[MPlayer-dev-eng] [PATCH] better handling of lavc's aspect option (was Re: Question about lavcopts's aspect= option)

[Michael Niedermayer]

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