[MPlayer-dev-eng] vf.c & PEREFER_ALIGNED_STRIDE

[Ivan Kalvachev]

Arpi said:
> Hi,
>
>> Arpi said:
>> > Hi,
>> >
>> >> I was browsing the source of mplayer to understand what and how the
>> vo system works.
>> >> Well this peace of code amaze me. I cannot understand what it does.
>> In fact i cannot understand why it does that it does. Well sounds
>> confusing.
>> >
>> > Why?
>> > It's quite easy:
>> >
>> > if the codec/filter wants aligned stride, then we ask the next
>> filter/vo if it supports stride!=width (ACCEPT_STRIDE) and if yes,
>> then adjust stride to be macroblock aligned.
>> But we DO NOT change the stride! We change the width.
>> That is what i cannot understand!
>
> stride is calculated from width ~20 lines bellow in that func when doing
> memalign() allocation.
Good. But the question remains. Why we change the width?
Look -> if a filter/vo ACCEPT_STRIDE, then it gets image that have
stride=width*bpp/8. And we change the width to perform this! No sense.
If a filter/vo doesn't accpet stride then we may change the width, but why
change it elsewere?

Best Regards
  Ivan Kalvachev