[FFmpeg-devel] [PATCH 2/2] libavfilter/scale2ref: Maintain main input's DAR

[Kevin Mark]

I've been using this patch for the past week now and I believe it's
good to go. Does someone want to take a second look before merging?

On Mon, Jun 5, 2017 at 6:55 AM, Kevin Mark <kmark937 at gmail.com> wrote:
> The scale2ref filter will now maintain the DAR of the main input and
> not the DAR of the reference input. This previous behavior was deemed
> counterintuitive for most (all?) use-cases.
>
> Before:
> scale2ref=iw/4:ow/mdar
> in  w:320 h:240 fmt:rgb24 sar:1/1
> ref w:640 h:360 fmt:rgb24 sar:1/1
> out w:160 h:120 fmt:rgb24 sar:4/3 flags:0x2
> SAR: ((120 * 640) / (160 * 360)) * (1 / 1) = 4 / 3
> DAR: (160 / 120) * (4 / 3) = 16 / 9
> (main out now same DAR as ref)
>
> Now:
> scale2ref=iw/4:ow/mdar
> in  w:320 h:240 fmt:rgb24 sar:1/1
> ref w:640 h:360 fmt:rgb24 sar:1/1
> out w:160 h:120 fmt:rgb24 sar:1/1 flags:0x2
> SAR: ((120 * 320) / (160 * 240)) * (1 / 1) = 1 / 1
> DAR: (160 / 120) * (1 / 1) = 4 / 3
> (main out same DAR as main in)
>
> The scale2ref FATE test has also been updated.
>
> Signed-off-by: Kevin Mark <kmark937 at gmail.com>
> ---
>  libavfilter/vf_scale.c                      | 6 +++---
>  tests/ref/fate/filter-scale2ref_keep_aspect | 2 +-
>  2 files changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/libavfilter/vf_scale.c b/libavfilter/vf_scale.c
> index 9232bc4439..5e55f9344b 100644
> --- a/libavfilter/vf_scale.c
> +++ b/libavfilter/vf_scale.c
> @@ -337,10 +337,10 @@ static int config_props(AVFilterLink *outlink)
>          }
>      }
>
> -    if (inlink->sample_aspect_ratio.num){
> -        outlink->sample_aspect_ratio = av_mul_q((AVRational){outlink->h * inlink->w, outlink->w * inlink->h}, inlink->sample_aspect_ratio);
> +    if (inlink0->sample_aspect_ratio.num){
> +        outlink->sample_aspect_ratio = av_mul_q((AVRational){outlink->h * inlink0->w, outlink->w * inlink0->h}, inlink0->sample_aspect_ratio);
>      } else
> -        outlink->sample_aspect_ratio = inlink->sample_aspect_ratio;
> +        outlink->sample_aspect_ratio = inlink0->sample_aspect_ratio;
>
>      if (ctx->filter == &ff_vf_scale2ref) {
>          av_log(ctx, AV_LOG_VERBOSE, "in  w:%d h:%d fmt:%s sar:%d/%d\n",
> diff --git a/tests/ref/fate/filter-scale2ref_keep_aspect b/tests/ref/fate/filter-scale2ref_keep_aspect
> index ca03277446..8dd0dbb13b 100644
> --- a/tests/ref/fate/filter-scale2ref_keep_aspect
> +++ b/tests/ref/fate/filter-scale2ref_keep_aspect
> @@ -5,7 +5,7 @@
>  #media_type 0: video
>  #codec_id 0: rawvideo
>  #dimensions 0: 160x120
> -#sar 0: 4/3
> +#sar 0: 1/1
>  #stream#, dts,        pts, duration,     size, hash
>  0,          0,          0,        1,    57600, 9a19c23dc3a557786840d0098606d5f1
>  0,          1,          1,        1,    57600, e6fbdabaf1bb0d28afc648ed4d27e9f0
> --
> 2.13.0
>