Re: [FFmpeg-devel] [PATCH] avfilter: add vf_yazf filter

[Gyan Doshi <ffmpeg@gyani.pro>]

On 2025-05-31 08:19 pm, Quentin RENARD wrote:
> zoompan filter with floating point precision

If this filter is meant to be same as existing zoompan but more precise, 
then you should modify the original filter with a mode option for FP use.

Regards,
Gyan


>
>   
>
> Signed-off-by: Quentin Renard <contact-github@asticode.com>
>
> ---
>
>   Changelog                |   1 +
>
>   doc/filters.texi         |  59 +++++++
>
>   libavfilter/Makefile     |   1 +
>
>   libavfilter/allfilters.c |   1 +
>
>   libavfilter/vf_yazf.c    | 360 +++++++++++++++++++++++++++++++++++++++
>
>   5 files changed, 422 insertions(+)
>
>   create mode 100644 libavfilter/vf_yazf.c
>
>   
>
> diff --git a/Changelog b/Changelog
>
> index 4217449438..632d0e03d1 100644
>
> --- a/Changelog
>
> +++ b/Changelog
>
> @@ -18,6 +18,7 @@ version <next>:
>
>   - APV encoding support through a libopenapv wrapper
>
>   - VVC decoder supports all content of SCC (Screen Content Coding):
>
>     IBC (Inter Block Copy), Palette Mode and ACT (Adaptive Color Transform
>
> +- yazf filter
>
>   
>
>   
>
>   version 7.1:
>
> diff --git a/doc/filters.texi b/doc/filters.texi
>
> index 63f55f5794..4fa5be9e94 100644
>
> --- a/doc/filters.texi
>
> +++ b/doc/filters.texi
>
> @@ -25986,6 +25986,65 @@ Set blur strength. Default value is 128.
>
>   @subsection Commands
>
>   This filter supports same @ref{commands} as options.
>
>   
>
> +@section yazf
>
> +
>
> +Apply Zoom & Pan effect with floating point precision ("yazf" means "yet another zoompan filter").
>
> +
>
> +This filter accepts the following options:
>
> +
>
> +@table @option
>
> +@item z
>
> +Set the zoom expression. Range is 1-10. Default is 1.
>
> +
>
> +@item x
>
> +@item y
>
> +Set the x and y expression. Default is 0.
>
> +
>
> +@item w
>
> +@item h
>
> +Set the output frame width and height expression. Default is 1.
>
> +@end table
>
> +
>
> +Each expression can contain the following constants:
>
> +
>
> +@table @option
>
> +@item in_w, iw
>
> +Input width.
>
> +
>
> +@item in_h, ih
>
> +Input height.
>
> +
>
> +@item n
>
> +Input frame count.
>
> +
>
> +@item t
>
> +The input timestamp expressed in seconds.
>
> +@end table
>
> +
>
> +Additionally x and y expressions can contain the following constants:
>
> +
>
> +@table @option
>
> +@item z
>
> +Last calculated zoom from 'z' expression for current input frame.
>
> +
>
> +@item zw
>
> +Last calculated zoom width for current input frame.
>
> +
>
> +@item zh
>
> +Last calculated zoom height for current input frame.
>
> +@end table
>
> +
>
> +@subsection Examples
>
> +
>
> +@itemize
>
> +@item
>
> +Zoom in 2x into center of picture for first 30 frames:
>
> +@example
>
> +yazf=x='(iw/2)-(zw/2)':y='(ih/2)-(zh/2)':z='min(2, 1+n*/30)':w=1080:h=1080"
>
> +@end example
>
> +
>
> +@end itemize
>
> +
>
>   @section zoompan
>
>   
>
>   Apply Zoom & Pan effect.
