The document summarizes Chris Adamson's presentation on mobile movies with HTTP Live Streaming. The presentation covered what streaming is and how it differs from traditional broadcast media, introduced HTTP Live Streaming (HLS) as a way to stream media over HTTP, and described how HLS works by serving media in short file segments using a playlist file. It also discussed features of HLS like providing multiple variants for different bandwidths and encrypting file segments for security.

1. Mobile Movies with
HTTP Live Streaming
Chris Adamson • @invalidname
CocoaConf DC • March 23, 2013 • Herndon, VA
Livestreaming at http://ustream.tv/channel/invalidstream
Sides and code available on my blog:
http://www.subfurther.com/blog
Monday, March 25, 13

2. So Many Streaming
Apps!
Monday, March 25, 13

3. So Many Streaming
Apps!
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4. Netflix
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5. Flixter
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6. Network TV Apps
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7. Network TV Apps
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8. NBC Olympics Live
Extra
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9. DirecTV
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10. UStream
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11. Crunchyroll
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12. TwitchTV
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13. TwitchTV
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14. TwitchTV
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15. iTunes Festival
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16. Apple Events
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17. Oh, and it can be embedded
in the <video> tag
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18. Oh, and it can be embedded
in the <video> tag
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19. Sounds good? How
do I get in on that?
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20. What You'll Learn
• What streaming is (and isn't)
• Setting up HLS on the server
• Using HLS streams in iOS apps
• Real-world deployment
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21. HLS: What It Is (and
isn't)
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22. Good Ol' Broadcast
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23. Broadcast Media
• Always live on some channel (a band of EM
spectrum).
• Every client tuned to that channel sees the
same thing, at the same time.
• One-way, one-to-many model.
Monday, March 25, 13

24. Internet
• Generally one-to-one (host to host).
• Multicast IP is an exception, but is rare on
the public Internet.
• Two-way communication over sockets.
• Routing can take many hops, via multiple
transport media (wire, wifi, cellular, etc.).
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25. Impedence Mismatch!
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26. Ye Olde Streaming
• Client makes socket connection and keeps it
open for duration of program.
• Server sends media at playback speed (plus
buffering).
• Shoutcast: MP3 files served slowly over HTTP.
• Typically use a special port number and special
server software.
Monday, March 25, 13

27. Streaming Problems
• Difficult and expensive to scale.
• Special port numbers routinely blocked by
businesses, ISPs, firewalls, etc.
• Competing standards: Real Player, Windows
Media, QuickTime (all with their own plugins).
• No wonder Flash won.
• Good luck holding a socket connection on cellular.
Monday, March 25, 13

28. What If…
• We didn't need an always-on socket
connection?
• We could just run over port 80?
• We could just adopt industry standards like
H.264 and AAC instead of cooking custom
codecs?
Monday, March 25, 13

29. HTTP Live Streaming
• Serves media as a series of short flat files, via
HTTP, usually on port 80.
• Any web server will do.
• Client software reassembles the data into a
continuous media stream.
• Spec does not specify contents, but Apple uses
H.264 and AAC, just like all their media apps.
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30. Serving up HLS
• Client URL is an .m3u8 playlist file
• Playlist points to the media segment files
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31. Monday, March 25, 13

32. The HLS playlist
#EXTM3U
#EXT-X-TARGETDURATION:10
#EXT-X-VERSION:3
#EXT-X-MEDIA-SEQUENCE:0
#EXT-X-PLAYLIST-TYPE:VOD
#EXTINF:9.975,!
fileSequence0.ts
#EXTINF:9.975,!
fileSequence1.ts
#EXTINF:9.975,!
fileSequence2.ts
#EXTINF:9.9767,!
fileSequence3.ts
#EXTINF:9.975,!
[...]
#EXT-X-ENDLIST
Monday, March 25, 13

33. The HLS playlist
#EXTM3U Format: .m3u8 format,
#EXT-X-TARGETDURATION:10
#EXT-X-VERSION:3
just a list of files to play
#EXT-X-MEDIA-SEQUENCE:0
#EXT-X-PLAYLIST-TYPE:VOD
#EXTINF:9.975,!
fileSequence0.ts
#EXTINF:9.975,!
fileSequence1.ts
#EXTINF:9.975,!
fileSequence2.ts
#EXTINF:9.9767,!
fileSequence3.ts
#EXTINF:9.975,!
[...]
#EXT-X-ENDLIST
Monday, March 25, 13

