Which software MPEG-2 decoder should I be using?

[deria]

Hi,

Yesterday, I posted indicating that I was evaluating Snapstream, and had questions about the "always timeshifting" option. Those questions were so favourably answered, and the software performed so well, that I decided to take the next step and purchase the software. At the same time, I also purchased a WinTV PVR 250.

Well, chaos ensued (as chaos usually does). In a frenzy of exuberant software installation, I blindly allowed the WinTV PVR-250 installation disc to install everything -- and I mean everything -- that it could. After this mass installation completed, I was unable to complete the Snapstream setup wizard due to an error indicating that the TV graph could not be built. I was eventually able to solve my problems, but it ultimately involved using system restore to revert to the configuration I was using last week, then reinstalling my ATI card, its drivers, then directx 9, then the windows media encoder, then the ten million other programs ATI requires in order for its software to work, THEN the WinTV PVR 250 (with the latest drivers from the web) and finally Snapstream. Whew!

You can imagine how glad I was when it started working. I'm thinking the problems were caused by me blindly installing the software that came with the WinTV PVR-250. I never did reinstall it in my working configuration (and I'm sure not going to now, since its working!).

All of this is leading somewhere, believe me. Im now paranoid about installing anything, or changing anything. Unfortunately, it looks like if I want my system to really excel I *should* be making a few changes. So, in no particular order, here are my questions that I'm hoping someone can answer before I insanely start acting on my desire to make things "gooder".

1. I read that Snapstream will allow you to use alternate MPEG decoders to allow the video card to offload some of the work of the decoding. I am sure that my ATI video card provides hardware assisted decoding, but the choices in my decoder list (in configuration, misc. settings, preferred mpeg-2 decoder) are:

Default
InterVideo NonCSS Video Decoder for Hauppauge

I cannot help but notice the lack of an ATI codec. Is that codec the thing that the ATI driver installation happily tells me its not going to install because my original CD is inconveniently lost? If so, which of the two choices should I use? Or, alternatively, should I be downloading and installing something else? I actually own Intervideo WinProducer, InterVideo WinCoder, AND Intervideo WinDVD 5.1 (from my NVIDIA video card I use in my other PC). Will any of those help, or will they merely open the door for the afore-mentioned chaos?

2. Capture resolution, now that I'm using the PVR-250, seems to detault to the "Better" setting. This setting seems more than good enough for timeshifting, but I'm thinking for recording I might want to record at a higher setting so that I can transcode to another format with less quality loss. Is that wise?

3. Timeshifting Buffer Size -- I have 100GB of storage. Is there any reason I should not choose a size of 4096 MB (or larger) instead of the default of 512 MB? On the one hand, I realize that the timeshifting buffer is only meaningful as long as you stay on one channel, but it might be handy to be able to sit down at 9pm and browse through the entire NBC prime-time lineup to watch what I like. Is there a performance penalty for having larger files?

4. Security -- I was more than slightly impressed that I could watch TV streamed from my PC to my other PC. I was more than slightly UNimpressed that by default the entire world could also do the same thing, requiring only my TCP/IP address. I normally use the Windows XP firewall, which works well enough at preventing ANYONE from accessing my PC. The only trouble is, I want to be able to access it myself from remote locations. Has anyone determined how to change the Windows XP firewall to allow certain TCP/IP addresses through the firewall, or should I be looking at an alternate firewalling package?

Well, thats all the questions I can think of at the moment. On the whole I'm very impressed with this product. I think the problems I ran into were more my fault than anything else, and once resolved the software has worked almost flawlessly. I'm really excited about what I can do with this thing -- maybe too excited.

[archie]

let me see if i can help a little:

1) the intervideo decoder should work great for you. follow the tweaks in this link to take advantage of your hardware assisted playback.

2) yes. i use the "best" quality modified to vbr with 4 (base) to 8 (peak) mbits/s. this gives excellent quality with smaller resulting file size.

