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Aspect Ratio problem with Series 2 649 Tivo

 
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AlexMouse



Joined: 13 May 2009
Posts: 14
Location: State of confusion

PostPosted: Fri May 15, 2009 1:52 am    Post subject: Aspect Ratio problem with Series 2 649 Tivo Reply with quote

Hey guys.

I have an issue that maybe someone might have an idea on that others might not have thought of. My basic question that comes out of this is what exactly controls the -aspect 4:3 or -aspect 16:9 settings?

Here's the issue:

I have a bunch of files (Nero-Digital-encoded mp4) that are supposed to be 4:3 aspect ratio files. I realize that technically they are not really encoded correctly to conform exactly to a 4:3 aspect ratio. For example, a resolution of 528x364, which equates to a display aspect ratio of 1.451.

When I transfer this file to my Series 2 Single tuner, or to my Series 3 box, it visibly looks fine with no distortion. (There may be padding that is not perceptible on my Series 2 Single tuner or on my HDTV with the Series 3, but the image itself is not distorted.)

When transferring these types of files to the above mentioned Tivo boxes, it's using the -aspect 4:3 setting.

However, when transferring the same file to my Series 2 Dual Tuner (TSN begining with 649) box, these files always use the - aspect 16:9 setting and the image is always distorted.

I've tried mucking about with the PyTivo setting, PAR settings, and other items, but nothing seems to change it. The only thing I can do to make these types of files play correctly on my Series 2 Dual Tuner is to re-encode them and change the resolution to something that comes closer to actually being true 4:3.

When I load these files into "MediaInfo" it reports "Original Display Aspect Ratio" as "4/3"

wmcbrine attempted to assist me with this issue before over at the Tivo community forum. He mentioned the 649 Tivo handles things a bit differently because it can supposedly handle 16:9 video natively. I'm not sure I understand this exactly. Changing the "TV Aspect Ratio" setting on this box has no effect whatsoever (that I can tell), even when connected to a 16x9 display. I'm thinking it means that if you send it anamorphic video that it knows what to do with it (correctly letterbox it). (am I right? I can't really test that since I encode all my videos as non-anamorphic square pixel shape)

He may be working on this issue. It still occurs with the latest PyTivo version.

As always I completely appreciate all the help from wmcbrine and anyone else who cares to chime in. I'm just wondering if anyone has any other ideas of a possible temporary work-around.

I'm guessing that in fact there's no way presently to override this on a per file basis, but would such a feature be difficult to add to PyTivo? What I'm thinking is that it could be part of the MetaData the same way that the PAR can be overriden (or could be, at least on previous versions of PyTivo.)

Does anyone else have this same issue?
What do y'all think?

Thanks as always!
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dlfl



Joined: 05 Jan 2008
Posts: 992
Location: Near Dayton, Ohio

PostPosted: Fri May 15, 2009 2:36 pm    Post subject: An idea to try Reply with quote

Maybe this is a problem with the aspect ratio signaling in your .mp4 files. You can use *** mp4box *** to examine the PAR (pixel aspect ratio) for each track and to change it. Changing it should be a fast operation.

An excerpt from mp4box documentation:

Quote:
-par trackID=PAR : sets pixel aspect ratio of given track. PAR can be "none" to remove PAR info, or of the form "N:D" where N is PAR numerator and D its denominator. Only supported for MPEG-4 Visual and MPEG-4 AVC/H264


To get information just: mp4box -info yourFile.mp4

An easy way to get mp4box.exe is to get YAMB (just google).

VideoHelp.com also has Windows Binary download links.

_________________
TiVo Roamio, Win 10 64bit, Wired Ethernet
Try metagenerator 3 and pyTivoMetaGen
VideoReDo users: try VAP
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AlexMouse



Joined: 13 May 2009
Posts: 14
Location: State of confusion

PostPosted: Fri May 15, 2009 8:05 pm    Post subject: Re: An idea to try Reply with quote

dlfl wrote:
Maybe this is a problem with the aspect ratio signaling in your .mp4 files. You can use *** mp4box *** to examine the PAR (pixel aspect ratio) for each track and to change it. Changing it should be a fast operation.


Thanks much for the suggestion. I've actually already tried messing with the PAR. It doesn't make any difference at all. (I originally thought PAR was the issue, just as you suggested.)

The only thing I've found that "fixes" the problem for these files is to change the actual resolution. I'm not really keen to re-encode all my "bad" files, since they play correctly on every other player I've tried. (Every other player being: PyTivo to Series 2 ST, PyTivo to Series 3, Windows Media Player 11, VLC Player, Nero Showtime, D-Link DSM-320, and D-Link DSM-520.)

The problem only manifests itself with the combination of PyTivo and Series 2 Dual Tuner (649).

I'd like an aspect ratio override option in the MetaData. Not so much a "fix" but a really acceptable work-around. I just need to be able to tell it to force "- aspect 4:3" on a per file basis.

I might try and mess with the PyTivo code to see what I can come up with. I'm not really that Python-savvy though so it will probably take me a good long while due to the learning curve.

Thanks for your input though, I do appreciate the response!
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