34. The HLS playlist
#EXTM3U Format: .m3u8 format,
#EXT-X-TARGETDURATION:10
#EXT-X-VERSION:3
just a list of files to play
#EXT-X-MEDIA-SEQUENCE:0
#EXT-X-PLAYLIST-TYPE:VOD Metadata tags describe
#EXTINF:9.975,!
fileSequence0.ts the contents
#EXTINF:9.975,!
fileSequence1.ts
#EXTINF:9.975,!
fileSequence2.ts
#EXTINF:9.9767,!
fileSequence3.ts
#EXTINF:9.975,!
[...]
#EXT-X-ENDLIST
Monday, March 25, 13

35. The HLS playlist
#EXTM3U Format: .m3u8 format,
#EXT-X-TARGETDURATION:10
#EXT-X-VERSION:3
just a list of files to play
#EXT-X-MEDIA-SEQUENCE:0
#EXT-X-PLAYLIST-TYPE:VOD Metadata tags describe
#EXTINF:9.975,!
fileSequence0.ts the contents
#EXTINF:9.975,!
fileSequence1.ts
#EXTINF:9.975,! Each segment file
fileSequence2.ts
#EXTINF:9.9767,!
preceded by metadata
fileSequence3.ts (e.g., duration)
#EXTINF:9.975,!
[...]
#EXT-X-ENDLIST
Monday, March 25, 13

36. The HLS playlist
#EXTM3U Format: .m3u8 format,
#EXT-X-TARGETDURATION:10
#EXT-X-VERSION:3
just a list of files to play
#EXT-X-MEDIA-SEQUENCE:0
#EXT-X-PLAYLIST-TYPE:VOD Metadata tags describe
#EXTINF:9.975,!
fileSequence0.ts the contents
#EXTINF:9.975,!
fileSequence1.ts
#EXTINF:9.975,! Each segment file
fileSequence2.ts
#EXTINF:9.9767,!
preceded by metadata
fileSequence3.ts (e.g., duration)
#EXTINF:9.975,!
[...] If no end tag, client
#EXT-X-ENDLIST refreshes periodically
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37. <video src="prog_index.m3u8" width="640" height="480"
controls autoplay>No video tag support</video>
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38. How is this better than
a flat .m4v file?
• Streams can provide variants for different
bandwidths (as we’ll see…)
• Segments make it easier to scrub into the
video
• Streams can be live video
Monday, March 25, 13

39. The “Live” in HLS
• A playlist is a live stream if it doesn’t have an
#EXT-X-ENDLIST tag
• Live playlist will generally just contain the last
minute or so of segments
• Client will refresh playlist every minute or so,
download whatever segments it doesn’t
already have, queue them locally
• “Live” isn’t really “live” (often a minute behind)
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40. Serving up HLS
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41. Monday, March 25, 13

42. Monday, March 25, 13

43. Monday, March 25, 13

44. Monday, March 25, 13

45. Monday, March 25, 13

46. mediafilesegmenter
• Splits an A/V file into segment files, creates
the .m3u8 playlist
• Source must be .mov or .m4v with H.264 video,
AAC audio
• Output segments will be MPEG-2 Transport
Stream (.ts) files, or .aac if audio-only
• Segment paths are relative, use -b to prepend
URL stub
Monday, March 25, 13

47. Technical Note TN2224
The following audio and video formats are supported:
• Video: H.264 Baseline Profile Level 3.0 (iPhone/iPod Touch),
Main Profile Level 3.1 (iPad 1,2)
• Audio: HE-AAC or AAC-LC up to 48 kHz, stereo audio OR
MP3 (MPEG-1 Audio Layer 3) 8 kHz to 48 kHz, stereo audio
Note: iPhone 3G supports Baseline Profile Level 3.1. If your
app runs on older iPhones, however, you should use H.264
Baseline Profile 3.0 for compatibility.
Monday, March 25, 13

