odd stretching of uncompressed video

mikemo wrote on 6/17/2003, 11:32 PM
hi -

I have 720x480 29.97fps uncompressed video clips. I also have 720x480 29.97fps regular DV clips. When I import them into DVDA and preview the clips, the DV clips look fine...but the uncompressed video clips look "pinched" (like 4:3 footage viewed at 16:9). Both file sets have the same pixel aspect ratios (4:3) and both use DV 0.9 pixels...

Any reason the uncompressed video clips look pinched and the dv files are fine? I imported the same files into Sonic Solutions DVDit...and they all worked fine.

Any insight would be much appreciated...thanks!

Comments

keith314 wrote on 6/18/2003, 12:29 PM
Are you sure you didn't get your uncompressed AVI from a 16x9 DVD? If you actually ripped content from a 16x9 DVD, you would observe 720x480x29.97 fps content with everything skinny. A distorted "resampling" of a frame out to about 854x480 would make the aspect ratio come out about right.
SonySDB wrote on 6/18/2003, 3:56 PM
An uncompressed AVI file does not store its pixel aspect ratio. So, DVD Architect assumes the pixel aspect ratio is 1.0, when in fact it was rendered as 0.909... That's why the uncompressed video clip looks "pinched".
mikemo wrote on 6/19/2003, 11:03 PM
thanks sonicsdb, that's exactly what appears to be happening...is there any way to fix this? or do I need to compress the files before bringing them into DVDA?

If the answer is yes, i do need to compress before bringing the files into DVDA - I did try rendering the uncompressed files using the MPG2 "DVD NTSC" template in the "render as" setup in V4. DVDA didn't allow me to import those files..incidentially, those files were saved by V4 with an ".mv2" extension, instead of just .mpg. Any ideas? Thanks!!!
SonySDB wrote on 6/20/2003, 7:40 AM
There is no good way to work around this problem. The best I can suggest is the following...

1. File | Render As...
2. Set 'Save as type' to 'Video for Windows (*.avi)'
3. Set 'Template' to 'Default Template (uncompressed)'
4. Click Custom...
5. On the Video page, set 'Frame size' to 'Custom frame size'
6. Set 'Width' to '655'
7. Set 'Pixel aspect ratio' to '1.000'
8. Click Ok
9. Click Save

I suspect you used the 'DVD NTSC video stream' template. This creates a .m2v file. A .m2v is a video elementary stream which DVD Architect does not open. Please use the 'DVD Architect NTSC video stream' template. This will create a video-only MPEG file.
eirikso wrote on 9/28/2003, 5:23 PM
This is actually extremely annoying, and the reason why I currently does not use DVDA very much.

I record high quality MJPEG 720x576 on my HTPC. Very often I want to throw some files on a DVD. Right now my files look bad if I throw them right into DVDA because it is impossible to tell DVDA to "stretch to fill output frame". My files are AVI and get interpeted as square pixels by DVDA. So, for serious projects I encode maually using Vegas so I am able to correct the aspect, for all "light and fast" more or less direct-to-DVD-projects I have to use Sonic myDVD, because that program stretch my files to the correct size.

Please include a "stretch to fit output frame" in the next release!

Best regards,
eirikso
RBartlett wrote on 10/2/2003, 10:42 AM
MJPEG 720x576 should be able to hold the aspect ratio field and should be OK in DVDA if it has been set correctly by the HTPC - right?
Uncompressed and MJPEG workflow by transcoding it to MPEG-2 in Vegas4 shouldn't be that much different in length to using DVDA to recompress - right? In both cases DVDA would subsequently have to author/compile the DVD-Video file set.

Perhaps going via Vegas4 when not editing seems like overkill - but surely not in this instance. I use Mediostream's neoDVDplus for quick and dirty, simple menu, MJPEG/DVcamcorder to DVD-Video compilations (Ligos encoder).
BillyBoy wrote on 10/2/2003, 12:05 PM
Exactly. I ALWAYS bring the source into Vegas FIRST then render as a compliant MPEG-2. Many more options and if you use either DV template, the default or the DVD-A one the quality is excellent. While DVD-A can handle uncompressed AVI, in my opinion not a good choice.