[FFmpeg-devel,1/2] lavfi/vf_stack_vaapi: factor out the common code for stack setting

From: Haihao Xiang <haihao.xiang@intel.com>

The common code will be used in QSV based stack filters.

Signed-off-by: Haihao Xiang <haihao.xiang@intel.com>
---
 libavfilter/stack_internal.c | 355 +++++++++++++++++++++++++++++++
 libavfilter/stack_internal.h |  60 ++++++
 libavfilter/vf_stack_vaapi.c | 395 ++++-------------------------------
 3 files changed, 452 insertions(+), 358 deletions(-)
 create mode 100644 libavfilter/stack_internal.c
 create mode 100644 libavfilter/stack_internal.h

On Di, 2023-02-07 at 11:59 +0800, Xiang, Haihao wrote:
> From: Haihao Xiang <haihao.xiang@intel.com>
> 
> The common code will be used in QSV based stack filters.
> 
> Signed-off-by: Haihao Xiang <haihao.xiang@intel.com>
> ---
>  libavfilter/stack_internal.c | 355 +++++++++++++++++++++++++++++++
>  libavfilter/stack_internal.h |  60 ++++++
>  libavfilter/vf_stack_vaapi.c | 395 ++++-------------------------------
>  3 files changed, 452 insertions(+), 358 deletions(-)
>  create mode 100644 libavfilter/stack_internal.c
>  create mode 100644 libavfilter/stack_internal.h
> 
> diff --git a/libavfilter/stack_internal.c b/libavfilter/stack_internal.c
> new file mode 100644
> index 0000000000..57661e1c97
> --- /dev/null
> +++ b/libavfilter/stack_internal.c
> @@ -0,0 +1,355 @@
> +/*
> + * 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
> + */
> +
> +#define OFFSET(x) offsetof(StackHWContext, x)
> +#define FLAGS (AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_FILTERING_PARAM)
> +
> +#define SET_OUTPUT_REGION(region, rx, ry, rw, rh) do {  \
> +        region->x = rx;                                 \
> +        region->y = ry;                                 \
> +        region->width = rw;                             \
> +        region->height = rh;                            \
> +    } while (0)
> +
> +static int init_framesync(AVFilterContext *avctx)
> +{
> +    StackBaseContext *sctx = avctx->priv;
> +    int ret;
> +
> +    ret = ff_framesync_init(&sctx->fs, avctx, avctx->nb_inputs);
> +    if (ret < 0)
> +        return ret;
> +
> +    sctx->fs.on_event = process_frame;
> +    sctx->fs.opaque = sctx;
> +
> +    for (int i = 0; i < sctx->nb_inputs; i++) {
> +        FFFrameSyncIn *in = &sctx->fs.in[i];
> +
> +        in->before = EXT_STOP;
> +        in->after = sctx->shortest ? EXT_STOP : EXT_INFINITY;
> +        in->sync = 1;
> +        in->time_base = avctx->inputs[i]->time_base;
> +    }
> +
> +    return ff_framesync_configure(&sctx->fs);
> +}
> +
> +static int config_comm_output(AVFilterLink *outlink)
> +{
> +    AVFilterContext *avctx = outlink->src;
> +    StackBaseContext *sctx = avctx->priv;
> +    AVFilterLink *inlink0 = avctx->inputs[0];
> +    int width, height, ret;
> +
> +    if (sctx->mode == STACK_H) {
> +        height = sctx->tile_height;
> +        width = 0;
> +
> +        if (!height)
> +            height = inlink0->h;
> +
> +        for (int i = 0; i < sctx->nb_inputs; i++) {
> +            AVFilterLink *inlink = avctx->inputs[i];
> +            StackItemRegion *region = &sctx->regions[i];
> +
> +            SET_OUTPUT_REGION(region, width, 0, av_rescale(height, inlink->w, 
> inlink->h), height);
> +            width += av_rescale(height, inlink->w, inlink->h);
> +        }
> +    } else if (sctx->mode == STACK_V) {
> +        height = 0;
> +        width = sctx->tile_width;
> +
> +        if (!width)
> +            width = inlink0->w;
> +
> +        for (int i = 0; i < sctx->nb_inputs; i++) {
> +            AVFilterLink *inlink = avctx->inputs[i];
> +            StackItemRegion *region = &sctx->regions[i];
> +
> +            SET_OUTPUT_REGION(region, 0, height, width, av_rescale(width,
> inlink->h, inlink->w));
> +            height += av_rescale(width, inlink->h, inlink->w);
> +        }
> +    } else if (sctx->nb_grid_rows && sctx->nb_grid_columns) {
> +        int xpos = 0, ypos = 0;
> +        int ow, oh, k = 0;
> +
> +        ow = sctx->tile_width;
> +        oh = sctx->tile_height;
> +
> +        if (!ow || !oh) {
> +            ow = avctx->inputs[0]->w;
> +            oh = avctx->inputs[0]->h;
> +        }
> +
> +        for (int i = 0; i < sctx->nb_grid_columns; i++) {
> +            ypos = 0;
> +
> +            for (int j = 0; j < sctx->nb_grid_rows; j++) {
> +                StackItemRegion *region = &sctx->regions[k++];
> +
> +                SET_OUTPUT_REGION(region, xpos, ypos, ow, oh);
> +                ypos += oh;
> +            }
> +
> +            xpos += ow;
