[FFmpeg-devel] avfilter: add pad opencl filter

Signed-off-by: Paul B Mahol <onemda@gmail.com>
---
 configure                   |   1 +
 doc/filters.texi            |  29 ++++
 libavfilter/Makefile        |   1 +
 libavfilter/allfilters.c    |   1 +
 libavfilter/opencl/pad.cl   |  34 +++++
 libavfilter/opencl_source.h |   1 +
 libavfilter/vf_pad_opencl.c | 289 ++++++++++++++++++++++++++++++++++++
 7 files changed, 356 insertions(+)
 create mode 100644 libavfilter/opencl/pad.cl
 create mode 100644 libavfilter/vf_pad_opencl.c

On 06/02/2020 18:54, Paul B Mahol wrote:
> Signed-off-by: Paul B Mahol <onemda@gmail.com>
> ---
>  configure                   |   1 +
>  doc/filters.texi            |  29 ++++
>  libavfilter/Makefile        |   1 +
>  libavfilter/allfilters.c    |   1 +
>  libavfilter/opencl/pad.cl   |  34 +++++
>  libavfilter/opencl_source.h |   1 +
>  libavfilter/vf_pad_opencl.c | 289 ++++++++++++++++++++++++++++++++++++
>  7 files changed, 356 insertions(+)
>  create mode 100644 libavfilter/opencl/pad.cl
>  create mode 100644 libavfilter/vf_pad_opencl.c
> 
> diff --git a/configure b/configure
> index 58419cd88c..45ba821f8b 100755
> --- a/configure
> +++ b/configure
> @@ -3535,6 +3535,7 @@ overlay_qsv_filter_deps="libmfx"
>  overlay_qsv_filter_select="qsvvpp"
>  overlay_vulkan_filter_deps="vulkan libglslang"
>  owdenoise_filter_deps="gpl"
> +pad_opencl_filter_deps="opencl"
>  pan_filter_deps="swresample"
>  perspective_filter_deps="gpl"
>  phase_filter_deps="gpl"
> diff --git a/doc/filters.texi b/doc/filters.texi
> index f96ba638b2..245968be34 100644
> --- a/doc/filters.texi
> +++ b/doc/filters.texi
> @@ -21096,6 +21096,35 @@ The inputs have same memory layout for color channels , the overlay has addition
>  
>  @end itemize
>  
> +@section pad_opencl
> +
> +Add paddings to the input image, and place the original input at the
> +provided @var{x}, @var{y} coordinates.
> +
> +It accepts the following options:
> +
> +@table @option
> +@item width, w
> +@item height, h
> +Specify the size of the output image with the
> +paddings added. If the value for @var{width} or @var{height} is 0, the
> +corresponding input size is used for the output.

No it isn't?  config_output always fails for me when I try to do this.

> +
> +The default value of @var{width} and @var{height} is 0.
> +
> +@item x
> +@item y
> +Specify the offsets to place the input image at within the padded area,
> +with respect to the top/left border of the output image.
> +
> +The default value of @var{x} and @var{y} is 0.
> +
> +@item color
> +Specify the color of the padded area. For the syntax of this option,
> +check the @ref{color syntax,,"Color" section in the ffmpeg-utils
> +manual,ffmpeg-utils}.
> +@end table
> +
>  @section prewitt_opencl
>  
>  Apply the Prewitt operator (@url{https://en.wikipedia.org/wiki/Prewitt_operator}) to input video stream.
> diff --git a/libavfilter/Makefile b/libavfilter/Makefile
> index 3053740dd3..f40849cdf8 100644
> --- a/libavfilter/Makefile
> +++ b/libavfilter/Makefile
> @@ -328,6 +328,7 @@ OBJS-$(CONFIG_OVERLAY_QSV_FILTER)            += vf_overlay_qsv.o framesync.o
>  OBJS-$(CONFIG_OVERLAY_VULKAN_FILTER)         += vf_overlay_vulkan.o vulkan.o
>  OBJS-$(CONFIG_OWDENOISE_FILTER)              += vf_owdenoise.o
>  OBJS-$(CONFIG_PAD_FILTER)                    += vf_pad.o
> +OBJS-$(CONFIG_PAD_OPENCL_FILTER)             += vf_pad_opencl.o opencl.o opencl/pad.o
>  OBJS-$(CONFIG_PALETTEGEN_FILTER)             += vf_palettegen.o
>  OBJS-$(CONFIG_PALETTEUSE_FILTER)             += vf_paletteuse.o framesync.o
>  OBJS-$(CONFIG_PERMS_FILTER)                  += f_perms.o
> diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
> index 1052978cd4..49e748ae88 100644
> --- a/libavfilter/allfilters.c
> +++ b/libavfilter/allfilters.c
> @@ -312,6 +312,7 @@ extern AVFilter ff_vf_overlay_qsv;
>  extern AVFilter ff_vf_overlay_vulkan;
>  extern AVFilter ff_vf_owdenoise;
>  extern AVFilter ff_vf_pad;
> +extern AVFilter ff_vf_pad_opencl;
>  extern AVFilter ff_vf_palettegen;
>  extern AVFilter ff_vf_paletteuse;
>  extern AVFilter ff_vf_perms;
> diff --git a/libavfilter/opencl/pad.cl b/libavfilter/opencl/pad.cl
> new file mode 100644
> index 0000000000..43f95cc2fb
> --- /dev/null
> +++ b/libavfilter/opencl/pad.cl
> @@ -0,0 +1,34 @@
> +/*
> + * 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
> + */
> +
> +const sampler_t sampler = CLK_NORMALIZED_COORDS_FALSE |
> +                          CLK_FILTER_NEAREST;
> +
> +__kernel void pad (
> +    __read_only  image2d_t src,
> +    __write_only image2d_t dst,
> +    float4 color,
> +    int2 xy)
> +{
> +    int2 size_src = get_image_dim(src);
> +    int2 loc = (int2)(get_global_id(0), get_global_id(1));
> +    int2 src_pos = (int2)(get_global_id(0) - xy.x, get_global_id(1) - xy.y);
> +    float4 pixel = read_imagef(src, sampler, src_pos);

This reads outside the image without a clamp.

