PAR aspect incorrect ?

Mike M. wrote on 9/2/2014, 1:45 AM

I searched a little for this, but got some inconsistent results.

I have some old media files that I encoded using MJPEG in an AVI container.
Using "MediaInfo" the file info is 720x480 @ 3:2

Matching project properties, it Vegas reads square pixels ...or... 1:1 for the PAR
But, I'm unsure if that is correct since it looks a little squashed or tubby.

If I change both the project properties and the media properties to .909 PAR,
the video looks (I think) better in terms of aspect.

Granted, I'm a bit baffled on figuring out just exactly what these source MJPEG videos are in terms of PAR and what settings I should use for both the Media and Project properties.

Mike

Source Media
Format : AVI
Format/Info : Audio Video Interleave
File size : 140 MiB
Duration : 3mn 32s
Overall bit rate : 5 550 Kbps

Video
ID : 1
Format : JPEG
Codec ID : MJPG
Duration : 3mn 32s
Bit rate : 4 122 Kbps
Width : 720 pixels
Height : 480 pixels
Display aspect ratio : 3:2
Frame rate : 25.000 fps
Standard : NTSC
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Compression mode : Lossy
Bits/(Pixel*Frame) : 0.477
Stream size : 104 MiB (74%)

Comments

musicvid10 wrote on 9/2/2014, 7:39 AM

Those files were meant for hardware decoding and rarely report correctly.
If .909 looks close, another one to try is .889.
The fact that it is NTSC and 25 fps bothers me also?
Sounds like there may have been some mistakes when it was captured.

John_Cline wrote on 9/2/2014, 7:44 AM

AVI files don't typically contain a field in the header for PAR, the exception being files encoded using the DV codec. If it's 720x480 and the display is intended to be 4:3, then the PAR is almost certainly .909 and will need to be set manually in the clip's properties.

I, too, am a little puzzled by the 25 frame per second rate.

musicvid10 wrote on 9/2/2014, 8:05 AM

My old mjpegs often look a bit 'squished' just because I am used to a wider display aspect. Although technically incorrect, I sometimes "fatten" them a bit when using alongside widescreen source in a project.

Mike M. wrote on 9/2/2014, 9:45 AM

As I recall, I used Vlc to stream web content ( youtube for example) and convert on the fly to avi/mjpeg. Doing that, produced the 25 fps. Some of that content may have been 720p.

I know this is very illconceived, but I only have a few files and they're just for family use.

Is there software that will report the true Par, or is it just a visual guess ?

musicvid10 wrote on 9/2/2014, 9:59 AM

That type of AVI does not support anamorphic, period, and uses a modulus of 4. You will never see a "correct" flag because it doesn't exist.

Find a circle in the footage to visually match, or set the PAR at .9091 and be done with it. As with John Cline, I suspect that is correct.

Mike M. wrote on 9/2/2014, 1:45 PM

Thanks for the help musicvid10, John and the group