> +        }
> +
> +        width = ow * sctx->nb_grid_columns;
> +        height = oh * sctx->nb_grid_rows;
> +    } else {
> +        char *arg, *p = sctx->layout, *saveptr = NULL;
> +        char *arg2, *p2, *saveptr2 = NULL;
> +        char *arg3, *p3, *saveptr3 = NULL;
> +        int xpos, ypos, size;
> +        int ow, oh;
> +
> +        width = avctx->inputs[0]->w;
> +        height = avctx->inputs[0]->h;
> +
> +        for (int i = 0; i < sctx->nb_inputs; i++) {
> +            AVFilterLink *inlink = avctx->inputs[i];
> +            StackItemRegion *region = &sctx->regions[i];
> +
> +            ow = inlink->w;
> +            oh = inlink->h;
> +
> +            if (!(arg = av_strtok(p, "|", &saveptr)))
> +                return AVERROR(EINVAL);
> +
> +            p = NULL;
> +            p2 = arg;
> +            xpos = ypos = 0;
> +
> +            for (int j = 0; j < 3; j++) {
> +                if (!(arg2 = av_strtok(p2, "_", &saveptr2))) {
> +                    if (j == 2)
> +                        break;
> +                    else
> +                        return AVERROR(EINVAL);
> +                }
> +
> +                p2 = NULL;
> +                p3 = arg2;
> +
> +                if (j == 2) {
> +                    if ((ret = av_parse_video_size(&ow, &oh, p3)) < 0) {
> +                        av_log(avctx, AV_LOG_ERROR, "Invalid size '%s'\n",
> p3);
> +                        return ret;
> +                    }
> +
> +                    break;
> +                }
> +
> +                while ((arg3 = av_strtok(p3, "+", &saveptr3))) {
> +                    p3 = NULL;
> +                    if (sscanf(arg3, "w%d", &size) == 1) {
> +                        if (size == i || size < 0 || size >= sctx->nb_inputs)
> +                            return AVERROR(EINVAL);
> +
> +                        if (!j)
> +                            xpos += sctx->regions[size].width;
> +                        else
> +                            ypos += sctx->regions[size].width;
> +                    } else if (sscanf(arg3, "h%d", &size) == 1) {
> +                        if (size == i || size < 0 || size >= sctx->nb_inputs)
> +                            return AVERROR(EINVAL);
> +
> +                        if (!j)
> +                            xpos += sctx->regions[size].height;
> +                        else
> +                            ypos += sctx->regions[size].height;
> +                    } else if (sscanf(arg3, "%d", &size) == 1) {
> +                        if (size < 0)
> +                            return AVERROR(EINVAL);
> +
> +                        if (!j)
> +                            xpos += size;
> +                        else
> +                            ypos += size;
> +                    } else {
> +                        return AVERROR(EINVAL);
> +                    }
> +                }
> +            }
> +
> +            SET_OUTPUT_REGION(region, xpos, ypos, ow, oh);
> +            width = FFMAX(width,  xpos + ow);
> +            height = FFMAX(height, ypos + oh);
> +        }
> +
> +    }
> +
> +    outlink->w = width;
> +    outlink->h = height;
> +    outlink->frame_rate = inlink0->frame_rate;
> +    outlink->sample_aspect_ratio = inlink0->sample_aspect_ratio;
> +
> +    for (int i = 1; i < sctx->nb_inputs; i++) {
> +        AVFilterLink *inlink = avctx->inputs[i];
> +        if (outlink->frame_rate.num != inlink->frame_rate.num ||
> +            outlink->frame_rate.den != inlink->frame_rate.den) {
> +            av_log(avctx, AV_LOG_VERBOSE,
> +                    "Video inputs have different frame rates, output will be
> VFR\n");
> +            outlink->frame_rate = av_make_q(1, 0);
> +            break;
> +        }
> +    }
> +
> +    ret = init_framesync(avctx);
> +    if (ret < 0)
> +        return ret;
> +
> +    outlink->time_base = sctx->fs.time_base;
> +
> +    return 0;
> +}
> +
> +static int stack_init(AVFilterContext *avctx)
> +{
> +    StackBaseContext *sctx = avctx->priv;
> +    int ret;
> +
> +    if (!strcmp(avctx->filter->name, HSTACK_NAME))
> +        sctx->mode = STACK_H;
> +    else if (!strcmp(avctx->filter->name, VSTACK_NAME))
> +        sctx->mode = STACK_V;
> +    else {
> +        int is_grid;
> +
> +        av_assert0(strcmp(avctx->filter->name, XSTACK_NAME) == 0);
> +        sctx->mode = STACK_X;
> +        is_grid = sctx->nb_grid_rows && sctx->nb_grid_columns;
> +
> +        if (sctx->layout && is_grid) {
> +            av_log(avctx, AV_LOG_ERROR, "Both layout and grid were specified.