Maybe it would be better to branch on the condition before the read, avoiding the redundant access entirely?

> +    write_imagef(dst, loc, loc.x >= size_src.x + xy.x || loc.y >= size_src.y + xy.y ||
> +                           loc.x <  xy.x || loc.y < xy.y ? color : pixel);
> +}
> diff --git a/libavfilter/opencl_source.h b/libavfilter/opencl_source.h
> index 4e262672ad..7e8133090e 100644
> --- a/libavfilter/opencl_source.h
> +++ b/libavfilter/opencl_source.h
> @@ -27,6 +27,7 @@ extern const char *ff_opencl_source_deshake;
>  extern const char *ff_opencl_source_neighbor;
>  extern const char *ff_opencl_source_nlmeans;
>  extern const char *ff_opencl_source_overlay;
> +extern const char *ff_opencl_source_pad;
>  extern const char *ff_opencl_source_tonemap;
>  extern const char *ff_opencl_source_transpose;
>  extern const char *ff_opencl_source_unsharp;
> diff --git a/libavfilter/vf_pad_opencl.c b/libavfilter/vf_pad_opencl.c
> new file mode 100644
> index 0000000000..ca365c8d92
> --- /dev/null
> +++ b/libavfilter/vf_pad_opencl.c
> @@ -0,0 +1,289 @@
> +/*
> + * 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/colorspace.h"
> +#include "libavutil/opt.h"
> +#include "libavutil/imgutils.h"
> +#include "avfilter.h"
> +#include "formats.h"
> +#include "internal.h"
> +#include "opencl.h"
> +#include "opencl_source.h"
> +#include "video.h"
> +
> +typedef struct PadOpenCLContext {
> +    OpenCLFilterContext ocf;
> +    int initialized;
> +    int is_rgb;
> +    int is_packed;
> +    int hsub, vsub;
> +
> +    cl_command_queue command_queue;
> +    cl_kernel kernel_pad;
> +
> +    int w, h;
> +    int x, y;
> +    uint8_t pad_rgba[4];
> +    uint8_t pad_color[4];
> +    cl_float4 pad_color_float;
> +    cl_int2 pad_pos;
> +} PadOpenCLContext;
> +
> +static int pad_opencl_init(AVFilterContext *avctx, AVFrame *input_frame)
> +{
> +    PadOpenCLContext *ctx = avctx->priv;
> +    AVHWFramesContext *input_frames_ctx = (AVHWFramesContext *)input_frame->hw_frames_ctx->data;
> +    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(input_frames_ctx->sw_format);
> +    cl_int cle;
> +    int err;
> +
> +    ctx->is_rgb = !!(desc->flags & AV_PIX_FMT_FLAG_RGB);
> +    ctx->is_packed = !(desc->flags & AV_PIX_FMT_FLAG_PLANAR);
> +    ctx->hsub = desc->log2_chroma_w;
> +    ctx->vsub = desc->log2_chroma_h;
> +
> +    err = ff_opencl_filter_load_program(avctx, &ff_opencl_source_pad, 1);
> +    if (err < 0)
> +        goto fail;
> +
> +    ctx->command_queue = clCreateCommandQueue(
> +        ctx->ocf.hwctx->context,
> +        ctx->ocf.hwctx->device_id,
> +        0,
> +        &cle
> +    );
> +
> +    if (ctx->is_rgb) {
> +        ctx->pad_color[0] = ctx->pad_rgba[0];
> +        ctx->pad_color[1] = ctx->pad_rgba[1];
> +        ctx->pad_color[2] = ctx->pad_rgba[2];
> +        ctx->pad_color[3] = ctx->pad_rgba[3];
> +    } else {
> +        ctx->pad_color[0] = RGB_TO_Y_BT709(ctx->pad_rgba[0], ctx->pad_rgba[1], ctx->pad_rgba[2]);
> +        ctx->pad_color[1] = RGB_TO_U_BT709(ctx->pad_rgba[0], ctx->pad_rgba[1], ctx->pad_rgba[2], 0);
> +        ctx->pad_color[2] = RGB_TO_V_BT709(ctx->pad_rgba[0], ctx->pad_rgba[1], ctx->pad_rgba[2], 0);
> +        ctx->pad_color[3] = ctx->pad_rgba[3];
> +    }
> +
> +    CL_FAIL_ON_ERROR(AVERROR(EIO), "Failed to create OpenCL command queue %d.\n", cle);
> +
> +    ctx->kernel_pad = clCreateKernel(ctx->ocf.program, "pad", &cle);
> +    CL_FAIL_ON_ERROR(AVERROR(EIO), "Failed to create pad kernel: %d.\n", cle);
> +
> +    for (int i = 0; i < 4; ++i) {
> +        ctx->pad_color_float.s[i] = (float)ctx->pad_color[i] / 255.0;
> +    }
> +
> +    ctx->pad_pos.s[0] = ctx->x;
> +    ctx->pad_pos.s[1] = ctx->y;
> +
> +    ctx->initialized = 1;
> +    return 0;
> +
> +fail:
> +    if (ctx->command_queue)
> +        clReleaseCommandQueue(ctx->command_queue);
> +    if (ctx->kernel_pad)
> +        clReleaseKernel(ctx->kernel_pad);
> +    return err;
> +}
> +
> +static int filter_frame(AVFilterLink *link, AVFrame *input_frame)
> +{
> +    AVFilterContext *avctx = link->dst;
> +    AVFilterLink *outlink = avctx->outputs[0];
> +    PadOpenCLContext *pad_ctx = avctx->priv;
> +    AVFrame *output_frame = NULL;
> +    int err;
> +    cl_int cle;
> +    size_t global_work[2];
> +    cl_mem src, dst;
> +
> +    if (!input_frame->hw_frames_ctx)
> +        return AVERROR(EINVAL);
> +
> +    if (!pad_ctx->initialized) {
> +        err = pad_opencl_init(avctx, input_frame);
> +        if (err < 0)
> +            goto fail;
> +    }
> +
> +    output_frame = ff_get_video_buffer(outlink, outlink->w, outlink->h);
> +    if (!output_frame) {
> +        err = AVERROR(ENOMEM);
> +        goto fail;
> +    }
> +
> +    for (int p = 0; p < FF_ARRAY_ELEMS(output_frame->data); p++) {
> +        cl_float4 pad_color_float;
> +        cl_int2 pad_pos;
> +
> +        if (pad_ctx->is_packed) {
> +            pad_color_float = pad_ctx->pad_color_float;
> +        } else {
> +            pad_color_float.s[0] = pad_ctx->pad_color_float.s[p];
> +        }

This colour choice is missing some cases: it's off for GBRP (wrong order), and for NV12/P010 (missing the second component on the chroma plane).

