play H.264 video up to (at least)
1080p, High Profile

Any video configured for mobile/computers should
play on OTT
Optimal Single File Strategy
 HTML5




with Flash Fallback
HTML5 to all mobile devices
HTML5 to all computers running HTML5
compatible browsers
Fallback to Flash for non-HTML5 compatible
browsers
Can encode WebM & H.264 for optimal support

Encode H.264 only and have Mozilla/Opera play Flash
What is Flash Fallback?
Video tag
MP4
WebM
If all else fails,
play Flash
From Sorenson
Squeeze 9
Scenario 2

When you need:




Adaptive streaming
Live streaming
DRM
Closed captioning
Targeting Desktops



Requirements may extend beyond just video
DRM, captions (public)
Multicast/P2P (intranets)
Bottom Line?


Flash or
HLS



Use JW Player in website
So long as Flash is installed, will play HLS
streams
One set of streams for desktop, iOS, OTT
http://bit.ly/Wijering
Targeting Mobile
*
* Android has issues playing back HLS - bit.ly/Rayburn_android
Realistically? It’s Just Not Easy
iOS – HLS
 Android


Universal coverage – AIR application
HLS – 56% penetration and aspect ratio issues

Windows Phone 8

Smooth

Targeting OTT



Flash is non-existent
HLS is ubiquitous and generally the preferred
technology
Can implement smooth in most platforms if preferred
Adobe Primetime

Library that sits above Flash Player


Includes SDKs for iOS/Android




Adds HLS (this summer) DASH (end of year)
iOS SDK will not include DASH
Android SDK includes HLS stack that avoids HLS
playback issues on that platform
OTT support for both DASH/HLS by end of year
Even with Primetime (licensing fees apply),
DASH will not be available on all platforms
Summary


HLS is the only technology available on every
target platform
Today, DASH is not available on any platform

Even though DASH is technically superior to HLS,
it’s hampered by:



The lack of player support
The potential for royalties
Seeming lack of interest from Apple and Google (for
Android, not Chrome)
Choosing a Delivery
Technology

Should be 11:35
Producing Adaptive
Streams

Basic configuration options




Number of streams
Resolutions/data rates
H.264 parameters
Encoding adaptive streams



Key frame settings
Bitrate control
Audio settings
The Big Question


One set of streams for all devices?
Customize streams for each class
What We Know

Most producers customize

Turner Broadcasting – NBA League Pass
My Consulting Experience


Big sites tend to customize
 Large network in the US
 Separate streams for web, mobile, OTT
 Movie site in US
 Ditto, though some crossover
Smaller sites
 Tend to use one set of files; all baseline
Why the Same Set of Streams?


Simplifies encoding (encode fewer streams)
Can transmux


Create one set for Mobile
Transmux to Flash/OTT
Synthesis


There is no right or wrong way
I recommend:


Attempt to find one set of streams that
satisfies all using Baseline profile
Test to see if Main or High delivers
noticeably higher quality
 If so, customize for different targets
 If not, go with one set of streams
Mobile First



Slowest connection, lowest quality
Configure for best service to mobile
Try to configure at same resolutions as low
end computer targets
Apple Tech Note TN2
Desktop (browser-based) Next
At least one stream for each window size
in web site (HBO)
Try to use same configuration as mobile


Then High End Mobile,
Desktop and OTT


Full screen viewing on all devices
Highest quality streams that you can afford
Apple Tech Note TN2224
Stream Count – Bottom Line
At least one stream for each playback window
More streams required for HD than SD




SD – usually 3, 4 maximum
HD – up to 11
More for entertainment than education/business



Entertainment – about the experience
Business – it’s about making sure the viewer can watch the
stream
More for subscription than general entertainment


Provide more options when viewer is paying
What Resolution?

Never encode at larger than source


Resolution should match playback window
whenever possible


Scaling upwards degrades quality
Optimal quality and playback efficiency
If you can’t match playback window, it’s better
to scale up to larger resolutions than to scale
down to smaller


More efficient playback (GPU assisted)
More efficient bandwidth consumption
What Data Rates?

Considerations

Must be sufficiently far apart to:



Avoid constant switching
Make a meaningful quality difference
Will vary with stream size


Smaller gaps at lower bandwidths
Larger gaps at higher bandwidths
What Data Rates?

MTV Schema
How do encoding parameters
change?


Now we know stream count, resolution and
data rate
How do we customize encoding for
adaptive?



Key frame settings
Bit rate control
Audio parameters
Key Frame Interval

Why important - RTMP Flash –
stream switches occur at key frame

Key frame location must be identical in
all streams



Use same interval
Typically shorter (2-5 seconds) to
enable more responsive switching
Key Frame Interval

Why important – HTTP technologies - key
frame must be first frame of every chunk

Key frame interval must divide evenly into
chunk duration



If 9-sec. chunks, use key frame interval of 3 sec
As with RTMP, key frame location must
be identical in all streams, so:
Use same interval

VBR vs. CBR


Most conservative - CBR
Or constrained VBR

Max data rate 125-150% of target
In General - Audio Parameters

Most conservative-same parameters for all
files


Popping can occur if audio
parameters change
But, does’t optimize experience at
higher bit rates
In General - Audio Parameters

If you do switch audio parameters

Switch from stereo to mono at same
per channel sampling rate and bit rate



From 64 kbps/44 kHz/16-bit/mono
To 128 kbps/44 kHz/16-bit/stereo
Test to ensure no artifacts when
switching streams
RTMP Flash Sources

Abhinav Kapoor, “Live dynamic streaming with Flash
Media Server 3.5,” (adobe.ly/kapoorlivefms)

Maxim Levkov, “Video encoding and transcoding
recommendations for HTTP Dynamic Streaming on the
Flash Platform,” (adobe.ly/Levkovhttp)

Larry Bouthillier, “How to do Dynamic Streaming with
Flash Media Server,” website (bit.ly/fmsdynamic)

“Tutorial: On-demand HTTP Dynamic Streaming,”
Adobe website (bit.ly/ondemanddynamic)

“Encoding Guidelines Dynamic Streaming for Flash
over HTTP,” Akamai website (bit.ly/akamaiwhitepaper) .
HTTP Flash Resources

Best sources:

Maxim Levkov - Adobe - very detailed
recommendations


adobe.ly/Levkovhttp
Akamai - White paper:”Encoding
Guidelines for Dynamic Streaming for
Flash over HTTP”

bit.ly/akamaiwhitepaper
Configuring your ABR streams


Questions?
Should be 11:55

Workshop_SMEast_2013_final

Transcription

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