Does SageTV do upconverting?

[smoogoo]

I was wondering if SageTV has a built in upconverter for boosting or change video quality

[emok]

Sage doesn't necessarily do this, but the HTPC does it.

I'm not an expert, but I think it's actually the work of your hardware/software decoder (for deinterlacing and image processing) and your video card's scaler that outputs to the specified resolution.

And then your TV also might do some scaling from the resolution that is output from your video card to the native resolution of the screen.

[emok]

I sat here thinking about your question and haven't been satisfied with my own answer, so I've been digging around looking for better explanations.

I think it's because "upconversion" is a somewhat vague term.

In most cases, the computer will always output at a set resolution to the TV. For example, you configure windows to have your video card output 1280x720 non-interlaced or 720p. Anything that the computer's video card sends to the tv is in 1280x720.

Now, if you're playing a source video that's recorded at 640x480, this video needs to be processed before the computer/video card can output it at 1280x720.

There are multiple steps to this processing, two most important are:
1) decoding -- This usually happens as part of a software process that takes the raw bits from the source and decodes them into actual pixel maps that can actually be sent to the video card. This is where most of the image improvements take place. Some of these software decoders can take advantage of specific hardware to offload this processing. For example, the nvidia purevideo decoder is written in such a way to take advantage of specific hardware APIs that allow the actual hardware (an nvidia video card) to take care of decoding or deinterlacing.

2) upscaling -- This is where the video from the decoder is actually resized to the output resolution of the video card. This process essentially takes pixels from a smaller canvas and maps them into multiple pixels on a larger canvas and the actual processing can take place in software or hardware. For example, if you are watching a video in a window and you maximize the window and the video grows to the size of the screen, this video is being upscaled.

Oh.. I forgot to mention the physical connection between the computer and the output display. If you are using a digital panel or using VGA/component as an output, these output resolutions are configurable and thus you have control more control over these processes mentioned above (namely upscaling).

Now if you're using SVGA or composite as your connection, these are fixed resolutions and an extra step of processing is added into the mix where the output from the videocard goes through some type of TV encoder to convert the signal to something that can be passed through this connection type. In some cases here, you may actually be "down-converting". But since you're talking about upconversion, you're probably not using this physical connection.

So back to your question. SageTV does not do the upconversion. SageTV DOES provide a decoder that will decode mpeg video, but it is the nature of an HTPC to actually do the "upconversion" and process the video. So just by using a Home Theater PC, you are essentially upconverting your video. That being said, there are many parameters you can use to tune your video quality, but it can only go so far in improving image quality of a low resolution source.

Does this all help? At least a little bit?

[emok]

sorry for the wordy reply. I'm just a little bored here.

[smoogoo]

This is what I’m working with:

TV
http://www.sharp.ca/products/index.asp?cat=30&id=669

Cable: DVI from the video card out to HDMI on the TV

Video card
http://ca.asus.com/products.aspx?mod...=6&l3=271&l4=0

Tuner
http://www.hauppauge.com/pages/produ...pvr500mce.html

OS
Vista Ultimate 32Bit

The pitcher quality is lower when I run the TV signal though my PVR then when I run the TV signal directly into the TV. I’m trying to find found where my bottlenecks are and if there is any way to increase my video quality. I was also wondering if going to real PVR software would make any difference?

(I don’t watch enough TV to justify paying for digital cable, the system doubles as a test and learning environment for Vista and the TV makes a not bad monitor.)

Some software I came a cross:
http://www.videohelp.com/tools/VLC_media_player
http://www.videohelp.com/tools/Media_Player_Classic

[emok]

What exactly are you seeing in terms of poor picture quality? Scanlines? Pixellation?

I believe what you're seeing is somewhat common, especially watching SD content and I believe the reason is because there's an extra step happening here. You're getting the analog signal from your cable, converting it to a compressed digital format, and then decompressing it to output back to the TV. The degredation you're seeing is this compression/decompression step.

That being said, you can perform extra steps to try to improve your picture quality. There are two areas you need to examine.

1) recording -- your pvr500 is taking the analog signal and encoding the source into an mpeg. I haven't used Vista/MCE, but there's probably a way for you to increase the recording bitrate (reduce compression). Your recordings will take more space, but *should* look better, depending on what your settings were at previously. With the PVR500, it will always output a compressed mpeg format. Perhaps with a different tuner card it may have a better compression algorithm or may not compress at all, allowing your software to do the compression (at the cost of processing power), which may allow you to get better results, depending on which codec you use.

2) playback -- Now that you have your mpeg source files that have been recorded, you need to decode/scale them, which is done with the aformentioned codec and processing utility (purevideo/ffdshow). With these utilities, you can tune the picture quality a little further. Do you know which mpeg decoders you're using?

Are you running your output resolution of your computer at the TV's native resolution (1366x768)?

E