Transcript Getting to Know TiVo: The Home Media Engine

Getting to Know TiVo: The Home
Media Engine (HME SDK)
Eric M. Upchurch
CS 525
Spring 2008
Introduction
• TiVo is a popular set-top DVR that can be connected to a
home network
• Through the network connection, the TiVo can access
applications through a special transport protocol (the
HME protocol)
• The HME SDK facilitates development of applications
that utilize the HME protocol
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Photo viewers
Music players
RSS feeds
Streaming radio
Games
etc
Motivation
• Interested in developing TiVo apps prior to
CS525
▫ Also seemed a perfect fit for the class
• Relatively new to TiVo, and wanted to play
around with it
• Have run several third-party applications
• Curious what the capabilities of the SDK are
• Could not find exactly what I was looking for
▫ A photo slideshow with music
The HME Protocol
• HME applications use a client/server architecture
▫ Server is a PC or possibly a server on the Internet
▫ Client is the TiVo receiver
• Protocol uses a single bi-directional TCP/IP socket
• Language independent
▫ Applications just have to communicate with TiVo via
the protocol, and so could be developed in any
language
• Uses chunked data encoding (1-65K byte chunks)
▫ Allows arbitrary data size by spanning chunks
▫ Enables reader of a stream to skip to next chunk if an
error occurs
HME Architecture
HME SDK
• A complete API and developer kit for creating HME
applications in Java
• Wraps the HME protocol into an event-driven
architecture
▫ More or less MVC, similar to Java Swing
• TiVo boxes find HME applications using Multicast
DNS (mDNS/Zeroconf) and DNS Service Discovery
(DNS-SD)
▫ “Bonjour”, developed by Apple Computer
▫ No network setup required
▫ Don’t need to know IP addresses, host names, or ports
HME SDK Class Structure
• Applications inherit from the Application class
• GUI is composed of Views containing Resources
▫ View instances contain a single resource, and provide a
coordinate system and transparency
▫ Resources are (mostly) visual elements: fonts, colors, images,
text, and animations. Also sounds, music (streamed)
▫ Views are laid out to draw a screen on the TiVo receiver’s display
HME Application Structure
• An application is composed of a view hierarchy
▫ Root view covers entire display
▫ Views can have child views, which cover some portion of
the screen relative to the parent
• Views may be invisible or zero size to accommodate nonvisual elements, such as sounds
• Views can have streaming image or music (MP3)
resources
▫ Events notify the application as the stream is read
• Animation resources provide visual effects (e.g. fadein/out)
▫ Useful for hiding network latency
• Views and resources handle events sent by TiVo
Bananas UI Toolkit
• TiVo toolkit for building TiVo user interfaces
• Extends the basic HME SDK
• Provides an application framework
▫ Applications are composed of a stack of screens
▫ Provides focus management between widgets
• Provides a standard widget set
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Button
Text
List
Keyboard
• Provides a standardized look and feel
▫ Similar to the base TiVo UI
HME Hosting Environment
• Uses factory pattern to serve up applications
▫ Each available application has a factory class that provides
instances of the app to a TiVo receiver
▫ New instances are created when a connection is established
from a TiVo receiver
• Single hosting environment (one JVM) can serve
multiple application types
• Applications are accessed via an HTTP URL request
from the receiver
▫ Example: http://myPC:7788/MyTiVoApp
▫ Hosting environment maps the URL to an application
factory by name (e.g. MyTiVoAppFactory)
• Custom hosting environments can be created for
extensibility to server domain
HME Hosting Environment
HME Simulator
• The HME SDK includes a TiVo simulator for testing
▫ Greatly facilitates rapid application development
• Works like the TiVo receiver
• Allows you to see the view hierarchy and memory
usage of application
• Provides debugging options
• Overlays “safe” television area bounding boxes
▫ This shows the area that is safe on all televisions,
including those that overscan
• Not a substitute for testing on a TiVo receiver
▫ Response speed is vastly different
▫ Network latency may be different
Conclusions
• TiVo HME is a powerful SDK for developing
applications for display on TiVo
• Bananas UI toolkit eases construction of
professional looking application
• A couple of shortcomings:
▫ An HD capable alpha version has been released,
but I could not get it to work. Stuck with SD
(640x480) for now.
▫ Does not allow streaming of video content!
References & Resources
• TiVo HME Software Developer Kit Developer's Guide Release
1.4. http://tivohme.sourceforge.net/docs/hmesdk/hmedevguideTOC.html
• TiVo Bananas UI Toolkit Developer’s Guide Release 1.3.
http://tivohme.sourceforge.net/docs/bananas/bananasdevguideTOC.html
• TiVo Home Media Engine (HME) SDK Info.
http://bitrazor.com/content/tivo/hme/index.php
• TiVo. Wikipedia. http://en.wikipedia.org/wiki/TiVo
• Flash demo: Getting Started with Eclipse and the TiVo HME
SDK.
http://bitrazor.com/content/tivo/hme/tivo_hme_eclipse_de
mo1.php
• TiVo Developer How-Tos.
http://bitrazor.com/content/tivo/hme/howtos/index.php
Backup Slides
In the event the demo doesn’t work
My HME Application – Intro Screen
• Currently one
slideshow
• Extend to multiple
XML defined
slideshows, listed
here
• Uses common TiVo
look and feel
• User selects enter or
right arrow button to
start slideshow
My HME Application – Slideshow Screen
• Photos randomly
change every N
seconds
• Photos fade in/out
• Music tracks
randomly selected
• User selects left
arrow button to
return to previous
screen