[MPlayer-dev-eng] [PATCH] better handling of lavc's aspect option (was Re: Question about lavcopts's aspect= option)
Michael Niedermayer
michaelni at gmx.at
Mon Nov 25 12:22:29 CET 2002
Hi
On Monday 25 November 2002 10:36, Michael Niedermayer wrote:
[...]
> btw, the aspect code for mpeg1/2 in video.c looks wrong too
heres the relevant part of the MPEG1 std
----------
pel_aspect_ratio -- This is a four-bit integer defined in the
following Table.
|pel_aspect_rati|height/width |example |
|o | | |
|0000 |forbidden | |
|0001 |1.0000 |VGA etc. |
|0010 |0.6735 | |
|0011 |0.7031 |16:9, 625line |
|0100 |0.7615 | |
|0101 |0.8055 | |
|0110 |0.8437 |16:9, 525line |
|0111 |0.8935 | |
|1000 |0.9157 |CCIR601, |
| | |625line |
|1001 |0.9815 | |
|1010 |1.0255 | |
|1011 |1.0695 | |
|1100 |1.0950 |CCIR601, |
| | |525line |
|1101 |1.1575 | |
|1110 |1.2015 | |
|1111 |reserved | |
----------
for MPEG2:
---------
aspect_ratio_information -- This is a four-bit integer defined in the
Table 6-3.
aspect_ratio_information either specifies that the "sample aspect ratio"
(SAR) of the reconstructed frame is 1,0 (square samples) or alternatively
it gives the "display aspect ratio" (DAR).
+ If sequence_display_extension() is not present then it is
intended that the entire reconstructed frame is intended to be mapped
to the entire active region of the display. The sample aspect ratio
may be calculated as follows:
[pic]
NOTE - In this case horizontal_size and vertical_size are
constrained by the SAR of the source and the DAR selected.
+ If sequence_display_extension() is present then the sample
aspect ratio may be calculated as follows:
[pic]
Table 6-3 - aspect_ratio_information
|aspect_ratio_informat|Sample Aspect|DAR |
|ion |Ratio | |
|0000 |forbidden |forbidden |
|0001 |1,0 (Square |- |
| |Sample) | |
|0010 |- |3÷4 |
|0011 |- |9÷16 |
|0100 |- |1÷2,21 |
|0101 |- |reserved |
|( | |( |
|1111 |- |reserved |
---------
[...]
Michael
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