48. Yuna:HTTP Live Streaming tests cadamson$ mediafilesegmenter
-f basic source/IMG_0251.MOV
Jun 24 2012 10:01:24.203: Using floating point is not
backward compatible to iOS 4.1 or earlier devices
Jun 24 2012 10:01:24.204: Processing file /Users/cadamson/
Documents/HTTP Live Streaming tests/source/IMG_0251.MOV
Jun 24 2012 10:01:24.338: Finalized /Users/cadamson/
Documents/HTTP Live Streaming tests/basic/fileSequence0.ts
Jun 24 2012 10:01:24.375: segment bitrate 3.78028e+06 is
new max
Jun 24 2012 10:01:24.468: Finalized /Users/cadamson/
Documents/HTTP Live Streaming tests/basic/fileSequence1.ts
Jun 24 2012 10:01:24.554: Finalized /Users/cadamson/
Documents/HTTP Live Streaming tests/basic/fileSequence2.ts
Jun 24 2012 10:01:24.631: Finalized /Users/cadamson/
Documents/HTTP Live Streaming tests/basic/fileSequence3.ts
Jun 24 2012 10:01:24.717: Finalized /Users/cadamson/
Documents/HTTP Live Streaming tests/basic/fileSequence4.ts
Monday, March 25, 13

49. Demo
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50. Variant Playlists
• One bitrate does not fit all: Mac on Ethernet
versus iPhone on Edge.
• Solution: encode your video at multiple
bitrates, offer metadata in playlist about what's
available, let client figure out which to use.
• HLS clients automatically switch to best
variant for current network conditions, switch
on the fly.
Monday, March 25, 13

51. variantplaylistcreator
• Creates a playlist that itself points to playlists
created with mediafilesegmenter.
• Each entry contains metadata describing the
bitrate and encoding of the variant.
• Tool takes argument pairs: file or URL of a
variant .m3u8, and metadata .plist created with
mediafilesegmenter -I flag
• First entry in variant playlist is default; client will try
this one first
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52. Encoding the variants
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53. TN2224
Recommendations
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54. Creating variants
Yuna:HTTP Live Streaming tests cadamson$
mediafilesegmenter -I -f variants/
broadband/ source/IMG_0254_Broadband.m4v
Yuna:HTTP Live Streaming tests cadamson$
mediafilesegmenter -I -f variants/wifi
source/IMG_0254_WiFi.m4v
Yuna:HTTP Live Streaming tests cadamson$
mediafilesegmenter -I -f variants/
cellular source/IMG_0254_Cellular.m4v
Monday, March 25, 13

55. Creating variant playlist
Yuna:HTTP Live Streaming tests cadamson$
variantplaylistcreator -o variants/
variants.m3u8 variants/broadband/
prog_index.m3u8 source/
IMG_0254_Broadband.plist variants/wifi/
prog_index.m3u8 source/
IMG_0254_WiFi.plist variants/cellular/
prog_index.m3u8 source/
IMG_0254_Cellular.plist
Monday, March 25, 13

56. Demo
Monday, March 25, 13

57. That's Great, but…
How do we keep people from stealing our stream?
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58. Encryption
• HLS encrypts files, not transport.
• Easy to scale: still serving flat files, but now
they're useless without decryption keys.
• Serving the keys still needs to be secure.
• Necessary, but not sufficient, for DRM.
Monday, March 25, 13

59. Encrypting a playlist
Yuna:HTTP Live Streaming tests cadamson$ mediafilesegmenter -
I -k keys -f encrypted/cellular source/IMG_0426_Cellular.m4v
Jun 24 2012 18:59:47.115: Using new key/iv rotation period;
this is not backward compatible to iOS 3.1.* or earlier
devices. Use the "-encrypt-iv=sequence" option for
compatibility with those devices.
Jun 24 2012 18:59:47.115: Using floating point is not
backward compatible to iOS 4.1 or earlier devices
Jun 24 2012 18:59:47.115: Processing file /Users/cadamson/
Documents/HTTP Live Streaming tests/source/
IMG_0426_Cellular.m4v
Jun 24 2012 18:59:47.152: changing IV
Jun 24 2012 18:59:47.160: Finalized /Users/cadamson/
Documents/HTTP Live Streaming tests/encrypted/cellular/
fileSequence0.ts
Jun 24 2012 18:59:47.160: segment bitrate 271257 is new max
Monday, March 25, 13

60. Encrypted .ts files
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61. Encrypted .ts files
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62. Encrypted .ts files
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63. Encrypted .ts files
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64. Protect those keys
/www/protected
/www/hls
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65. Demo
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66. Captions
• HLS supports CEA-608 closed captions in the
MPEG-2 Transport Stream
• If using file segmenter, add a closed-
caption track (type 'clcp') to your source
QuickTime .mov
• Or use Compressor and Sonic Scenarist
Monday, March 25, 13

67. Captions in Netflix App
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68. Client-side HLS
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69. Opening an HLS
stream
• Provide the .m3u8 URL to
MPMoviePlayerController or AVPlayer
• Add the movie view or layer to your UI,
customizing size or scaling if necessary
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70. Create an
MPMoviePlayerController
// create new movie player
self.moviePlayer = [[MPMoviePlayerController alloc]
! ! ! ! ! ! ! ! initWithContentURL:streamURL];
[self.moviePlayer prepareToPlay];
• This is the same as playing a local file or
any other URL
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71. Add it to your UI
[self.moviePlayer.view setFrame:
! ! ! ! ! ! ! self.movieContainerView.bounds];
[self.movieContainerView addSubview:
! ! ! ! ! ! ! ! self.moviePlayer.view];
self.moviePlayer.scalingMode =
! ! ! ! ! ! ! ! MPMovieScalingModeFill;
• Can inspect the moviePlayer's naturalSize, though
it may change during playback (listen for
MPMovieNaturalSizeAvailableNotification),
or just setFullscreen:animated:
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72. MPMovieScalingMode
AspectFit
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73. MPMovieScalingMode
AspectFill
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74. MPMovieScalingMode
Fill
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75. Accessing Encrypted
Streams
• Media Player and AV Foundation can use
NSURLCredentials that you've provided
• Place credentials in
NSURLCredentialStorage
• Server can provide the keys securely(*) with
HTTP Basic or Digest authentication, an
HTTPS script, etc.
* - For various values of "secure"
Monday, March 25, 13

76. Setting credentials (1)
NSURLProtectionSpace *protectionSpace =
! [[NSURLProtectionSpace alloc]
! ! initWithHost:host
! ! port:port
! ! protocol:protocol
! ! realm:realm
! ! authenticationMethod:
! ! ! NSURLAuthenticationMethodDefault];
Monday, March 25, 13

77. Setting credentials (2)
NSURLCredential *credential =
! [NSURLCredential credentialWithUser:username
! ! ! ! ! ! ! ! ! password:password
! ! ! ! ! ! ! ! ! ! ! persistence:
! ! ! NSURLCredentialPersistenceForSession];
[[NSURLCredentialStorage
! sharedCredentialStorage]
! ! setDefaultCredential:credential
! ! forProtectionSpace:protectionSpace];
Monday, March 25, 13

78. Live Streaming
Monday, March 25, 13

79. Live Streaming
• mediastreamsegmenter mostly works like the
file version, but takes its input from UDP
stream or a Unix pipe
• Only difference is that .m3u8 file doesn't
have an EXT-X-ENDLIST tag, so client
reloads periodically to fetch new segments
• How the heck do you create a UDP A/V
stream?
Monday, March 25, 13

80. You Don't
• None of Apple's tools create the required
MPEG-2 stream
• This is a "third party opportunity"
• Which begs the question… buy or build?
Monday, March 25, 13

81. Streaming in the Real
World
It's not all about iPhones…
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82. Streaming Clients
• Mobile Devices: iPhone, iPad, iPod Touch…
plus Android, Windows Mobile, etc.
• Mac and Windows PCs
• Game consoles
• Over-the-top (OTT) boxes: Apple TV, Roku
Monday, March 25, 13

