steven at openmedia
Aug 19, 2008, 11:48 PM
Post #22 of 58
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On 20/08/2008, at 6:08 PM, Steven Ellis wrote:
>
> On 20/08/2008, at 4:45 PM, Robin Gilks wrote:
>
>>> The H264 decode flatlines all OSs if done in software due to the
>>> complexity of the decode when dealing with our broadcast streams.
>>>
>>> I've compared Linux and Mac software decode on the same hardware,
>>> EyeTV vs MPlayer, and they appear to use similar amounts of CPU.
>>>
>>> The best windows codec for software decode is CoreAVC which is a
>>> proprietary commercial codec.
>>>
>>> Until we get a way to accelerate some of the decode on the GPU we
>>> are
>>> going to lag behind Windows users who have hardware accelerated
>>> decode
>>> via the main graphics card vendors.
>>>
>>> As to STBs, as mentioned they have chips designed to accelerate the
>>> decode in hardware. If you have had a play with the Zinwell STB you
>>> would notice that it can get very hot due to the load.
>>>
>>> Steve
>>
>> So if all the work is done in the CPU, would a mother board such as
>> the
>> "Asus M2A-VM HDMI Motherboard" with an ATI embedded video
>> controller do
>> the job or is it still better to spend another $40 or so and use an
>> nvidia
>> based board such as the "Asus M3A78-EMH HDMI Motherboard".
>
>
> The pay off with the GPU will come in with the new Google Summer of
> Code projects to perform GPU based acceleration.
>
>>
>> c
>> In either case, what would be the minimum spec CPU required (assuming
>> these m/b will support the required speed that is!!) to handle both
>> TV1
>> and TV3 HD?
>>
>
> I did a bunch of performance comparison tests on an X2 3600+ test
> rig today. I looked at the CPU load for both H.264 and MPEG 2
> playback of the same channels, and locked the CPU to its max
> frequency of 2GHz.
>
> I also used the CPU++ profile and allocated a max of 2 cores to
> video decode. It appears that some of the frames are slice
> compatible so there is a benefit in enabling dual CPU, but until
> FFMPEG can do true multi cpu decode we really need a CPU fast enough
> to decode on a single core. This is a shame given the drop in price
> of triple and quad core processors
>
>
> Channel Resolution Load H.264 Load MPEG2
> freeview|HD 720p 95-100+
> TV One 720p 98-108 11-15
> TV 2 720p 100+ 11-15
> TV 3 1080i 130+ 12-15
> C4 576i 45 13-15
> TVNZ 6 576i 26-35 9-10
> Sports Extra 576i 25-40 10-12
> Maori 576i 37-40 9-10
>
> Now the CPU load for C4 on freeview|HD is a little higher than the
> other channels, which might be explained by the higher bit rate they
> are using compared with TVNZ 6+7 etc.
>
> For SD it appears we need 3.5 - 4x the CPU of SD and the X2 3600+
> copes
>
> For 720p the CPU is borderline and occasionally copes.
>
> For 1080i I'm well out of power.
>
> Right now I'd look at the fastest 65W processor I can buy. Sadly the
> only X2 5600s in the market are still 89W units, so it would be a
> 5400 which runs a 2.8 GHz. The question is will this be enough?
Hmm it appears there are some 65W 5600 X2 processors around. Any
chance some one on list has a 5400 or 5600 cpu that they can report on?
Steve
Steven Ellis - Technical Director
OpenMedia Limited
email - steven[at]openmedia.co.nz
website - http://www.openmedia.co.nz
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