[FFmpeg-devel] [PATCH v3] avfilter/vf_zoompan: fix shaking when zooming

[Paul B Mahol]

On 1/28/20, Robert Deibel <deibel.robert at googlemail.com> wrote:
> On 27.01.20 16:44, Paul B Mahol wrote:
>> On 1/27/20, Robert Deibel <deibel.robert at googlemail.com> wrote:
>>> -    y = *dy = av_clipd(*dy, 0, FFMAX(in->height - h, 0));
>>> -    var_values[VAR_Y] = *dy;
>>> -    y &= ~((1 << s->desc->log2_chroma_h) - 1);
>>> -
>>> -    out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
>>> +    out = ff_get_video_buffer(outlink, overscaled_w, overscaled_h);
>> This is wrong. outlink->w/h should be used always, otherwise outlink
>> w/h differs from frame w/h.
>>
> So how should I create a video buffer? I tried av_frame_alloc + setting
> width, height and format + av_frame_get_buffer, but this resulted in a
> heavy performance impact. Apart from the fact, that I can't get the
> correct data copied.
>
> Also, if it's not allowed to pass other w/h why is it even possible? Or
> is it only a problem if I use the outlink? Could I request a buffer from
> the inlink with the modified sizes?

Frame w/h should be exactly same as outlink w/h.
Otherwise output will not have always same w/h.
Why are you changing w/h at all?

>
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