Re: Anyone here made a "TV computer"?
On Tue, Apr 12, 2011 at 12:02 AM, Phil Endecott
<spam_from_debian_arm@chezphil.org> wrote:
> Luke Kenneth Casson Leighton <lkcl <at> lkcl.net> writes:
>> so let's assume you're happy with 1080p30 (when all the DVB2 and
>> ISDB-T broadcasts will be 1080p50 or 1080p60... *sigh*...)
>
> I only notice the difference in video resolution when the plot is failing to
> hold my attention....
:) it's not the resolution that's of concern, it's the framerate.
DVB2 / ISDB-T are transmitted in 1080p50 (or 1080p60 in the US) - at
50 (or 60) frames per second. that's the standard. if you don't have
hardware that can keep up (i.e. can only decode 1080p30) you're
buggered. with sky for example i *believe* you're ok because they
blatantly ignore the standard and transmit 1080i50 (1920x1080,
*interlaced*, at 50fps so you can drop every other frame. you'd need
to check this).
to add to the confusion, as i mentioned last night, is that although
the display capability of outputs may support the resolution and
framerate of the device to which it is attached (1080p60), this has
*nothing* to do with the *decode* capability of the hardware
acceleration.
basically, HD TV decode requires double the amount of accelerated
hardware (or double the speed), and in cost-sensitive mass-produced
devices all the SoC manufacturers are coughing and spluttering into
their tea / soup / noodles / beer at the extra cost, and are leaving
it up to the specialist teams such as celestial, mstarsemi, nxp (now
tridentmicro) etc. etc.
there, unfortunately, you have the paranoid cartel of the hollywood
industry, who are dictating (sieg heil!) even to intel that thou shalt
not have an analogue output path for full HD video. this is why the
CE4100 *doesn't* have LCD out or LVDS - only HDMI - because you can't
put encryption onto 24-pin RGB/TTL or LVDS.
>> the list is something like: Samsung's S5PV210 (and S5PC110); NXP's
>> PNX8491 (bought out by tridentmicro recently); TI's OMAP4440; Ziilab's
>> ZMS-08 (watch out for this one: creativelabs are GPL violators, see
>> latest list.gpl-violations.org post), Telechips TCC8902 (ARM11,
>> massive GPL violations going on with this one)
>
> How about also:
>
> - NVidia Tegra 250
there was an announcement last week that the upcoming boxee box just
abandoned the nvidia tegra 250 in favour of the intel atom ce4100 with
embedded PowerVR + hardware 1080p60 accelerated decode, if that gives
you any indication. boxee are said to be working wiht
> - ST-Ericsson Nova A9500 (i.e.
> http://www.calao-systems.com/articles.php?lng=en&pg=6186)
http://www.stericsson.com/press_releases/NovaThor.jsp
*whistles*. wooow.
http://www.stericsson.com/products/u9500-novathor.jsp
very cool. they don't say what they mean by "1080p" though, so you
miiight be lucky. the U9600 however woooow - 28nm, and predicted to
be capable of 120fps video decode. that's pretty f*****g impressive.
2.5ghz dual-core cortex A15. well.... i'll believe it when i see it
:)
>> [ oh wait - there's that marvell armada 610, but who wants to sign
>> marvell's NDAs to get at the required info?? ]
>
> Interesting; I didn't realise Marvell had anything with video.
yeah i've been trawling a *lot* of processor web sites :) the armada
610 is in the OLPC XO 1.75 that was announced ooo couple months back?
surpriise - no mention of HD video playback in the OLPC announcement
:) but the chip's definitely capable of it - marvell just won't tell
you how until you sign their nonfree NDA.
>> i installed the linux pvr project several years ago, got on with it
>> quite well, but now am quite happy with the command-line tool, scantv,
>> to find the stations, and then just use "xine dvb://{program name}"
>> and it works really well. ...but i'm a luddite
>
> Me too...
:)
>> yeahhh, bottom line: i'd pick a pandaboard and use DVB dongles and
>> USB-to-SATA converters. the OMAP44xx has a 4-port hub built-in so you
>> will *not* be overloading one single USB channel with SATA data.
>
> I thought it had an external chip that combined a USB hub with an ethernet
> controller. That probably still isn't a bottleneck, though.
naaah you're right. the data rates for HD broadcasts right now are
about 6 to 8 mbytes per second (i think). you *don't* decode that
until you actually need it, so you just grab the raw MPEG data stream
off the DVB channel and shove it to disk. playback, even with
simultaneous record, that's still only 16 mbytes per second, but as i
mentioned last night *do* get one of those dual-head drives: people
have found the constant drrrdrrrdrrr of the hard drive heads has set
up resonant patterns sufficient to shake coffee tables - not the kind
of thing you want in the middle of your romantic film's quiet
moment...
> I also googled for variations on "open linux arm set top box", and as you might
> guess there is some x86 stuff and various dead links....
:) surpriise! this is a massive GPL violating industry. the
companies who produce set-top boxes consider it to be a failure if you
even NOTICE that they're violating copyright law. they take and steal
whatever they can get, and DO NOT release back to the community.
period. they have teams of lawyers to advise them on how to perform
tivoisation, for example.
if you googled "MIPS" instead, you *might* get some hints that there
are systems (and software) out there, and SoCs capable of HD playback,
but as i said last night, they're absolutely shit at general-purpose
computing. they're only just coming out of 600mhz land, some of them
are only just capable of running the menus. the only reason why the
set-top processor companies are just beginning to increase the speed a
bit (800mhz dual-core MIPS... in 2011... woooow!) is because of the
demands for "in'ur'ne" and "anduuhroyyd" are now quite insistent.
> BTW, not completely off-topic, I have just turned on my "tit cam" for the
> season.
*snort* :)
Reply to: