Blackbird In, Nvidia 5200 out

[BergoniaC]

I am new to HTPC, so please bear with me. (Hope I am using the term correctly). I recently purcahse the SageTV bundle, video capture and SageTV 2.0.

I understand that Blackbird has a MPEG 2 encoder, which lessen the amount of CPU usage (uses about 10% avg.) Currently I am using my onboard graphics for play back and it uses 45-50% of my CPU. So I decided to purchase a Nvidia 5200 AGP card with DVI out. According to the spec it has a MPEG 2 decode.

My question is, will the MPEG 2 decode on the nvidia decrease my CPU usage? Is MPEG 2 encode and decode universal or do different manufacture create their own implementation of MPEG 2?

I want to hear what more experience people have to say before I open my video card box. Hate to pay the 15% open box fee if I have to return it.

Thanks

[xlr8shun]

the video card doesnt have hardware mpeg decoding, it only has hardware accelerated decoding. and would only work if you used vmr, as that uses the video card to display the stream rather then softwrae (such as overlay).

yes it will lower your cpu usage, might not be a lot though. it would depend on the codec you are using also. i have a friend who uses sage, with sonic decoders, and uses 2-5% cpu while watching tv.

[kny3twalker]

Yeah it should reduce your CPU usage to under 30 %
yes nvidia and ATI both are liars it only does assisted decoding
mine CPU is about 15 %
if you watch a DVD you are doing the same thing so just watch a DVD on friends computer with similiar processor and video card and you should know what it will be like
2-5% huh wow thats low
I seen mine drop that low but usually around 15

[BergoniaC]

Kind of confused about acceleration and hardware MPEG decoding. According to Nvidia home page, the 5200FX hardware decodes MPEG. Also what is VMR? I am probably asking more than I can comprehend but I have a need for knowledge.

This is what I am trying to do. I record TV shows for my wife for later viewing. Usally when she views it, I want to mess around the internet. So I came up with this set up. FX5200 card with DVI out and RGB out. Plug the DVI and RGB to my TV (yes my TV has RGB and DVI). Split the screen and have one screen play the movie and one screen doing what ever. Since watching MPEG recorded show takes 45-50% of the CPU, I wanted something that could lessen the CPU load so the play back doesn't become jerky if I need some CPU time.

[mikejaner]

Kind of confused about acceleration and hardware MPEG decoding. According to Nvidia home page, the 5200FX hardware decodes MPEG. Also what is VMR? I am probably asking more than I can comprehend but I have a need for knowledge.


The hardware decoding Nvidia is talking about is the accelleration of the mpeg decoding process by using their GPU on the video card. They say "Full Hardware Decoding", but that is not true. Their marketing geniuses threw that one in, probably after modifying it from something like "Full Speed Playback of MPEG2 using Hardware Accelleration, and Motion Compensation".
The reason why Full Hardware Accelleration is not correct is because the video card makes no effort to reconstruct the true interlaced images through the monitor or tv output. The software decoders kind of muck this up by blending the two fields together using a couple of techniques.

VMR is a mode that certain video cards support that lets the card take some of the video decoding load off of the processor. The current implimentation of VMR has a limitation that makes most people turn it off. Somewhere in the process of getting the video to the screen, it puts the image through a 256 color filter of some sort which dulls the colors and makes them seem soapy. I am not super technical, so anybody correct me if I am way off here.

[stanger89]

Originally posted by mikejaner
The hardware decoding Nvidia is talking about is the accelleration of the mpeg decoding process by using their GPU on the video card. They say "Full Hardware Decoding", but that is not true. Their marketing geniuses threw that one in, probably after modifying it from something like "Full Speed Playback of MPEG2 using Hardware Accelleration, and Motion Compensation".

Exactly, no video cards offer full hardware MPEG decoding.

The reason why Full Hardware Accelleration is not correct is because the video card makes no effort to reconstruct the true interlaced images through the monitor or tv output. The software decoders kind of muck this up by blending the two fields together using a couple of techniques.

I'm going to have to disagree with you on this one. The reason why hardware accelleration can't be called hardware decoding, is because only part of the decoding is done in hardware. Currently the Inverse Discrete Cosine Transform (IDCT) and Motion Compensation are done in HW on the video card, while a significant portion of the decoding is still done in software.

While software/HW-accelerated decoding does have problems with interlaced, it's not inherent to the technology, progressive scan DVD players don't output interlace video either.

What's done when using software decoders is similar to this, taking the progressive output of a PS DVD player, runing it through a scaler to say 800x600 resolution, and then running it through a Scan Converter back to NTSC/S-Video output. I suspect you'd get a similar picture to the TV out of most video cards. (If someone has an Xcard and a scan converter they could try it just for kicks)

VMR is a mode that certain video cards support that lets the card take some of the video decoding load off of the processor. The current implimentation of VMR has a limitation that makes most people turn it off. Somewhere in the process of getting the video to the screen, it puts the image through a 256 color filter of some sort which dulls the colors and makes them seem soapy. I am not super technical, so anybody correct me if I am way off here.

I'm not sure that's quite right either. Traditionaly, video cards have used special hardware, the Overlay mixer, to display video, VMR on the other hand uses the video card's GPU to render video. There are actually two versions of VMR available now, VMR7 which draws video using DirectDraw, and VMR9 which uses Direct3D and renders video with the video card's 3D engine. VMR7 is known to be inferior to Overlay, probably due to lack of precision in the processing and/or bad colorspace conversions. VMR9 on the other hand, is capable of equalling or even exceding the picture quality of overlay. However VMR9, which uses DirectX 9 and the videocard's 3D engine, actually has much higher system requirements than Overlay. For good results with VMR9, you generally need a mid to high end video card (Radeon 9600 Pro, Geforce FX 5700, or better), while most any video card with overlay support can give a good picture.

But to answer your question BergoniaC, yes the FX should reduce your CPU usage, it could drop about half.

[kny3twalker]

http://msdn.microsoft.com/library/de...guide_9inb.asp

here's technical info on this if you want more info

[BergoniaC]

This alot of good information. It brings me to the question of Blackbird PVR250 encoding. Is this Hardware MPEG encoding or Accelerated MPEG encoding?

[mikejaner]

Your right Stranger89. I just couldn't think of how to word a couple of things. When I was talking about the colors being filtered in VMR, I couldn't remember the term for Colorspace Conversion. I didn't know the VMR9 was more accurate in Colorspace Conversion. I guess I only knew the details about VMR7

[justme]

It brings me to the question of Blackbird PVR250 encoding. Is this Hardware MPEG encoding or Accelerated MPEG encoding?

The blackbird uses Hardware Mpeg encoding for SageTV. When just recording with one of these cards(no video being played back) you should only see ~ 2-5 % CPU usage. This is mainly being used by Sage for the purpose of moving the encoded video from the PVR card to your hard drive for storage.

[stanger89]

Originally posted by mikejaner
Your right Stranger89. I just couldn't think of how to word a couple of things. When I was talking about the colors being filtered in VMR, I couldn't remember the term for Colorspace Conversion. I didn't know the VMR9 was more accurate in Colorspace Conversion. I guess I only knew the details about VMR7

The colorspace conversion is a guess on my part.

But I do know that VMR9 is capable of surpassing Overlay in PQ, although it is different. One common complaint about VMR9 is that it looks softer than Overlay, especially on Radeons, however ATI artificially sharpens the picture in Overlay, so the picture is probably slightly more accurate.

