[Theora-dev] Directshow filters 0.64.7923

[illiminable]

----- Original Message ----- 
From: "Timothy B. Terriberry" <tterribe at vt.edu>
To: "Robert Huitl" <theora-dev at huitl.de>
Cc: <theora-dev at xiph.org>
Sent: Sunday, October 10, 2004 1:24 AM
Subject: Re: [Theora-dev] Directshow filters 0.64.7923


>> The yOffset is wrong, though. With this theora block for decoding, the 
>> result is as seen on http://www.huitl.de/theora/wrong-yoffset.jpg. I get 
>> correct results using this formula:
>> xOffset = width % 16
>> yOffset = height % 16
>> For the example shown above, yOffset will then be 8. With resolution 320 
>> x 240, yOffset will be 0 and this seems to be correct, too.
>
> This is probably a confusion over whether yOffset is counted from the top 
> or from the bottom of the image (I actually forget which way is which in 
> the reference library). Also, note that both xOffset and yOffset should be 
> made even by the encoder to make chroma siting work as expected. See 
> Chapter 4 of the spec for details.

I followed the code in example_player... which centralises the offsets... if 
there will be x_offset at the left and right and y_offset at the top and 
bottom.

  frame_x_offset=(video_x-frame_x)/2;
  frame_y_offset=(video_y-frame_y)/2;

So in the example shown above... i think 4 is correct... Are you sure the 
offset values are being correctly propagated to the decoder ?

Zen.
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