Possible To Filter MPEG On The Fly Whilst Capturing

[EViS]

Now that I've bought myself a Hauppauge PVR250 MPEG capturing card, is it possible for me to capture and filter the VHS at the same time? Obviously it'd be ideal for me to capture in DV-AVI and then filter, but as recommended by other forumites in my other threads, my budget does not extend to purchasing a DV-AVI capturing device having already bought the following;

JVC HR8600E VCR
TCB-100 TBC

So, any software (combination?) that can capture into MPEG & filter at the same time? As I understand, capturing in 9000Kbps MPEG and then filtering in say TMPGENC, thus re-encoding the MPEG video will only damage the MPEG picture quality...

[guns1inger]

It depends what sort of filtering. It would have to be very light adjustments, and nothing temporal, or you will lose the real-time encoding. For example, slight adjustments to brightness and contrast might be possible (if your capture software supports it), but good quality noise filtering and clean-up is probably out of the question.

[EViS]

Why is good quality noise filtering and clean-up out of the question? Is it down to the capture card hardware itself or my (very good) PC spec?

[guns1inger]

If the card can do it in hardware then you are OK. If it is software, most use temporal algorithms that look at compare the noise across several frames (usually at least current, next and previous). This cannot be done in real time.

I know my PC isn't up to your spec, but it is still reasonably fast. I recently processed a 2 hour VHS capture for brightness, contrast, slight colour correction and moderate noise reduction. This was done using avisynth, and saved using lagarith lossless compression. It took eleven hours to process the 125 minute file.

if you want truly realtime filtering, you need to do it in hardware.

[jagabo]

The PVR-250 has hardware temporal noise filtering. Unfortunately, Hauppauge doesn't give you access to the controls. You can download third party software though:

http://www.shspvr.com/download/hcwpp2ut.zip

More useful information and utilities for PVR-250 owners:

http://www.shspvr.com/
http://www.cask-of-amontillado.com/htpc.html

[EViS]

if you want truly realtime filtering, you need to do it in hardware.

By in hardware you mean not in real time? And thus I've been advised not to edit an MPEG capture due to probably doing more damage to it than good... However, the following has interested me;

Taken from digitalFAQ:

"MPEG-2 with I-frames only with CBR encoding, which is almost the same as an MJPEG"

Can I capture as above using the PVR-250? How would I go about doing this?

[jagabo]

The PVR-250 can't capture as I-frame only.

If you really think you need more filtering that the PVR-250 can provide you can capture at 15,000 kbps MPEG2 then work with that. For VHS caps you also want to turn down the sharpness setting unless you capture at 352x480. See the sites I linked to.

[EViS]

Does increasing the Kbps theoretically decrease the lossyness of the MPEG capture? Would it also be a good idea to capture in CBR?

Does WinTV offer me these settings?

[jagabo]

Does increasing the Kbps theoretically decrease the lossyness of the MPEG capture?

Yes. In theory and in practice with the PVR-250.

Would it also be a good idea to capture in CBR?

Yes.

Does WinTV offer me these settings?

Yes, but you have to set up your own template:

Press the PREF button. Go to the Movies tab. Press the Advanced button. Select the "MPEG2 12.0 MBit/sec (CBR)" template as a starting point. Go to the Video tab, change the bitrate to 15,000. Go back to the Configurations tab. Enter a name for your template in the box next to the Save New Config button. Press the Save New Config button. Close the dialog. Back at the previous dialog select your new template with the Quality Level pulldown.

For VHS you might also try making a 15,000 kbps 352x480 template and using that.

[EViS]

Together with your above post and the shspvr forum I've suddenly got very exicted about the new card !

Just two final questions if you could jagabo;

1. Should I be capturing at 720×576 (PAL) as opposed to VHS resolution of 352x480?
2. By capturing using the above settings (and some others I've bookmarked from the forum), is there any point in applying any filters in real time? Or will I now be able to add filters to the high bitrate MPEG in TMPGENC without any noticeable quality reductions?

[jagabo]

1. Should I be capturing at 720×576 (PAL) as opposed to VHS resolution of 352x480?

Oh sorry, you're in the UK. You should capture at 720x576 or 352x576.

2. By capturing using the above settings (and some others I've bookmarked from the forum), is there any point in applying any filters in real time? Or will I now be able to add filters to the high bitrate MPEG in TMPGENC without any noticeable quality reductions?

I don't remember exactly what the PVR-250's default filter settings are. I think both the temporal noise filtering and sharpening are pretty high by default. I usually disable both if I'm going to filter in software. But I haven't worked with VHS in quite a while.

BTW, the temporal filter tweaker I linked to earlier works in realtime. You can see the results in WinTV2000 as you move the slider.

[EViS]

But would you advise me to filter in real time or as I'm capturing high-bitrate MPEG, will TMPGENC be fine to filter & re-encode the MPEG again? Or will re-encoding the MPEG severely damage the picture quality despite an original high-bitrate MPEG video...

[thecoalman]

But would you advise me to filter in real time ,

Any filtering you can apply is preferable in real time providing the filter works well, the filter is applied to the video before it's encoded.

Or will re-encoding the MPEG severely damage the picture quality despite an original high-bitrate MPEG video...

This is one of those depends questions but severely would be a big overstatement in most cases. Any time you renecode, no matter what format your're working with you lose quality. The higher the compression the more your going to lose than if you started with a less compressed source. Using the higher bitrate will certainly help negate this.

Any noise filtering is a detructive process, detail is removed along with noise. Even though you are removing detail light noise removal has a overall pleasing result. You could remove all noise if you wanted but everything is going to have a plastic look. There's a fine line between removing noise and turning your video into a plastic looking animation.

Do some tests once you get your card, make sure to view your tests on a TV.