[MPlayer-dev-eng] mpeg muxer & dvd pack scr

[Tobias Diedrich]

Hi Nico,

I'm currently comparing the output from mplex and mencoder -of mpeg
and found that mencoder seems to put wrong scr timestamps into the
pack headers.

Looking at stream generated by mplex it looks like this:

pack  scr_base   scr_ext   scr       △scr
0     0          0         0
                                     43885
1     146        85        43885
                                     43886
2     292        171       87771
                                     43886
3     438        257       131657


This looks alright, since the pack size is 2048Byte, muxrate is
10080kbit and reference clock is 27MHz, so reading the sector
should take 2048/(10080*1000/8)*27000000 = 43885.7136 cycles.

However mencoder generates the following:

pack  scr_base   scr_ext   scr       △scr
0     0          0         0
                                     0
1     0          0         0
                                     252300
2     841        0         252300
                                     253200
3     1685       0         505500
                                     253800
4     2531       0         759300

Looking at the code, it seems that the muxer uses the same reference
clock for both audio/video and the pack headers, which is wrong
AFAICT (and explains why the first two packs have the same scr).
It also does not write the scr extension even though it has an extra
function for writing mpeg2 scr.

Note that dvdauthor recalculates this anyway, so this is not
terribly important, but still...

-- 
Tobias						PGP: http://9ac7e0bc.uguu.de