>
> diff --git a/libavfilter/Makefile b/libavfilter/Makefile
>
> index 97f8f17272..409a9f10dc 100644
>
> --- a/libavfilter/Makefile
>
> +++ b/libavfilter/Makefile
>
> @@ -582,6 +582,7 @@ OBJS-$(CONFIG_YADIF_VIDEOTOOLBOX_FILTER)     += vf_yadif_videotoolbox.o \
>
>                                                   metal/utils.o \
>
>                                                   yadif_common.o
>
>   OBJS-$(CONFIG_YAEPBLUR_FILTER)               += vf_yaepblur.o
>
> +OBJS-$(CONFIG_YAZF_FILTER)                   += vf_yazf.o
>
>   OBJS-$(CONFIG_ZMQ_FILTER)                    += f_zmq.o
>
>   OBJS-$(CONFIG_ZOOMPAN_FILTER)                += vf_zoompan.o
>
>   OBJS-$(CONFIG_ZSCALE_FILTER)                 += vf_zscale.o
>
> diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
>
> index 3bc045b28f..5fc80303f5 100644
>
> --- a/libavfilter/allfilters.c
>
> +++ b/libavfilter/allfilters.c
>
> @@ -544,6 +544,7 @@ extern const FFFilter ff_vf_yadif;
>
>   extern const FFFilter ff_vf_yadif_cuda;
>
>   extern const FFFilter ff_vf_yadif_videotoolbox;
>
>   extern const FFFilter ff_vf_yaepblur;
>
> +extern const FFFilter ff_vf_yazf;
>
>   extern const FFFilter ff_vf_zmq;
>
>   extern const FFFilter ff_vf_zoompan;
>
>   extern const FFFilter ff_vf_zscale;
>
> diff --git a/libavfilter/vf_yazf.c b/libavfilter/vf_yazf.c
>
> new file mode 100644
>
> index 0000000000..36c158fd32
>
> --- /dev/null
>
> +++ b/libavfilter/vf_yazf.c
>
> @@ -0,0 +1,360 @@
>
> +/*
>
> + * Copyright (c) 2025 Quentin Renard
>
> + *
>
> + * This file is part of FFmpeg.
>
> + *
>
> + * FFmpeg is free software; you can redistribute it and/or
>
> + * modify it under the terms of the GNU Lesser General Public
>
> + * License as published by the Free Software Foundation; either
>
> + * version 2.1 of the License, or (at your option) any later version.
>
> + *
>
> + * FFmpeg is distributed in the hope that it will be useful,
>
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>
> + * Lesser General Public License for more details.
>
> + *
>
> + * You should have received a copy of the GNU Lesser General Public
>
> + * License along with FFmpeg; if not, write to the Free Software
>
> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
>
> + */
>
> +
>
> +#include "libavutil/eval.h"
>
> +#include "libavutil/opt.h"
>
> +#include "video.h"
>
> +
>
> +static const char *const var_names[] = {
>
> +    "in_w",   "iw",
>
> +    "in_h",   "ih",
>
> +    "z",
>
> +    "zw",
>
> +    "zh",
>
> +    "n",
>
> +    "t",
>
> +    NULL
>
> +};
>
> +
>
> +enum var_name {
>
> +    VAR_IN_W,   VAR_IW,
>
> +    VAR_IN_H,   VAR_IH,
>
> +    VAR_Z,
>
> +    VAR_ZW,
>
> +    VAR_ZH,
>
> +    VAR_N,
>
> +    VAR_T,
>
> +    VARS_NB
>
> +};
>
> +
>
> +typedef struct YAZFContext {
>
> +    const AVClass *class;
>
> +    char *x_expr_str, *y_expr_str, *w_expr_str, *h_expr_str, *zoom_expr_str;
>
> +    AVExpr *x_expr, *y_expr, *w_expr, *h_expr, *zoom_expr;
