#7623: Wrong interpretation of (m)jpeg aspect ratio
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Reporter: UlfZibis | Owner:
Type: defect | Status: new
Priority: normal | Component: avcodec
Version: git-master | Resolution:
Keywords: mjpeg aspect | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
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Comment (by UlfZibis):
The unit of SAR is length/dot
The unit of x/y-resolution is dots/length
So values 12/11 have to be switched for dpi.
If you print the picture on paper, you will get:
x-width = 704/12 = 58.6666... inch
y-height = 576/11 = 52.3636... inch
The resulting DAR then is 1.12 instead 1.333 (4:3).
Additionally it may be better to set the dpi to a reasonable value for the
case if one tries to print the pictures on paper. 72 dpi is a common
value, so here 66/72 dpi may be practicable. For higher resolutions e.g.
HD-Video, the print should not exceed a normal paper sheet.
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Ticket URL: <https://trac.ffmpeg.org/ticket/7623#comment:8>
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