CurtPalme.com Home Theater Forum

[perisoft]

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First the story, and then the idea.

Here's the story:

I haven't got high def where I live - or at least, only a few HD channels via ATSC over cable. I use a regular TiVo so no hidef there anyway, and I don't feel like upgrading the tivo ($$$$) for a few HD channels when I have the PJ and can get a TV card cheaper if I ever want to do that.

I'm going to be feeding either a 42" RPTV or a 42" SD plasma with the signal from the TiVo - the best output is s-video.

Here's the idea:

One of the biggest pains-in-the-ass of SD content on an HD or ED TV is the letterboxing. I can set either TV to expand the image so 16:9 content fills correctly, but then 4:3 content is broken. It sucks to have to constantly switch back and forth depending on material.

What I'd like to do is: Take the s-video TiVo output, and run it to a dedicated PC via a TV card. I want to feed that input through FFDShow and Avisynth, and write an Avisynth script to detect letterboxed frames and automatically expand the video to match.

This has the side effect of being able to perform a bit of other processing, but since it's getting processed by the tivo and re-encoded as MPEG2, and then upconverted to progressive by the display anyway, 'line doubling' or deinterlacing is a moot point.

The main thing is to detect and compensate for letterboxing.

Has anybody ever fed a live TV card capture through ffdshow/avisynth in real time? Advice appreciated!

[ecrabb]

I don't know why it wouldn't work, but if it would/does, I bet there are guys over at the AVS HTPC forum who have already done it. If you haven't already, I'd post over there.

Funny anecdote... I just found out week before last, that my little USB HDTV receiver software does almost what you're talking about. We had it hooked up to our office XGA projector during a few of the March Madness games. Obviously, during all the basketball HD commercials, it was letterboxed, right? What was interesting is when it came to a 4:3 commercial, the video would 'pop' into 4:3 mode and use the whole XGA panel. If the software wouldn't have had that feature, those commercials would have been letterboxed and pillarboxed. I haven't looked, but I assume there was a preference in there somewhere because it wouldn't have been too handy if we'd had a 16:9 screen at the office.

Man, I can't wait until everything is 16:9 99% of the time and we won't have to worry about aspect ratio. It will help when there's enough HDTV's out there that the broadcasters can just start broadcasting everything anamorphic and let everybody with the dinosaur TV's watch tall/skinny programming instead of everybody with the nice widescreen TV's having to watch short/fat programming.

SC

[perisoft]

I'm thinking that any TV tuner software which supports FFDShow ought to be able to do what I need; I'll just have it feed in straight from the DVR. The main trick is that my extra PC is a celeron 1000 or something, so I'm not sure it can do the processing I need. I don't need much; it's going to capture in 640x480 and process to 852x480, but I'm not sure how efficient I can make the letterbox detector without having it zoom way the hell in on scenes which are very dark with a little content in the middle! If I make it infinitely fast and smooth it a bit it'll just look like the director was on crack for all of those scenes... if I stick to Michael Bay movies I'll never know the difference

[Tedd]

I've used an Immersive Holo3Dgraph card (for a sdi'ed dvd player). It can accept 480i via component, composite, s-video or sdi.

The pci bus is limited to 480i input (480P will mean dropped frames- the bandwidth is just not there....) so that is a limiting factor.

[Angus_rg]