>
> +    double var_values[VARS_NB];
>
> +} YAZFContext;
>
> +
>
> +typedef struct ThreadData {
>
> +    AVFrame *in, *out;
>
> +    float crop_h, crop_x, crop_y, crop_w;
>
> +    int w, h;
>
> +} ThreadData;
>
> +
>
> +static av_cold int init(AVFilterContext *ctx)
>
> +{
>
> +    YAZFContext *s = ctx->priv;
>
> +    int ret;
>
> +
>
> +    ret = av_expr_parse(&s->x_expr, s->x_expr_str, var_names, NULL, NULL, NULL, NULL, 0, ctx);
>
> +    if (ret < 0)
>
> +        return ret;
>
> +
>
> +    ret = av_expr_parse(&s->y_expr, s->y_expr_str, var_names, NULL, NULL, NULL, NULL, 0, ctx);
>
> +    if (ret < 0)
>
> +        return ret;
>
> +
>
> +    ret = av_expr_parse(&s->w_expr, s->w_expr_str, var_names, NULL, NULL, NULL, NULL, 0, ctx);
>
> +    if (ret < 0)
>
> +        return ret;
>
> +
>
> +    ret = av_expr_parse(&s->h_expr, s->h_expr_str, var_names, NULL, NULL, NULL, NULL, 0, ctx);
>
> +    if (ret < 0)
>
> +        return ret;
>
> +
>
> +    ret = av_expr_parse(&s->zoom_expr, s->zoom_expr_str, var_names, NULL, NULL, NULL, NULL, 0, ctx);
>
> +    if (ret < 0)
>
> +        return ret;
>
> +
>
> +    return 0;
>
> +}
>
> +
>
> +static int config_props(AVFilterLink *outlink)
>
> +{
>
> +    AVFilterContext *ctx = outlink->src;
>
> +    AVFilterLink *inlink = ctx->inputs[0];
>
> +    YAZFContext *s = ctx->priv;
>
> +
>
> +    s->var_values[VAR_IN_W] = s->var_values[VAR_IW] = inlink->w;
>
> +    s->var_values[VAR_IN_H] = s->var_values[VAR_IH] = inlink->h;
>
> +
>
> +    outlink->w = FFMAX(av_expr_eval(s->w_expr, s->var_values, NULL), 1);
>
> +    outlink->h = FFMAX(av_expr_eval(s->h_expr, s->var_values, NULL), 1);
>
> +    return 0;
>
> +}
>
> +
>
> +static inline uint8_t zoompan_pixel(const uint8_t *src, const int src_stride,
>
> +                                    const int src_w, const int src_h,
>
> +                                    const float x, const float y)
>
> +{
>
> +    int x0 = (int)floorf(x);
>
> +    int y0 = (int)floorf(y);
>
> +    int x1 = x0 + 1;
>
> +    int y1 = y0 + 1;
>
> +
>
> +    float fx = x - x0;
>
> +    float fy = y - y0;
>
> +
>
> +    x0 = FFMAX(0, FFMIN(x0, src_w - 1));
>
> +    x1 = FFMAX(0, FFMIN(x1, src_w - 1));
>
> +    y0 = FFMAX(0, FFMIN(y0, src_h - 1));
>
> +    y1 = FFMAX(0, FFMIN(y1, src_h - 1));
>
> +
>
> +    float p00 = src[y0 * src_stride + x0];
>
> +    float p10 = src[y0 * src_stride + x1];
>
> +    float p01 = src[y1 * src_stride + x0];
>
> +    float p11 = src[y1 * src_stride + x1];
>
> +
>
> +    return (1 - fx) * (1 - fy) * p00 +
>
> +           fx * (1 - fy) * p10 +
>
> +           (1 - fx) * fy * p01 +
>
> +           fx * fy * p11;
>
> +}
>
> +
>
> +static void zoompan_plane(const uint8_t *src, const int src_stride,
>
> +                            const int src_w, const int src_h, const float crop_x,
>
> +                            const float crop_y, const float crop_w,
>
> +                            const float crop_h, uint8_t *dst,
