avfilter: add pad_cuda filter

This patch adds the pad_cuda video filter. A filter similar to the existing pad filter but accelerated by CUDA.

The filter shares the same options as the software pad filter.

Example usage:
ffmpeg -hwaccel cuda -hwaccel_output_format cuda -i input.mp4 -vf "pad_cuda=w=iw+100:h=ih+100:x=-1:y=-1:color=red" out.mp4

Signed-off-by: Timo Rothenpieler <timo@rothenpieler.org>

Changelog

@@ -19,6 +19,7 @@ version <next>:
 - VVC decoder supports all content of SCC (Screen Content Coding):
   IBC (Inter Block Copy), Palette Mode and ACT (Adaptive Color Transform
 - G.728 decoder
+- pad_cuda filter
 
 
 version 7.1:

configure

@@ -3362,6 +3362,8 @@ thumbnail_cuda_filter_deps_any="cuda_nvcc cuda_llvm"
 transpose_npp_filter_deps="ffnvcodec libnpp"
 overlay_cuda_filter_deps="ffnvcodec"
 overlay_cuda_filter_deps_any="cuda_nvcc cuda_llvm"
+pad_cuda_filter_deps="ffnvcodec"
+pad_cuda_filter_deps_any="cuda_nvcc cuda_llvm"
 sharpen_npp_filter_deps="ffnvcodec libnpp"
 
 ddagrab_filter_deps="d3d11va IDXGIOutput1 DXGI_OUTDUPL_FRAME_INFO"

doc/filters.texi

@@ -26686,6 +26686,30 @@ See @ref{framesync}.
 
 This filter also supports the @ref{framesync} options.
 
+
+@anchor{pad_cuda}
+@subsection pad_cuda
+Add paddings to an input video stream using CUDA.
+
+This filter is the CUDA-accelerated version of the @ref{pad} filter. It accepts the same options and expressions and provides the same core functionality.
+For a detailed description of available options, please see the documentation for the @ref{pad} filter.
+
+@subsubsection Examples
+
+@itemize
+@item
+Add a 200-pixel black border to all sides of a video frame:
+@example
+ffmpeg -hwaccel cuda -hwaccel_output_format cuda -i input.mp4 -vf "pad_cuda=w=iw+400:h=ih+400:x=200:y=200" -c:v h264_nvenc out.mp4
+@end example
+
+@item
+Pad the input video to a 16:9 aspect ratio, filling with the color "blue":
+@example
+ffmpeg -hwaccel cuda -hwaccel_output_format cuda -i input.mp4 -vf "pad_cuda=w=ih*16/9/sar:h=ih:x=(ow-iw)/2:y=(oh-ih)/2:color=blue" -c:v h264_nvenc out.mp4
+@end example
+@end itemize
+
 @anchor{scale_cuda}
 @subsection scale_cuda
 

libavfilter/Makefile

@@ -422,6 +422,7 @@ OBJS-$(CONFIG_OVERLAY_VAAPI_FILTER)          += vf_overlay_vaapi.o framesync.o v
 OBJS-$(CONFIG_OVERLAY_VULKAN_FILTER)         += vf_overlay_vulkan.o vulkan.o vulkan_filter.o
 OBJS-$(CONFIG_OWDENOISE_FILTER)              += vf_owdenoise.o
 OBJS-$(CONFIG_PAD_FILTER)                    += vf_pad.o
+OBJS-$(CONFIG_PAD_CUDA_FILTER)               += vf_pad_cuda.o vf_pad_cuda.ptx.o cuda/load_helper.o
 OBJS-$(CONFIG_PAD_OPENCL_FILTER)             += vf_pad_opencl.o opencl.o opencl/pad.o
 OBJS-$(CONFIG_PALETTEGEN_FILTER)             += vf_palettegen.o palette.o
 OBJS-$(CONFIG_PALETTEUSE_FILTER)             += vf_paletteuse.o framesync.o palette.o

libavfilter/allfilters.c

@@ -395,6 +395,7 @@ extern const FFFilter ff_vf_overlay_vulkan;
 extern const FFFilter ff_vf_overlay_cuda;
 extern const FFFilter ff_vf_owdenoise;
 extern const FFFilter ff_vf_pad;
+extern const FFFilter ff_vf_pad_cuda;
 extern const FFFilter ff_vf_pad_opencl;
 extern const FFFilter ff_vf_palettegen;
 extern const FFFilter ff_vf_paletteuse;

libavfilter/version.h

@@ -31,7 +31,7 @@
 
 #include "version_major.h"
 
-#define LIBAVFILTER_VERSION_MINOR   0
+#define LIBAVFILTER_VERSION_MINOR   1
 #define LIBAVFILTER_VERSION_MICRO 100
 
 

libavfilter/vf_pad_cuda.c

@@ -0,0 +1,636 @@
+/*
+ * 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
+ */
+
+/**
+ * @file
+ * CUDA video padding filter
+ */
+
+#include <float.h>
+
+#include "filters.h"
+#include "libavutil/avstring.h"
+#include "libavutil/common.h"
+#include "libavutil/cuda_check.h"
+#include "libavutil/eval.h"
+#include "libavutil/hwcontext.h"
+#include "libavutil/hwcontext_cuda_internal.h"
+#include "libavutil/imgutils.h"
+#include "libavutil/internal.h"
+#include "libavutil/opt.h"
+#include "libavutil/pixdesc.h"
+#include "libavutil/colorspace.h"
+
+#include "cuda/load_helper.h"
+
+#define CHECK_CU(x) FF_CUDA_CHECK_DL(ctx, device_hwctx->internal->cuda_dl, x)
+#define DIV_UP(a, b) ( ((a) + (b) - 1) / (b) )
+#define BLOCK_X 32
+#define BLOCK_Y 16
+
+static const enum AVPixelFormat supported_formats[] = {
+    AV_PIX_FMT_YUV420P,
+    AV_PIX_FMT_YUV444P,
+    AV_PIX_FMT_YUVA420P,
+    AV_PIX_FMT_YUVA444P,
+    AV_PIX_FMT_NV12,
+};
+
+typedef struct CUDAPadContext {
+    const AVClass *class;
+
+    AVBufferRef *frames_ctx;
+
+    int w, h;       ///< output dimensions, a value of 0 will result in the input size
+    int x, y;       ///< offsets of the input area with respect to the padded area
+    int in_w, in_h; ///< width and height for the padded input video
+
+    char *w_expr;   ///< width expression
+    char *h_expr;   ///< height expression
+    char *x_expr;   ///< x offset expression
+    char *y_expr;   ///< y offset expression
+
+    uint8_t rgba_color[4];    ///< color for the padding area
+    uint8_t parsed_color[4];
+    AVRational aspect;
+
+    int eval_mode;
+
+    int last_out_w, last_out_h; ///< used to evaluate the prior output width and height with the incoming frame
+
+    AVCUDADeviceContext *hwctx;
+    CUmodule cu_module;
+    CUfunction cu_func_uchar;
+    CUfunction cu_func_uchar2;
+} CUDAPadContext;
+
+static const char *const var_names[] = {
+    "in_w",  "iw",
+    "in_h",  "ih",
+    "out_w", "ow",
+    "out_h", "oh",
+    "x",
+    "y",
+    "a",
+    "sar",
+    "dar",
+    "hsub",
+    "vsub",
+    NULL
+};
+
+enum {
+    VAR_IN_W,
+    VAR_IW,
+    VAR_IN_H,
+    VAR_IH,
+    VAR_OUT_W,
+    VAR_OW,
+    VAR_OUT_H,
+    VAR_OH,
+    VAR_X,
+    VAR_Y,
+    VAR_A,
+    VAR_SAR,
+    VAR_DAR,
+    VAR_HSUB,
+    VAR_VSUB,
+    VARS_NB
+};
+
+enum EvalMode {
+    EVAL_MODE_INIT,
+    EVAL_MODE_FRAME,
+    EVAL_MODE_NB
+};
+
+static int eval_expr(AVFilterContext *ctx)
+{
+    CUDAPadContext *s = ctx->priv;
+    AVFilterLink *inlink = ctx->inputs[0];
+    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
+
+    double var_values[VARS_NB], res;
+    char *expr;
+    int ret;
+
+    var_values[VAR_IN_W]   = var_values[VAR_IW]   = s->in_w;
+    var_values[VAR_IN_H]   = var_values[VAR_IH]   = s->in_h;
+    var_values[VAR_OUT_W]  = var_values[VAR_OW]  = NAN;
+    var_values[VAR_OUT_H]  = var_values[VAR_OH]  = NAN;
+    var_values[VAR_A]      = (double)s->in_w / s->in_h;
+    var_values[VAR_SAR]    = inlink->sample_aspect_ratio.num ?
+                             (double)inlink->sample_aspect_ratio.num /
+                             inlink->sample_aspect_ratio.den : 1;
+    var_values[VAR_DAR]    = var_values[VAR_A] * var_values[VAR_SAR];