(Check the format list that hwcontext_opencl logs on AV_LOG_DEBUG in get_constraints() from hwupload.)

> +
> +        if (p > 0 && p < 3) {
> +            pad_pos.s[0] = pad_ctx->pad_pos.s[0] >> pad_ctx->hsub;
> +            pad_pos.s[1] = pad_ctx->pad_pos.s[1] >> pad_ctx->vsub;
> +        } else {
> +            pad_pos.s[0] = pad_ctx->pad_pos.s[0];
> +            pad_pos.s[1] = pad_ctx->pad_pos.s[1];
> +        }
> +
> +        src = (cl_mem)input_frame->data[p];
> +        dst = (cl_mem)output_frame->data[p];
> +
> +        if (!dst)
> +            break;
> +
> +        CL_SET_KERNEL_ARG(pad_ctx->kernel_pad, 0, cl_mem, &src);
> +        CL_SET_KERNEL_ARG(pad_ctx->kernel_pad, 1, cl_mem, &dst);
> +        CL_SET_KERNEL_ARG(pad_ctx->kernel_pad, 2, cl_float4, &pad_color_float);
> +        CL_SET_KERNEL_ARG(pad_ctx->kernel_pad, 3, cl_int2, &pad_pos);
> +
> +        err = ff_opencl_filter_work_size_from_image(avctx, global_work, output_frame, p, 16);
> +        if (err < 0)
> +            goto fail;
> +
> +        cle = clEnqueueNDRangeKernel(pad_ctx->command_queue, pad_ctx->kernel_pad, 2, NULL,
> +                                     global_work, NULL, 0, NULL, NULL);
> +
> +        CL_FAIL_ON_ERROR(AVERROR(EIO), "Failed to enqueue pad kernel: %d.\n", cle);
> +    }
> +
> +    // Run queued kernel
> +    cle = clFinish(pad_ctx->command_queue);
> +    CL_FAIL_ON_ERROR(AVERROR(EIO), "Failed to finish command queue: %d.\n", cle);
> +
> +    err = av_frame_copy_props(output_frame, input_frame);
> +    if (err < 0)
> +        goto fail;
> +
> +    av_frame_free(&input_frame);
> +
> +    return ff_filter_frame(outlink, output_frame);
> +
> +fail:
> +    clFinish(pad_ctx->command_queue);
> +    av_frame_free(&input_frame);
> +    av_frame_free(&output_frame);
> +    return err;
> +}
> +
> +static av_cold void pad_opencl_uninit(AVFilterContext *avctx)
> +{
> +    PadOpenCLContext *ctx = avctx->priv;
> +    cl_int cle;
> +
> +    if (ctx->kernel_pad) {
> +        cle = clReleaseKernel(ctx->kernel_pad);
> +        if (cle != CL_SUCCESS)
> +            av_log(avctx, AV_LOG_ERROR, "Failed to release "
> +                   "kernel: %d.\n", cle);
> +    }
> +
> +    if (ctx->command_queue) {
> +        cle = clReleaseCommandQueue(ctx->command_queue);
> +        if (cle != CL_SUCCESS)
> +            av_log(avctx, AV_LOG_ERROR, "Failed to release "
> +                   "command queue: %d.\n", cle);
> +    }
> +
> +    ff_opencl_filter_uninit(avctx);
> +}
> +
> +static int pad_opencl_config_output(AVFilterLink *outlink)
> +{
> +    AVFilterContext *avctx = outlink->src;
> +    PadOpenCLContext *ctx = avctx->priv;
> +    int err;
> +
> +    if (ctx->w < avctx->inputs[0]->w ||
> +        ctx->h < avctx->inputs[0]->h) {
> +        return AVERROR(EINVAL);
> +    }
> +
> +    if (ctx->w > avctx->inputs[0]->w && ctx->h > avctx->inputs[0]->h) {
> +        ctx->ocf.output_width  = ctx->w;
> +        ctx->ocf.output_height = ctx->h;
> +    } else {
> +        ctx->ocf.output_width  = avctx->inputs[0]->w;
> +        ctx->ocf.output_height = avctx->inputs[0]->h;
> +    }

This goes wrong if you're only padding in one direction (e.g. to change aspect ratio).

Consider a 1080p input with args like h=1200:y=60.

