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I was finally able to build a long ethernet cable to test things out. You were right.The problem was the powerline adaptor. One of my adaptors had started to fail. I was only getting 10mbps between the two computers. Implementng a different adaptor I was up to 26mbps. which seems to be more than enough for ServerWMC and WTV files
Sorry for the false alarm. Appreciate the helpful comments as I was troubleshooting.
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This PC is about 50 ft from the closest network adaptor so I had to dig into my supplies to get a ethernet cable that was long enough to test wih <grin>
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Well I got past my immediate problem by using a wireless N USB adaptor. The story is a little more complicated though. The wireless N. Adaptor is only transferring the way files at about 13mbps but it does stutter. That is the same rate I am seeing with the power line adaptor that stutters. I am going to run more tests this weekend
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Oh I thought you replaced one of hte adapters and were getting 26Mbps and the stuttering went away?
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The 26Mbps was the maximum download when copying a large file from one computer to the next. The 13Mbps is the transfer rate when playing a WTV file with the Ethernet cable or the wireless N adaptor. I had thought that the stuttering had gone away with the replacement powerline adaptor but it must have been wishful thinking. I haven't had a chance to go back to the older version of ServerWMC either. Based on yours and Krusty's comments, that shouldn't be the cause but I will confirm
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What's the transfer rate playing the wtv over the regular wired connection?
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I think I finally figured out what is killing my playback and why the problem was so sporatic. I use Comskip to identify the commercials in my recordings. When ComSkip starts up watching shows in XBMC via WMCServer is laggy even on the WMC box itself. I have never noticed the issue when watching shows in WMC
Comskip is set to be used "idle" only. and I still have lots of CPU left (typically running about <50%). Perhaps I am limited by the drive IO. I do regularly record up to 5 channels at once in WMC and watch one show without any obvious problem. Through Comskip and ServerWMC in the mix and it seems that all bets are off.
I realize my configuration might be unique but any thoughts on what I can try or where I can look?
Ian
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2014-06-26, 04:02
(This post was last modified: 2014-06-26, 04:04 by scarecrow420.)
Live viewing in WMC is probably not needing the hard drives much/at all, whereas "live" viewing in ServerWMC is really performing a recording then remuxing that recording to TS and the client plays the TS file, so is definitely going to be impacted by IO slow downs.
People in this forum have mentioned comskip being pretty intensive on IO previously, I believe their workaround was to run it overnight rather than constantly scanning and "kicking in" at inopportune times. THat's obviously not a solution but a workaround.
If you want an atual solution, one obvious avenue to pursue is boosting your storage performance. What storage do you currently have? If it isn't using an SSD already, try that? You could archive completed recordings off to a larger/slower hard drive if you didnt have a big enough SSD to hold everything. Im assuming comskip can move the files somewhere once it's done etc....
Another option would be to have comskip running on a different box altogether, and shift completed recordings to that box with ServerWMC. That box could be a watched folder in WMC so the recordings would still be shared to all clients etc.
We could also look at making a change in ServerWMC that allows it to target different activities at different hard drives, that way you could have 1 drive dedicated for "live viewing" and a different one for recordings?
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Appreciate the comments. SSD is possible. I have been reluctant to use an SSD fot this purpose but maybe this is the answer
I have asked the question directly on scheduling ComSkip so that it doesn't kick into at in opportune times. I haven't found a way to do this but it is an obvious approach.
I am not sure why Comskip would be more IO intensive that just playing a video but I could easily be missing something. I will take the tie to ask the developer directly as I have been registered user there for many years now.
In the multi tuner configuration, it may be valuable to allow live viewing recordings to go to a different drive. I am not sure where the limit is but 5 tuners (as in my configuration) is probably getting close. Is there a way we could evaluate if this would improve things without too much effort?
Edit
I was good I asked Erik (Comskip). Since Comskip tries to process the video file as fast as possible (with the only throttling due a function of CPU.usage) it can saturate the IO on a disk. From this my takeaway is that it is clearly an IO limitation, There are a couple of new parameters in Comskip (playnice) that can used to control when and how much Comskip is throttled by making sure there are x msec free per frame processed but there is no way to specifically leave IO available for other applications.
I have not isolated the problem specifically to live-tv recordings. That is just when I noticed it the most.
I have implemented the required playnice .parameters for Comskip and will see how that works. Will make sure to report back. That said, on multituner setups, it may still be advantageous to enable recording liveTV to a separate hard drive.
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2014-06-26, 13:54
(This post was last modified: 2014-06-26, 13:54 by scarecrow420.)
one way that could be used to evaluate it would be to use a symbolic link to have the Recorded TV/TempSWMC directory physically located on another drive, but symlinked to still appear as though it lives in the default recording directory. The TempSWMC directory is used by ServerWMC for temporary live viewing streams and remux jobs, whilst the default recording directory is used by the WMC recording service for scheduled recordings.
So assuming D:\Recorded TV is your default recording directory and E: is your new "live TV" drive you would move the TempSWMC folder to E: and then use the following command in windows admin cmd prompt
d:
cd "\Recorded TV"
mklink /D TempSWMC E:\TempSWMC
I haven't tested this myself but I think it would work...
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I will give that a shot tonight
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When wmc creates a live tv stream it is creating on disk something they call 'backing files', and it stores them in the hidden temprec folder it creates in the rec-tv folder. These are essentially just four wtv files of fixed size that wmc is using as a kind of ring buffer, that's what enables you to rewind 20 minutes or so in a live-tv stream in wmc. However these files are not designated on disk as wtv files, instead they have an extension of .SBE. When we do live tv though, we just tell the com to produce a single wtv, and keep the whole thing rather than use a ring buffer approach.
So I think ComSkip is ignoring the SBE files that wmc produces, that's why it never effects wmc's live-tv. However it thinks the wmc file we are producing is just a recording and, like the comskip guy said, it is as fast as possible trying to convert it.
So if that's right, I think another solution is to configure ComSkip to ignore the TempSWMC directory that we store the wtv file in, if that's possible. It its not, on our end we could think about using an SBE file extension on the file we produce in TempSWMC so that comskim ignores it.