+    var_values[VAR_HSUB]   = 1 << desc->log2_chroma_w;
+    var_values[VAR_VSUB]   = 1 << desc->log2_chroma_h;
+
+    expr = s->w_expr;
+    ret = av_expr_parse_and_eval(&res, expr, var_names, var_values, NULL, NULL, NULL, NULL, NULL, 0, ctx);
+    if (ret < 0)
+        goto fail;
+
+    s->w = res;
+    if (s->w < 0) {
+        av_log(ctx, AV_LOG_ERROR, "Width expression is negative.\n");
+        ret = AVERROR(EINVAL);
+        goto fail;
+    }
+
+    var_values[VAR_OUT_W] = var_values[VAR_OW] = s->w;
+
+    expr = s->h_expr;
+    ret = av_expr_parse_and_eval(&res, expr, var_names, var_values, NULL, NULL, NULL, NULL, NULL, 0, ctx);
+    if (ret < 0)
+        goto fail;
+
+    s->h = res;
+    if (s->h < 0) {
+        av_log(ctx, AV_LOG_ERROR, "Height expression is negative.\n");
+        ret = AVERROR(EINVAL);
+        goto fail;
+    }
+    var_values[VAR_OUT_H] = var_values[VAR_OH] = s->h;
+
+    if (!s->h)
+        s->h = s->in_h;
+
+    var_values[VAR_OUT_H] = var_values[VAR_OH] = s->h;
+
+
+    expr = s->w_expr;
+    ret = av_expr_parse_and_eval(&res, expr, var_names, var_values, NULL, NULL, NULL, NULL, NULL, 0, ctx);
+    if (ret < 0)
+        goto fail;
+
+    s->w = res;
+    if (s->w < 0) {
+        av_log(ctx, AV_LOG_ERROR, "Width expression is negative.\n");
+        ret = AVERROR(EINVAL);
+        goto fail;
+    }
+    if (!s->w)
+        s->w = s->in_w;
+
+    var_values[VAR_OUT_W] = var_values[VAR_OW] = s->w;
+
+
+    expr = s->x_expr;
+    ret = av_expr_parse_and_eval(&res, expr, var_names, var_values, NULL, NULL, NULL, NULL, NULL, 0, ctx);
+    if (ret < 0)
+        goto fail;
+
+    s->x = res;
+
+
+    expr = s->y_expr;
+    ret = av_expr_parse_and_eval(&res, expr, var_names, var_values, NULL, NULL, NULL, NULL, NULL, 0, ctx);
+    if (ret < 0)
+        goto fail;
+
+    s->y = res;
+
+    if (s->x < 0 || s->x + s->in_w > s->w) {
+        s->x = (s->w - s->in_w) / 2;
+        av_log(ctx, AV_LOG_VERBOSE, "centering X offset.\n");
+    }
+
+    if (s->y < 0 || s->y + s->in_h > s->h) {
+        s->y = (s->h - s->in_h) / 2;
+        av_log(ctx, AV_LOG_VERBOSE, "centering Y offset.\n");
+    }
+
+    s->w = av_clip(s->w, 1, INT_MAX);
+    s->h = av_clip(s->h, 1, INT_MAX);
+
+    if (s->w < s->in_w || s->h < s->in_h) {
+        av_log(ctx, AV_LOG_ERROR, "Padded size < input size.\n");
+        return AVERROR(EINVAL);
+    }
+
+    av_log(ctx, AV_LOG_DEBUG,
+           "w:%d h:%d -> w:%d h:%d x:%d y:%d color:0x%02X%02X%02X%02X\n",
+           inlink->w, inlink->h, s->w, s->h, s->x, s->y, s->rgba_color[0],
+           s->rgba_color[1], s->rgba_color[2], s->rgba_color[3]);
+
+    return 0;
+
+fail:
+    av_log(ctx, AV_LOG_ERROR, "Error evaluating '%s'\n", expr);
+    return ret;
+}
+
+static int cuda_pad_alloc_out_frames_ctx(AVFilterContext *ctx, AVBufferRef **out_frames_ctx, const int width, const int height)
+{
+    AVFilterLink *inlink = ctx->inputs[0];
+    FilterLink *inl = ff_filter_link(inlink);
+    AVHWFramesContext *in_frames_ctx = (AVHWFramesContext *)inl->hw_frames_ctx->data;
+    int ret;
+
+    *out_frames_ctx = av_hwframe_ctx_alloc(in_frames_ctx->device_ref);
+    if (!*out_frames_ctx) {
+        return AVERROR(ENOMEM);
+    }
+
+    AVHWFramesContext *out_fc = (AVHWFramesContext *)(*out_frames_ctx)->data;
+    out_fc->format    = AV_PIX_FMT_CUDA;
