[mythtv-users] Choppy Playback & prebuffering message

[Chris]

glen martin wrote:
> Steven Adeff wrote:
>> On 4/17/06, glen martin <lists at locutory.org> wrote:
>>   
>>> Scott Petler wrote:
>>>     
>>>> After reading more about your particular machine, I think the issue is
>>>> even more likely due to
>>>> a pci bus bandwidth issue.  This is because your video card is PCI
>>>> rather than AGP.
>>>>
>>>> Having both the backend and frontend on the same machine is using up
>>>> your PCI bandwidth.
>>>> I would suggest a system with AGP video to keep your playback path off
>>>> of the PCI bus.
>>>>
>>>>       
>>> Interesting. What does this mean for 'modern' machines with PCI-E cards,
>>> or those with onboard video? Or mine, which has both (onboard video that
>>> can be overridden with a PCI-E16 card)? Is there something magic about
>>> AGP, and I should preferably replace my frontend with a mobo that
>>> supports AGP?
>>>     
>> PCIE!=PCI. PCIE is faster than AGP, its one of the AGP replacement bus designs.
>>
>>   
> That's what I'd been thinking, too, but the earlier message in this
> thread made me wonder. That message talked about network and video both
> being PCI, so I inferred the same myth traffic goes across the bus twice
> and saturates it. Now PCIE has more bandwidth than PCI, true, but it is
> still one bus.
>>   
>>> lspci shows my onboard video and network and ide all on the same pci bus.
>>>
>>> My own situation is that I can playback analog content fine, but certain
>>> HD streams (again, playback) cause some prebuffering messages as the
>>> play starts up or when inserting onscreen menus or messages (eg. 'I'),
>>> and if I switch aspect ratios ('W'), playback (and frontend) hangs with
>>> incessant prebuffering messages.
>>>
>>> The issue seems bandwidth related. The streams for which I have problems
>>> have very high bitrates.  My confusion has been that the cpu isn't
>>> overly taxed, ticking along at perhaps 50% load.  XvMC, realtime, yadda
>>> yadda.
>>>     
>> are you playing over a network?
>>   
> Nope, prerecorded, local disc. So onboard IDE, onboard video, both on
> the pci bus per the lspci. Heck, the only actual cards in the box are
> the tuners, both of which are idle as I'm testing.
> 
> FWIW, this is an Asus A8N-VM/CSM GeForce 6150 / nForce 430, with
> Athlon64 3200+.
> 
FWIW, I'm seeing similar problems running a 3.0Ghx P4 with a FX5200 agp 
card.  My cpu utilization is under 30% playing back an mpg file but the 
video is jaggy wherever motion is present.  Playing the same file with 
Win2k on the same hardware I see no jaggies at all but it drops a few 
frames every so often.  Sure seems hardware related, but not cpu...