[vlc-devel] [PATCH 6/7] codec/schroedinger: update to inform vlc about clean area

[Laurent Aimar]

On Thu, Nov 27, 2008, davidf+nntp at woaf.net wrote:
> +    /* aspect_ratio_[numerator|denominator] describes the pixel aspect ratio
> +     * the picture aspect ratio is related to the clean width and height */
> +    /* i_aspect is the aspect ratio of the entire frame, vlc will calculate
> +     * the SAR later, and hopefully just display the clean area: Eg.
> +     *  625 line video shuold be 702 active samples which is rounded to 704.
> +     *  This is often transmited as 720 samples, with 8|9 black pels on either
> +     *  side (ie clean area is ~704).  For wide screen, the SAR makes the
> +     *  704x576 raster be 16:9; however the physical aspect ratio for using
> +     *  720 samples would be >16:9.  The same applies to 4:3.
> +     */
> +    p_dec->fmt_out.video.i_aspect = VOUT_ASPECT_FACTOR *
>          ( p_sys->p_format->aspect_ratio_numerator * p_sys->p_format->width ) /
> +        ( p_sys->p_format->aspect_ratio_denominator * p_sys->p_format->height );
 I do not know the range of aspect_ratio_numerator/denominator, but the whole calcul
might overflow 31 bits:
 - VOUT_ASPECT_FACTOR is 432000
 - width can be 1920
 -> numerator has to be lower or equal to 2 to not overflow 2^31...
A cast to int64_t is needed.

-- 
fenrir