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Re: [HDTV-in-SFbay] Cozi Sherlock Holmes Postage Stamp aspect continues.

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  • Ron Economos
    The pixel (sample) aspect ratio can be calculated like this (from section 6.3.3 of the MPEG-2 specification I linked to): sample aspect ratio = display aspect
    Message 1 of 30 , Mar 1, 2013
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      The pixel (sample) aspect ratio can be calculated like this (from
      section 6.3.3 of the MPEG-2 specification I linked to):

      sample aspect ratio = display aspect ratio * horizontal size / vertical size

      So for 1920x1080 at 16:9 it would be:

      (9/16) * (1920/1080) = 1 (square pixels)

      For 704x480 at 16:9 it would be:

      (9/16) * (704/480) = 0.825 (non-square pixels).

      The typical way to test aspect ratios is to use a test pattern
      with circles. Any distortion can be easily seen. Here's a
      few bitstreams I created with a hardware MPEG-2 encoder.

      1) 720x480 at 16:9, just like Cozi is sending except 720 wide instead of 704

      http://www.w6rz.net/aspect16x9.ts

      2) 544x480 at 16:9, just to see how the decoder handles it. 544 wide is a
      valid MPEG-2 resolution.

      http://www.w6rz.net/aspect16x9_544.ts

      3) 720x480 at 4:3 with a display extension for 16:9. Again, just to see
      how the decoder handles it. A compliant decoder should display a
      16:9 image even though the aspect ratio is signaled as 4:3. Most
      (but not all) versions of VLC will do the correct thing.

      http://www.w6rz.net/aspect16x9_ext.ts

      All clips are about a minute long and about 144 Megabytes. Audio
      is silent. Have fun!

      Ron

      On 2/28/2013 10:00 PM, Stephen H. Fischer wrote:
       

      Hi,

      I was able to download the documents. There is not sufficient time remaining in my life to understand much.

      Thanks.

      I am wondering if this guess is ~ correct,

      That the pixel shapes for the following resolutions is about the same:

      1920x1080 (16:9 program on 16:9 display)

      1280x720 (16:9 program on 16:9 display)

      704x480 (16:9 program on 16:9 display)

      704x480 (4:3 program on 4:3 display)

      > For some reason, the aspect ratio of non-square pixel

      > formats like 704x480 is very difficult for folks to understand.

      I think I am in that class, but then "string theory" is just as far beyond me.

      You do say non square, does that mean that the first two are square?

      I do have an idea of the "big bang" down very hot.

      Looking at your pictures I think that they were not helpful to me was because they did not show the additional black bands I am seeing.

      I was looking at a screen that is fixed in size with an additional black band and your pictures were wider than each other with out the additional black band.

      The document parts I scanned clearly show 704x480 in places. So that was not just stations guessing at a V and H.

      Finding two streams marked 704x480 (4:3) in addition to COZI's 704x480 (16:9) was a surprise.

      ------------------------------

      I now have a Magnum, P.I. Which the OP first complained about.

      It looks exactly like Sherlock Holmes does on Fusion with original ratio selected, an additional BLACK band on both sides. Selecting 16:9 Fixed produces a normal picture. MyHD and VLC Media Player also show a normal picture.

      So this problem is understood, an programming error in the tuner!

      SHF

    • Stephen H. Fischer
      Hi, Fusion with 16:9 Fixed showed all three clips at full width on my 16:9 screen When I switched to Original Ratio 3) had the BLACK bands added to each
      Message 2 of 30 , Mar 1, 2013
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        Hi,
         
        Fusion with "16:9 Fixed" showed all three clips at full width on my 16:9 screen
         
        When I switched to "Original Ratio" 3) had the BLACK bands added to each side and the circles were not round.
         
        My new 6 - Million Dollar Man Eyes could not really tell any difference with "16:9 Fixed" between the three.
         
        If you have a FTP for uploads, send me a PM with password, I captured an interesting KGO test pattern long ago. (3/6/2006) It's 39 MB in size.
         

        mailto:a_nani_mouse@...

        SHF
        ----- Original Message -----
        Sent: Friday, March 01, 2013 4:49 PM
        Subject: Re: [HDTV-in-SFbay] Cozi Sherlock Holmes Postage Stamp aspect continues.

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