[mythtv-users] Hardware resrouces required for s/w encode

belcampo belcampo at zonnet.nl
Thu Feb 4 10:18:10 UTC 2010


Michael PARKER wrote:
> Garry,
> 
>> As far as I understand, for both SD and HD recording, Linux just dumps
>> the raw stream to disk. There is no encoding required.
> 
> This is contradicted by Section 10.5 of the MythTV HOWTO:
> 
> http://www.mythtv.org/docs/mythtv-HOWTO-10.html#ss10.5
> 
> "For cards without hardware encoding capabilities (all cards supported by V4L not listed above),
> Myth includes two methods for software encoding: RTjpeg and MPEG-4. RTjpeg has significantly fewer
> CPU demands than MPEG-4, but it generates larger files than MPEG-4 for a given recording."
> 
> It sounds as if s/w encode of a PAL/NTSC/Composite/S-video (i.e. non MPEG-2 or h.264) input to
> either RTjpeg or MPEG-4 is mandatory if h/w MPEG-2 encode is not available.
> 
> I'm cc'ing mythtv-users to see if anyone else can shed any light on this.
The Wiki is about analog signals. DVB as the nam says is already digital 
and is encoded already.
> 
> Thanks for your help,
> 
> Mike
> 
>> -----Original Message-----
>> From: Garry Parker [mailto:parker13 at gmail.com] 
>> Sent: Thursday, February 04, 2010 8:44 AM
>> To: michael.parker at st.com
>> Subject: Re: MthTV Combined FE/BE box spec.
>>
>> Hi Michael,
>>
>> As far as I understand, for both SD and HD recording, Linux just dumps
>> the raw stream to disk. There is no encoding required.
>>
>> What is important when watching HD is the *decoding* of the h.264.
>> This can be done in s/w, but you're much better off using the VDPAU
>> functionality on your nVidia GPU. This will allow the h.264 decoding
>> to be completely offloaded onto the GPU so that even when watching HD
>> your CPU will be pretty much idle.
>>
>> http://en.wikipedia.org/wiki/VDPAU
>>
>> Garry.
>>
>> On 4 February 2010 08:27, Michael PARKER 
>> <michael.parker at st.com> wrote:
>>> Garry,
>>>
>>> If this isn't a really dumb question:
>>>
>>> Having just spoken with Hauppauge UK, it appears that the 
>> analogue/composite/S-video input of the
>>> HVR-4000 card doesn't have hardware encode. The DVB-T/S/S2 
>> inputs don't need a h/w encoder (being
>>> already in either MPEG-2 or h.264), so the 
>> ana./comp./S-video input has to make do with s/w encode.
>>> For the time being, the majority of my recording will be 
>> done from a cable STB so I'll be using the
>>> composite input a lot. I may, at a late date, switch to 
>> DVB-T/S/S2 and dump the cable TV (which I
>>> only need for a few, non-free-to-air channels).
>>>
>>> Since I've got a 2.3GHz X4 CPU, I'm assuming that s/w 
>> MPEG-4 (or RTjpeg) encode can easily be taken
>>> care of by the CPU.
>>>
>>> Am I correct? Or have I overlooked something?
>>>
>>> I'm also assuming that the GHz performance of a single core 
>> is not the determining factor in whether
>>> or not s/w encode is possible, and that codecs are 
>> multi-threaded to share the load across cores. If
>>> not, I'm concerned (given Hauppauge's min. requirement of a 
>> 3GHz P4) that a single 2.3GHz core won't
>>> be man enough for the job.
>>>
>>> And I said, probably a dumb question, but....
>>>
>>> Cheers,
>>>
>>> Mike
>>>
>>>> -----Original Message-----
>>>> From: Garry Parker [mailto:parker13 at gmail.com]
>>>> Sent: Tuesday, February 02, 2010 2:31 PM
>>>> To: michael.parker at st.com
>>>> Subject: Re: MthTV Combined FE/BE box spec.
>>>>
>>>> Hi Michael,
>>>>
>>>> Looks like you've got it nailed down. Interesting to know that that
>>>> board can handle the 605e. All I'd say is that I know a couple of
>>>> people who have that exact board and it works great for 
>> MythTV with HD
>>>> over HDMI.
>>>>
>>>> I'm thinking of upgrading myself, but as I don't mind an ATX form
>>>> factor I think I'll get the Asus Pro board.
>>>>
>>>> Good luck with it all!
>>>>
>>>> Garry.
>>>>
>>>>
>>>> On 2 February 2010 11:48, Michael PARKER
>>>> <michael.parker at st.com> wrote:
>>>>> Garry,
>>>>>
>>>>> Following your (and others replies), I posted the following
>>>> to the MythTV Talk hardware forum.
>>>>> ---
>>>>>
>>>>> All,
>>>>>
>>>>> Thanks for feedback received to-date. I think I'm getting
>>>> closer to nailing this spec. down.
>>>>> In light of the feedback wrt. ATI vs. Nvidia GPUs (and
>>>> having spent a while browsing forums full of
>>>>> ATI driver woes!), I'm moving to an Nvidia GPU.
>>>>>
>>>>> Since the original Gigabyte mboard is unlikley to be able
>>>> to accommodate a passivley cooled PCIex16
>>>>> card (since both neighbouring PCI slots will be populated)
>>>> and I'm keen to retain the uATX form
>>>>> factor, I'm taking Garry's advice and moving to the Asus
>>>> M3N78-EM with an onboard GeForce 8300.
>>>>> This loses me DDR3 support (and gains ~16% more power for
>>>> the memory), but I'm hoping a shift to
>>>>> DDR2-1066 (from DDR3-1333) won't be noticeable. I guess
>>>> it's the price I need to pay to have a
>>>>> VDPAU-supported GPU.