> +
> +    if (ctx->x + avctx->inputs[0]->w > ctx->ocf.output_width ||
> +        ctx->y + avctx->inputs[0]->h > ctx->ocf.output_height) {
> +        return AVERROR(EINVAL);
> +    }
> +
> +    err = ff_opencl_filter_config_output(outlink);
> +    if (err < 0)
> +        return err;
> +
> +    return 0;
> +}
> +
> +static const AVFilterPad pad_opencl_inputs[] = {
> +    {
> +        .name = "default",
> +        .type = AVMEDIA_TYPE_VIDEO,
> +        .filter_frame = filter_frame,
> +        .config_props = &ff_opencl_filter_config_input,
> +    },
> +    { NULL }
> +};
> +
> +static const AVFilterPad pad_opencl_outputs[] = {
> +    {
> +        .name = "default",
> +        .type = AVMEDIA_TYPE_VIDEO,
> +        .config_props = &pad_opencl_config_output,
> +    },
> +    { NULL }
> +};
> +
> +#define OFFSET(x) offsetof(PadOpenCLContext, x)
> +#define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
> +
> +static const AVOption pad_opencl_options[] = {
> +    { "width",  "set the pad area width",       OFFSET(w), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT16_MAX, FLAGS },
> +    { "w",      "set the pad area width",       OFFSET(w), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT16_MAX, FLAGS },
> +    { "height", "set the pad area height",      OFFSET(h), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT16_MAX, FLAGS },
> +    { "h",      "set the pad area height",      OFFSET(h), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT16_MAX, FLAGS },
> +    { "x",      "set the x offset for the input image position", OFFSET(x), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT16_MAX, FLAGS },
> +    { "y",      "set the y offset for the input image position", OFFSET(y), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT16_MAX, FLAGS },
> +    { "color", "set the color of the padded area border", OFFSET(pad_rgba), AV_OPT_TYPE_COLOR, { .str = "black" }, CHAR_MIN, CHAR_MAX, FLAGS },
> +    { NULL }
> +};
> +
> +AVFILTER_DEFINE_CLASS(pad_opencl);
> +
> +AVFilter ff_vf_pad_opencl = {
> +    .name           = "pad_opencl",
> +    .description    = NULL_IF_CONFIG_SMALL("Pad the input video."),
> +    .priv_size      = sizeof(PadOpenCLContext),
> +    .priv_class     = &pad_opencl_class,
> +    .init           = &ff_opencl_filter_init,
> +    .uninit         = &pad_opencl_uninit,
> +    .query_formats  = &ff_opencl_filter_query_formats,
> +    .inputs         = pad_opencl_inputs,
> +    .outputs        = pad_opencl_outputs,
> +    .flags_internal = FF_FILTER_FLAG_HWFRAME_AWARE
> +};
> 

