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[raym]

Hi there. This problem was dicussed briefly here : http://yabb.jriver.com/interact/index.php?topic=41571.0. Unfortunately, that thread is covering a lot of ground. I'd like to discuss this specific issue in more detail here if possible.

Basically, the problem is this:- I watch live DVB-T broadcasts via MC (from Theater View). It's excellent. However, with timeshifting active, things go south in terms of MC responsiveness and general performance. The problem gets worse the longer you use it.

This is what I see while timeshifting is in progress:-

1. In Theater View, animations stutter (even at a reduced frame rate) and there are large delays between page transitions
2. MC is slow to respond to remote/keyboard keypresses 
3. Slow channel changing (6-8 seconds compared to 1-2 seconds with TS off)
4. Huge increase in time required to load other programs (like Internet Explorer etc).

As soon as timeshifting is stopped, things return to normal - no probs.  Also, the problem is exacerbated when the TS buffer catches up to the live broadcast. Pausing a few seconds (to increase the gap) and then resuming playback seems to help the situation a little.

I'm guessing disk IO is huge with timeshifting active and could well be the culprit but my PC specs should be more than adequate to handle this feature... Intel Core 2 Duo E6320, SATA II (3gb/sec) local disk (TS buffer is written here), 2gb 800Mhz RAM, ATI 2400HD HDMI video card - all running WinXP SP2 with the latest updates and drivers. Virus checkers etc are non existent. CPU utilisation while watching HD content on this PC is < 20%.

I should point out also that I've done some comparitive tests with some other well known tv software and these don't seem to exhibit the slowness I'm observing with MC during timeshifting. 
 
Now, I'm interested to know if others have these issues too. It's curious that more people aren't complaining but maybe the majority of users don't use MC for digital tv playback? Maybe ATSC users are fine and the problem is specific to MC's DVB-T implementation?

Thanks in advance for any help with this.

[raym]

I'm interested to know if others have these issues too.

Surely I'm not the only one.. I find myself turning off timeshifting a lot of the time due to these issues and no one wants to watch tv without timeshifting anymore 

If what I've described in the first post is not clear, try this and see for yourself:-

1. Goto TheaterView
2. Start TV (with TS on!)
3. Leave it playing for a good 30-60mins.
4. Hit Shift+F11 to toggle from Display View to Theater View.... It can take seconds... Up to 10! Theater View animations are really jumpy. Try seeking the TS buffer (back and forth). It all feels a little, well, unstable.

Once again, there are no virus checkers or background tasks/services running. No plugins etc. CPU is under 20% during HD playback. Same thing is observed on the numerous PC's I have and on both XP and Vista.

Thanks.

[rpalmer68]

I've been running with TS off due to the channel change slowness, now that that's sorted in the latest beta, I'll run TS all the time and report back

Richard

[rpalmer68]

Last night I noticed seeking forward/back in the timeshift file was sluggish (timeshift file was approx 1.5 hours), by slugging is took a moment to respond to the keypress on my remote, which doesn't happen when playing back recorded file.

Also the OSD at the bottom showing the position in the file would only flash up for a brief moment and go again, so quick that if I didn't know it was supposed to be there I probably wouldn't even notice it appearing.

Running 12.452 wiht Nvidia video decoder and VMR9.

[raym]

Thanks for checking Richard. Nice to know it's not just me. The biggest issue I have is that my PVR software takes ages to load (via IE) when TS is on and running for a while. Under no other circumstances is this ever a problem. Perhaps you could look at this also please? As I've said, my guess is that the amount of disk IO that's going on is causing this, and the other slowdowns. It'd be nice to know from the devs though if this is the actual cause and whether there's anything that can be done to improve the situation. As you've stated, I don't experience any problems during any other video playback of any type.

Thanks.

[JimH]

That could also happen if there was disk swapping going on because of insufficient RAM memory.

[raym]

That could also happen if there was disk swapping going on because of insufficient RAM memory.

Sure, but with 2GB of DDRII 800 RAM and perfmon stats reporting loads of available memory, RAM is not the issue here.

[rpalmer68]

The biggest issue I have is that my PVR software takes ages to load (via IE) when TS is on and running for a while. Under no other circumstances is this ever a problem. Perhaps you could look at this also please?
Thanks.

I can't remember, are you running Webscheduler?

I just tried with about 45 minutes of TS and Webscheduler loaded fine for me, I'll leave it a bit longer and try again and report back.

[raym]

I can't remember, are you running Webscheduler?

I just tried with about 45 minutes of TS and Webscheduler loaded fine for me, I'll leave it a bit longer and try again and report back.

