Why does the resolution change after burning?

[tastypoison]

I download TV episode SVCD's from newsgroups - I don't create my own.

I extract the mpeg's from the rar files and always test them before burning with Nero. I test with PowerDVD.

Now, on some of these episodes (not all), when I test the file on my harddrive, PowerDVD reports its resolution as 480 x 480. However, once I burn the video to disk using Nero, PowerDVD then reports the resolution as 352 x 480. Almost all of the Futurama episodes I found do this (Fullscreen). Some of the Stargate SG-1 episodes are this way as well (Fullscreen or Widescreen depending on the source).

Nero is not re-encoding the files - just checking them, and they are found to be standard compliant. So, why is the reported resolution different once the file is burned on a disk?

Something else I've noticed is the reporting of the TV standard (NTSC/PAL). Playing the file back from the hard drive and checking the options shows the resolution, frames per second, and TV system (NTSC/PAL). The same file burned to CD only shows resolution and frames per second - the TV system tag is lost.

Any ideas?

[tastypoison]

I'm sorry, I don't think this is the appropriate forum...

Can this thread be moved to a more appropriate location?

[adam]

I wonder if PowerDVD is just misreporting the resolution. You source is clearly 480x480 and if Nero did transcode it to 352x480 you would surely realize it. I don't see how your output could be anything but 480x480. Try analyzing the mpg in BitrateViewer. It should give accurate resolution.
http://www.tecoltd.com/bitratev.htm

I think your SVCDs are probably fine.

[tastypoison]

Here is an example of what I am seeing. For some reason, the screen shot is not capturing the video in the PowerDVD window, but it is the same video in both cases. I'm sorry the screens look so bad...I had to compress the heck out of them to get them under the max 50 KB size.

Copy on my hard drive:


Copy burned to CD as an SVCD in Nero:

[tastypoison]

And here, BitrateViewer shows the 480x480 resolution for the burned CD...It's definately wrong in PowerDVD. Any ideas why? Is it related to Nero?

[adam]

Well the only thing that should be different about the burnt mpg is that a riff file header is added. This essentially tells the playback device certain info about the stream. Perhaps PowerDVD is misinterpreting this somehow. The closest DVD compliant resolutoin to 480x480 is 352x480. Perhaps PowerDVD is reverting to this. Sorry I really have no idea.

In any case its not that big of a deal now that you know. PowerDVD is only misreporting the resolution, its still playing it at the same resolution. At least from your post it sounds like the video looks the same, and on of course on a hardware player it should look correct. In the future just don't use PowerDVD to test resolution.

BTW: If PowerDVD allows you to adjust hardware accellaration, then you may be able to capture the video picture by turning it all the way off. Otherwise, you can use capture proggies like Hyersnap to take the screen capture.

[tastypoison]

Yeah, it's not a big deal...it just bugs me

I had just read an article here about CVD with resolution of 352x480, and it got me to wondering if what I had wasn't really SVCD.

Thanks.