> Only one is allowed.\n");
> +            return AVERROR(EINVAL);
> +        }
> +
> +        if (!sctx->layout && !is_grid) {
> +            if (sctx->nb_inputs == 2) {
> +                sctx->nb_grid_rows = 1;
> +                sctx->nb_grid_columns = 2;
> +                is_grid = 1;
> +            } else {
> +                av_log(avctx, AV_LOG_ERROR, "No layout or grid
> specified.\n");
> +                return AVERROR(EINVAL);
> +            }
> +        }
> +
> +        if (is_grid)
> +            sctx->nb_inputs = sctx->nb_grid_rows * sctx->nb_grid_columns;
> +
> +        if (strcmp(sctx->fillcolor_str, "none") &&
> +            av_parse_color(sctx->fillcolor, sctx->fillcolor_str, -1, avctx)
> >= 0) {
> +            sctx->fillcolor_enable = 1;
> +        } else {
> +            sctx->fillcolor_enable = 0;
> +        }
> +    }
> +
> +    for (int i = 0; i < sctx->nb_inputs; i++) {
> +        AVFilterPad pad = { 0 };
> +
> +        pad.type = AVMEDIA_TYPE_VIDEO;
> +        pad.name = av_asprintf("input%d", i);
> +
> +        if (!pad.name)
> +            return AVERROR(ENOMEM);
> +
> +        if ((ret = ff_append_inpad_free_name(avctx, &pad)) < 0)
> +            return ret;
> +    }
> +
> +    sctx->regions = av_calloc(sctx->nb_inputs, sizeof(*sctx->regions));
> +    if (!sctx->regions)
> +        return AVERROR(ENOMEM);
> +
> +    return 0;
> +}
> +
> +static av_cold void stack_uninit(AVFilterContext *avctx)
> +{
> +    StackBaseContext *sctx = avctx->priv;
> +
> +    av_freep(&sctx->regions);
> +    ff_framesync_uninit(&sctx->fs);
> +}
> +
> +static int stack_activate(AVFilterContext *avctx)
> +{
> +    StackBaseContext *sctx = avctx->priv;
> +    return ff_framesync_activate(&sctx->fs);
> +}
> +
> +static const AVFilterPad stack_outputs[] = {
> +    {
> +        .name          = "default",
> +        .type          = AVMEDIA_TYPE_VIDEO,
> +        .config_props  = config_output,
> +    },
> +};
> +
> +#define STACK_COMMON_OPTS                                               \
> +    { "inputs", "Set number of inputs", OFFSET(base.nb_inputs),
> AV_OPT_TYPE_INT, { .i64 = 2 }, 2, UINT16_MAX, .flags = FLAGS }, \
> +    { "shortest", "Force termination when the shortest input terminates",
> OFFSET(base.shortest), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, FLAGS },
> +
> +#define DEFINE_HSTACK_OPTIONS(api)                                      \
> +    static const AVOption hstack_##api##_options[] = {                  \
> +        STACK_COMMON_OPTS                                               \
> +        { "height", "Set output height (0 to use the height of input 0)",
> OFFSET(base.tile_height), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, UINT16_MAX, FLAGS
> }, \
> +        { NULL }                                                        \
> +    }
> +
> +#define DEFINE_VSTACK_OPTIONS(api)                                      \
> +    static const AVOption vstack_##api##_options[] = {                  \
> +        STACK_COMMON_OPTS                                               \
> +        { "width",   "Set output width (0 to use the width of input 0)",
> OFFSET(base.tile_width), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, UINT16_MAX, FLAGS
> }, \
> +        { NULL }                                                        \
> +    }
> +
> +#define DEFINE_XSTACK_OPTIONS(api)                                      \
> +    static const AVOption xstack_##api##_options[] = {                  \
> +        STACK_COMMON_OPTS                                               \
> +        { "layout", "Set custom layout", OFFSET(base.layout),
> AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, .flags = FLAGS }, \
> +        { "grid",   "set fixed size grid layout",
> OFFSET(base.nb_grid_columns), AV_OPT_TYPE_IMAGE_SIZE, {.str = NULL}, 0, 0,
> .flags = FLAGS }, \
> +        { "grid_tile_size",   "set tile size in grid layout",
> OFFSET(base.tile_width), AV_OPT_TYPE_IMAGE_SIZE, {.str = NULL}, 0, 0, .flags =
> FLAGS }, \
> +        { "fill",   "Set the color for unused pixels",
> OFFSET(base.fillcolor_str), AV_OPT_TYPE_STRING, {.str = "none"}, .flags =
> FLAGS }, \
> +        { NULL }                                                        \
> +    }
> +
> +#define DEFINE_STACK_FILTER(category, api, capi)                        \
> +    static const AVClass category##_##api##_class = {                   \
> +        .class_name = #category "_" #api,                               \
> +        .item_name  = av_default_item_name,                             \
> +        .option     = category##_##api##_options,                       \