83. Demo
Monday, March 25, 13

84. Playing HLS on Roku
Roku "channels" are programmed in the
"BrightScript" programming language:
port = CreateObject("roMessagePort")
screen = CreateObject("roVideoScreen")
screen.SetMessagePort(port)
screen.SetPositionNotificationPeriod(30)
screen.SetContent(episode)
screen.Show()
episode is an "associative array" with
key/value pairs for URLs, formats ("hls"),
bitrates, etc.
Monday, March 25, 13

85. Let's Get Practical
• HLS is the preferred format for Roku
• What other devices do you get for free?
• What other devices do you have to be on?
• How to encode and deliver to the devices
you need?
Monday, March 25, 13

86. HLS Alternatives
• Flash still rules on the desktop/browser
space, thanks in part to Mozilla's obstinance
about H.264 in <video> (irony alert: H.264 is
the de facto standard for Flash video)
• Adobe Dynamic Streaming and Microsoft
Smooth Streaming are highly similar to HLS:
bitrate-adaptive streams over HTTP
Monday, March 25, 13

87. MPEG-DASH
• Attempt at a standardized approach to HTTP
adaptive-bitrate streaming. ISO/IEC 23009-1.
http://xkcd.com/927/
Monday, March 25, 13

88. Emerging Consensus
• Flash for PCs
• HTTP Live Streaming for iOS
• Plus whatever other devices you need / are
able to support
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89. Real-World HLS
• Can you competently encode all your media
at all the variant bitrates you need?
• Do you have a way to QC all your streams?
• Can you handle the server load?
Monday, March 25, 13

90. Build or Buy: Services
• Provide hosting, live transcoding, bandwidth
• All-in-one: UStream, LiveStream, Justin.tv /
Twitch.tv (all of which have iOS apps)
• May provide broadcast tools (Flash applet,
Telestream Wirecast, etc.
• Often free with ads; you pay to go ad-free,
embed on your site, etc.
Monday, March 25, 13

91. invalidstream
http://www.ustream.tv/channel/invalidstream
Monday, March 25, 13

92. Production Demo
http://www.telestream.net/wirecast/
Monday, March 25, 13

93. Content Delivery
Networks
http://en.wikipedia.org/wiki/Content_delivery_network
Monday, March 25, 13

94. Content Delivery
Networks
• CDNs host your media on edge servers that
are closer to your clients. Less strain on your
servers and the backbones.
• Examples: Akamai, Limelight, EdgeCast
• Big media companies may have their own
CDN
• Most already know how to do HLS
Monday, March 25, 13

95. Buy or Build: Encoders
$25,000
$4,000
Monday, March 25, 13

96. Buy or Build:
Bandwidth
• Each HLS client will consume up to 1GB /
hour, depending on variant bitrates, client
bandwidth, etc.
• Many CDNs charge around $0.20/GB.
Monday, March 25, 13

97. Bandwidth Costs
Prices from ScaleEngine, UStream, and LiveStream as of
October 2012
Monday, March 25, 13

98. Bandwidth Costs
Prices from ScaleEngine, UStream, and LiveStream as of
October 2012
Monday, March 25, 13

99. Bandwidth Costs
Prices from ScaleEngine, UStream, and LiveStream as of
October 2012
Monday, March 25, 13

100. Bandwidth Costs
Prices from ScaleEngine, UStream, and LiveStream as of
October 2012
Monday, March 25, 13

101. Self-Hosted Costs
Prices from MacMiniColo and Amazon EC2 as of March 2013
Monday, March 25, 13

102. Self-Hosted Costs
Prices from MacMiniColo and Amazon EC2 as of March 2013
Monday, March 25, 13

103. Self-Hosted Costs
Prices from MacMiniColo and Amazon EC2 as of March 2013
Monday, March 25, 13

104. Wrap Up
Monday, March 25, 13

105. Takeaways
• HLS is a very practical streaming solution
• Only part of the picture if you're multi-platform
• Encoding and serving correctly requires
some care and expertise, and a lot of money
• Client-side software requirements are fairly
simple
Monday, March 25, 13

106. Q&A
Slides and code will be available on my blog:
http://www.subfurther.com/blog
http://www.slideshare.net/invalidname
@invalidname
Monday, March 25, 13