3) set it to whatever you like. there is no performance issue for a larger file. there are performance issues for "always time shifting." but that has been extensively covered elsewhere.

4) try zonealarm. it's free and much more powerful than ms xp firewall. it also offers much better protection. to see the failure of your current firewall, check out gibson research's free security tests.

hope that helps, archie

[deria]

Hi,

First, thanks for your reply!

I activated the Intervideo decoder, and immediately saw a decrease in CPU utilization from 35-45 down to 25-35. I enacted the two registry tweaks mentioned in your message (which I had previously come across independently) and the CPU utilization decreased even further -- typically it is 8-20 percent, with the peak utilization being relatively rare.

For the quality setting, I will try what you suggested. My current setting (which I adopted because I noticed extreme blurring/tearing in high motion scenes) is 720x480, 12000000 bits per second, 2 bidirectional frames per group (default), 4 predictive frames per group (default), video noise reduction filter NOT enabled, motion precision of 20 percent, and variable bit rate encoding disabled. The change up to 12000000 bits per second seemed to largely resolve my issues with high motion scenes (such as music videos). The resulting file sizes however, are... well, excessive. Still, I value the quality more than the hard disk space. I'll try your suggestion and see how it works out.

Regarding firewalls, I actually ended up installing zonealarm a few days ago and it is very good. It seems to be exactly what I was looking for, and quite completely replaced the MS Windows XP firewall. I also like the price... free. They have a non-free version, but the free one seems good for what I want and it works well.

On the whole, the system is working very well. The quality in low motion scenes is actually on-par with the quality of my native television signal (to be honest, it seems better for some reason) and the quality in high motion scenes is at least acceptable.

One thing that still baffles me is what resolution I should be setting my PC too. I have a monitor and a TV attached, and both are running at 1024x768 (the TV is a clone of the monitor, as far as the ATI video card is concerned). I'm thinking that the image is actually being scaled up to 1024x768 prior to display, and the ATI drivers are doing some fancy behind the scenes stuff to create a viewable image on my TV. I might not be right, but it seems to me that less scaling = better, though I'm not sure if lowering the resolution to 800x600 would really help me much, since the image would still be stretched slightly. I don't think I can use the true fullscreen setting in Snapstream, as they seem to go out of their way to point out that it does not work with ATI Radeon cards (and I have a Radeon 7500).

Despite all that stuff about resolutions, I'm currently very happy with the picture quality. The only time I can tell its not a live signal is in high motion scenes, and when objects containing straight diagonal lines are prominent in the display (they look slightly, but noticeably, pixelated).

[archie]

i agree with merrypig. a couple of other thoughts.

with ati, to change to 640x480, right click the desktop, then click settings, advanced, adapter, list all modes. i use 640x480 32 bit 60 hz. this requires less processor to playback, i believe.

now, you obviously don't want your desktop at 640x480, so hit the displays tab and set the tv to "1" and the monitor to "2." apply. then set the resolution you want for your monitor and extend windows onto the monitor.

ss requires the fs interface to run on the primary monitor (tv). you can then either move the start bar to the monitor, or, open ss fs interface, then change the monitor to the primary monitor. as long as you don't exit the fs, that will work.

true fs will work for ati's as merrypig said if your capture device is not the aiw. in the above scenario, you may not want to do that though because the mouse is limited to the fs monitor (tv) and you can't use the desktop on the monitor.

one other problem you may have when an aiw is in the system is that your system won't go into standby after you open fs or windowed modes. to get it to go into standby in that situation, shut down ss then restart it in taskbar mode.

another person reported using ampsoft.net winoff to get his system to go into standby, but i haven't tried it yet.

one other note, i've set motion precision to 1% and don't seem to have blurring others are talking about. but maybe i'm just lucky.

probably more of a response than you wanted, but it took me awhile to get my system working the way i wanted and thought some part of it might help.

archie