+    out_fc->sw_format = in_frames_ctx->sw_format;
+
+    out_fc->width     = FFALIGN(width, 32);
+    out_fc->height    = FFALIGN(height, 32);
+
+    ret = av_hwframe_ctx_init(*out_frames_ctx);
+    if (ret < 0) {
+        av_log(ctx, AV_LOG_ERROR, "Failed to init output ctx\n");
+        av_buffer_unref(out_frames_ctx);
+        return ret;
+    }
+
+    return 0;
+}
+
+static av_cold int cuda_pad_init(AVFilterContext *ctx)
+{
+    CUDAPadContext *s = ctx->priv;
+
+    s->last_out_w = -1;
+    s->last_out_h = -1;
+
+    return 0;
+}
+
+static av_cold void cuda_pad_uninit(AVFilterContext *ctx)
+{
+    CUDAPadContext *s = ctx->priv;
+    CUcontext dummy;
+
+    av_buffer_unref(&s->frames_ctx);
+
+    if (s->hwctx && s->cu_module) {
+        CudaFunctions *cu = s->hwctx->internal->cuda_dl;
+        AVCUDADeviceContext *device_hwctx = s->hwctx;
+        CHECK_CU(cu->cuCtxPushCurrent(s->hwctx->cuda_ctx));
+        CHECK_CU(cu->cuModuleUnload(s->cu_module));
+        CHECK_CU(cu->cuCtxPopCurrent(&dummy));
+    }
+
+    s->cu_module = NULL;
+    s->hwctx = NULL;
+}
+
+static av_cold int cuda_pad_load_functions(AVFilterContext *ctx)
+{
+    CUDAPadContext *s = ctx->priv;
+    CudaFunctions *cu = s->hwctx->internal->cuda_dl;
+    CUcontext dummy_cu_ctx;
+    int ret;
+
+    AVCUDADeviceContext *device_hwctx = s->hwctx;
+
+    extern const unsigned char ff_vf_pad_cuda_ptx_data[];
+    extern const unsigned int ff_vf_pad_cuda_ptx_len;
+
+    ret = CHECK_CU(cu->cuCtxPushCurrent(device_hwctx->cuda_ctx));
+    if (ret < 0)
+        return ret;
+
+    ret = ff_cuda_load_module(ctx, device_hwctx, &s->cu_module,
+                              ff_vf_pad_cuda_ptx_data, ff_vf_pad_cuda_ptx_len);
+    if (ret < 0) {
+        av_log(ctx, AV_LOG_ERROR, "Failed to load CUDA module\n");
+        goto end;
+    }
+
+    ret = CHECK_CU(cu->cuModuleGetFunction(&s->cu_func_uchar, s->cu_module, "pad_uchar"));
+    if (ret < 0) {
+        av_log(ctx, AV_LOG_ERROR, "Failed to load pad_planar_cuda\n");
+        goto end;
+    }
+
+    ret = CHECK_CU(cu->cuModuleGetFunction(&s->cu_func_uchar2, s->cu_module, "pad_uchar2"));
+    if (ret < 0)
+        av_log(ctx, AV_LOG_ERROR, "Failed to load pad_uv_cuda\n");
+
+end:
+    CHECK_CU(cu->cuCtxPopCurrent(&dummy_cu_ctx));
+
+    return ret;
+}
+
+static int cuda_pad_config_props(AVFilterLink *outlink)
+{
+    AVFilterContext *ctx = outlink->src;
+    CUDAPadContext *s = ctx->priv;
+
+    AVFilterLink *inlink = ctx->inputs[0];
+    FilterLink *inl = ff_filter_link(inlink);
+
+    FilterLink *ol = ff_filter_link(outlink);
+
+    AVHWFramesContext *in_frames_ctx;
+    int format_supported = 0;
+    int ret;
+
+    s->in_w = inlink->w;
+    s->in_h = inlink->h;
+    ret = eval_expr(ctx);
+    if (ret < 0)
+        return ret;
+
+    if (!inl->hw_frames_ctx) {
+        av_log(ctx, AV_LOG_ERROR, "No hw context provided on input\n");
+        return AVERROR(EINVAL);
+    }
+
+    in_frames_ctx = (AVHWFramesContext *)inl->hw_frames_ctx->data;
+    s->hwctx = in_frames_ctx->device_ctx->hwctx;
+
+    for (int i = 0; i < FF_ARRAY_ELEMS(supported_formats); i++) {
+        if (in_frames_ctx->sw_format == supported_formats[i]) {
+            format_supported = 1;
+            break;
+        }
+    }
+    if (!format_supported) {
+        av_log(ctx, AV_LOG_ERROR, "Unsupported input format.\n");
