Archived from groups: alt.video.ptv.tivo (
More info?)
Once upon a time, <relaxification@hotmail.com> said:
>I only have experience with .ty files, but I assume that a TiVo file is
>similar, but encrypted.
Yep. I'm running it through GraphEdit with the DirectShow filters to
get a non-encrypted MPEG2 file.
>When I decode a .ty file to an mpeg I end up with a 480x480, 29.97 fps
>mpeg. It's not exactly spec, but my dvd player can handle it. I do a
>quick author and it burns and plays perfectly without any sync issues.
I haven't tried just taking the decrypted MPEG and putting it on DVD. I
want to cut out the commercials, chop the bars off to make an anamorphic
16:9 video, etc.
>I think it's unlikely that the TiVo is going to do any inverse telecine
>on anything. TV is broadcast at 29.97 (in NTSC land, but that should
>be obvious, because we're talking about 3:2 pulldown here, which
>doesn't happen in PAL land...) and
The MPEG encoder in the Series 2 (Broadcom BCM7040) is capable of doing
it according to the data sheet. That obivously doesn't mean TiVo is
configuring it that way, but they could (it would result in better video
compression and maybe a little better quality).
>If it's film-originated, but video-finished, like a high end TV show
>(Law & Order or ER) there will be 3:2 pulldown, but the cadence will
>(likely) change at every cut. It will be indeterminate during
>dissolves.
Not only that, but some filmed TV shows are not 100% filmed. For
example, "Babylon 5" was filed (so 24 fps), but the CGI was rendered at
30 fps for some seasons, so the 3:2 pulldown was done before CGI
compositing.
>I think it's unlikely that a SA TiVo would perform inverse telecine.
>It's an inexact science at best (I used to spend hours figuring out
>cadence changes by eye using a Henry on poorly duped video-finished
>material) and the compression is such that an 80 gig drive provides
>plenty of storage, even with the redundant frames.
20% less space is a significant savings (especially since the hardware
already supports it).
>My guess is that you're messing the file up somehow. Can you examine
>the mpeg? If you're using windows, gspot will tell you the frame rate
>and size. This should be your first clue - if it's not NTSC-like then
>something is happening during the transcoding.
>
>Can you play the mpeg you end up with?
I'm running Linux. The file plays fine in mplayer, but mplayer spits
out warnings that the frame rate is changing between 24000/1001 and
30000/1001. If I try to transcode it, the video ends up out of sync
(and gets progressively worse, which would seem to indicate a frame rate
mismatch).
The file is marked 29.97 fps, 480x480, 4:3 aspect ratio, 3500 kbps
(recorded at "High" quality).
It seems like the problem is that the video is changing frame rates and
that the programs I've tried under Linux can't handle that.
>Try grabbing something you know to be fully film-finished. Make sure
>there's plenty of motion in it. Have a look at your mpeg frame by
>frame (including both fields) and you will be able to tell if inverse
>telecine is happening or (more likely) you're dropping frames somewhere
>in the process.
I will give it a try. However, nothing is reporting that any frames are
being dropped.
--
Chris Adams <cmadams@hiwaay.net>
Systems and Network Administrator - HiWAAY Internet Services
I don't speak for anybody but myself - that's enough trouble.
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