Might want to check out this thread on AVS for some thoughts on the possibilities of VMR9:
http://www.avsforum.com/avs-vb/showt...ht=quadro+1100

And this is another interesting thread, none other than Joe Kane himself evaluated the HTPC discussed in that previous thread.
http://www.avsforum.com/avs-vb/showt...ht=quadro+1100

[BergoniaC]

For anyone that is interested: I finally received and installed my FX5200 card. I played back a sample recording and got somewhat of a decrease in CPU usage. It drop from 45-50% to about 20-25%. Sometimes it would spike up to 45% but it would drop back down to 20-25%. I was hoping for something lower but a 50% decrease is not bad.

A good secondary benefit I was not expecting was that my CPU temp went down 2-3 degress. I was normally geting 52-53 degrees during show play back or normal usage and know I get about 50-51 degrees. I guess it is because the on board graphics card is not using the CPU anymore.

The draw back is that the fan on the FX5200 makes my system louder. Since I have a IDEQ SFF, putting a fanless or quiet cooling solution pretty much out of the window. However, I have my system inside a entertainment center with a glass front, which helps dampens the noise to a very reasonable level. Also the TV speakers is loud enough, especially if I have the surrond sound speakers on, that I don't notice the fan at all. It is all about compromise.

BTW: Thanks for all the insight on MPEG encoding and decoding. My knowlege has just increased.

[kny3twalker]

you can remove the fan and buy a big heatsink but the temp will not be as low probably

[BergoniaC]

To everybody, I have to recant my previous statement about decrease CPU. Messing around with SageTV, I notice a slow down of my computer when I was watching a recorded show and crusing the internet. Pop open the manager and saw that SageTV was using 45-50%, sometimes higher, of the CPU for play back. I used PowerDVD, which I normally use to playback recorded videos. PowerDVD was only using 20-25% CPU. I didn't see any difference in playback quality.

Can anyone tell me why the difference in CPU usage between two different programs playing back the same show?

[stanger89]

Could be due VMR9, it often requires more CPU and is generally not used by DVD software.

[insomniac]

Codecs? try the hauppauge intervideo ones with the registry dxva and hwmc changes.

Would the dxva setting decrease your cpu on playback all?

I.

Originally posted by BergoniaC
To everybody, I have to recant my previous statement about decrease CPU. Messing around with SageTV, I notice a slow down of my computer when I was watching a recorded show and crusing the internet. Pop open the manager and saw that SageTV was using 45-50%, sometimes higher, of the CPU for play back. I used PowerDVD, which I normally use to playback recorded videos. PowerDVD was only using 20-25% CPU. I didn't see any difference in playback quality.

Can anyone tell me why the difference in CPU usage between two different programs playing back the same show?

[TunaBoo]

What is weird, is my sage use 25% (power dvd and overlay) on my PC.

When I "switch" over to a different profile and come back, sage uses 75% of my CPU. I have to close it and reopen to have a useable system.

*sigh*

[kny3twalker]

actually I have seen this with sage and decoding(using any decoder)
I can play a file back in a software DVD player and the CPU usage is lower than in Sage
it is probably because of the UI maybe????

also stanger89 there is a bug with powerDVD where it will not do VMR9 remember?

TunaBoo
powerDVD I use it as well but it is not the most stable decoder

for good picture quality and stability I think sonic makes a good decoder

but powerDVD also produces good picture quality but it has some issues

[sundansx]

Sage TV is using the PowerDVD directshow components (decoder, splitter, etc.) that get installed with PowerDVD. The PowerDVD app uses internal componets to playback video. The two are not necessarliy equal. For example, WinDVD 5 shipped with version 5 internal components, and WinDVD 4 directshow filters. I confirmed that with Intervideo tech support.
This may cause the difference you are seeing. To eliminate Sage in your scenerio, you can play back your video with Windoze Media player. Assuming the Power DVD filter merit is high enough, it will use the PowerDVD direct show filters that you are using on sage tv.

[kny3twalker]

yeah but why would I want to use windows media player
also windows media player would use the direct show filter as sage

I said it could be the OSD which is causing more CPU usage
media player does not have OSD it has just the player

would it not be easier in this case just to use the powerDVD application
or do you like the windows media player one better