Need some help from some of you more adventurous types; I may have found a way to improve the quality of LiveTV in MCE2005...

I was pondering why LiveTV's quality should be bad... worse, in fact, than I thought it was under MCE2004, when it occurred to me that when we're watching LiveTV, we are, in fact, watching a buffered recording... and thus, that recording has to have a BITRATE.  Since I'd already figured out that Microsoft had actually lowered the standard bitrate settings for "Good" and "Better" in MCE2005 versus MCE2004, I wondered if they'd actually done the same for LiveTV.

After a little digging in the registry, I turned up under the following branch:

HKEY_LOCAL_MACHINE/Software/Microsoft/Windows/CurrentVersion/Media Center/Service/Video/Tuners/DVR

...a key called DefAvgBitRate with a value of 20000000.  Now, I know that the bitrate values for encoding quality elsewhere in the registry have one less zero on the end than that, but I decided to back up the branch and change the value to 40000000.  Well, nothing blew up and if I wasn't hallucinating, it seemed that LiveTV had become smoother and less blocky.  So I tried setting it to 60000000.  Again... this could just be my imagination, but I thought it looked better still... and again, nothing blew up.

Do any of the braver experts out there have any thoughts on this?  Am I hallucinating and screwing with something important?  Irrelevant?  Does changing this affect the buffer size (it sure as heck should affect the size of the files, but I dunno about the length of the buffer...)?  Or have I actually found a real, honest-to-gosh hack for this thing?

Help me out here, guys, I think I may be on to something even if I got it wrong... but this pair of 40-year-old eyeballs could sure use some feedback and confirmation...

Steve

PS: If anyone reading this is still running MCE2004 or earlier, could you check this value in your registry and report back whether it's the same or not?

Sounds interesting...

Does your CPU load go up as you increase this value?

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Travis Bell
themoviedb.org | The open movie database

Good question; I haven't looked... but logically, as MPEG encoding is done by your tuner card, the answer *ought* to be "no".  I noticed a couple of video hiccups right after launching LiveTV, but it smoothed out immediately and being that this is a brand new box, a brand new install, and I just installed the second tuner, a PVR-150MCE earlier today and set it as the default, I'm not entirely certain that THAT behavior isn't normal anyway.

Steve

Wondering what you consider to be "bad", and why a "fix" is needed.  There have been numerous discussions on here about image quality coming from a standard analog cable source, and to be honest, I'm quite happy with my system. 

A long time back I had posted some sample screen captures as a comparison point.  I'll attach them here again also.  Do these look "bad" to you?

 

MartinC,

The captures you posted look very good, what tuner card are you using?

No offense, Martin, but I have no way of telling from a couple of PNG files how blocky or not your LiveTV capture looks in motion on a TV set.  Clearly, there are people who are unsatisfied with the quality issue and justifiably so.  What I'd hoped is that some folks would try out the registry change and report back.  If you're happy with what you're getting, then this isn't the thread for you... unless you're going to be a mensch and show us the contents of *your* "PVR" registry branch and tell us what tuner card you're using.

Folks, how about it... will anyone here help me look into this?

Steve

i agree with sds on this one. how can we tell the quality of your livetv from a couple of png's, especially when those appear to be from recorded shows and not screens from livetv.

ive noticed in the past (although i am still kind of new to this) that my recorded shows have a little higher quality than when i am watching livetv, not as much smearing and grainyness and things of that nature.

im gonna try this as soon as i can, my theatrix 550pro could definately use a little bit of help in the quality department. i will have to say that i started getting a little better quality when i updated to the latest driver (version 6.14.10.52); but they still need a little help. thanks!

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System Specs:
Athlon 64 X2 4800+
Giga-Byte GA-MA69GM-S2H
ATI IGP X1250
1 GB RAM
2xT550Tuners
1x80 GB (C: Drive)
1x200 GB (Recorded TV)
1x500 GB (Docs, Music, Video, Pics, DVDs)
Toshiba 40" 40RF350U

Steve,

I will give it a try tonight. I've been struggeling with the same problems for some time now, tried everything earlier mentioned in several MCE forums . I will give u feedback asap.

