[mythtv-users] X2 5000 enough to play HD?

[Michael T. Dean]

On 08/27/2008 01:24 PM, kanetse wrote:
> I have recently built myself a new MythTV system, which will
> eventually become a master backend/frontend.  However, for now, I'm
> testing it in frontend only mode.  I seem to be unable to play HD on
> it without either stuttering or severe audio-sync issues.
>
> The system is a:
>
> AMD Athlon 64 X2 5000
> Gigabyte GA-MA78GM-S2H (AMD 780G)
> 2 GB RAM
> CentOS 5.2
>
> MythTV-0.21 (from ATrpms)
>
> I was originally running it with ATI's proprietary drivers (Catalyst
> 8.8); however, there were other issues with, which I attribute to the
> quality of the driver itself.  Recently, I popped in a nVidia GeForce
> 6600 (PCI-E), and set up XvMC.
>
> XvMC is, by all accounts, working properly (for example, I see a B&W
> OSD).  However, HD playback is very poor.  If closed captions are on,
> the audio stutters and movement is not smooth.  Skipping ahead or back
> (using the arrow keys) causes audio to get severely out of sync with
> the video.  All the while, CPU utilization is around 50% on one of the
> cores only; the other is nearly idle.  SD seems to play fine.
>
> Could it be an issue of streaming the HD streams over the network?
> Maybe the master backend can't supply data fast enough?
>
> There don't appear to be any error messages in the mythfrontend.log,
> except a lot of NVP: Prebuffering pause message.
>
> My config should be able to handle HDTV even without XvMC, right?

Your timing is impeccable.

Assuming you're talking about MPEG-2-based HDTV (i.e. like in the US), 
your processor will work without any issues for HDTV decoding.  I had a 
frontend with an AMD X2 4800+ (with 2GB RAM on an Asus A8N-E (with 
NVIDIA chipset), using the integrated sound card (an ALC662, IIRC) and 
the integrated LAN (a forcedeth GigE NIC)).  It played HDTV perfectly, 
and I could go up to 1.5x without stuttering.

However, I've been maintaining a Myth system for a friend (with software 
that's identical to mine), and I've been trying to convince them to 
switch to HDTV.  I finally got them interested enough to switch, 
and--since I had been wanting an upgrade so I could get better than 1.5x 
timestretch--I donated my mobo/CPU/RAM to them and replaced them.

When I set up the system at their house (by taking an image of my 
frontend and putting it on their HDD), we were able to get 2x 
timestretch without issue...  :)  I'm pretty sure it's due to LAN 
configuration and I/O issues.

Then, to make matters even stranger, I found the exact same issues 
you're having with my new setup (and without modifying /any/ of the 
software on the system).

My new setup started with an AMD Athlon X2 6000+, 2GB RAM, a Biostar 
A740G M2+ (with AMD chipset).  The state of the audio drivers for the 
integrated sound (intel-hda) left something to be desired, so I tried a 
MadDog ICE724 and a SoundBlaster Live! Value--neither of which helped.  
The integrated NIC (a Realtek 100Mb using the r8169 driver) seemed very 
slow, so I tried a PCI 100Mb one (forgot which driver) and a PCIe Gig-E 
one (using via-velocity).  Neither helped.

So, I thought, perhaps I just need a nicer mobo.  I got an Asus M3A 
(with AMD chipset) and swapped out the hardware.  This one also uses the 
intel-hda audio drivers, but has an integrated Gig-E NIC (using atl1 
driver).  Again, I tried the SB Live! Value and the ICE1724 and the 2 
other NIC's without effect

What I've noticed on /both/ systems was that NIC performance drops to 
unacceptable levels (about 4MB/sec between my frontend and 
backends--where both backends have 100Mb NIC's) after transferring 
several tens of gigabytes of data (around 50GiB received--generally, 
while I've been testing it, within one day).

The big overlap on the two motherboards (and the big disconnect from the 
previous) is the AMD chipset (versus the NVIDIA nForce on the previous 
mobo).  The AMD chipset is only /very/ recently supported (sometime 
after 2.6.21), so I'm starting to think that the chipset support is 
still too immature for the kind of work a Myth HDTV frontend needs to 
do.  I'm considering getting another mobo with an NVIDIA chipset.  (The 
really annoying thing is each time I do, I have to get another AM2+ 
processor and some RAM so I don't waste the other mobo--which seem to 
work more than well enough for a "normal" non-Myth computer.  Oh well, 
the Biostar has become my new Myth dev box and was >>4x faster at 
compiling Myth than my old Athlon XP 1700+ dev box. :)

I'll let you know once I figure it out.

In all the above configurations, I'm using Linux kernel 2.6.26.2 and 
ALSA 1.0.17.

Moral of the story, don't mess with a working Myth system... :)

What chipset are you using?

Mike