> +        .version    = LIBAVUTIL_VERSION_INT,                            \
> +    };                                                                  \
> +    const AVFilter ff_vf_##category##_##api = {                         \
> +        .name           = #category "_" #api,                           \
> +        .description    = NULL_IF_CONFIG_SMALL(#capi " " #category),    \
> +        .priv_size      = sizeof(StackHWContext),                       \
> +        .priv_class     = &category##_##api##_class,                    \
> +        .init           = api##_stack_init,                             \
> +        .uninit         = api##_stack_uninit,                           \
> +        .activate       = stack_activate,                               \
> +        FILTER_QUERY_FUNC(api##_stack_query_formats),                   \
> +        FILTER_OUTPUTS(stack_outputs),                                  \
> +        .flags_internal = FF_FILTER_FLAG_HWFRAME_AWARE,                 \
> +        .flags          = AVFILTER_FLAG_DYNAMIC_INPUTS,                 \
> +    }
> diff --git a/libavfilter/stack_internal.h b/libavfilter/stack_internal.h
> new file mode 100644
> index 0000000000..2847fc620b
> --- /dev/null
> +++ b/libavfilter/stack_internal.h
> @@ -0,0 +1,60 @@
> +/*
> + * 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
> + */
> +
> +#ifndef AVFILTER_STACK_INTERNAL_H
> +#define AVFILTER_STACK_INTERNAL_H
> +
> +enum {
> +    STACK_H = 0,
> +    STACK_V = 1,
> +    STACK_X = 2
> +};
> +
> +typedef struct StackItemRegion {
> +    int x;
> +    int y;
> +    int width;
> +    int height;
> +} StackItemRegion;
> +
> +typedef struct StackBaseContext {
> +    HWContext hwctx; /**< must be the first field */
> +
> +    FFFrameSync fs;
> +    int mode;
> +    uint8_t fillcolor[4];
> +    int fillcolor_enable;
> +    StackItemRegion *regions;
> +
> +    /* Options */
> +    int nb_inputs;
> +    int shortest;
> +    int tile_width;
> +    int tile_height;
> +    int nb_grid_columns;
> +    int nb_grid_rows;
> +    char *layout;
> +    char *fillcolor_str;
> +} StackBaseContext;
> +
> +static int config_comm_output(AVFilterLink *outlink);
> +static int stack_init(AVFilterContext *avctx);
> +static av_cold void stack_uninit(AVFilterContext *avctx);
> +static int stack_activate(AVFilterContext *avctx);
> +
> +#endif /* AVFILTER_STACK_INTERNAL_H */
> \ No newline at end of file
> diff --git a/libavfilter/vf_stack_vaapi.c b/libavfilter/vf_stack_vaapi.c
> index 403fbb19eb..26dbe3f7aa 100644
> --- a/libavfilter/vf_stack_vaapi.c
> +++ b/libavfilter/vf_stack_vaapi.c
> @@ -42,33 +42,17 @@
>  #include "framesync.h"
>  #include "vaapi_vpp.h"
>  
> -#define OFFSET(x) offsetof(StackVAAPIContext, x)
> -#define FLAGS (AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_FILTERING_PARAM)
> -
> -enum {
> -    STACK_VAAPI_H = 0,
> -    STACK_VAAPI_V = 1,
> -    STACK_VAAPI_X = 2
> -};
> +#define HSTACK_NAME             "hstack_vaapi"
> +#define VSTACK_NAME             "vstack_vaapi"
> +#define XSTACK_NAME             "xstack_vaapi"
> +#define HWContext               VAAPIVPPContext
> +#define StackHWContext          StackVAAPIContext
> +#include "stack_internal.h"
>  
>  typedef struct StackVAAPIContext {
> -    VAAPIVPPContext vppctx; /**< must be the first field */
> +    StackBaseContext base;
>  
> -    FFFrameSync fs;
> -    int mode;
>      VARectangle *rects;
> -    uint8_t fillcolor[4];
> -    int fillcolor_enable;
> -
> -    /* Options */
> -    int nb_inputs;
> -    int shortest;
> -    int tile_width;
> -    int tile_height;
> -    int nb_grid_columns;
> -    int nb_grid_rows;
> -    char *layout;
> -    char *fillcolor_str;
>  } StackVAAPIContext;
>  
>  static int process_frame(FFFrameSync *fs)
> @@ -122,14 +106,14 @@ static int process_frame(FFFrameSync *fs)
>          params[i].surface = (VASurfaceID)(uintptr_t)iframe->data[3];
>          params[i].output_region = &sctx->rects[i];
>  
> -        if (sctx->fillcolor_enable)
> -            params[i].output_background_color = (sctx->fillcolor[3] << 24 |
> -                                                 sctx->fillcolor[0] << 16 |
> -                                                 sctx->fillcolor[1] << 8 |
> -                                                 sctx->fillcolor[2]);
> +        if (sctx->base.fillcolor_enable)
> +            params[i].output_background_color = (sctx->base.fillcolor[3] <<
> 24 |
> +                                                 sctx->base.fillcolor[0] <<
> 16 |
> +                                                 sctx->base.fillcolor[1] << 8
> |
> +                                                 sctx->base.fillcolor[2]);
>      }