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Yours truly,

Simon

 

Sunmorgus:

Thanks much... let me know what you come up with!

I'm starting to thing that the Hacks & Mods board might have been a more appropriate place for this one... but rather than crossposting, I'll let it be for now and see if the mods want to do anything about it...

Steve

Steve, you could be right.  If you look in registry settings above for Recording their are 4 values ranging from 25000000 to 60000000 which could explain recording quality being better

Moved Here

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Chris Lanier
The Green Button Forum Moderator

Thank you, Chris... much appreciated.

If some of the hack wizards can look into this, it would be warmly appreciated.

Latest update: had an unexplained system lockup during LiveTV after 45 minutes of viewing; was forced to crash the eHome system and tried backing that value off in the registry to 40000000.  Will do more testing later.

Steve

Lochindaal...

Those settings refer to the equivalents of the Fair, Good, Better and Best recording quality settings in the user interface for recording programs and series.  Please see my post at http://www.thegreenbutton.com/community/shwmessage.aspx?ForumID=42&MessageID=97761 which will show you how those settings were changed between MCE2003/4 and MCE2005 which may have a negative effect on one's experience and how they can be changed back.

Note that the settings in THAT registry key are most definitely referring to bitrate (2500000 = 2.5Mbps) while the settings in the key we're discussing here are, for some reason, longer by a digit and therefore may not really be what I think they are...

Even if it's the wrong setting, one would think that the bitrate for encoding the LiveTV buffer would have to be a registry setting somewhere, no?

Let's crack this, gang...!

Steve

 

sds, I posted to the thread not because I wanted to be a troublemaker - I seriously want to help out.  I have had very few problems with MCE2005, so as I frequent the board, I try to help out others, even though I may not have had any problems with what is being discussed.

Those captures are from a PVR350.  Captures from a PVR150 on another system are of equal quality, maybe a little better.  I would be happy to post sample video clips if you want to look for motion artifacts, etc.  Although those images I posted were using the free imageshack hosting service, which doesn't accept videos. 

Anyone know of a free hosting services where we can exchange some video samples?  I keep hearing people talk about bad quality, but would really like to see what they are talking about (and share mine too) firsthand.

I have not changed any registry settings with respect to recording quality.  Everything defaults.  I always record at Best setting, and don't see any difference between Recorded and LiveTV.

Those captures from the PVR350 are from many months back, so as another sample, here's a new full resolution capture from the PVR150.  It's converted to PNG since imageshack does that.  I uploaded to imageshack as BMP.  Same analog feed.

Edit: image removed

Martin:

Not thinking or concerned that you're trying to be a "troublemaker" at all -- but the images just don't help at all since the quality issue that I'm trying to overcome is one that's mostly going to be apparent in motion.  Furthermore, as a 350 and 150 user myself, I'm not concerned with the hardware's ability to do a good job; I know that they can and do.  What concerns me is that on a brand-new install of MCE2005 on a newly-built box, I'm seeing a distinct degradation in the quality of the LiveTV buffer versus what I'm used to on my previous install: an MCE2004 system running on hardware so ancient you'd have to call an archaeologist to help identify the remains.  Furthermore, having discovered independently that Microsoft quite clearly made changes in the 2005 registry defaults which reduced the bitrate of the user-controlled "Good" and "Better" settings, I am extraordinarily leery of the implication that they may have done something similar and undocumented with the bitrate settings on the LiveTV (aka PVR in the registry) side.  We can subjectively compare pictures all day, but what I'm trying to discover is a fact... current registry defaults versus last year's registry defaults -- and which registry key is, in fact, the setting that controls this behavior (or did I actually find the right one in my ham-fisted luck?).

Once we've determined just HOW MCE knows at what bitrate to record the LiveTV buffer, we will have a handle on this issue and then we can talk about more esoteric and subjective tweaks to our hardware and software ad nauseum...

Steve