mpeg pixel aspect ratio

alexj
Posts: 9
Joined: Tue Sep 10, 2013 9:39 pm

mpeg pixel aspect ratio

Postby alexj » Wed Dec 18, 2013 6:33 pm

Hello RT techies

The files rendered by Video4 and re-encoded by Analysis 8.5 when exported seem to be missing the correct pixel aspect ratio flag so they aren't displayed correctly on computer displays (squashed horizontally).

I guess the pixels in the RT supplied cameras aren't square so you need to display anamorphic-ly on a pc, which means you need to indicate the PAR/display width in the video file. You can re-encode using handbrake with the correct display width to see what I mean.

From the log files I see you are using the ffmpeg library so you may just need to add some params in the right place, you may need to update to the latest version, in which case you might be able to tell it to use a better de-interlacer while you're in there.

Cheers

Alex

Support
Posts: 352
Joined: Mon Nov 21, 2005 4:09 pm

Support

Postby Support » Fri Dec 20, 2013 4:33 pm

Hi Alex,

Can you confirm it is when you are re-encoding NTSC for a video4?

Kind regards,
Support (K)
______________________________
Posted by Race Technology Support

alexj
Posts: 9
Joined: Tue Sep 10, 2013 9:39 pm

Postby alexj » Fri Dec 20, 2013 6:15 pm

In the UK so I am using PAL, this is selected in the config, so 720x576

alexj
Posts: 9
Joined: Tue Sep 10, 2013 9:39 pm

Postby alexj » Mon Feb 29, 2016 8:26 am

I never did get this figured out. Do you have any suggestions why the video created by the video 4 is squashed horizontally when played back?

I have been using Handbrake to reencode the output with the correct par but that has been updated and it is no longer an option. So now I really need a solution from RT otherwise I will end up paying for video editing software to correct the footage.

Maxx
Posts: 194
Joined: Tue Jan 09, 2007 10:25 am
Location: Nottingham, UK
Contact:

Postby Maxx » Tue Mar 01, 2016 10:33 am

Alex,

I've not come across your problem before and do lots with VD4 files.

Does it play OK in the RT VD4 Player?
What about VLC (either using "open with" or altering extension to MPG)?

This is what comes up in my video editing software.

Image

What program are you using for playback?

M.

alexj
Posts: 9
Joined: Tue Sep 10, 2013 9:39 pm

Postby alexj » Tue Mar 01, 2016 10:52 am

Thanks for the reply :)

It plays in the RT VD4 player but the interlacing is horrible and the aspect ratio is not correct.

Here's what it looks like if you render it straight from RT Analysis
https://www.youtube.com/watch?v=xDZ5vlS0GTo

And this is what it looks like corrected in handbrake
https://youtu.be/bvjq8YMngvQ?t=1m32s

Two different 964s but you can see the first one is a bit thin.

Maxx
Posts: 194
Joined: Tue Jan 09, 2007 10:25 am
Location: Nottingham, UK
Contact:

Postby Maxx » Tue Mar 01, 2016 11:23 am

Hmm, the sorts of things I can think might cause that are :-

1) NTSC bulletcams
2) Using an NTSC .VGL for layout.

I know the layout in the handbrake corrected video is correct as it's originally one of mine (could have been messed with though)

Do you record straight video and add the overlay later (post process) or do you capture WITH the overlay already in the layout on the Video4?

M.

alexj
Posts: 9
Joined: Tue Sep 10, 2013 9:39 pm

Postby alexj » Tue Mar 01, 2016 11:27 am

Yes indeed it is based on one of your layouts that you kindly shared. Most of the layout is rendered in the Video 4 and I overlay a couple of items when rendering in Analysis.

The bullet cameras are labelled as PAL but if they were infact NTSC and just mislabelled it did occur to me that could be where the issues lie.

The VGL is setup for PAL.

In some ways NTSC is more useful these days as youtube and the defaults for video rendering are often setup for NTSC line count.

Maxx
Posts: 194
Joined: Tue Jan 09, 2007 10:25 am
Location: Nottingham, UK
Contact:

Postby Maxx » Tue Mar 01, 2016 11:39 am

I think you should be able to check the camera spec by looking at the FPS. NTSC is 30fps (near enough) whereas PAL is 25fps.

NTSC is 525 line (vertical) and PAL is 576 so if something was recorded at 525 but displayed at 576 then you'd get the sort of effect you are seeing.

I'm not sure what effect having a PAL layout on an NTSC camera would have or vice-versa so this complicates things somewhat.

If the cams are NTSC by mistake then just using NTSC layouts will give you proper proportions. I don't THINK the fps is controlled by the .VGL layout file but not 100% sure.

If your vids are not 25fps though then they aren't being captured on a PAL camera.

HTH

M.

pault
Posts: 64
Joined: Fri Nov 02, 2007 4:53 pm
Location: St Charles, IL

Video Formats

Postby pault » Tue Mar 01, 2016 4:15 pm

PAL has 576 active video lines but NTSC doesn't have 525 active video lines. About 40 of the 525 NTSC lines do not have video on them.

Paul


Return to “Bug reports”

Who is online

Users browsing this forum: No registered users and 1 guest