>
> +                            const int dst_stride, const int dst_w, const int dst_h,
>
> +                            const int dst_y_start, const int dst_y_end)
>
> +{
>
> +    float u, v, x, y, val;
>
> +    for (int dst_y = dst_y_start; dst_y < dst_y_end; dst_y++) {
>
> +        for (int dst_x = 0; dst_x < dst_w; dst_x++) {
>
> +            u = (dst_w > 1) ? (float)dst_x / (float)(dst_w - 1) : 0.0f;
>
> +            v = (dst_h > 1) ? (float)dst_y / (float)(dst_h - 1) : 0.0f;
>
> +
>
> +            x = crop_x + u * crop_w;
>
> +            y = crop_y + v * crop_h;
>
> +
>
> +            val = zoompan_pixel(src, src_stride, src_w, src_h, x, y);
>
> +
>
> +            dst[dst_y * dst_stride + dst_x] = FFMIN(FFMAX(val, 0), 255);
>
> +        }
>
> +    }
>
> +}
>
> +
>
> +static int zoompan_slice(AVFilterContext *ctx, void *arg, int jobnr, int nb_jobs)
>
> +{
>
> +    AVFilterLink *inlink = ctx->inputs[0];
>
> +    ThreadData *td = arg;
>
> +
>
> +    const int slice_start = (td->out->height * jobnr) / nb_jobs;
>
> +    const int slice_end = (td->out->height * (jobnr+1)) / nb_jobs;
>
> +
>
> +    int nb_planes = 4;
>
> +    struct {
>
> +        int resolution_w;
>
> +        int resolution_h;
>
> +    } planes[4] = {
>
> +        {.resolution_h = 1, .resolution_w = 1},
>
> +        {.resolution_h = 1, .resolution_w = 1},
>
> +        {.resolution_h = 1, .resolution_w = 1},
>
> +        {.resolution_h = 1, .resolution_w = 1},
>
> +    };
>
> +    switch (inlink->format) {
>
> +        case AV_PIX_FMT_YUV410P:
>
> +            nb_planes = 3;
>
> +            planes[1].resolution_h = 4;
>
> +            planes[1].resolution_w = 4;
>
> +            planes[2].resolution_h = 4;
>
> +            planes[2].resolution_w = 4;
>
> +            break;
>
> +        case AV_PIX_FMT_YUV411P:
>
> +        case AV_PIX_FMT_YUVJ411P:
>
> +            nb_planes = 3;
>
> +            planes[1].resolution_w = 4;
>
> +            planes[2].resolution_w = 4;
>
> +            break;
>
> +        case AV_PIX_FMT_YUV420P:
>
> +        case AV_PIX_FMT_YUVJ420P:
>
> +            nb_planes = 3;
>
> +            planes[1].resolution_h = 2;
>
> +            planes[1].resolution_w = 2;
>
> +            planes[2].resolution_h = 2;
>
> +            planes[2].resolution_w = 2;
>
> +            break;
>
> +        case AV_PIX_FMT_YUVA420P:
>
> +            nb_planes = 4;
>
> +            planes[1].resolution_h = 2;
>
> +            planes[1].resolution_w = 2;
>
> +            planes[2].resolution_h = 2;
>
> +            planes[2].resolution_w = 2;
>
> +            break;
>
> +        case AV_PIX_FMT_YUV422P:
>
> +        case AV_PIX_FMT_YUVJ422P:
>
> +            nb_planes = 3;
>
> +            planes[1].resolution_w = 2;
>
> +            planes[2].resolution_w = 2;
>
> +            break;
>
> +        case AV_PIX_FMT_YUVA422P:
>
> +            nb_planes = 4;
>
> +            planes[1].resolution_w = 2;
