[mythtv-users] BBC HD (1080) h.264 / AVC playback

[Steven Adeff]

On 2/19/07, Tim Small <tim at buttersideup.com> wrote:
> Hi all,
>
> I've recently put together a new box, and thought I'd share my
> experiences viewing the BBC HD trials, which are broadcast in H.264
> (Mpeg-4 Part10 "Advanced Video Coding" AVC) as DVB-S broadcasts on Astra
> @ 28.2 degrees east.  The box uses a mobile Core 2 Duo T7400 (2.16GHz),
> on an Asus "N4L-VM DH" board (Intel 945 GM chipset, integrated "Intel
> GMA 950" graphics with an additional DVI "ADD-2" card - to provide a DVI
> output from the onboard graphics).  The box has 2 interleaved sticks of
> DDR-2 667, but I don't know if this chipset is capable of running them
> at the full 667 or not (I happened to have the RAM spare, and didn't buy
> it especially for this machine).
>
> I used mplayer to play back recordings of "Planet Earth" in 1080p -
> 1440x1080 16:9 25(?)fps - files which mythtv has recorded (but not
> transcoded).
>
> I'm pretty sure that the transmissions are 1080p - I can't see any
> interlacing artefacts.
>
> 1. The i810 driver for the integrated graphics doesn't allocate enough
> resources for XVideo scaling at this resolution by default, and I ended
> up with the following entries in my /etc/X11/xorg.conf:
>
> Section "Device"
>         Identifier      "Intel Corporation Mobile 945GM/GMS/940GML
> Express Integrated Graphics Controller rev 3"
>         Driver          "i810"
>         Option          "Cachelines"    "1024"
>         VideoRam        65536 # You don't actually need this much for
> 1080p playback
> EndSection
>
>
> Although the Xorg i810 driver supports the XvMC (X-Video Motion
> Compensation) extension on the (ancient) i810/i815 integrated graphics,
> it doesn't appear to offer it on newer chipsets at this time :o(.  XvMC
> isn't any good for decoding H.264 anyway, but I don't know what
> facilities the GMA 950 offers which could assist H.264 decoding (other
> than de-interlace support), were the necessary hardware support implemented.
>
> I am able to play back these recordings at full FPS, with the following
> mplayer options:
>
> -vo xv -vfm ffmpeg -lavdopts skiploopfilter=all
>
> One core is utilised at approx 90%, whilst the other remains largely
> idle (there is no multi-threading support in the H.264 ffmpeg decoder at
> present).
>
> Without "skiploopfilter=all", the decoder can't keep up, but the drop in
> quality with the option in (at least on my 1280x1024 19" DVI monitor)
> seems negligible on this material.
>
> I haven't tried getting mythtv to do the "skiploopfilter=all" option
> yet, as I'm not sure how to set that option, and haven't had time to
> look yet..
>
> I did look into using the cheaper, and lower power (?), but also 64bit
> "Celeron M 520" on the same board (single "Core 2" core, 1M L2,
> 1.66GHz), but it looks like this wouldn't have been fast enough for this
> material with the current software (this wasn't the only reason for
> choosing this CPU, as this box is not just intended for MythTV output!).
>
> Attached is a screenshot from xosview whilst playing back the recording
> with mplayer.
>
> Cheers,
>
> Tim.
>
>
> p.s. I'm using Debian "Etch" amd64, with mythtv and mplayer packages
> from Christian Marillat's Debian Multimedia repository.
>
>
> p.p.s this box (with 2x 60G Toshiba 2.5" drives, a keyboard, a mouse,
> the stock Asus fan, and a bog-standard 330W ATX PSU) uses a fairly
> respectable (for the processing abilities, IMO) total of 64 watts as
> measured at the wall socket with both cores running 100% (running BOINC
> climateprediction.net), and 41 watts when sitting Idle at a logged-in
> KDE desktop (without any power saving).
>

Have you tried the DirectShow patch in Trac for using CoreAVC?
http://svn.mythtv.org/trac/ticket/3053

-- 
Steve
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