>  
> -    oframe->pts = av_rescale_q(sctx->fs.pts, sctx->fs.time_base, outlink-
> >time_base);
> +    oframe->pts = av_rescale_q(sctx->base.fs.pts, sctx->base.fs.time_base,
> outlink->time_base);
>      oframe->sample_aspect_ratio = outlink->sample_aspect_ratio;
>  
>      ret = ff_vaapi_vpp_render_pictures(avctx, params, avctx->nb_inputs,
> oframe);
> @@ -147,37 +131,6 @@ fail:
>      return ret;
>  }
>  
> -static int init_framesync(AVFilterContext *avctx)
> -{
> -    StackVAAPIContext *sctx = avctx->priv;
> -    int ret;
> -
> -    ret = ff_framesync_init(&sctx->fs, avctx, avctx->nb_inputs);
> -    if (ret < 0)
> -        return ret;
> -
> -    sctx->fs.on_event = process_frame;
> -    sctx->fs.opaque = sctx;
> -
> -    for (int i = 0; i < sctx->nb_inputs; i++) {
> -        FFFrameSyncIn *in = &sctx->fs.in[i];
> -
> -        in->before = EXT_STOP;
> -        in->after = sctx->shortest ? EXT_STOP : EXT_INFINITY;
> -        in->sync = 1;
> -        in->time_base = avctx->inputs[i]->time_base;
> -    }
> -
> -    return ff_framesync_configure(&sctx->fs);
> -}
> -
> -#define SET_INPUT_REGION(rect, rx, ry, rw, rh) do {     \
> -        rect->x = rx;                                   \
> -        rect->y = ry;                                   \
> -        rect->width = rw;                               \
> -        rect->height = rh;                              \
> -    } while (0)
> -
>  static int config_output(AVFilterLink *outlink)
>  {
>      AVFilterContext *avctx = outlink->src;
> @@ -185,7 +138,7 @@ static int config_output(AVFilterLink *outlink)
>      VAAPIVPPContext *vppctx = avctx->priv;
>      AVFilterLink *inlink0 = avctx->inputs[0];
>      AVHWFramesContext *hwfc0 = NULL;
> -    int width, height, ret;
> +    int ret;
>  
>      if (inlink0->format != AV_PIX_FMT_VAAPI || !inlink0->hw_frames_ctx ||
> !inlink0->hw_frames_ctx->data) {
>          av_log(avctx, AV_LOG_ERROR, "Software pixel format is not
> supported.\n");
> @@ -194,7 +147,7 @@ static int config_output(AVFilterLink *outlink)
>  
>      hwfc0 = (AVHWFramesContext *)inlink0->hw_frames_ctx->data;
>  
> -    for (int i = 1; i < sctx->nb_inputs; i++) {
> +    for (int i = 1; i < sctx->base.nb_inputs; i++) {
>          AVFilterLink *inlink = avctx->inputs[i];
>          AVHWFramesContext *hwfc = NULL;
>  
> @@ -219,168 +172,19 @@ static int config_output(AVFilterLink *outlink)
>      ff_vaapi_vpp_config_input(inlink0);
>      vppctx->output_format = hwfc0->sw_format;
>  
> -    if (sctx->mode == STACK_VAAPI_H) {
> -        height = sctx->tile_height;
> -        width = 0;
> -
> -        if (!height)
> -            height = inlink0->h;
> -
> -        for (int i = 0; i < sctx->nb_inputs; i++) {
> -            AVFilterLink *inlink = avctx->inputs[i];
> -            VARectangle *rect = &sctx->rects[i];
> -
> -            SET_INPUT_REGION(rect, width, 0, av_rescale(height, inlink->w,
> inlink->h), height);
> -            width += av_rescale(height, inlink->w, inlink->h);
> -        }
> -    } else if (sctx->mode == STACK_VAAPI_V) {
> -        height = 0;
> -        width = sctx->tile_width;
> -
> -        if (!width)
> -            width = inlink0->w;
> -
> -        for (int i = 0; i < sctx->nb_inputs; i++) {
> -            AVFilterLink *inlink = avctx->inputs[i];
> -            VARectangle *rect = &sctx->rects[i];
> -
> -            SET_INPUT_REGION(rect, 0, height, width, av_rescale(width,
> inlink->h, inlink->w));
> -            height += av_rescale(width, inlink->h, inlink->w);
> -        }
> -    } else if (sctx->nb_grid_rows && sctx->nb_grid_columns) {
> -        int xpos = 0, ypos = 0;
> -        int ow, oh, k = 0;
> -
> -        ow = sctx->tile_width;
> -        oh = sctx->tile_height;
> -
> -        if (!ow || !oh) {
> -            ow = avctx->inputs[0]->w;
> -            oh = avctx->inputs[0]->h;
> -        }
> -
> -        for (int i = 0; i < sctx->nb_grid_columns; i++) {
> -            ypos = 0;
> -
> -            for (int j = 0; j < sctx->nb_grid_rows; j++) {
> -                VARectangle *rect = &sctx->rects[k++];
> -
> -                SET_INPUT_REGION(rect, xpos, ypos, ow, oh);
> -                ypos += oh;
> -            }
> -
> -            xpos += ow;
> -        }
> -
> -        width = ow * sctx->nb_grid_columns;
> -        height = oh * sctx->nb_grid_rows;
> -    } else {
> -        char *arg, *p = sctx->layout, *saveptr = NULL;
> -        char *arg2, *p2, *saveptr2 = NULL;
> -        char *arg3, *p3, *saveptr3 = NULL;
> -        int xpos, ypos, size;
> -        int ow, oh;
> -
> -        width = avctx->inputs[0]->w;
> -        height = avctx->inputs[0]->h;
> -
> -        for (int i = 0; i < sctx->nb_inputs; i++) {