+        return AVERROR(EINVAL);
+    }
+
+    s->parsed_color[0] = RGB_TO_Y_BT709(s->rgba_color[0], s->rgba_color[1], s->rgba_color[2]);
+    s->parsed_color[1] = RGB_TO_U_BT709(s->rgba_color[0], s->rgba_color[1], s->rgba_color[2], 0);
+    s->parsed_color[2] = RGB_TO_V_BT709(s->rgba_color[0], s->rgba_color[1], s->rgba_color[2], 0);
+    s->parsed_color[3] = s->rgba_color[3];
+
+    ret = cuda_pad_alloc_out_frames_ctx(ctx, &s->frames_ctx, s->w, s->h);
+    if (ret < 0)
+        return ret;
+
+    ol->hw_frames_ctx = av_buffer_ref(s->frames_ctx);
+    if (!ol->hw_frames_ctx)
+        return AVERROR(ENOMEM);
+
+    outlink->w         = s->w;
+    outlink->h         = s->h;
+    outlink->time_base = inlink->time_base;
+    outlink->format    = AV_PIX_FMT_CUDA;
+
+    s->last_out_w = s->w;
+    s->last_out_h = s->h;
+
+    ret = cuda_pad_load_functions(ctx);
+    if (ret < 0)
+        return ret;
+
+    return 0;
+}
+
+static int cuda_pad_pad(AVFilterContext *ctx, AVFrame *out, const AVFrame *in)
+{
+    CUDAPadContext *s = ctx->priv;
+    FilterLink *inl = ff_filter_link(ctx->inputs[0]);
+
+    AVHWFramesContext *in_frames_ctx = (AVHWFramesContext *)inl->hw_frames_ctx->data;
+    const AVPixFmtDescriptor *pixdesc = av_pix_fmt_desc_get(in_frames_ctx->sw_format);
+
+    CudaFunctions *cu = s->hwctx->internal->cuda_dl;
+    AVCUDADeviceContext *device_hwctx = s->hwctx;
+    int ret;
+
+
+    const int nb_planes = av_pix_fmt_count_planes(in_frames_ctx->sw_format);
+    for (int plane = 0; plane < nb_planes; plane++) {
+        const AVComponentDescriptor *cur_comp = &pixdesc->comp[0];
+        for (int comp = 1; comp < pixdesc->nb_components && cur_comp->plane != plane; comp++)
+            cur_comp = &pixdesc->comp[comp];
+
+        int hsub = (plane == 1 || plane == 2) ? pixdesc->log2_chroma_w : 0;
+        int vsub = (plane == 1 || plane == 2) ? pixdesc->log2_chroma_h : 0;
+
+        int src_w = AV_CEIL_RSHIFT(s->in_w, hsub);
+        int src_h = AV_CEIL_RSHIFT(s->in_h, vsub);
+
+        int dst_w = AV_CEIL_RSHIFT(s->w, hsub);
+        int dst_h = AV_CEIL_RSHIFT(s->h, vsub);
+
+        int y_plane_offset = AV_CEIL_RSHIFT(s->y, vsub);
+        int x_plane_offset = AV_CEIL_RSHIFT(s->x, hsub);
+
+        if (x_plane_offset + src_w > dst_w || y_plane_offset + src_h > dst_h) {
+            av_log(ctx, AV_LOG_ERROR,
+                   "ROI out of bounds in plane %d: offset=(%d,%d) in=(%dx%d) "
+                   "out=(%dx%d)\n",
+                   plane, x_plane_offset, y_plane_offset, src_w, src_h, dst_w, dst_h);
+            return AVERROR(EINVAL);
+        }
+
+        int dst_linesize = out->linesize[plane] / cur_comp->step;
+        int src_linesize = in->linesize[plane] / cur_comp->step;
+
+        CUdeviceptr d_dst = (CUdeviceptr)out->data[plane];
+        CUdeviceptr d_src = (CUdeviceptr)in->data[plane];
+
+        CUfunction cuda_func;
+
+        if (cur_comp->step == 1 && cur_comp->depth == 8)
+            cuda_func = s->cu_func_uchar;
+        else if(cur_comp->step == 2 && cur_comp->depth == 8)
+            cuda_func = s->cu_func_uchar2;
+        else
+            return AVERROR_BUG;
+
+        void *kernel_args[] = {
+            &d_dst, &dst_linesize, &dst_w, &dst_h,
+            &d_src, &src_linesize, &src_w, &src_h,
+            &x_plane_offset, &y_plane_offset, &s->parsed_color[plane]