Yeah that's right. The other annoyance is toggling from Display View to Theater View (Shift+F11) - this takes ages for me. After doing it once or twice, things return to normal.

Thanks for checking...

[rpalmer68]

OK 1 hour 37 minutes of TS.

- Seeking sluggish, and button presses can get buffered which is a pain!

- Shift-F11 is pretty much instant for me, no problems there.

- Loading Webscheduler takes approx 8 seconds to come up with the keyboard interface.

I'm running a P4 3.2Ghz with 1GB RAM, Win XP and the Nvidia decoders using VMR9

Richard

[raym]

Richard, thanks for your feedback.

JRiver, I realise that good application performance can be a subjective thing and often dependant on many factors. However, I have what I consider to be a modern, fast PC and while MC is one of the best applications I own from a performance and general responsiveness point of view, I feel this takes a notable turn when it comes to TV playback with TS enabled. I only persist with the topic because I honestly believe MC's TV component is one of the most feature rich on the market and I just want to be able to get the most out of it. If the symptoms described in this thread are not apparent on your test systems, I'm curious to know the following: a) what are the recommended system specs for TV playback inside MC and b) what are the main system bottlenecks which may impede on achieving a successful TV playback experience? On the other hand, if the symptoms described in this thread have indeed been noted on your test systems, are there any plans for some future improvements? I appreciate that some of these "problems" may be specific to DVB-T playback which I'm guessing is difficult (at best) for you guys to test fully. Therefore, as always, if there's anything I can do to help get to the bottom of this, I'm more than willing to assist.

Thanks for a great product!

[rpalmer68]

Update from me

Tonight I had a longer TS buffer (about 1 hour 50 minutes I think) and Webscheduler took about 30 seconds to load.

Also trying to skip forward 30 seconds was a pain as key presses on the remote could take a second or two to respond and were being buffered so I'd skip past and have to then rewind back.


There is a TS slowness issue here somewhere, I do tend to agree.

[JimH]

I said this once before, but didn't see the answer.   Edit -- I just saw your reply above.

If your system didn't have enough memory for all the processes running, the OS could swap some to disk.  It would look like what you see.  Until it swapped something else to disk, you wouldn't be able to get a response.

Also, MC unloads parts of itself when not needed, so a key press after a long period of activity might not get a quick response.

Take a look at task manager to see memory useage.

Not saying that it's not our problem.  Just trying to get more information.

[Yaobing]

Does turning off logging make any difference? I wonder if it is caused by too much time-shifting logging.

[raym]

Does turning off logging make any difference? I wonder if it is caused by too much time-shifting logging.

Logging is not on. I tend to only enable logging if I know I need to collect them.

Yaobing, do you NOT see the issues described? If not, as suggested, maybe it really is something unique to MC's DVB-T implementation??

Thanks.

[Yaobing]

I am not sure. I can not say I am not seeing the issues, but I am not sure what I have seen is what you have seen.

For example, I tried starting Internet Explorer multiple times while TS is running. I got one slow start. Similarly I got Theater View stutter once in many tries.

I wonder if OSD has anything to do with it.

[raym]

...I tried starting Internet Explorer multiple times while TS is running. I got one slow start. Similarly I got Theater View stutter once in many tries.

I think the key thing is you need to leave it alone to play / build up the buffer for a while. Then launch IE and look at Theater View etc. Even for me, the issues only reveal themselves after extended use. In my case, this equates to at least 60 mins (sometimes less). But yes, starting TS and then doing stuff straight away seems fine. Similarly, as you described, you may see one "slow start" but subsequent repeated attempts will be ok - maybe because by that time, the functions have been cached?

Like Jim was saying, if MC is unloading certain components over time, maybe this is causing some undesirable effects. This could certainly be a good lead...

Thanks.

[raym]

Still no joy with all this unfortunately. As a result, TS will have to stay off  I tried reducing the size of the TS buffer to just 1hr (the min) but to no avail. The latest issue I'm facing is once TV reaches the end of the buffer (the 1 hr mark) I get audio/video stutter. I need to pause and rewind a bit to fix it. It's just not a workable solution especially for those in my family who aren't very PC saavy. I really wish there was some progress here. I feel a bit helpless but I think I've done all I can. It certainly seems I'm the minority. Or, perhaps people just aren't using MC TV as much as I am and so aren't experiencing the problems reveiled after extended use. I guess if it was a major issue more people would have complained. It's a shame because digital tv without timeshifting kinda defeats the purpose. I really don't want to have to go back to my old TV software but....