[mythtv-users] State of mythtv on the beagleboard

[Marc Randolph]

On Sat, Jul 18, 2009 at 11:18 AM, Michael D. O'Brien<obrienmd at gmail.com> wrote:
>
> Does it have the power to decode, deinterlace and display 1080i mpeg2?

I think the answer is yes....  but let me put my question up top here
for those that don't make it through this whole message:   What is the
slimmest memory footprint anyone has run with a front-end?  These only
have 256 MBytes of RAM.


Looks like it is based on the OMAP3530 processor from TI
(http://focus.ti.com/docs/prod/folders/print/omap3530.html), which
includes (among a TON of other stuff, described in multiple
documents):

MPU Subsystem
* 600-MHz ARM Cortex™-A8 Core
* NEON™ SIMD Coprocessor

-plus-

High Performance Image, Video, Audio (IVA2.2™) Accelerator Subsystem
* 430-MHz TMS320C64x+™ DSP Core
* Enhanced Direct Memory Access (EDMA) Controller (128 Independent Channels)
* Video Hardware Accelerators

-plus-

POWERVR SGX™ Graphics Accelerator (OMAP3530 Device Only)
* Tile Based Architecture delivering 10 MPoly/sec
* Universal Scalable Shader Engine: Multi-threaded Engine
Incorporating Pixel and Vertex Shader Functionality
* Industry Standard API Support: OpenGLES 1.1 and 2.0, OpenVG1.0
* Fine Grained Task Switching, Load Balancing, and Power Management
* Programmable High Quality Image Anti-Aliasing

Searching the 3517 page tech reference manual, I think the accelerator
they are referring to may be an encoder, rather than a decoder.  But
all is not lost... the DSP core itself is more than capable (with
appropriate programming that may have already been done) for decoding.
  Searching around on that, I found this quote:

"A 430 MHz C64x+ DSP core is capable of handling high-definition (HD)
video (MPEG-4 decode at 720p) for embedded applications, such as home
media centers, robotics, web kiosks and digital signage."

and this quote:

"The key difference between an OMAP3530 and a desktop PC CPU like the
Pentium 4 is the level of integration. The OMAP chip includes a DSP
capable of H.264 4CIF resolution full duplex real-time encode and
decode, something your average modern PC struggles with. Without the
DSP, the OMAP would struggle too."

Having said that, it looks like the "NEON" co-processor hanging off
the ARM processor might be capable enough to do it on its own if
required:

"a NEON accelerated mplayer and the popular NEON accelerated
omapfbplay which gives you fullscreen 720p decoding"

Also found this:

"ARM has released highly optimized source code versions of the OpenMAX
DL (Development Layer) libraries for decoding the AAC and MP3 formats
in the audio domain, and decoding the MPEG-4 and H.264 formats in the
video domain"  (http://www.design-reuse.com/news/18429/aac-mp3-mpeg-4-h-264-fft-openmax-cortex-a8-neon-arm11-processors.html)

In summary, looks to me like it should be more than capable of
decoding, deinterlacing, and playing your mpeg2.  Less certain about
1080p H.264... but the Beagleboard is only $150, so I could probably
live without that.  It even has built-in HDMI!  Is this the perfect
front-end motherboard?   If we can run in 256 MBytes of RAM, maybe so.

   Marc