Compact MythTV Frontend

Advisor:

Professor Wilsey

Dustin

GrimmeissenRichard

Anderson

David Kesler

MythTV• Open source software intended to replace TIVO

and other proprietary DVR systems

• Runs on a Linux machine storing video and other media to the hard drive

• Media can be played back from hard drive

• Can have multiple frontends serving media off a dedicated backend

MythTV Problem

• Users may not want to purchase a PC to sit next to their TVs

• PC’s are large and often unsightly

• Separate frontend/backend allows for a small, low power computer by the TV– Small general purpose computer are

expensive

Desired Features

• MythTV communicating and playing video from a backend

• NTSC output on an S-Video cable to a television

• Finished product size of approximately 50 cubic inches

Accomplishments• Software:

– An x86 Gentoo image less than 64 mb• With MythTV Frontend Compiled

– A compiled Gumstix image with:• Framebuffer and core system drivers < 10 mb• X-Windows server• DirectFB Graphics Library• SDL Graphics Library• Sample Framebuffer Graphics Applications

Accomplishments• Hardware:

– Board capable of converting digital RGB signals to drive a VGA monitor

– Successfully connected the board to the Gumstix, displaying the contents of the framebuffer on a VGA monitor

– Hardware meets space requirements

Design Process• Base system:

– Used Gumsitx as the base system• Features:

– 400 MHz ARM Processor– 64 MB of RAM– 16 MB of internal storage– MMC/SD Slot for high capacity permanent storage– Built in Ethernet and audio capability

• Why:– Extremely small form factor– Low power, heat, and noise– Several features built in

Design Process• Software:

– Compiled Linux image using Gentoo for x86 architecture, with MythTV frontend included.

– Attempted building Gentoo image for ARM processor, but found MythTV to be infeasible.

– Created Gumstix image from scratch, manually building framebuffer drivers and core system programs.

– Compiled and installed framebuffer testing applications to Gumstix.

– Compiled and installed DirectFB and SDL graphics libraries for future development.

Design Process• Hardware:

– Initial design planned on utilizing Sigma Designs EM8620L or similar graphical processing unit

– Second plan involved converting the Gumstix LCD controller output to S-Video

• Created circuit board utilizing Analog Devices ADV7120 and AD723

• Intended to interface with Gumstix through a CPLD downsampler / interleaver

Hardware Design

• Initial Test: Display colored bars using signals generated from a CPLD– Could not generate proper NTSC signal

• Discovered output of ADV7120 can directly drive a VGA monitor– Successfully interfaced ADV7120 with

Gumstix and VGA monitor

Conclusion• With further work it may still be possible to convert the

Gumstix LCD controller signals to an NTSC signal

• Due to the limitations of 16-bit color running MythTV or a movie player may not result in acceptable video quality

• Due to cross-compilation difficulties, getting MythTV to run on an ARM processor may be unfeasible anyway

• Compiled graphics libraries may allow for other media players to be compiled and executed in place of MythTV