+        };
+
+        unsigned int grid_x = DIV_UP(dst_w, BLOCK_X);
+        unsigned int grid_y = DIV_UP(dst_h, BLOCK_Y);
+
+        ret = CHECK_CU(cu->cuLaunchKernel(cuda_func, grid_x, grid_y, 1,
+                                          BLOCK_X, BLOCK_Y, 1,
+                                          0, s->hwctx->stream, kernel_args, NULL));
+
+        if (ret < 0) {
+            av_log(ctx, AV_LOG_ERROR, "Failed to launch kernel for plane %d\n", plane);
+            return ret;
+        }
+    }
+
+    return 0;
+}
+
+static int cuda_pad_filter_frame(AVFilterLink *inlink, AVFrame *in)
+{
+    AVFilterContext *ctx = inlink->dst;
+    CUDAPadContext *s = ctx->priv;
+    AVFilterLink *outlink = ctx->outputs[0];
+
+    FilterLink *outl = ff_filter_link(outlink);
+
+    AVHWFramesContext *out_frames_ctx = (AVHWFramesContext *)outl->hw_frames_ctx->data;
+    AVCUDADeviceContext *device_hwctx = out_frames_ctx->device_ctx->hwctx;
+
+    int ret;
+
+    if (s->eval_mode == EVAL_MODE_FRAME) {
+        s->in_w   = in->width;
+        s->in_h   = in->height;
+        s->aspect = in->sample_aspect_ratio;
+
+        ret = eval_expr(ctx);
+        if (ret < 0) {
+            av_frame_free(&in);
+            return ret;
+        }
+    }
+
+
+    if (s->x == 0 && s->y == 0 &&
+        s->w == in->width && s->h == in->height) {
+        av_log(ctx, AV_LOG_DEBUG, "No border. Passing the frame unmodified.\n");
+        s->last_out_w = s->w;
+        s->last_out_h = s->h;
+        return ff_filter_frame(outlink, in);
+    }
+
+
+    if (s->w != s->last_out_w || s->h != s->last_out_h) {
+
+        av_buffer_unref(&s->frames_ctx);
+
+        ret = cuda_pad_alloc_out_frames_ctx(ctx, &s->frames_ctx, s->w, s->h);
+        if (ret < 0)
+            return ret;
+
+        av_buffer_unref(&outl->hw_frames_ctx);
+        outl->hw_frames_ctx = av_buffer_ref(s->frames_ctx);
+        if (!outl->hw_frames_ctx) {
+            av_frame_free(&in);
+            av_log(ctx, AV_LOG_ERROR, "Failed to allocate output frame context.\n");
+            return AVERROR(ENOMEM);
+        }
+        outlink->w = s->w;
+        outlink->h = s->h;
+
+        s->last_out_w = s->w;
+        s->last_out_h = s->h;
+    }
+
+    AVFrame *out = av_frame_alloc();
+    if (!out) {
+        av_frame_free(&in);
+        av_log(ctx, AV_LOG_ERROR, "Failed to allocate output AVFrame.\n");
+        return AVERROR(ENOMEM);
+    }
+    ret = av_hwframe_get_buffer(outl->hw_frames_ctx, out, 0);
+    if (ret < 0) {
+        av_log(ctx, AV_LOG_ERROR, "Unable to get output buffer: %s\n",
+               av_err2str(ret));
+        av_frame_free(&out);
+        av_frame_free(&in);
+        return ret;
+    }
+
+    CUcontext dummy;
+    ret = CHECK_CU(device_hwctx->internal->cuda_dl->cuCtxPushCurrent(
+        device_hwctx->cuda_ctx));
+    if (ret < 0) {
+        av_frame_free(&out);
+        av_frame_free(&in);
+        return ret;
+    }
+
+    ret = cuda_pad_pad(ctx, out, in);
+
+    CHECK_CU(device_hwctx->internal->cuda_dl->cuCtxPopCurrent(&dummy));
+
+    if (ret < 0) {
+        av_frame_free(&out);
+        av_frame_free(&in);
+        return ret;
+    }
+
+    av_frame_copy_props(out, in);
+    out->width  = s->w;
+    out->height = s->h;
+
+
+    av_reduce(&out->sample_aspect_ratio.num, &out->sample_aspect_ratio.den,