Thanks,

- Mark

On 2/9/20, Mark Thompson <sw@jkqxz.net> wrote:
> On 06/02/2020 18:54, Paul B Mahol wrote:
>> Signed-off-by: Paul B Mahol <onemda@gmail.com>
>> ---
>>  configure                   |   1 +
>>  doc/filters.texi            |  29 ++++
>>  libavfilter/Makefile        |   1 +
>>  libavfilter/allfilters.c    |   1 +
>>  libavfilter/opencl/pad.cl   |  34 +++++
>>  libavfilter/opencl_source.h |   1 +
>>  libavfilter/vf_pad_opencl.c | 289 ++++++++++++++++++++++++++++++++++++
>>  7 files changed, 356 insertions(+)
>>  create mode 100644 libavfilter/opencl/pad.cl
>>  create mode 100644 libavfilter/vf_pad_opencl.c
>>
>> diff --git a/configure b/configure
>> index 58419cd88c..45ba821f8b 100755
>> --- a/configure
>> +++ b/configure
>> @@ -3535,6 +3535,7 @@ overlay_qsv_filter_deps="libmfx"
>>  overlay_qsv_filter_select="qsvvpp"
>>  overlay_vulkan_filter_deps="vulkan libglslang"
>>  owdenoise_filter_deps="gpl"
>> +pad_opencl_filter_deps="opencl"
>>  pan_filter_deps="swresample"
>>  perspective_filter_deps="gpl"
>>  phase_filter_deps="gpl"
>> diff --git a/doc/filters.texi b/doc/filters.texi
>> index f96ba638b2..245968be34 100644
>> --- a/doc/filters.texi
>> +++ b/doc/filters.texi
>> @@ -21096,6 +21096,35 @@ The inputs have same memory layout for color
>> channels , the overlay has addition
>>
>>  @end itemize
>>
>> +@section pad_opencl
>> +
>> +Add paddings to the input image, and place the original input at the
>> +provided @var{x}, @var{y} coordinates.
>> +
>> +It accepts the following options:
>> +
>> +@table @option
>> +@item width, w
>> +@item height, h
>> +Specify the size of the output image with the
>> +paddings added. If the value for @var{width} or @var{height} is 0, the
>> +corresponding input size is used for the output.
>
> No it isn't?  config_output always fails for me when I try to do this.
>
>> +
>> +The default value of @var{width} and @var{height} is 0.
>> +
>> +@item x
>> +@item y
>> +Specify the offsets to place the input image at within the padded area,
>> +with respect to the top/left border of the output image.
>> +
>> +The default value of @var{x} and @var{y} is 0.
>> +
>> +@item color
>> +Specify the color of the padded area. For the syntax of this option,
>> +check the @ref{color syntax,,"Color" section in the ffmpeg-utils
>> +manual,ffmpeg-utils}.
>> +@end table
>> +
>>  @section prewitt_opencl
>>
>>  Apply the Prewitt operator
>> (@url{https://en.wikipedia.org/wiki/Prewitt_operator}) to input video
>> stream.
>> diff --git a/libavfilter/Makefile b/libavfilter/Makefile
>> index 3053740dd3..f40849cdf8 100644
>> --- a/libavfilter/Makefile
>> +++ b/libavfilter/Makefile
>> @@ -328,6 +328,7 @@ OBJS-$(CONFIG_OVERLAY_QSV_FILTER)            +=
>> vf_overlay_qsv.o framesync.o
>>  OBJS-$(CONFIG_OVERLAY_VULKAN_FILTER)         += vf_overlay_vulkan.o
>> vulkan.o
>>  OBJS-$(CONFIG_OWDENOISE_FILTER)              += vf_owdenoise.o
>>  OBJS-$(CONFIG_PAD_FILTER)                    += vf_pad.o
>> +OBJS-$(CONFIG_PAD_OPENCL_FILTER)             += vf_pad_opencl.o opencl.o
>> opencl/pad.o
>>  OBJS-$(CONFIG_PALETTEGEN_FILTER)             += vf_palettegen.o
>>  OBJS-$(CONFIG_PALETTEUSE_FILTER)             += vf_paletteuse.o
>> framesync.o
>>  OBJS-$(CONFIG_PERMS_FILTER)                  += f_perms.o
>> diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
>> index 1052978cd4..49e748ae88 100644
>> --- a/libavfilter/allfilters.c
>> +++ b/libavfilter/allfilters.c
>> @@ -312,6 +312,7 @@ extern AVFilter ff_vf_overlay_qsv;
>>  extern AVFilter ff_vf_overlay_vulkan;
>>  extern AVFilter ff_vf_owdenoise;
>>  extern AVFilter ff_vf_pad;
>> +extern AVFilter ff_vf_pad_opencl;
>>  extern AVFilter ff_vf_palettegen;
>>  extern AVFilter ff_vf_paletteuse;
>>  extern AVFilter ff_vf_perms;
>> diff --git a/libavfilter/opencl/pad.cl b/libavfilter/opencl/pad.cl
>> new file mode 100644
>> index 0000000000..43f95cc2fb
>> --- /dev/null
>> +++ b/libavfilter/opencl/pad.cl
>> @@ -0,0 +1,34 @@
>> +/*
>> + * 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
>> + */
>> +
>> +const sampler_t sampler = CLK_NORMALIZED_COORDS_FALSE |
>> +                          CLK_FILTER_NEAREST;
>> +
>> +__kernel void pad (
>> +    __read_only  image2d_t src,
>> +    __write_only image2d_t dst,
>> +    float4 color,
>> +    int2 xy)
>> +{
>> +    int2 size_src = get_image_dim(src);
>> +    int2 loc = (int2)(get_global_id(0), get_global_id(1));
>> +    int2 src_pos = (int2)(get_global_id(0) - xy.x, get_global_id(1) -
>> xy.y);
>> +    float4 pixel = read_imagef(src, sampler, src_pos);
>
> This reads outside the image without a clamp.
>
> Maybe it would be better to branch on the condition before the read,
> avoiding the redundant access entirely?
>
>> +    write_imagef(dst, loc, loc.x >= size_src.x + xy.x || loc.y >=
>> size_src.y + xy.y ||
>> +                           loc.x <  xy.x || loc.y < xy.y ? color :
>> pixel);
>> +}
>> diff --git a/libavfilter/opencl_source.h b/libavfilter/opencl_source.h
>> index 4e262672ad..7e8133090e 100644
>> --- a/libavfilter/opencl_source.h
>> +++ b/libavfilter/opencl_source.h
>> @@ -27,6 +27,7 @@ extern const char *ff_opencl_source_deshake;
>>  extern const char *ff_opencl_source_neighbor;
>>  extern const char *ff_opencl_source_nlmeans;
>>  extern const char *ff_opencl_source_overlay;
>> +extern const char *ff_opencl_source_pad;
>>  extern const char *ff_opencl_source_tonemap;
>>  extern const char *ff_opencl_source_transpose;
>>  extern const char *ff_opencl_source_unsharp;
>> diff --git a/libavfilter/vf_pad_opencl.c b/libavfilter/vf_pad_opencl.c
>> new file mode 100644
>> index 0000000000..ca365c8d92
>> --- /dev/null
>> +++ b/libavfilter/vf_pad_opencl.c
>> @@ -0,0 +1,289 @@
>> +/*
>> + * 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/colorspace.h"
>> +#include "libavutil/opt.h"
>> +#include "libavutil/imgutils.h"
>> +#include "avfilter.h"
>> +#include "formats.h"
>> +#include "internal.h"
>> +#include "opencl.h"
>> +#include "opencl_source.h"
>> +#include "video.h"
>> +
>> +typedef struct PadOpenCLContext {
>> +    OpenCLFilterContext ocf;
>> +    int initialized;
>> +    int is_rgb;
>> +    int is_packed;
>> +    int hsub, vsub;
>> +
>> +    cl_command_queue command_queue;
>> +    cl_kernel kernel_pad;
>> +
>> +    int w, h;
>> +    int x, y;
>> +    uint8_t pad_rgba[4];
>> +    uint8_t pad_color[4];
>> +    cl_float4 pad_color_float;
>> +    cl_int2 pad_pos;
>> +} PadOpenCLContext;
>> +
>> +static int pad_opencl_init(AVFilterContext *avctx, AVFrame *input_frame)
>> +{
>> +    PadOpenCLContext *ctx = avctx->priv;
>> +    AVHWFramesContext *input_frames_ctx = (AVHWFramesContext
>> *)input_frame->hw_frames_ctx->data;
>> +    const AVPixFmtDescriptor *desc =
>> av_pix_fmt_desc_get(input_frames_ctx->sw_format);
>> +    cl_int cle;
>> +    int err;
>> +
>> +    ctx->is_rgb = !!(desc->flags & AV_PIX_FMT_FLAG_RGB);
>> +    ctx->is_packed = !(desc->flags & AV_PIX_FMT_FLAG_PLANAR);
>> +    ctx->hsub = desc->log2_chroma_w;
>> +    ctx->vsub = desc->log2_chroma_h;
>> +
>> +    err = ff_opencl_filter_load_program(avctx, &ff_opencl_source_pad, 1);
>> +    if (err < 0)
>> +        goto fail;
>> +
>> +    ctx->command_queue = clCreateCommandQueue(
>> +        ctx->ocf.hwctx->context,
>> +        ctx->ocf.hwctx->device_id,
>> +        0,
>> +        &cle
>> +    );
>> +
>> +    if (ctx->is_rgb) {
>> +        ctx->pad_color[0] = ctx->pad_rgba[0];
>> +        ctx->pad_color[1] = ctx->pad_rgba[1];
>> +        ctx->pad_color[2] = ctx->pad_rgba[2];
>> +        ctx->pad_color[3] = ctx->pad_rgba[3];
>> +    } else {
>> +        ctx->pad_color[0] = RGB_TO_Y_BT709(ctx->pad_rgba[0],
>> ctx->pad_rgba[1], ctx->pad_rgba[2]);
>> +        ctx->pad_color[1] = RGB_TO_U_BT709(ctx->pad_rgba[0],
>> ctx->pad_rgba[1], ctx->pad_rgba[2], 0);
>> +        ctx->pad_color[2] = RGB_TO_V_BT709(ctx->pad_rgba[0],
>> ctx->pad_rgba[1], ctx->pad_rgba[2], 0);
>> +        ctx->pad_color[3] = ctx->pad_rgba[3];
>> +    }
>> +
>> +    CL_FAIL_ON_ERROR(AVERROR(EIO), "Failed to create OpenCL command queue
>> %d.\n", cle);
>> +
>> +    ctx->kernel_pad = clCreateKernel(ctx->ocf.program, "pad", &cle);
>> +    CL_FAIL_ON_ERROR(AVERROR(EIO), "Failed to create pad kernel: %d.\n",
>> cle);
>> +
>> +    for (int i = 0; i < 4; ++i) {
>> +        ctx->pad_color_float.s[i] = (float)ctx->pad_color[i] / 255.0;
>> +    }
>> +
>> +    ctx->pad_pos.s[0] = ctx->x;
>> +    ctx->pad_pos.s[1] = ctx->y;
>> +
>> +    ctx->initialized = 1;
>> +    return 0;
>> +
>> +fail:
>> +    if (ctx->command_queue)
>> +        clReleaseCommandQueue(ctx->command_queue);
>> +    if (ctx->kernel_pad)
>> +        clReleaseKernel(ctx->kernel_pad);
>> +    return err;
>> +}
>> +
>> +static int filter_frame(AVFilterLink *link, AVFrame *input_frame)
>> +{
>> +    AVFilterContext *avctx = link->dst;
>> +    AVFilterLink *outlink = avctx->outputs[0];
>> +    PadOpenCLContext *pad_ctx = avctx->priv;
>> +    AVFrame *output_frame = NULL;
>> +    int err;
>> +    cl_int cle;
>> +    size_t global_work[2];
>> +    cl_mem src, dst;
>> +
>> +    if (!input_frame->hw_frames_ctx)
>> +        return AVERROR(EINVAL);
>> +
>> +    if (!pad_ctx->initialized) {
>> +        err = pad_opencl_init(avctx, input_frame);
>> +        if (err < 0)
>> +            goto fail;
>> +    }
>> +
>> +    output_frame = ff_get_video_buffer(outlink, outlink->w, outlink->h);
>> +    if (!output_frame) {
>> +        err = AVERROR(ENOMEM);
>> +        goto fail;
>> +    }
>> +
>> +    for (int p = 0; p < FF_ARRAY_ELEMS(output_frame->data); p++) {
>> +        cl_float4 pad_color_float;
>> +        cl_int2 pad_pos;
>> +
>> +        if (pad_ctx->is_packed) {
>> +            pad_color_float = pad_ctx->pad_color_float;
>> +        } else {
>> +            pad_color_float.s[0] = pad_ctx->pad_color_float.s[p];
>> +        }
>
> This colour choice is missing some cases: it's off for GBRP (wrong order),
> and for NV12/P010 (missing the second component on the chroma plane).
>
> (Check the format list that hwcontext_opencl logs on AV_LOG_DEBUG in
> get_constraints() from hwupload.)

