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FFmpeg/libavcodec/vulkan/prores_ks_estimate_slice.comp.glsl
IndecisiveTurtle cebe0b577e lavc: implement a Vulkan-based prores encoder
Adds a vulkan implementation of the reference prores kostya encoder. Provides about 3-4x speedup over the CPU code
2026-03-05 14:02:39 +00:00

303 lines
9.7 KiB
GLSL

/*
* 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
*/
#version 460
#pragma shader_stage(compute)
#extension GL_EXT_scalar_block_layout : require
#extension GL_EXT_shader_explicit_arithmetic_types : require
#extension GL_KHR_shader_subgroup_clustered : require
#extension GL_KHR_shader_subgroup_shuffle : require
#extension GL_GOOGLE_include_directive : require
#include "common.glsl"
layout (constant_id = 0) const int max_mbs_per_slice = 8;
layout (constant_id = 1) const int chroma_factor = 0;
layout (constant_id = 2) const int alpha_bits = 0;
layout (constant_id = 3) const int num_planes = 0;
layout (constant_id = 4) const int slices_per_picture = 0;
layout (constant_id = 5) const int min_quant = 0;
layout (constant_id = 6) const int max_quant = 0;
layout (constant_id = 7) const int bits_per_mb = 0;
struct SliceData {
uint32_t mbs_per_slice;
int16_t coeffs[4][8 * 256];
};
struct SliceScore {
ivec4 bits[16];
ivec4 score[16];
int total_bits[16];
int total_score[16];
int overquant;
int buf_start;
int quant;
};
layout (set = 0, binding = 0, scalar) readonly buffer SliceBuffer {
SliceData slices[];
};
layout (set = 0, binding = 1, scalar) writeonly buffer SliceScores {
SliceScore scores[];
};
layout (set = 0, binding = 2, scalar) uniform ProresDataTables {
int16_t qmat[128][64];
int16_t qmat_chroma[128][64];
};
#define CFACTOR_Y444 3
#define GET_SIGN(x) ((x) >> 31)
#define MAKE_CODE(x) (((x) * 2) ^ GET_SIGN(x))
int estimate_vlc(uint codebook, int val)
{
/* number of prefix bits to switch between Rice and expGolomb */
uint switch_bits = (codebook & 3) + 1;
uint rice_order = codebook >> 5; /* rice code order */
uint exp_order = (codebook >> 2) & 7; /* exp golomb code order */
uint switch_val = switch_bits << rice_order;
if (val >= switch_val) {
val -= int(switch_val - (1 << exp_order));
int exponent = findMSB(val);
return int(exponent * 2 - exp_order + switch_bits + 1);
} else {
return int((val >> rice_order) + rice_order + 1);
}
}
#define FIRST_DC_CB 0xB8 // rice_order = 5, exp_golomb_order = 6, switch_bits = 0
int estimate_dcs(inout int error, uint slice, uint plane, uint q)
{
const uint8_t dc_codebook[7] = { U8(0x04), U8(0x28), U8(0x28), U8(0x4D), U8(0x4D), U8(0x70), U8(0x70) };
uint blocks_per_mb = plane != 0 && chroma_factor != CFACTOR_Y444 ? 2 : 4;
uint blocks_per_slice = slices[slice].mbs_per_slice * blocks_per_mb;
int codebook = 5;
int coeff = slices[slice].coeffs[plane][0];
int scale = plane != 0 ? qmat_chroma[q][0] : qmat[q][0];
int prev_dc = (coeff - 0x4000) / scale;
int bits = estimate_vlc(FIRST_DC_CB, MAKE_CODE(prev_dc));
int sign = 0;
for (int i = 1; i < blocks_per_slice; ++i) {
coeff = slices[slice].coeffs[plane][i];
int dc = (coeff - 0x4000) / scale;
error += abs(coeff - 0x4000) % scale;
int delta = dc - prev_dc;
int new_sign = GET_SIGN(delta);
delta = (delta ^ sign) - sign;
int code = MAKE_CODE(delta);
bits += estimate_vlc(dc_codebook[codebook], code);
codebook = min(code, 6);
sign = new_sign;
prev_dc = dc;
}
return bits;
}
#define FFALIGN(x, a) (((x)+(a)-1)&~((a)-1))
#define SCORE_LIMIT 1073741823
int estimate_acs(inout int error, uint slice, uint plane, uint q)
{
const uint8_t run_to_cb[16] = { U8(0x06), U8(0x06), U8(0x05), U8(0x05), U8(0x04), U8(0x29),
U8(0x29), U8(0x29), U8(0x29), U8(0x28), U8(0x28), U8(0x28),
U8(0x28), U8(0x28), U8(0x28), U8(0x4C) };
const uint8_t level_to_cb[10] = { U8(0x04), U8(0x0A), U8(0x05), U8(0x06), U8(0x04), U8(0x28),
U8(0x28), U8(0x28), U8(0x28), U8(0x4C) };
uint blocks_per_mb = plane != 0 && chroma_factor != CFACTOR_Y444 ? 2 : 4;
uint blocks_per_slice = slices[slice].mbs_per_slice * blocks_per_mb;
uint max_coeffs = blocks_per_slice << 6;
int prev_run = 4;
int prev_level = 2;