> -            AVFilterLink *inlink = avctx->inputs[i];
> -            VARectangle *rect = &sctx->rects[i];
> -
> -            ow = inlink->w;
> -            oh = inlink->h;
> -
> -            if (!(arg = av_strtok(p, "|", &saveptr)))
> -                return AVERROR(EINVAL);
> -
> -            p = NULL;
> -            p2 = arg;
> -            xpos = ypos = 0;
> -
> -            for (int j = 0; j < 3; j++) {
> -                if (!(arg2 = av_strtok(p2, "_", &saveptr2))) {
> -                    if (j == 2)
> -                        break;
> -                    else
> -                        return AVERROR(EINVAL);
> -                }
> -
> -                p2 = NULL;
> -                p3 = arg2;
> -
> -                if (j == 2) {
> -                    if ((ret = av_parse_video_size(&ow, &oh, p3)) < 0) {
> -                        av_log(avctx, AV_LOG_ERROR, "Invalid size '%s'\n",
> p3);
> -                        return ret;
> -                    }
> -
> -                    break;
> -                }
> -
> -                while ((arg3 = av_strtok(p3, "+", &saveptr3))) {
> -                    p3 = NULL;
> -                    if (sscanf(arg3, "w%d", &size) == 1) {
> -                        if (size == i || size < 0 || size >= sctx->nb_inputs)
> -                            return AVERROR(EINVAL);
> -
> -                        if (!j)
> -                            xpos += sctx->rects[size].width;
> -                        else
> -                            ypos += sctx->rects[size].width;
> -                    } else if (sscanf(arg3, "h%d", &size) == 1) {
> -                        if (size == i || size < 0 || size >= sctx->nb_inputs)
> -                            return AVERROR(EINVAL);
> -
> -                        if (!j)
> -                            xpos += sctx->rects[size].height;
> -                        else
> -                            ypos += sctx->rects[size].height;
> -                    } else if (sscanf(arg3, "%d", &size) == 1) {
> -                        if (size < 0)
> -                            return AVERROR(EINVAL);
> -
> -                        if (!j)
> -                            xpos += size;
> -                        else
> -                            ypos += size;
> -                    } else {
> -                        return AVERROR(EINVAL);
> -                    }
> -                }
> -            }
> -
> -            SET_INPUT_REGION(rect, xpos, ypos, ow, oh);
> -            width = FFMAX(width,  xpos + ow);
> -            height = FFMAX(height, ypos + oh);
> -        }
> -
> -    }
> -
> -    outlink->w = width;
> -    outlink->h = height;
> -    outlink->frame_rate = inlink0->frame_rate;
> -    outlink->sample_aspect_ratio = inlink0->sample_aspect_ratio;
> -
> -    for (int i = 1; i < sctx->nb_inputs; i++) {
> -        AVFilterLink *inlink = avctx->inputs[i];
> -        if (outlink->frame_rate.num != inlink->frame_rate.num ||
> -            outlink->frame_rate.den != inlink->frame_rate.den) {
> -            av_log(avctx, AV_LOG_VERBOSE,
> -                    "Video inputs have different frame rates, output will be
> VFR\n");
> -            outlink->frame_rate = av_make_q(1, 0);
> -            break;
> -        }
> -    }
> -
> -    ret = init_framesync(avctx);
> +    ret = config_comm_output(outlink);
>      if (ret < 0)
>          return ret;
>  
> -    outlink->time_base = sctx->fs.time_base;
> +    for (int i = 0; i < sctx->base.nb_inputs; i++) {
> +        sctx->rects[i].x = sctx->base.regions[i].x;
> +        sctx->rects[i].y = sctx->base.regions[i].y;
> +        sctx->rects[i].width = sctx->base.regions[i].width;
> +        sctx->rects[i].height = sctx->base.regions[i].height;
> +    }
>  
> -    vppctx->output_width = width;
> -    vppctx->output_height = height;
> +    vppctx->output_width = outlink->w;
> +    vppctx->output_height = outlink->h;
>  
>      return ff_vaapi_vpp_config_output(outlink);
>  }
> @@ -391,59 +195,12 @@ static int vaapi_stack_init(AVFilterContext *avctx)
>      VAAPIVPPContext *vppctx = avctx->priv;
>      int ret;
>  
> -    if (!strcmp(avctx->filter->name, "hstack_vaapi"))
> -        sctx->mode = STACK_VAAPI_H;
> -    else if (!strcmp(avctx->filter->name, "vstack_vaapi"))
> -        sctx->mode = STACK_VAAPI_V;
> -    else {
> -        int is_grid;
> -
> -        av_assert0(strcmp(avctx->filter->name, "xstack_vaapi") == 0);
> -        sctx->mode = STACK_VAAPI_X;
> -        is_grid = sctx->nb_grid_rows && sctx->nb_grid_columns;
> -
> -        if (sctx->layout && is_grid) {
> -            av_log(avctx, AV_LOG_ERROR, "Both layout and grid were specified.