>>>>>
>>>>> Revised spec is as follows:
>>>>>
>>>>> MB: ASUS M3N78-EM
>>>>> CPU: AMD Athlon II X4 605e Energy Efficient Quad Core, S
>>>> AM3, 2.3GHz, 2MB Cache, 45W
>>>>> RAM: Crucial DDR2-1066/PC2-8500 2x2GB (Part CT2KIT25664AA1067)
>>>>> PCI1: D-Link AirPlus Xtreme G DWL G520
>>>>> PCI2: Hauppauge WinTV-HVR-4000
>>>>> HDD: 2TB Samsung HD203WI Spinpoint F3EG, EcoGreen, SATA
>>>> 3Gb/s, 32MB Cache, 8.9 ms, NCQ
>>>>> CASE: Antec Fusion Remote Black
>>>>> PSU: 385W Enermax PRO82+ EPR385AWT
>>>>> FAN: Scythe Shuriken Rev.B Quiet Low Profile
>>>>> OPTICAL: Samsung SH-B083L/BSBP Blu-Ray Combo Player 8x
>>>> BD-ROM, 16x DVD-ROM, 48x CD-ROM Read,
>>>>> LightScribe, OEM
>>>>>
>>>>> --
>>>>>
>>>>> Have I missed anything else in moving from the Gigabyte to
>>>> ASUS board?
>>>>> Although strictly AM2+ compliant, ASUS do list the AM3 605e
>>>> CPU in their supported CPU list - you
>>>>> just lose DDR3 functionality. I'll need to ensure that I
>>>> get Rev 1.01G board with BIOS v0601 or
>>>>> later, though.....
>>>>>
>>>>> Comments, as ever, welcome and gratefully received.
>>>>>
>>>>> Mike
>>>>>
>>>>>> -----Original Message-----
>>>>>> From: Garry Parker [mailto:parker13 at gmail.com]
>>>>>> Sent: Monday, February 01, 2010 11:10 AM
>>>>>> To: michael.parker at st.com
>>>>>> Subject: Re: MthTV Combined FE/BE box spec.
>>>>>>
>>>>>> Hi Mike,
>>>>>>
>>>>>> I'd advise anybody who is building a MythTV box at the
>>>> moment to get
>>>>>> one which has an nVidia card which supports VDPAU. This 
>> is known to
>>>>>> work with Ubuntu to offload MPEG4 HD playback.
>>>>>>
>>>>>> A great ATX board is the Asus M4N78 PRO (AM3)
>>>>>> For mini ATX, try the ASUS M3N78-EM (AM2)
>>>>>>
>>>>>> The good thing about the Asus M4N78 PRO is that it
>>>> supports AM3 socket
>>>>>> chips, such as the 605e you have listed. Note that this CPU is
>>>>>> probably overkill for a MythTV box and if you want to save
>>>> a few bob a
>>>>>> 240e would be fine.
>>>>>>
>>>>>> The above boards have onboard graphics which support VDPAU. An
>>>>>> alternative, which you mentioned, is to buy a separate 
>> nVidia card,
>>>>>> but if you're building from scratch you're better off with
>>>> an onboard
>>>>>> GPU.
>>>>>>
>>>>>> The HVR 4000 is supposed to have the same chipset as my
>>>> Nova-HD-S2, so
>>>>>> you should have no problems there.
>>>>>>
>>>>>> Hope that helps!
>>>>>> Garry.
>>>>>>
>>>>>> On 1 February 2010 10:23, Michael PARKER
>>>>>> <michael.parker at st.com> wrote:
>>>>>>> Garry,
>>>>>>>
>>>>>>> I hope you don't mind me emailing your directly but I'm a
>>>>>> work colleague of Steve Firth, who you talked with back in
>>>>>> May'09 about his Myth box spec.
>>>>>>> I'm trying to spec. out a combined FE/BE Myth box currently
>>>>>> and, having talked with Steve about his experiences, he
>>>>>> suggested I email you.
>>>>>>> The spec. I've got so far is as follows:
>>>>>>>
>>>>>>> MB: Gigabyte GA-MA785GMT-UD2H
>>>>>>> CPU: AMD Athlon II X4 605e
>>>>>>> RAM: Crucial DDR3-1333/PC3-10600 2x2GB (Part 
>> CT2KIT25664BA1339)
>>>>>>> PCI1: D-Link AirPlus Xtreme G DWL G520
>>>>>>> PCI2: Hauppauge WinTV-HVR-4000
>>>>>>> HDD: 2TB Samsung HD203WI Spinpoint F3EG
>>>>>>> CASE: Antec Fusion Remote Black
>>>>>>> PSU: 385W Enermax PRO82+ EPR385AWT
>>>>>>> FAN: Scythe Shuriken Rev.B Quiet Low Profile
>>>>>>> OPTICAL: Samsung SH-B083L/BSBP
>>>>>>>
>>>>>>> The box is intended to be a combined FE/BE, "living room"
>>>>>> box with enough horsepower for s/w HD decode and display
>>>>>> (assuming the maturity of the current fglrx driver is
>>>>>> insufficient to allow offload to the onboard GPU). I'm
>>>>>> reasonably confident that the WinTV-HVR-4000 can be made to
>>>>>> work (I only need composite/S-video input initially as my
>>>>>> current input is a cable STB), but have concerns over the
>>>>>> onboard ATI graphics.
>>>>>>> Should I also budget for a NVPAU-capable graphics card? I'm
>>>>>> tempted to build the above box and "suck-it-and-see", buying
>>>>>> a NVidia card if performance is inadequate.
>>>>>>> Any thoughts you may have on the above spec. would be very
>>>>>> gratefully received.
>>>>>>> Many thanks,
>>>>>>>
>>>>>>> Mike
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>
>>>
> 
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