[mythtv-users] Fwd: Pixelation/Bad Recordings HDHR Prime -- I am at my wits end

[Stephen P. Villano]

On 9/11/13 11:19 PM, Joseph Fry wrote:
>>>>>>> I have rewired everything again as I am not comfortable using an
>>>>>>> amplifier
>>>>>>> to amplify my signal, only to use multiple splitters to reduce it
>>>>>>> back
>>>>>>> down.
>>>>>>> It doesn't seem to make sense.  Instead I have connected the Monster
>>>>>>> cable
>>>>>>> 4-way splitter (-7.5dBmV/output) to the cable coming in from Comcast
>>>>>>> and
>>>>>>> connected my HDHR Prime directly to one of the outputs.  Another
>>>>>>> output
>>>>>>> of
>>>>>>> the Monster Cable splitter is connected to another splitter
>>>>>>> (-3.5dBmV/output) which goes to my TVs.  Another output of the
>>>>>>> Monster
>>>>>>> Cable
>>>>>>> splitter then goes to my existing long run to my cable modem.
>>>>
>>>> I don't know if it's relevant, but you only mention 3 feeds off of the
>>>> splitter, is the other output terminated properly? Or did you mean a
>>>> four
>>>> outlet splitter, one in and 3 out? And are all outputs on the second
>>>> splitter also terminated properly?
>>>>
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>>>>
>>> Regarding interference, I am seeing this on what seems like every
>>> single channel at least some of the time, so I don't think that it is
>>> interference, unless I am seeing interference on everything on the
>>> HDHR Prime and this isn't affecting my cable modem or either Comcast
>>> set top box (including one which is a DVR).
>>>
>>> My mistake on the wiring; I probably confused myself I rewired it so
>>> many times.  I just looked at it and I have the following:
>>>
>>> Comcast signal in to MoCA filter to a two output splitter.  One end
>>> goes to my HDHR Prime, the other end goes to another two output
>>> splitter.  This two output splitter is then connected to my cable
>>> modem and then the other end goes into yet another two output splitter
>>> that goes to my two televisions.  So between my HDHR Prime and the
>>> Comcast "feed", I only have one splitter.  Yet on my TVs, I have three
>>> splitters in front of them and no issues; and my cable modem has two
>>> splitters in front of it and no issues.
>>
>> I believe I have narrowed this down to an issue with my hardware, or my
>> MythTV setup and have been wasting my time chasing signal issues.  I have a
>> thread on Silicon Dust's site (much is duplicated here, but here is the link
>> if you are bored:
>> http://www.silicondust.com/forum2/viewtopic.php?f=44&t=15543) and a member
>> of their team was assisting me.  It appears that the HDHR Prime is getting
>> perfect signal, and the video in both my desktop (Windows MCE) and VLC (HDHR
>> GUI in Linux on my frontend) are pristine with zero audio dropouts or video
>> pixelation when watched simultaneously.
>>
>> Now I am not sure where to go from here. In looking at the performance data
>> in vSphere, I am not seeing anything that may cause this. This is a pretty
>> decent machine, i5 3570K (overclocked to 4 ghz, though I don't know that
>> ESXi is respecting this), 16GB of RAM. I have 4 CPU cores and 12GB of RAM
>> provisioned to the Myth Backend server and I am not doing anything else with
>> it, so I can't imagine it is a performance issue with anything other than
>> the storage, which is all in the same box and carved up as VMDKs by ESXi.
>>
>> I have a few routes I can go here; first, I could use a separate spindle for
>> just my recordings (right now it is being shared with a Windows Server data
>> share that sees fairly little i/o). Second, I could pop in a 60gb SSD I have
>> laying around and write some recordings to that to see if it makes a
>> difference.
>>
>> Any suggestions?  I really don't want to build another box and turn it into
>> a NAS, though that's probably my best bet...  I have enough money sunk into
>> this at this point.
> I hate to say this... but this is the exact reason why running the
> backend on a VM is only recommended by those that have done it
> successfully for themselves, and not by anyone who actually has had to
> try and resolve an issue with one.
>
> You should have plenty of horsepower to actually play the stream on
> your backend in VLC, at least then you could determine if it is an
> issue with the data coming into the backend, or the the IO with the
> disk.
>
> Next, you might try shutting down the Windows VM (and any others),
> just to remove them from the equation.
>
> If you suspect a network IO issue, rather than disk (seeing pixelation
> playing the stream in vlc), you might add a network card and dedicate
> it to the backend VM.
>
> If you suspect disk IO (stream plays fine in vlc),  I would first
> ensure that your recording drives are formatted using advanced format
> (4k sectors) and that they are properly aligned.  Misalignment can
> cause a VERY significant impact to write speeds (
> http://hothardware.com/Articles/WDs-1TB-Caviar-Green-w-Advanced-Format-Windows-XP-Users-Pay-Attention/?page=2).
>  Next, you might try changing the filesystem your using, EXT4 is a
> pretty safe bet; just to see if it makes any difference.  Finally, you
> might need to see if there is any way to give the backend direct
> access to the SATA controller (assuming you have more than one)... it
> may be an issue with ESX's drivers, or the virtual controller driver.
> Oh, and did you select the LSI virtual SCSI controller when you
> configured the VM, the other one isn't supposed to be as fast?
>
> There are just so many places thing can go wrong with a VM... I wish you luck.
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You should also warn against fake raid, which can suck the performance
out of a system so horrifically that one could end up swearing that the
thing needs to be wound up again.