+              (int64_t)in->sample_aspect_ratio.num * out->height * in->width,
+              (int64_t)in->sample_aspect_ratio.den * out->width * in->height,
+              INT_MAX);
+
+    av_frame_free(&in);
+    return ff_filter_frame(outlink, out);
+}
+
+#define OFFSET(x) offsetof(CUDAPadContext, x)
+#define FLAGS (AV_OPT_FLAG_FILTERING_PARAM | AV_OPT_FLAG_VIDEO_PARAM)
+
+static const AVOption cuda_pad_options[] = {
+    { "width",  "set the pad area width expression",                             OFFSET(w_expr),     AV_OPT_TYPE_STRING,   {.str = "iw"},       0, 0,        FLAGS },
+    { "w",      "set the pad area width expression",                             OFFSET(w_expr),     AV_OPT_TYPE_STRING,   {.str = "iw"},       0, 0,        FLAGS },
+    { "height", "set the pad area height expression",                            OFFSET(h_expr),     AV_OPT_TYPE_STRING,   {.str = "ih"},       0, 0,        FLAGS },
+    { "h",      "set the pad area height expression",                            OFFSET(h_expr),     AV_OPT_TYPE_STRING,   {.str = "ih"},       0, 0,        FLAGS },
+    { "x",      "set the x offset expression for the input image position",      OFFSET(x_expr),     AV_OPT_TYPE_STRING,   {.str = "0"},        0, 0,        FLAGS },
+    { "y",      "set the y offset expression for the input image position",      OFFSET(y_expr),     AV_OPT_TYPE_STRING,   {.str = "0"},        0, 0,        FLAGS },
+    { "color",  "set the color of the padded area border",                       OFFSET(rgba_color), AV_OPT_TYPE_COLOR,    {.str = "black"},    .flags =      FLAGS },
+    { "eval",   "specify when to evaluate expressions",                          OFFSET(eval_mode),  AV_OPT_TYPE_INT,      {.i64 = EVAL_MODE_INIT}, 0, EVAL_MODE_NB-1, FLAGS, .unit = "eval" },
+         { "init",  "eval expressions once during initialization", 0, AV_OPT_TYPE_CONST, {.i64=EVAL_MODE_INIT},  .flags = FLAGS, .unit = "eval" },
+         { "frame", "eval expressions during initialization and per-frame", 0, AV_OPT_TYPE_CONST, {.i64=EVAL_MODE_FRAME}, .flags = FLAGS, .unit = "eval" },
+    { "aspect", "pad to fit an aspect instead of a resolution",                  OFFSET(aspect),     AV_OPT_TYPE_RATIONAL, {.dbl = 0},        0, DBL_MAX,    FLAGS },
+    { NULL }
+};
+
+static const AVClass cuda_pad_class = {
+    .class_name = "pad_cuda",
+    .item_name  = av_default_item_name,
+    .option     = cuda_pad_options,
+    .version    = LIBAVUTIL_VERSION_INT,
+};
+
+static const AVFilterPad cuda_pad_inputs[] = {{
+        .name         = "default",
+        .type         = AVMEDIA_TYPE_VIDEO,
+        .filter_frame = cuda_pad_filter_frame
+}};
+
+static const AVFilterPad cuda_pad_outputs[] = {{
+        .name         = "default",
+        .type         = AVMEDIA_TYPE_VIDEO,
+        .config_props = cuda_pad_config_props,
+}};
+
+const FFFilter ff_vf_pad_cuda = {
+    .p.name         = "pad_cuda",
+    .p.description  = NULL_IF_CONFIG_SMALL("CUDA-based GPU padding filter"),
+    .init           = cuda_pad_init,
+    .uninit         = cuda_pad_uninit,
+
+    .p.priv_class   = &cuda_pad_class,
+
+    FILTER_INPUTS(cuda_pad_inputs),
+    FILTER_OUTPUTS(cuda_pad_outputs),
+
+    FILTER_SINGLE_PIXFMT(AV_PIX_FMT_CUDA),
+
+    .priv_size      = sizeof(CUDAPadContext),
+    .flags_internal = FF_FILTER_FLAG_HWFRAME_AWARE,
+};

