[vlc-devel] [PATCH] swscale: modify output aspect ratio if transformation is not homothetic

[Rémi Denis-Courmont]

Le mercredi 30 avril 2014, 17:41:25 Felix Abecassis a écrit :
> Close #10745

Seems OK, but but maybe a XXX EXPLICIT HACK PARENTAL ADVISORY warning is 
missing.

> ---
>  modules/video_chroma/swscale.c | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
> 
> diff --git a/modules/video_chroma/swscale.c b/modules/video_chroma/swscale.c
> index 4b763dd..03cc414 100644
> --- a/modules/video_chroma/swscale.c
> +++ b/modules/video_chroma/swscale.c
> @@ -430,6 +430,24 @@ static int Init( filter_t *p_filter )
>          return VLC_EGENERIC;
>      }
> 
> +    if (p_filter->b_allow_fmt_out_change)
> +    {
> +        /*
> +         * If the transformation is not homothetic we must modify the
> +         * aspect ratio of the output format in order to have the
> +         * output picture displayed correctly and not stretched
> +         * horizontally or vertically.
> +         */
> +        unsigned i_sar_num = p_fmti->i_sar_num * p_fmti->i_visible_width;
> +        unsigned i_sar_den = p_fmti->i_sar_den * p_fmto->i_visible_width;
> +        vlc_ureduce(&i_sar_num, &i_sar_den, i_sar_num, i_sar_den, 65536);
> +        i_sar_num *= p_fmto->i_visible_height;
> +        i_sar_den *= p_fmti->i_visible_height;
> +        vlc_ureduce(&i_sar_num, &i_sar_den, i_sar_num, i_sar_den, 65536);
> +        p_fmto->i_sar_num = i_sar_num;
> +        p_fmto->i_sar_den = i_sar_den;
> +    }
> +
>      p_sys->b_add_a = cfg.b_add_a;
>      p_sys->b_copy = cfg.b_copy;
>      p_sys->fmt_in  = *p_fmti;

-- 
Rémi Denis-Courmont
http://www.remlab.net/