> Only one is allowed.\n");
> -            return AVERROR(EINVAL);
> -        }
> -
> -        if (!sctx->layout && !is_grid) {
> -            if (sctx->nb_inputs == 2) {
> -                sctx->nb_grid_rows = 1;
> -                sctx->nb_grid_columns = 2;
> -                is_grid = 1;
> -            } else {
> -                av_log(avctx, AV_LOG_ERROR, "No layout or grid
> specified.\n");
> -                return AVERROR(EINVAL);
> -            }
> -        }
> -
> -        if (is_grid)
> -            sctx->nb_inputs = sctx->nb_grid_rows * sctx->nb_grid_columns;
> -
> -        if (strcmp(sctx->fillcolor_str, "none") &&
> -            av_parse_color(sctx->fillcolor, sctx->fillcolor_str, -1, avctx)
> >= 0) {
> -            sctx->fillcolor_enable = 1;
> -        } else {
> -            sctx->fillcolor_enable = 0;
> -        }
> -    }
> -
> -    for (int i = 0; i < sctx->nb_inputs; i++) {
> -        AVFilterPad pad = { 0 };
> -
> -        pad.type = AVMEDIA_TYPE_VIDEO;
> -        pad.name = av_asprintf("input%d", i);
> -
> -        if (!pad.name)
> -            return AVERROR(ENOMEM);
> -
> -        if ((ret = ff_append_inpad_free_name(avctx, &pad)) < 0)
> -            return ret;
> -    }
> +    ret = stack_init(avctx);
> +    if (ret)
> +        return ret;
>  
>      /* stack region */
> -    sctx->rects = av_calloc(sctx->nb_inputs, sizeof(*sctx->rects));
> +    sctx->rects = av_calloc(sctx->base.nb_inputs, sizeof(*sctx->rects));
>      if (!sctx->rects)
>          return AVERROR(ENOMEM);
>  
> @@ -457,14 +214,9 @@ static av_cold void vaapi_stack_uninit(AVFilterContext
> *avctx)
>  {
>      StackVAAPIContext *sctx = avctx->priv;
>  
> -    ff_framesync_uninit(&sctx->fs);
> -    av_freep(&sctx->rects);
> -}
> +    stack_uninit(avctx);
>  
> -static int vaapi_stack_activate(AVFilterContext *avctx)
> -{
> -    StackVAAPIContext *sctx = avctx->priv;
> -    return ff_framesync_activate(&sctx->fs);
> +    av_freep(&sctx->rects);
>  }
>  
>  static int vaapi_stack_query_formats(AVFilterContext *avctx)
> @@ -477,98 +229,25 @@ static int vaapi_stack_query_formats(AVFilterContext
> *avctx)
>      return ff_set_common_formats_from_list(avctx, pixel_formats);
>  }
>  
> -static const AVFilterPad vaapi_stack_outputs[] = {
> -    {
> -        .name          = "default",
> -        .type          = AVMEDIA_TYPE_VIDEO,
> -        .config_props  = config_output,
> -    },
> -};
> -
> -#define STACK_COMMON_OPTS \
> -    { "inputs", "Set number of inputs", OFFSET(nb_inputs), AV_OPT_TYPE_INT, {
> .i64 = 2 }, 2, UINT16_MAX, .flags = FLAGS },                   \
> -    { "shortest", "Force termination when the shortest input terminates",
> OFFSET(shortest), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, FLAGS },
> +#include "stack_internal.c"
>  
>  #if CONFIG_HSTACK_VAAPI_FILTER
>  
> -static const AVOption hstack_vaapi_options[] = {
> -    STACK_COMMON_OPTS
> -
> -    { "height", "Set output height (0 to use the height of input 0)",
> OFFSET(tile_height), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, UINT16_MAX, FLAGS },
> -    { NULL }
> -};
> -
> -AVFILTER_DEFINE_CLASS(hstack_vaapi);
> -
