[mythtvnz] CPU required for Freeview HD

[Aaron Whitehouse]

Steve,

This may be a really silly question, but with the new Bravias
including HD tuners  (that presumably decode the H264 stream in
hardware), is there any way of passing an encoded stream to the TV and
let it do the decoding?

A long shot, I know, but the TV clearly has the ability to decode the
streams in real time.

Regards,

Aaron

2008/8/20 Steven Ellis <steven at openmedia.co.nz>:
>
> 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?
>
> In the Intel space I've been playing with a MacBook and EyeTV on a 2.4
> GHz T8300. Eye TV runs both cores at 90% when running TV3. I need to do a
> reboot and try mplayer native under Ubuntu to see how it compares.
> Steve
>
> Steven Ellis - Technical Director
> OpenMedia Limited
> email   - steven at openmedia.co.nz
> website - http://www.openmedia.co.nz
>
>
> _______________________________________________
> mythtvnz mailing list
> mythtvnz at lists.linuxnut.co.nz
> http://lists.ourshack.com/mailman/listinfo/mythtvnz
> Archives http://www.gossamer-threads.com/lists/mythtv/mythtvnz/
>
>



-- 
FSF Associate Member: 5632
http://www.fsf.org