>
> +            planes[2].resolution_w = 2;
>
> +            break;
>
> +        case AV_PIX_FMT_YUV440P:
>
> +        case AV_PIX_FMT_YUVJ440P:
>
> +            nb_planes = 3;
>
> +            planes[1].resolution_h = 2;
>
> +            planes[2].resolution_h = 2;
>
> +            break;
>
> +        case AV_PIX_FMT_YUV444P:
>
> +        case AV_PIX_FMT_YUVJ444P:
>
> +            nb_planes = 3;
>
> +            break;
>
> +        case AV_PIX_FMT_YUVA444P:
>
> +            nb_planes = 4;
>
> +            break;
>
> +    }
>
> +
>
> +    for (int i = 0; i < nb_planes; i++) {
>
> +        zoompan_plane(td->in->data[i], td->in->linesize[i], td->in->width/planes[i].resolution_w,
>
> +                    td->in->height/planes[i].resolution_h, td->crop_x/planes[i].resolution_w,
>
> +                    td->crop_y/planes[i].resolution_h, td->crop_w/planes[i].resolution_w,
>
> +                    td->crop_h/planes[i].resolution_h, td->out->data[i], td->out->linesize[i],
>
> +                    td->out->width/planes[i].resolution_w, td->out->height/planes[i].resolution_h,
>
> +                    slice_start/planes[i].resolution_h, slice_end/planes[i].resolution_h);
>
> +    }
>
> +    return 0;
>
> +}
>
> +
>
> +static int filter_frame(AVFilterLink *inlink, AVFrame *in)
>
> +{
>
> +    AVFilterContext *ctx = inlink->dst;
>
> +    YAZFContext *s = ctx->priv;
>
> +    AVFilterLink *outlink = ctx->outputs[0];
>
> +    int ret;
>
> +    AVFrame *out = NULL;
>
> +    ThreadData td;
>
> +    float zoom, a;
>
> +
>
> +    inlink->w = in->width;
>
> +    inlink->h = in->height;
>
> +    s->var_values[VAR_N] = ff_filter_link(inlink)->frame_count_out;
>
> +    s->var_values[VAR_T] = TS2T(in->pts, inlink->time_base);
>
> +
>
> +    if ((ret = config_props(outlink)) < 0)
>
> +        goto err;
>
> +
>
> +    td.w = outlink->w;
>
> +    td.h = outlink->h;
>
> +    a = (float)outlink->w / (float)outlink->h;
>
> +
>
> +    s->var_values[VAR_Z] = zoom = av_clipd(av_expr_eval(s->zoom_expr, s->var_values, NULL), 1, 10);
>
> +
>
> +    td.crop_w = (float)inlink->w / zoom;
>
> +    td.crop_h = td.crop_w / a;
>
> +    if (td.crop_h > inlink->h) {
>
> +        td.crop_h = inlink->h;
>
> +        td.crop_w = td.crop_h * a;
>
> +    }
>
> +    s->var_values[VAR_ZW] = td.crop_w;
>
> +    s->var_values[VAR_ZH] = td.crop_h;
>
> +
>
> +    td.crop_x = av_clipd(av_expr_eval(s->x_expr, s->var_values, NULL), 0, FFMAX(inlink->w - td.crop_w, 0));
>
> +    td.crop_y = av_clipd(av_expr_eval(s->y_expr, s->var_values, NULL), 0, FFMAX(inlink->h - td.crop_h, 0));
>
> +
>
> +    out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
>
> +    if (!out) {
>
> +        ret = AVERROR(ENOMEM);
>
> +        goto err;
>
> +    }
>
> +
>
> +    if ((ret = av_frame_copy_props(out, in)) < 0)
>
> +        goto err;
>
> +
>
> +    td.out = out, td.in = in;
>
> +    if ((ret = ff_filter_execute(ctx, zoompan_slice, &td, NULL,
>
