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/*
* Copyright (c) 2022 Mohamed Khaled <Mohamed_Khaled_Kamal@outlook.com>
*
* 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 "cuda/vector_helpers.cuh"
extern "C"
{
/**
* @brief function contains the main logic of chroma keying, and changes the alpahc channel with the suitable value
*
* @param src_tex texture U or texture UV , decided based on the passed is_uchar2 flag
* @param src_tex_V texture V , used only if is_uchar2 flag is false
* @param dst_A alpha channel destination
* @param width_uv width of uv channels
* @param height_uv height of uv channels
* @param width width of alpha channel
* @param height height of alpha channel
* @param pitch pitch of alpha channel
* @param x current x coordinate of pixel
* @param y current y coordinate of pixel
* @param chromakey_uv uv values for chroma keying
* @param similarity similarity of keying
* @param blend blend of keying
*/
__device__ static inline void change_alpha_channel(
cudaTextureObject_t src_tex, cudaTextureObject_t src_tex_V, uchar *dst_A,
int width_uv, int height_uv,
int width, int height, int pitch,
int x, int y,
float2 chromakey_uv, float similarity, float blend)
{
int window_size = 3;
int start_r = x - window_size / 2;
int start_c = y - window_size / 2;
int resize_ratio = width / width_uv;
int counter = 0;
float diff = 0.0f;
float du, dv;
uchar alpha_value;
// loop over the eight neighbourhood of the current pixel(x,y)
for (uchar i = 0; i < window_size; i++)
{
for (uchar j = 0; j < window_size; j++)
{
float u_value, v_value;
int r = start_r + i;
int c = start_c + j;
if (r < 0 || r >= width_uv || c < 0 || c >= height_uv)
continue;
if (!src_tex_V) {
float2 temp_uv = tex2D<float2>(src_tex, r, c);
u_value = temp_uv.x;
v_value = temp_uv.y;
} else {
u_value = tex2D<float>(src_tex, r, c);
v_value = tex2D<float>(src_tex_V, r, c);
}
du = (u_value * 255.0f) - chromakey_uv.x;
dv = (v_value * 255.0f) - chromakey_uv.y;
diff += sqrtf((du * du + dv * dv) / (255.0f * 255.0f * 2.f));
counter++;
}
}
if (counter > 0)
diff = diff / counter;
else
diff /= 9.0f;
if (blend>0.0001f)
alpha_value = __saturatef((diff - similarity) / blend) * 255;
else
alpha_value = (diff < similarity) ? 0 : 255;
//write the value in the alpha channel with regarding the ratio of (alpha_size : uv_size)
for (uchar k = 0; k < resize_ratio; k++)
{
for (uchar l = 0; l < resize_ratio; l++)
{
int x_resize = x * resize_ratio + k;
int y_resize = y * resize_ratio + l;
int a_channel_resize = y_resize * pitch + x_resize;
if (y_resize >= height || x_resize >= width)
continue;
dst_A[a_channel_resize] = alpha_value;
}
}
}
__global__ void Process_uchar(
cudaTextureObject_t src_tex_Y, cudaTextureObject_t src_tex_U, cudaTextureObject_t src_tex_V,
uchar *dst_Y, uchar *dst_U, uchar *dst_V, uchar *dst_A,
int width, int height, int pitch,
int width_uv, int height_uv, int pitch_uv,
float u_key, float v_key, float similarity, float blend)
{
int x = blockIdx.x * blockDim.x + threadIdx.x;
int y = blockIdx.y * blockDim.y + threadIdx.y;
if (y >= height || x >= width)
return;
dst_Y[y * pitch + x] = tex2D<float>(src_tex_Y, x, y)*255;
if (y >= height_uv || x >= width_uv)
return;
int uv_index = y * pitch_uv + x;
dst_U[uv_index] = tex2D<float>(src_tex_U, x, y) * 255;
dst_V[uv_index] = tex2D<float>(src_tex_V, x, y) * 255;
change_alpha_channel(src_tex_U, src_tex_V, dst_A,
width_uv, height_uv,
width, height, pitch,
x, y,
make_float2(u_key, v_key), similarity, blend);
}
__global__ void Process_uchar2(
cudaTextureObject_t src_tex_Y, cudaTextureObject_t src_tex_UV, cudaTextureObject_t unused1,
uchar *dst_Y, uchar *dst_U, uchar *dst_V, uchar *dst_A,
int width, int height, int pitch,
int width_uv, int height_uv,int pitch_uv,
float u_key, float v_key, float similarity, float blend)
{
int x = blockIdx.x * blockDim.x + threadIdx.x; // x coordinate of current pixel
int y = blockIdx.y * blockDim.y + threadIdx.y; // y coordinate of current pixel
if (y >= height || x >= width)
return;
dst_Y[y * pitch + x] = tex2D<float>(src_tex_Y, x, y) * 255;
if (y >= height_uv || x >= width_uv)
return;
int uv_index = y * pitch_uv + x;
float2 uv_temp = tex2D<float2>(src_tex_UV, x, y);
dst_U[uv_index] = uv_temp.x * 255;
dst_V[uv_index] = uv_temp.y * 255;
change_alpha_channel(src_tex_UV, (cudaTextureObject_t)nullptr,
dst_A, width_uv, height_uv,
width, height, pitch,
x, y,
make_float2(u_key, v_key), similarity, blend);
}
}
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