Placeshifter - HD playback is Jerky

[scoob101]

Hi, I`m trialling Sage TV for WHS at the moment, and i`v managed to tune some stations, and get one Client to view TV via placeshifter on my local network (got issues with the other client, but thats for another thread)

The problem I have is that HDTV playback (BBC HD) is very jerky. This is the same over both 100mbit wired Or G Wireless.

Wireless will of course be iffy with HD, but Im getting sustained transfer rates of 24megabits over wireless (tested with file transfers from my WHS shares, coming in at 3.1MB/s) which I think should be good enough for HD. I haven`t got stats for my wired transfer rates, i`ll test those tonight.

With wired being jerky on HD - Coupled with the fact that placeshifter is supposed to be adaptive to the available bandwidth, leaves me to suspect there is a configuration issue within Sage.

Can someone give some pointers about what Sage config to start checking?


p.s Would "Sage advice" be an over-used pun on these forums??

[reggie14]

Sage doesn't transcode files to use less bandwidth when the placeshifter client is on the local network. You can force it to, though, in the placeshifter settings (on the placeshifter client, not the server).

I've found that 802.11g is just a little too slow to work reliably. But, since you also have this problem with a wired connection that is plenty fast, we know that's not the problem.

If I had to guess, I'd say your placeshifter client is too slow to play back HD files. The mpeg2 decoder used in the placeshifter isn't hardware accelerated, and isn't terribly well optimized for a CPU either. If you force your server to transcode the files, there's a good chance your server isn't fast enough to do that.

[scoob101]

Many thanks for the helpful response. What youre saying sounds logical. I`ve played back other HD stuff on the same machine and its OK, but as you point out its not via the Sage software, so that proves nothing.

I would like to prove it through testing if I can. I`ll try to get the other client working (its a newer laptop with a faster graphics card), and see what difference that makes. If its less jerky on the other client, then thats a solid pointer to the client not being up to the job.

If you can think of some other tests which could make things clearer, please let me know.


Cheers!

[reggie14]

What kind of computer do you have? What is the processor speed?

The easiest thing to do is to look at the CPU utilization in the task manager. If you see 100% CPU utilization, you know that's the problem. If you have a dual core processor, 50% utilization is pretty much the most you'll see (meaning you're maxing out one core).

Out of curiosity, have you tried using the Sage Client software? Then you can use whatever mpeg2 decoder you want. The current one included with Sage even includes some hardware acceleration (though many of us use a different mpeg2 decoder, like WinDVD's or Cyberlink's). You can get away with a much slower processor then.

[zoundz]

This thread brings up a question that's been bothering me for a while. Under identical circumstances, same laptop, same wireless, same time, same day, same location, same HD mpeg file, VLC can play the HD perfectly. No skips, no herky jerks. Placeshifter doesn't even come close: more like 1 or 2 frames/second. Obviously this is not a network bandwidth issue, since the same data is squeezing down the same network pipe. The most likely answer is that SageTV Placeshifter is grotesquely slow and inefficient compared to VLC. IIRC, Placeshifter is using a modified version of MPlayer for it's playback engine. I wonder if there's any possibility of it being massaged into using VLC, which is open source and readily available to the SageTV development team. It's not the end of the world to watch HD shows with VLC when I'm out on the patio with the laptop, but I'd rather use SageTV for everything. It works great for all the SD stuff, but it's absolutely useless for HD.

Happy SageTV user just wondering

[scoob101]

Originally Posted by reggie14

What kind of computer do you have? What is the processor speed?

The easiest thing to do is to look at the CPU utilization in the task manager. If you see 100% CPU utilization, you know that's the problem. If you have a dual core processor, 50% utilization is pretty much the most you'll see (meaning you're maxing out one core).

Out of curiosity, have you tried using the Sage Client software? Then you can use whatever mpeg2 decoder you want. The current one included with Sage even includes some hardware acceleration (though many of us use a different mpeg2 decoder, like WinDVD's or Cyberlink's). You can get away with a much slower processor then.

The Placeshifter Client is running on a Turion 64 X2 Laptop with a Geforce Go 6100 Graphics chip and 2 gig of ram. The hardware may or may not be "perfect" for HD playback, but Im confident that it should be alot better than the performance i`m currently experiencing.

CPU utilisation is not maxing out on either core during playback. The other thing which puzzles me is that for a brief period last night whilst watchin BBC HD, the playback quality improved significantly, and then after changing channels ang going back again, its was jerky as hell.

Something else which I found strange was that even with paceshifter set to transcode (which was the default setting after I installed - although I did toggel it a couple of times) I`m not getting a processor hit on the WHS server. I would expect the WHS server to be loaded with the transcoding load, when attempting to view HD over a wireless G connection. The WHS machine is a new 2.5 ghz dual core athlon 4850e with a gig of ram. It hardly went above 10% utilisation whilst serving up HD to the placeshifter client. Sounds like its not even transcoding to me.

Like I say, the placeshifter clients hardware may not be 100% ideal for HD playback, but right now I don`t think the bottlenecks I`m experiencing are down to the hardware. I need to prove this through testing.


As a comparison, I`ll try the sage client and see how that performs.

[scoob101]

Originally Posted by zoundz

This thread brings up a question that's been bothering me for a while. Under identical circumstances, same laptop, same wireless, same time, same day, same location, same HD mpeg file, VLC can play the HD perfectly. No skips, no herky jerks. Placeshifter doesn't even come close: more like 1 or 2 frames/second. Obviously this is not a network bandwidth issue, since the same data is squeezing down the same network pipe. The most likely answer is that SageTV Placeshifter is grotesquely slow and inefficient compared to VLC.

Hmmm.. Any ideas if Sage is Planning to optimise placeshifter to make it a leaner, meaner player??

Thanks for the VLC tip tho - I`ll install that aswell.

[Fuzzy]

I'm not sure they ever really expected Placeshifter to play HD material, and it works fine on VERY weak hardware for SD. The thought was that HD would only be playable over a local network, and over a local network, you should be using SageTVClient.

As much as I like VLC, I'd much rather Placeshifter implement a directshow playback scheme. This would allow for hardware accelleration, and that, along with some Save-Password options, could actually eliminate the need for the Client program at all.

[zoundz]

Originally Posted by Fuzzy

I'm not sure they ever really expected Placeshifter to play HD material, and it works fine on VERY weak hardware for SD. The thought was that HD would only be playable over a local network, and over a local network, you should be using SageTVClient.

As much as I like VLC, I'd much rather Placeshifter implement a directshow playback scheme. This would allow for hardware accelleration, and that, along with some Save-Password options, could actually eliminate the need for the Client program at all.

Hmmm. I would happily use SageTVClient over the local network except then I'd have to buy yet another license. Are we suggesting that SageTV has deliberately crippled Placeshifter playback so that we are forced to buy a client license to watch HD? Doesn't really sound like the way they usually operate. I suspect that Placeshifter just needs to be tuned up a bit.

As far as directshow vs. VLC, I wonder if we really need another buggy, error message prone, somewhat unpredictable directshow graph builder. While VLC does have it's shortcomings, it is a well developed player that will play just about anything. And as an added bonus, M$ had nothing to do with it.

Just my $.02