> +                                FFMIN(td.h, ff_filter_get_nb_threads(ctx)))) < 0)
>
> +        goto err;
>
> +
>
> +    av_frame_free(&in);
>
> +    return ff_filter_frame(outlink, out);
>
> +
>
> +err:
>
> +    av_frame_free(&in);
>
> +    av_frame_free(&out);
>
> +    return ret;
>
> +}
>
> +
>
> +static const enum AVPixelFormat pix_fmts[] = {
>
> +    AV_PIX_FMT_YUV410P, AV_PIX_FMT_YUV411P,
>
> +    AV_PIX_FMT_YUV420P, AV_PIX_FMT_YUV422P,
>
> +    AV_PIX_FMT_YUV440P, AV_PIX_FMT_YUV444P,
>
> +    AV_PIX_FMT_YUVJ411P, AV_PIX_FMT_YUVJ420P,
>
> +    AV_PIX_FMT_YUVJ422P, AV_PIX_FMT_YUVJ440P,
>
> +    AV_PIX_FMT_YUVJ444P,
>
> +    AV_PIX_FMT_YUVA420P, AV_PIX_FMT_YUVA422P,
>
> +    AV_PIX_FMT_YUVA444P,
>
> +    AV_PIX_FMT_NONE
>
> +};
>
> +
>
> +static av_cold void uninit(AVFilterContext *ctx)
>
> +{
>
> +    YAZFContext *s = ctx->priv;
>
> +
>
> +    av_expr_free(s->x_expr);
>
> +    av_expr_free(s->y_expr);
>
> +    av_expr_free(s->zoom_expr);
>
> +    av_expr_free(s->w_expr);
>
> +    av_expr_free(s->h_expr);
>
> +}
>
> +
>
> +#define OFFSET(x) offsetof(YAZFContext, x)
>
> +#define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
>
> +
>
> +static const AVOption yazf_options[] = {
>
> +    { "z", "set the zoom expression", OFFSET(zoom_expr_str), AV_OPT_TYPE_STRING, {.str = "1" }, .flags = FLAGS },
>
> +    { "x", "set the zoom x expression", OFFSET(x_expr_str), AV_OPT_TYPE_STRING, {.str = "0" }, .flags = FLAGS },
>
> +    { "y", "set the zoom y expression", OFFSET(y_expr_str), AV_OPT_TYPE_STRING, {.str = "0" }, .flags = FLAGS },
>
> +    { "w", "set the output w expression", OFFSET(w_expr_str), AV_OPT_TYPE_STRING, {.str = "1" }, .flags = FLAGS },
>
> +    { "h", "set the output h expression", OFFSET(h_expr_str), AV_OPT_TYPE_STRING, {.str = "1" }, .flags = FLAGS },
>
> +    { NULL }
>
> +};
>
> +
>
> +AVFILTER_DEFINE_CLASS(yazf);
>
> +
>
> +static const AVFilterPad avfilter_vf_yazf_inputs[] = {
>
> +    {
>
> +        .name         = "default",
>
> +        .type         = AVMEDIA_TYPE_VIDEO,
>
> +        .filter_frame = filter_frame,
>
> +    },
>
> +};
>
> +
>
> +static const AVFilterPad avfilter_vf_yazf_outputs[] = {
>
> +    {
>
> +        .name         = "default",
>
> +        .type         = AVMEDIA_TYPE_VIDEO,
>
> +        .config_props = config_props,
>
> +    },
>
> +};
>
> +
>
> +const FFFilter ff_vf_yazf = {
>
> +    .p.name          = "yazf",
>
> +    .p.description   = NULL_IF_CONFIG_SMALL("Apply Zoom & Pan effect with floating point precision."),
>
> +    .p.priv_class    = &yazf_class,
>
> +    .p.flags         = AVFILTER_FLAG_SLICE_THREADS,
>
> +    .init            = init,
>
> +    .priv_size       = sizeof(YAZFContext),
>
> +    .uninit          = uninit,
>
> +    FILTER_INPUTS(avfilter_vf_yazf_inputs),
>
> +    FILTER_OUTPUTS(avfilter_vf_yazf_outputs),
>
> +    FILTER_PIXFMTS_ARRAY(pix_fmts),
>
> +};
>

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