> -const AVFilter ff_vf_hstack_vaapi = {
> -    .name           = "hstack_vaapi",
> -    .description    = NULL_IF_CONFIG_SMALL("VA-API hstack."),
> -    .priv_size      = sizeof(StackVAAPIContext),
> -    .priv_class     = &hstack_vaapi_class,
> -    .init           = vaapi_stack_init,
> -    .uninit         = vaapi_stack_uninit,
> -    .activate       = vaapi_stack_activate,
> -    FILTER_QUERY_FUNC(vaapi_stack_query_formats),
> -    FILTER_OUTPUTS(vaapi_stack_outputs),
> -    .flags_internal = FF_FILTER_FLAG_HWFRAME_AWARE,
> -    .flags          = AVFILTER_FLAG_DYNAMIC_INPUTS,
> -};
> +DEFINE_HSTACK_OPTIONS(vaapi);
> +DEFINE_STACK_FILTER(hstack, vaapi, "VA-API");
>  
>  #endif
>  
>  #if CONFIG_VSTACK_VAAPI_FILTER
>  
> -static const AVOption vstack_vaapi_options[] = {
> -    STACK_COMMON_OPTS
> -
> -    { "width",   "Set output width (0 to use the width of input 0)",
> OFFSET(tile_width), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, UINT16_MAX, FLAGS },
> -    { NULL }
> -};
> -
> -AVFILTER_DEFINE_CLASS(vstack_vaapi);
> -
> -const AVFilter ff_vf_vstack_vaapi = {
> -    .name           = "vstack_vaapi",
> -    .description    = NULL_IF_CONFIG_SMALL("VA-API vstack."),
> -    .priv_size      = sizeof(StackVAAPIContext),
> -    .priv_class     = &vstack_vaapi_class,
> -    .init           = vaapi_stack_init,
> -    .uninit         = vaapi_stack_uninit,
> -    .activate       = vaapi_stack_activate,
> -    FILTER_QUERY_FUNC(vaapi_stack_query_formats),
> -    FILTER_OUTPUTS(vaapi_stack_outputs),
> -    .flags_internal = FF_FILTER_FLAG_HWFRAME_AWARE,
> -    .flags          = AVFILTER_FLAG_DYNAMIC_INPUTS,
> -};
> +DEFINE_VSTACK_OPTIONS(vaapi);
> +DEFINE_STACK_FILTER(vstack, vaapi, "VA-API");
>  
>  #endif
>  
>  #if CONFIG_XSTACK_VAAPI_FILTER
>  
> -static const AVOption xstack_vaapi_options[] = {
> -    STACK_COMMON_OPTS
> -
> -    { "layout", "Set custom layout", OFFSET(layout), AV_OPT_TYPE_STRING,
> {.str = NULL}, 0, 0, .flags = FLAGS },
> -    { "grid",   "set fixed size grid layout", OFFSET(nb_grid_columns),
> AV_OPT_TYPE_IMAGE_SIZE, {.str = NULL}, 0, 0, .flags = FLAGS },
> -    { "grid_tile_size",   "set tile size in grid layout", OFFSET(tile_width),
> AV_OPT_TYPE_IMAGE_SIZE, {.str = NULL}, 0, 0, .flags = FLAGS },
> -    { "fill",   "Set the color for unused pixels", OFFSET(fillcolor_str),
> AV_OPT_TYPE_STRING, {.str = "none"}, .flags = FLAGS },
> -    { NULL }
> -};
> -
> -AVFILTER_DEFINE_CLASS(xstack_vaapi);
> -
> -const AVFilter ff_vf_xstack_vaapi = {
> -    .name           = "xstack_vaapi",
> -    .description    = NULL_IF_CONFIG_SMALL("VA-API xstack."),
> -    .priv_size      = sizeof(StackVAAPIContext),
> -    .priv_class     = &xstack_vaapi_class,
> -    .init           = vaapi_stack_init,
> -    .uninit         = vaapi_stack_uninit,
> -    .activate       = vaapi_stack_activate,
> -    FILTER_OUTPUTS(vaapi_stack_outputs),
> -    FILTER_QUERY_FUNC(vaapi_stack_query_formats),
> -    .flags_internal = FF_FILTER_FLAG_HWFRAME_AWARE,
> -    .flags          = AVFILTER_FLAG_DYNAMIC_INPUTS,
> -};
> +DEFINE_XSTACK_OPTIONS(vaapi);
> +DEFINE_STACK_FILTER(xstack, vaapi, "VA-API");
>  
>  #endif

Will apply the patchset.

-Haihao