Live TV stutters in server / PC client setup

[cumak]

Hi,

I'm new to GB-PVR so please bear with me if I'm missing something obvious here. I recently attempted to configure a server / PC client setup by following Sub's instructions towards the beginning of this thread:
Streaming to other networked PCs

I know this setup isn't officially supported, but I figured I'd throw this post out there anyway to see if anyone can help. After changing the <RecordingServiceLocation> and <DatabaseConnectionString> lines in config.xml, and the basic functionality seems fine. I can access the TV listings, schedule and cancel recordings, etc. I can watch recorded shows and they play very smoothly. Live TV, however, is a different story. After 5 seconds or so waiting for timeshift mode to initialize, live TV begins to play but it stutters very badly.

CPU usage is steady at 30%-40%, and the network utilization is showing about 6%-8% (I'm on a 100Mbps LAN). Both seem well within limits. Also, Live Preview" mode is disabled on the client.

I don't understand why recorded shows play smoothly while Live TV stutters so badly. Isn't GB-PVR's video player doing the same exact thing in both cases?

I think this would be a great setup if I can fix the stutter. Any help would be appreciated.

Thank you.

[cumak]

Okay, let me try asking a slightly different question that might help me debug this...

If recorded shows play back smoothly, is there any reason to suspect that I'm having a decoder issue that's causing the stuttering in live TV? I'm assuming that if the decoder is good for recorded shows then it is also good for live TV, but maybe there's more to it than I'm aware of.

Thanks.

[sub]

I'm not 100% sure, but this may be your problem:

Its much more file intensive reading a file while it is still growing (ie timeshift mode). In between reading the file, it's continually having to jump and read the last few hundred kbytes from the file. This is done because it needs to keep reading the last presentation timestamp in the file to determine it's duration.

[capone]

Depending on your settings, the recordings will be at a lower bitrate. My guess would be then that you're not getting good/consistant speed over your lan. I had this problem in the past w/ video over the lan once when I found the card was only 10 and not 10/100, and then again when I had a cable go bad (they don't last forever and can lose performance over time).

If you manually record something at low, and then at high, and the high recording stutters, then it's probably a speed issue (especially if the live is fine on the source machine).

[A_Brass]

I'm having the same problem described here. When I changed my recording directory and liveTVbuffer (on the "server")from a folder on a local drive to a UNC share my playback of live TV and recording programs started to stutter.

Example :
f:\livebuffer\ was change to \\media-1\livebuffer\
and
f:\recordedtv\ was changed to \\media-1\recordedtv\

So the question is : Is the "server" actually looking out to the network and back towards itself for the file? Or does it look to the local drive. If its looking accross the network I think I can understand why it stutters.

Oddly enough, my "client" works fine. LiveTV and recording shows playback just fine. Note my "client" pc is much faster then the "server".

Any thoughts?

[sub]

As I said above, I think its just the way I process in-progressing recordings. The way GB-PVR processes these is much more intensive than just playing a file that already exists. In between reading the file, it's continually having to jump and read the last few hundred kbytes from the file. This is done because it needs to keep reading the last presentation timestamp in the file to determine it's duration. It just wasnt designed for this purpose, so the logic is not optimized for operations over a network drive, and sounds to me like the most likely cause of this problem.

[cumak]

Sub,

If it's an issue with limitations on file access, then I would have the same live TV problem when viewing on server, right? This is, of course, assuming that it's time shifted like the client.

I haven't had smooth viewing on the server (live or recorded) for other reasons (I'm using on-board video on cheap mobo so I believe it's a decoder issue), but I will try to get my hands on a better video card and decoder so I can test your theory. Or, I can grab the video out of the client PC.

[sub]

If it's an issue with limitations on file access, then I would have the same live TV problem when viewing on server, right?

No, if you directly play live tv on the server it's not having to go across the network so it should be fine.

[cumak]

Okay, now I understand. I thought you were sayng that the server itself couldn't handle all of the read operations, but it really just can't get the data across the network fast enough. I still think that there is a lot of overhead in the network throughput, but I'll try to run some testing tonight to find out. If what you're saying is true, then I guess I'll have to leave it alone for now.

Thanks for your help

[sub]

Its not that the network cant transfer data fast enough. It's more of an issue that seeking back and forth in the file, continually reading the duration, is a little slower and unforntunately this is enough to cause the stutter. Its probably not much slower, but definitely slower than asking a local disk to seek to a different part of the file, read some data, then seek back to the original position.