[mythtvnz] CPU required for Freeview HD

[Steven Ellis]

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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