why AVI DV<->AVI uncompressed conversion changes video

[ferro]

Hello everyone!
I tried hard to find a solution on the forum thru Search, but I did not succeed. Perhaps I just do know what keywords to look for, so at least redirect me to the right topic.

I have the following observations.

UVS8.0 shrinks videos horizontally (about 22 pixels from each side) when I create AVI(DV, type-2) files from uncompressed AVIs. I perform the format change as follows: in a new project I put AVI on timeline and create a new video file with Share > Create Video File.

It also crops videos vertically (about 18 pixel at top and bottom) when I create an uncompressed AVI from AVI(DV, type-2).

When simply converting these same files with VirtualDub, the changes do not occur. When I use Panasonic DV type 2 codec in place of built-in UVS DV type 2 codec, the software behaves in the same way shrinking/cropping.

The changes do cumulate if next format change is performed on the outcome of the previous one.

Please tell me what I am doing wrong.

PAL (25 fps)
Microsoft AVI files
24 Bits, 720 x 576, 4:3, 25 fps
Lower Field First
Panasonic DV CODEC -- type 2
Interleave audio for every 1 frames
PCM, 44,100 kHz; 16 Bit; Stereo

Ulead VideoStudio 8.00.000
Win XP Pro SP1
Dell Latitude Pentium 4 2,0GHz

[Ken Berry]

I have not done the same as you (converting to or from Type2 DV/AVI and uncompressed AVI), but I have noticed the same thing when producing a DV Type 2 video in Adobe Premiere 2.0 then opening it for conversion to DVD-compatible mpeg-2 in VS10+. I don't appear to have vertical cropping, though -- only horizontal. I think it has something to do with the different codecs used by the two programs. I have searched for quite some time to find a way around this, but no luck so far.

It is annoying, but I have learned to live with it. This is because when I burn those particular mpeg-2s to DVD, they display perfectly on my TV i.e. the same width and height as my other mpeg-2s. I think this is probably because the amount trimmed off the DV video is well within the 'safe area' and so the black bars will never show (except perhaps on a progressive scan TV?)

The curious thing, though, is that the properties of those files show as conforming perfectly to the PAL frame size of 720 x 576. So I am stumped. Maybe it is only a display attribute associated with the codec which shows one size on the computer screen, but behaves normally when burned to disc.

[Data-Base]

as I know Ulead, Adobe and Sony Vegas use MainConcept MPEG Codecs

[Ken Berry]

Yes. I agree they are supposed to use MainConcept mpeg-2 codecs. Adobe, at least, also used the MainConcept DV2 encoder.

My problem with that, though, is that with the DV files out of Adobe Premiere Pro, when I open them in VS10+ and look at the properties, it actually tells me that a MainConcept codec was used (and apparently produced the loss of pixels on the side). When I use Video Studio to capture and edit and then produce a new DV/AVI file, its properties are 'Microsoft AVI files -- Open DML'. It is this difference that I cannot understand and which is driving me crazy at the moment (in a restrained kind of way!)

[ferro]

I have some observation that might explain the situation to some extent. On the other hand I still do not know where is the real reason.

In Media Player Classic, AVI(DV) clips created by UVS8 play with screen resolution 768x576 even though in file properties, the tool says the clip is "720 x 576 (AR 4:3)". AVI(uncompressed) and other AVIs (DivX for example) are displayed with vertical size identical to the one stated in the file, that is 720 pixels. VirtualDub displays all these AVIs with a width of 720 pixels.

My guess is MPC somehow assumes pixel aspect ratio different then 1:1. This is also might also be why UVS is fooled by files it created.

Best regards,
ferro.