Re: Anyone here made a "TV computer"?
+++ Phil Endecott [2011-04-10 23:02 +0000]:
> Dear All,
>
> For a while I have been planning to make some sort of "TV computer" i.e. DVB
> recorder + DVD player + web video device etc.
Did you make any progress on this Phil?
There was a session as linaro connect on set-top-boxes with quite a
few interested people, but no-one present who'd actually made it work
usefully.
This caused me to note that Geexbox 2.0 has support from some ARM
boards (and have images for pandaboard and Harmony). I'll try that on
my panda forthwith (I was a big fan of geexbox 1.0 and used it for
several years).
So there is significant interest in this topic within Linaro.
The notes from the session are here (and copied below):
http://summit.ubuntu.com/uds-p/meeting/19090/linaro-summits-stb-1/
(not entirely sure you can see that without having a login (which
would be annoying))
Anyone interested should say so, or add themselves to that doc. It's
not entirely clear what the most appropriate forum is for discussion
of this subject. Suggestions welcome.
-------Summit Notes-------------------
Part 1: Education
- STB Hardware needs
- ARMv7, AMP versus SMP
- Cortex A9 enables widgets, windowing (X)
- Older products use 1176 etc plus DSPs
- Graphics hardware, 3D plus video (1080p x N streams)
- What STB specific hardware is needed for STB products
- Dedicated video logic (DSP) versus older cores (shrunk) / predominantly MIPS plus DSP
- CA hardware/software
- HDMI/Composite output
- Features
- 1080p x N streams
- OpenGL(ES)
- Overlays (directly out to HDMI, security implications)
- Dedicated H/W DRM (rights management)
- Tuner(s) x N
- Dolby Digital and DTS
-- Applicaton Framework
- Enigma2 (by DreamBox) vs Android AF vs QT vs HTML5
Distributions:
- Android (AndroidTV is Gingerbread based, but GoogleTV is a bit
different, based on HoneyComb only)
- MeeGo (MeeGo and X) set top box, Amino. Drivers (display,
network), video accelleration
- Tizen (HTML5 to replace QT?)
Examples:
- XBMC (Xbox Media Center (OpenGL?) / Boxee (x86))
- Myhtv
- Freevo (already built for arm in Debian+Ubuntu)
- VDR http://www.yavdr.org/
Issues
- Overlays versus compositing (per pixel blending), should support
both usually. e.g. Android Multimedia framework
- Most of embedded graphics drivers not ready for X
- DVB* decryption for proprietary satellite broadcast systems may
require dedicated, specialized hardware
- What software stacks need to be supported?
- Proprietary versus open source software
- Standard APIs (existing or emerging)
- DVB*
- OpenGL ES
- Collect the top technical issues that need to be solved
- Graphics (not running an XServer (new might have an X Server),
direct FB?)
- EGL layer varies by mechanism (DirectFB, Wayland,
SurfaceFlinger)
- Video (V4L)
- Multimedia, gstreamer
- Security (DRM, Conditional Access support, HDCP)
- hedge off memory separately - done by secure monitor code, at boot time
- verifiable security / keys, similar to phones
- Kernel
- Power management
- 20 / 30 watts, world standards for proper low power
- Some low power running, background services?
- memory management (maybe give an update of where we are with UMM)
- Buffer reuse maybe doesn't apply to overlay
- systemMMU versus contiguous memory
- buffer handles help
- Maybe important for on screen displays
- Validation?
- transport stream error recovery
- keeping in sync
- interlace top/bottom field
- aspect ratio through jumping in stream
- standard tests, such as video essentials
- video frame rate matching refresh rate...
- Build tools
- open embedded (but relates to 1176 etc)
- Yocto?
- Standards
- media formats
- Digital Video Broadcast (V4L)
- Scheduling
- APIs (DLNA - sharing audio and video)
Part 2: Technical Discussions
- Discussed above
Part 2: Planning and Coordination
- Interesting experiment is to build a Xbmc proof of concept
- is there a code base that we can play with, measure etc?
- DVB, ATSC, MythTV worth looking at (QT, C++)
- XBMC has a new PVR module (OpenGLES)
- MythBuntu, live and install image, out of box (Dev platform?).
- Take the package list and build it
- OpenGL versus OpenGLES
- neither mythtv nor xbmc are built for arm in Debian or Ubuntu at the moment.
- Freevo is built
ACTION: Contact the MythBuntu folks, email list
- What forums / steering committees / standards bodies exist now?
- Ad hoc mailing lists?
- What can / should Linaro do to help? Issues to prioritize,
opportunities to consider
Web References
- http://www.mythbuntu.org
- http://www.minimyth.org/ - small Linux distribution that turns a
diskless computer into a MythTV
- #mythtv on Freenode - markk has had it working on ARM, both under
linux and iOS, and has written 100% of the OpenGL ES support so far.
mkendall@mythtv.org
- Geexbox/(Openbricks) http://www.geexbox.org/ - mini TV distro, that
spawned embedded build system. They already have support for
pandaboard and Tegra2 Harmony in v2.0.
Interested People
James Tunnicliffe
Alan Pope (alan@canonical.com)
Wookey
Wookey
--
Principal hats: Linaro, Emdebian, Wookware, Balloonboard, ARM
http://wookware.org/
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