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

Thu Feb 4 09:05:49 UTC 2010

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.

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
> >> >> >
> >> >> >
> >> >> >
> >> >>
> >> >
> >> >
> >>
> >
> >
> 