Placeshifter and HD-PVR

[Skiier__Dude]

So a further update to this thread.

I've now upgraded the CPU on my server from a dual core machine (2.4 Ghz) to a Quad Core (3.4Ghz) machine.

I do find the experience with Placeshifter much improved playing HDPVR recorded content -- however, it's not perfect yet. I find that when playback starts, it will skip and stutter initially. If I pause playback for about 1 minute and allow it to buffer, playback is perfect until the first commercial -- once Comskip skips through the buffer, it stutters again so I have to pause.

I am still not sure whether the stutter is a function of upload bandwidth or the CPU. My upload maxes out at 1Mbps and I generally attain about 500kbps on a speedtest. The CPU on the new quad-core sits at around 25% when transcoding so that is greatly improved from the 100% hit earlier. However, even when I set Sage to limit the upload to 500kbps, it still stutters. Leads me to believe that this is a bandwidth issue not CPU.

[Spectrum]

Try using placeshifter on the local network and force it to transcode. That will eliminate bandwidth as a problem. I can transcode HDPVR recordings fine with a 3Ghz dually (using V7) so that quad should be able to do it without issue.

[WormyOne]

New poster here; I too have been infuriated by this stuttering, and just updated to v7 in the hope that I'd see resolution. I'm a paid-up placeshifter user who has never had it working...

No joy with v7, but it did get me searching for a solution again, and led me to this thread.

My config: HD-PVR recording 1080i from cable box, 6 core 2.6GHz CPU in the server, forcing transcoding via Placeshifter client options.

I did some checking of some other files (e.g. DVD rips) via placeshifter and what do you know, it works just fine for basically any content that is not 1080i from HDPVR. Even some 1080p content plays back fine (very slight stuttering on one 1080p file)

Some investigation shows that SageTVTranscoder.exe (spawned by SageTV when transcoding) uses CPU as follows:

- for lower-than-SD content (480x360), CPU usage 20-50% (corresponds to 2-3 cores consumed)

- for some 1080p content, CPU usage 20-35% (~2+ cores consumed)

- for HDPVR 1080i content, 16.8-17% (exactly 1 core consumed)

I surmise that generally, the transcoder is well multi-threaded, but that something about the interlaced HDPVR transcode (presumably, the de-interlacing) is single threaded, and is the bottleneck for this problem.

I was thinking of switching over to 720p recording (feel that quality might actually be better with no interlacing and that digital cable lobotomizes the bitrate before it gets to HD-PVR anyhow), but I think I'll go ahead. Side thread: anyone have thoughts on this quality tradeoff?

Full-on solutions to this 1080i problem likely include:
1. SageTV folks multithreading their de-interlace code (yes please)
2. use a 7+ GHz processor single-core processor (this might be a few years, so see option 1)

Workaround remains: use 720p recording (I will try this next but am hopeful given the experience of others)

Another interesting side note that I found in investigation is that the transcoder process is actually transcoding well ahead of realtime. This may be why the low res content I did test had higher CPU usage than 1080p. The transcode process died minutes ahead of me getting to the end of the stream in placeshifter.

Hope this helps refine the problem/workaround/solution

[wayner]

I kind of like the idea of a 7+ GHz CPU. For us Canadians that would also help to negate the need for a furnace in the winter!

Others have gone the 720p option to facilitate Placeshifting and some websites have religious debates on the relative merits of 720p vs 1080i.

[Chriscic]

I don't see much difference in 1080i vs. 720p played back on my HD300 (and no difference from normal viewing distance). YMMV.

[tvmaster2]

Originally Posted by Chriscic

I don't see much difference in 1080i vs. 720p played back on my HD300 (and no difference from normal viewing distance). YMMV.

Have you tried Placeshifter on a laptop over 802.11b in a Holiday Inn located in India? That's why it was invented, or at least that's what I was led to believe. In that scenario - forget 1080 anything.