libavfilter/vf_pad_cuda.cu

@@ -0,0 +1,61 @@
+/*
+ * 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
+ */
+
+template <typename T>
+__device__ void pad_impl(T* dst, int dst_pitch, int dst_w, int dst_h,
+                         const T* src, int src_pitch, int src_w, int src_h,
+                         int roi_x, int roi_y, T fill_val)
+{
+    const int x = blockIdx.x * blockDim.x + threadIdx.x;
+    const int y = blockIdx.y * blockDim.y + threadIdx.y;
+
+    if (x >= dst_w || y >= dst_h) {
+        return;
+    }
+
+    if (x >= roi_x && x < (roi_x + src_w) && y >= roi_y && y < (roi_y + src_h)) {
+        const int src_x = x - roi_x;
+        const int src_y = y - roi_y;
+        dst[y * dst_pitch + x] = src[src_y * src_pitch + src_x];
+    } else {
+        dst[y * dst_pitch + x] = fill_val;
+    }
+}
+
+
+extern "C" {
+
+__global__ void pad_uchar(unsigned char* dst, int dst_pitch, int dst_w, int dst_h,
+                          const unsigned char* src, int src_pitch, int src_w, int src_h,
+                          int roi_x, int roi_y, unsigned char fill_val)
+{
+    pad_impl<unsigned char>(dst, dst_pitch, dst_w, dst_h,
+                            src, src_pitch, src_w, src_h,
+                            roi_x, roi_y, fill_val);
+}
+
+__global__ void pad_uchar2(uchar2* dst, int dst_pitch, int dst_w, int dst_h,
+                           const uchar2* src, int src_pitch, int src_w, int src_h,
+                           int roi_x, int roi_y, uchar2 fill_val)
+{
+    pad_impl<uchar2>(dst, dst_pitch, dst_w, dst_h,
+                     src, src_pitch, src_w, src_h,
+                     roi_x, roi_y, fill_val);
+}
+
+}