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  1. Member brassplyer's Avatar
    Join Date: Apr 2008
    Location: United States
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    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.

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    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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  2. Member DB83's Avatar
    Join Date: Jul 2007
    Location: United Kingdom
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    You do realise that vdub can import video formats other than avi. It only exports to avi. Nos 2-5 refer to mpeg2-dvd.

    DV is always 720*576 for PAL. You can simply check the PAR by loading your video into mediainfo. But Digital8 is surely not DV ???????
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  3. Member
    Join Date: Jun 2012
    Location: USA
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    Electronically digital 8 is exactly DV. (Apologies for contradicting a generally wise contributor.)

    Standard PAL/NTSC is 4:3, Anamorphic PAL/NTSC is 16:9 Lagarith and Huff conversions might be anything.
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  4. Member DB83's Avatar
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    No apology needed. One learns something new every day
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  5. Member
    Join Date: Sep 2007
    Location: Canada
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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.
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  6. Originally Posted by brassplyer View Post
    Ultimately what I'm trying to determine is the right PAR for 4:3 and 16:9 DV from a Digital8 Sony Handycam.
    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.

    Originally Posted by brassplyer View Post
    Also what about video that's been converted to Huffyuv or Lagarith from this same video?
    PAR is a property of the pixels, not the encoder. It doesn't change because you use a different codec.

    Originally Posted by brassplyer View Post
    I've gotten the answer in here before that "avi doesn't support pixel aspect ratio"
    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 12:08.
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