How to fix?

>
>> +
>> +        if (p > 0 && p < 3) {
>> +            pad_pos.s[0] = pad_ctx->pad_pos.s[0] >> pad_ctx->hsub;
>> +            pad_pos.s[1] = pad_ctx->pad_pos.s[1] >> pad_ctx->vsub;
>> +        } else {
>> +            pad_pos.s[0] = pad_ctx->pad_pos.s[0];
>> +            pad_pos.s[1] = pad_ctx->pad_pos.s[1];
>> +        }
>> +
>> +        src = (cl_mem)input_frame->data[p];
>> +        dst = (cl_mem)output_frame->data[p];
>> +
>> +        if (!dst)
>> +            break;
>> +
>> +        CL_SET_KERNEL_ARG(pad_ctx->kernel_pad, 0, cl_mem, &src);
>> +        CL_SET_KERNEL_ARG(pad_ctx->kernel_pad, 1, cl_mem, &dst);
>> +        CL_SET_KERNEL_ARG(pad_ctx->kernel_pad, 2, cl_float4,
>> &pad_color_float);
>> +        CL_SET_KERNEL_ARG(pad_ctx->kernel_pad, 3, cl_int2, &pad_pos);
>> +
>> +        err = ff_opencl_filter_work_size_from_image(avctx, global_work,
>> output_frame, p, 16);
>> +        if (err < 0)
>> +            goto fail;
>> +
>> +        cle = clEnqueueNDRangeKernel(pad_ctx->command_queue,
>> pad_ctx->kernel_pad, 2, NULL,
>> +                                     global_work, NULL, 0, NULL, NULL);
>> +
>> +        CL_FAIL_ON_ERROR(AVERROR(EIO), "Failed to enqueue pad kernel:
>> %d.\n", cle);
>> +    }
>> +
>> +    // Run queued kernel
>> +    cle = clFinish(pad_ctx->command_queue);
>> +    CL_FAIL_ON_ERROR(AVERROR(EIO), "Failed to finish command queue:
>> %d.\n", cle);
>> +
>> +    err = av_frame_copy_props(output_frame, input_frame);
>> +    if (err < 0)
>> +        goto fail;
>> +
>> +    av_frame_free(&input_frame);
>> +
>> +    return ff_filter_frame(outlink, output_frame);
>> +
>> +fail:
>> +    clFinish(pad_ctx->command_queue);
>> +    av_frame_free(&input_frame);
>> +    av_frame_free(&output_frame);
>> +    return err;
>> +}
>> +
>> +static av_cold void pad_opencl_uninit(AVFilterContext *avctx)
>> +{
>> +    PadOpenCLContext *ctx = avctx->priv;
>> +    cl_int cle;
>> +
>> +    if (ctx->kernel_pad) {
>> +        cle = clReleaseKernel(ctx->kernel_pad);
>> +        if (cle != CL_SUCCESS)
>> +            av_log(avctx, AV_LOG_ERROR, "Failed to release "
>> +                   "kernel: %d.\n", cle);
>> +    }
>> +
>> +    if (ctx->command_queue) {
>> +        cle = clReleaseCommandQueue(ctx->command_queue);
>> +        if (cle != CL_SUCCESS)
>> +            av_log(avctx, AV_LOG_ERROR, "Failed to release "
>> +                   "command queue: %d.\n", cle);
>> +    }
>> +
>> +    ff_opencl_filter_uninit(avctx);
>> +}
>> +
>> +static int pad_opencl_config_output(AVFilterLink *outlink)
>> +{
>> +    AVFilterContext *avctx = outlink->src;
>> +    PadOpenCLContext *ctx = avctx->priv;
>> +    int err;
>> +
>> +    if (ctx->w < avctx->inputs[0]->w ||
>> +        ctx->h < avctx->inputs[0]->h) {
>> +        return AVERROR(EINVAL);
>> +    }
>> +
>> +    if (ctx->w > avctx->inputs[0]->w && ctx->h > avctx->inputs[0]->h) {
>> +        ctx->ocf.output_width  = ctx->w;
>> +        ctx->ocf.output_height = ctx->h;
>> +    } else {
>> +        ctx->ocf.output_width  = avctx->inputs[0]->w;
>> +        ctx->ocf.output_height = avctx->inputs[0]->h;
>> +    }
>
> This goes wrong if you're only padding in one direction (e.g. to change
> aspect ratio).
>
> Consider a 1080p input with args like h=1200:y=60.

