I asked about this before but never got a satisfactory answer. On the Thalin Deshaker plugin for Virtualdub, you find this dropdown for selecting pixel aspect ratio.
What specifically do these numbers refer to and which type of video would each pertain to?
I've gotten the answer in here before that "avi doesn't support pixel aspect ratio" but that can't be correct unless Gunnar Thalin was just making these numbers up for fun. The Deshaker plugin is for use with avi video.
Ultimately what I'm trying to determine is the right PAR for 4:3 and 16:9 DV from a Digital8 Sony Handycam. Some of it recorded digitally by the camera, some is analog that the camera is converting. Also what about video that's been converted to Huffyuv or Lagarith from this same video?
Thanks
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Those values come from ITU BT.601
http://www.itu.int/rec/R-REC-BT.601/e
http://lipas.uwasa.fi/~f76998/video/conversion/
For example, looking at the chart in the link the PAR of PAL 720x576 DV is 128/117 or ~1.094
But there are different interpretations and actual usage of PAR values
If you've converted your DV to lagarith properly the actual PAR would be the same as the original. For example, for 4:3 NTSC DV, you would use the same setting in deshaker. -
The real explanation is quite complex because the usual calculations involve a lot of rounding of partial pixels and partial scan lines:
http://lipas.uwasa.fi/~f76998/video/conversion/
Knowing the exact PAR won't help you because DeShaker is limited to the choices you listed. Use the Standard NTSC (0.912) setting for 4:3 NTSC video, Anamorphic NTSC (1.215) setting for 16:9 NTSC video. The values are used internally by DeShaker and won't be reflected in your output AVI file.
When dealing with 704x480 frames most programs use a PAR of 10:11 (0.909) for 4:3 NTSC video, 40:33 (1.212) for 16:9 NTSC video.
PAR is a property of the pixels, not the encoder. It doesn't change because you use a different codec.
The AVI CONTAINER does not support pixel aspect ratios*. That doesn't stop codecs from including such information within their encoded data. It's like putting your video in a box with no label on the outside that says what the pixel aspect ratio is. You can still put a note inside the box indicating the pixel aspect ratio.
Actually, the ODML extension to the original AVI spec have fields for aspect ration information. But I've never seen a program set or use those fields.Last edited by jagabo; 1st Feb 2014 at 11:08.
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