On Sat, Jul 2, 2011 at 8:24 AM, Maksym Veremeyenko <[email protected]> wrote:
> Hi,
>
> i recently notices higher cpu activity for some files during playback
> and found they been rescaled from 720x576 to 720x562.
>
> problem comes from different PAR that files has, actually differently
> overridden.
>
> default consumer *dv_pal* has:
> [...]
> sample_aspect_num=16
> sample_aspect_den=15
> [...]
>
> producer *producer_avformat.c* has own PAR override code in
> *get_aspect_ratio* that setup:
>
> 64:45 for PAL 16:9
> 16:15 for PAL 4:3
> 32:27 for NTSC 16:9
> 8:9 for NTSC 4:3

These are consistent. The reason we prefer these values is for
symmetry with avcodec mpeg2 and other mathematically-correct profiles,
i.e. width/height * sar = dar. To be correct requires some automatic
cropping, which we did not have for a long time, or padding, which is
uglier. Now I can add automatic-cropping, but I have not yet gotten
around to (it is on the ToDo list on the wiki).

> in the same time  *producer_libdv.c* defined PAR for video according to
> ITU Rec.601:
>
> 118.0/81.0 for PAL 16:9
> 40.0/33.0 for NTSC 16:9
> 59.0/54.0 for PAL 4:3
> 10.0/11.0 for NTSC 4:3

oops, these are not consistent. Why was your application use dv
producer instead of avformat?

> so, what is solution?:
> 1. honor ITU 601: change dv_pal profile to 59:54, drop avformat
> overriding code
> 2. use non-ITU PARs and fix *producer_libdv.c* to provide non-ITU pixel
> aspect ratios

I will apply your patch.

-- 
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