I do not follow.

>
>> +
>> +    if (ctx->x + avctx->inputs[0]->w > ctx->ocf.output_width ||
>> +        ctx->y + avctx->inputs[0]->h > ctx->ocf.output_height) {
>> +        return AVERROR(EINVAL);
>> +    }
>> +
>> +    err = ff_opencl_filter_config_output(outlink);
>> +    if (err < 0)
>> +        return err;
>> +
>> +    return 0;
>> +}
>> +
>> +static const AVFilterPad pad_opencl_inputs[] = {
>> +    {
>> +        .name = "default",
>> +        .type = AVMEDIA_TYPE_VIDEO,
>> +        .filter_frame = filter_frame,
>> +        .config_props = &ff_opencl_filter_config_input,
>> +    },
>> +    { NULL }
>> +};
>> +
>> +static const AVFilterPad pad_opencl_outputs[] = {
>> +    {
>> +        .name = "default",
>> +        .type = AVMEDIA_TYPE_VIDEO,
>> +        .config_props = &pad_opencl_config_output,
>> +    },
>> +    { NULL }
>> +};
>> +
>> +#define OFFSET(x) offsetof(PadOpenCLContext, x)
>> +#define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
>> +
>> +static const AVOption pad_opencl_options[] = {
>> +    { "width",  "set the pad area width",       OFFSET(w),
>> AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT16_MAX, FLAGS },
>> +    { "w",      "set the pad area width",       OFFSET(w),
>> AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT16_MAX, FLAGS },
>> +    { "height", "set the pad area height",      OFFSET(h),
>> AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT16_MAX, FLAGS },
>> +    { "h",      "set the pad area height",      OFFSET(h),
>> AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT16_MAX, FLAGS },
>> +    { "x",      "set the x offset for the input image position",
>> OFFSET(x), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT16_MAX, FLAGS },
>> +    { "y",      "set the y offset for the input image position",
>> OFFSET(y), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT16_MAX, FLAGS },
>> +    { "color", "set the color of the padded area border",
>> OFFSET(pad_rgba), AV_OPT_TYPE_COLOR, { .str = "black" }, CHAR_MIN,
>> CHAR_MAX, FLAGS },
>> +    { NULL }
>> +};
>> +
>> +AVFILTER_DEFINE_CLASS(pad_opencl);
>> +
>> +AVFilter ff_vf_pad_opencl = {
>> +    .name           = "pad_opencl",
>> +    .description    = NULL_IF_CONFIG_SMALL("Pad the input video."),
>> +    .priv_size      = sizeof(PadOpenCLContext),
>> +    .priv_class     = &pad_opencl_class,
>> +    .init           = &ff_opencl_filter_init,
>> +    .uninit         = &pad_opencl_uninit,
>> +    .query_formats  = &ff_opencl_filter_query_formats,
>> +    .inputs         = pad_opencl_inputs,
>> +    .outputs        = pad_opencl_outputs,
>> +    .flags_internal = FF_FILTER_FLAG_HWFRAME_AWARE
>> +};
>>
>
> Thanks,
>
> - Mark
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel@ffmpeg.org
> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>
> To unsubscribe, visit link above, or email
> ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".

On 09/02/2020 19:33, Paul B Mahol wrote:
> On 2/9/20, Mark Thompson <sw@jkqxz.net> wrote:
>> On 06/02/2020 18:54, Paul B Mahol wrote:
>>> Signed-off-by: Paul B Mahol <onemda@gmail.com>
>>> ---
>>>  configure                   |   1 +
>>>  doc/filters.texi            |  29 ++++
>>>  libavfilter/Makefile        |   1 +
>>>  libavfilter/allfilters.c    |   1 +
>>>  libavfilter/opencl/pad.cl   |  34 +++++
>>>  libavfilter/opencl_source.h |   1 +
>>>  libavfilter/vf_pad_opencl.c | 289 ++++++++++++++++++++++++++++++++++++
>>>  7 files changed, 356 insertions(+)
>>>  create mode 100644 libavfilter/opencl/pad.cl
>>>  create mode 100644 libavfilter/vf_pad_opencl.c
>>>
>>> ...
>>> +
>>> +static int filter_frame(AVFilterLink *link, AVFrame *input_frame)
>>> +{
>>> +    AVFilterContext *avctx = link->dst;
>>> +    AVFilterLink *outlink = avctx->outputs[0];
>>> +    PadOpenCLContext *pad_ctx = avctx->priv;
>>> +    AVFrame *output_frame = NULL;
>>> +    int err;
>>> +    cl_int cle;
>>> +    size_t global_work[2];
>>> +    cl_mem src, dst;
>>> +
>>> +    if (!input_frame->hw_frames_ctx)
>>> +        return AVERROR(EINVAL);
>>> +
>>> +    if (!pad_ctx->initialized) {
>>> +        err = pad_opencl_init(avctx, input_frame);
>>> +        if (err < 0)
>>> +            goto fail;
>>> +    }
>>> +
>>> +    output_frame = ff_get_video_buffer(outlink, outlink->w, outlink->h);
>>> +    if (!output_frame) {
>>> +        err = AVERROR(ENOMEM);
>>> +        goto fail;
>>> +    }
>>> +
>>> +    for (int p = 0; p < FF_ARRAY_ELEMS(output_frame->data); p++) {
>>> +        cl_float4 pad_color_float;
>>> +        cl_int2 pad_pos;
>>> +
>>> +        if (pad_ctx->is_packed) {
>>> +            pad_color_float = pad_ctx->pad_color_float;
>>> +        } else {
>>> +            pad_color_float.s[0] = pad_ctx->pad_color_float.s[p];
>>> +        }
>>
>> This colour choice is missing some cases: it's off for GBRP (wrong order),
>> and for NV12/P010 (missing the second component on the chroma plane).
>>
>> (Check the format list that hwcontext_opencl logs on AV_LOG_DEBUG in
>> get_constraints() from hwupload.)
> 
> How to fix?

I think those two are the only interesting cases, so just apply them manually.  Something like:

If RGB and planar and p in 0..2 then use pad_color_float.s[0] = pad_ctx->pad_color_float[(p + 1) % 3].

If YUV and planar and p is 1 then also set pad_color_float.s[1] = pad_ctx->pad_color_float.s[p + 1].

>>> +
>>> +        if (p > 0 && p < 3) {
>>> +            pad_pos.s[0] = pad_ctx->pad_pos.s[0] >> pad_ctx->hsub;
>>> +            pad_pos.s[1] = pad_ctx->pad_pos.s[1] >> pad_ctx->vsub;
>>> +        } else {
>>> +            pad_pos.s[0] = pad_ctx->pad_pos.s[0];
>>> +            pad_pos.s[1] = pad_ctx->pad_pos.s[1];
>>> +        }
>>> +
>>> +        src = (cl_mem)input_frame->data[p];
>>> +        dst = (cl_mem)output_frame->data[p];
>>> +
>>> +        if (!dst)
>>> +            break;
>>> +
>>> +        CL_SET_KERNEL_ARG(pad_ctx->kernel_pad, 0, cl_mem, &src);
>>> +        CL_SET_KERNEL_ARG(pad_ctx->kernel_pad, 1, cl_mem, &dst);
>>> +        CL_SET_KERNEL_ARG(pad_ctx->kernel_pad, 2, cl_float4,
>>> &pad_color_float);
>>> +        CL_SET_KERNEL_ARG(pad_ctx->kernel_pad, 3, cl_int2, &pad_pos);
>>> +
>>> +        err = ff_opencl_filter_work_size_from_image(avctx, global_work,
>>> output_frame, p, 16);
>>> +        if (err < 0)
>>> +            goto fail;
>>> +
>>> +        cle = clEnqueueNDRangeKernel(pad_ctx->command_queue,
>>> pad_ctx->kernel_pad, 2, NULL,
>>> +                                     global_work, NULL, 0, NULL, NULL);
>>> +
>>> +        CL_FAIL_ON_ERROR(AVERROR(EIO), "Failed to enqueue pad kernel:
>>> %d.\n", cle);
>>> +    }
>>> +
>>> +    // Run queued kernel
>>> +    cle = clFinish(pad_ctx->command_queue);
>>> +    CL_FAIL_ON_ERROR(AVERROR(EIO), "Failed to finish command queue:
>>> %d.\n", cle);
>>> +
>>> +    err = av_frame_copy_props(output_frame, input_frame);
>>> +    if (err < 0)
>>> +        goto fail;
>>> +
>>> +    av_frame_free(&input_frame);
>>> +
>>> +    return ff_filter_frame(outlink, output_frame);
>>> +
>>> +fail:
>>> +    clFinish(pad_ctx->command_queue);
>>> +    av_frame_free(&input_frame);
>>> +    av_frame_free(&output_frame);
>>> +    return err;
>>> +}
>>> +
>>> ...
>>> +
>>> +static int pad_opencl_config_output(AVFilterLink *outlink)
>>> +{
>>> +    AVFilterContext *avctx = outlink->src;
>>> +    PadOpenCLContext *ctx = avctx->priv;
>>> +    int err;
>>> +
>>> +    if (ctx->w < avctx->inputs[0]->w ||
>>> +        ctx->h < avctx->inputs[0]->h) {
>>> +        return AVERROR(EINVAL);
>>> +    }
>>> +
>>> +    if (ctx->w > avctx->inputs[0]->w && ctx->h > avctx->inputs[0]->h) {
>>> +        ctx->ocf.output_width  = ctx->w;
>>> +        ctx->ocf.output_height = ctx->h;
>>> +    } else {
>>> +        ctx->ocf.output_width  = avctx->inputs[0]->w;
>>> +        ctx->ocf.output_height = avctx->inputs[0]->h;
>>> +    }
>>
>> This goes wrong if you're only padding in one direction (e.g. to change
>> aspect ratio).
>>
>> Consider a 1080p input with args like h=1200:y=60.
> 
> I do not follow.

If I pad top and bottom only with h=1200:y=60 then the first half of the condition is not true, so it falls into the second branch and incorrectly uses the height of the input stream rather than the height I specified.

>>> +
>>> +    if (ctx->x + avctx->inputs[0]->w > ctx->ocf.output_width ||
>>> +        ctx->y + avctx->inputs[0]->h > ctx->ocf.output_height) {
>>> +        return AVERROR(EINVAL);
>>> +    }
>>> +
>>> +    err = ff_opencl_filter_config_output(outlink);
>>> +    if (err < 0)
>>> +        return err;
>>> +
>>> +    return 0;
>>> +}
>>> +
>>> ...