int bits = 0;
int run = 0;
for (uint i = 1; i < 64; i++) {
int quant = plane != 0 ? qmat_chroma[q][i] : qmat[q][i];
for (uint j = 0; j < blocks_per_slice; j++) {
uint idx = i * blocks_per_slice + j;
int coeff = slices[slice].coeffs[plane][idx];
int level = coeff / quant;
error += abs(coeff) % quant;
if (level != 0) {
int abs_level = abs(level);
bits += estimate_vlc(run_to_cb[prev_run], run);
bits += estimate_vlc(level_to_cb[prev_level], abs_level - 1) + 1;
prev_run = min(run, 15);
prev_level = min(abs_level, 9);
run = 0;
} else {
run++;
}
}
}
return bits;
}
int estimate_slice_plane(inout int error, uint slice, uint plane, uint q)
{
int bits = 0;
bits += estimate_dcs(error, slice, plane, q);
bits += estimate_acs(error, slice, plane, q);
return FFALIGN(bits, 8);
}
int est_alpha_diff(int cur, int prev)
{
const int dbits = (alpha_bits == 8) ? 4 : 7;
const int dsize = 1 << dbits - 1;
int diff = cur - prev;
diff = zero_extend(diff, alpha_bits);
if (diff >= (1 << alpha_bits) - dsize)
diff -= 1 << alpha_bits;
if (diff < -dsize || diff > dsize || diff == 0)
return alpha_bits + 1;
else
return dbits + 1;
}
int estimate_alpha_plane(uint slice)
{
const int mask = (1 << alpha_bits) - 1;
const int num_coeffs = int(slices[slice].mbs_per_slice) * 256;
int prev = mask, cur;
int idx = 0;
int run = 0;
int bits;
cur = slices[slice].coeffs[3][idx++];
bits = est_alpha_diff(cur, prev);
prev = cur;
do {
cur = slices[slice].coeffs[3][idx++];
if (cur != prev) {
if (run == 0)
bits++;
else if (run < 0x10)
bits += 5;
else
bits += 16;
bits += est_alpha_diff(cur, prev);
prev = cur;
run = 0;
} else {
run++;
}
} while (idx < num_coeffs);
if (run != 0) {
if (run < 0x10)
bits += 5;
else
bits += 16;
} else {
bits++;
}
return bits;
}
int sum_of_planes(int value)
{
if (num_planes == 3) {
uint base = (gl_SubgroupInvocationID / 3) * 3;
return subgroupShuffle(value, base) + subgroupShuffle(value, base + 1) + subgroupShuffle(value, base + 2);
} else
return subgroupClusteredAdd(value, 4);
}
void main()
{
uint slice = gl_GlobalInvocationID.x / num_planes;
uint plane = gl_LocalInvocationID.x % num_planes;
uint q = min_quant + gl_GlobalInvocationID.y;
if (slice >= slices_per_picture)
return;
/* Estimate slice bits and error for specified quantizer and plane */
int error = 0;
int bits = 0;
if (plane == 3)
bits = estimate_alpha_plane(slice);
else
bits = estimate_slice_plane(error, slice, plane, q);
/* Write results to score buffer */
scores[slice].bits[q][plane] = FFALIGN(bits, 8);
scores[slice].score[q][plane] = error;
/* Accumulate total bits and error of all planes */
int total_bits = sum_of_planes(bits);
int total_score = sum_of_planes(error);
if (total_bits > 65000 * 8)
total_score = SCORE_LIMIT;
scores[slice].total_bits[q] = total_bits;
scores[slice].total_score[q] = total_score;
if (q != max_quant)
return;
/* Task threads that computed max_quant to also compute overquant if necessary */
uint mbs_per_slice = slices[slice].mbs_per_slice;
if (total_bits <= bits_per_mb * mbs_per_slice) {
/* Overquant isn't needed for this slice */
scores[slice].total_bits[max_quant + 1] = total_bits;
scores[slice].total_score[max_quant + 1] = total_score + 1;
scores[slice].bits[max_quant + 1][plane] = FFALIGN(bits, 8);
scores[slice].score[max_quant + 1][plane] = error;
scores[slice].overquant = int(max_quant);
} else {
/* Keep searching until an encoding fits our budget */
for (q = max_quant + 1; q < 128; ++q) {
/* Estimate slice bits and error for specified quantizer and plane */
error = 0;
bits = 0;
if (plane == 3)
bits = estimate_alpha_plane(slice);
else
bits = estimate_slice_plane(error, slice, plane, q);
/* Accumulate total bits and error of all planes */
total_bits = sum_of_planes(bits);
total_score = sum_of_planes(error);
/* If estimated bits fit within budget, we are done */
if (total_bits <= bits_per_mb * mbs_per_slice)
break;
}
scores[slice].bits[max_quant + 1][plane] = bits;
scores[slice].score[max_quant + 1][plane] = error;
scores[slice].total_bits[max_quant + 1] = total_bits;
scores[slice].total_score[max_quant + 1] = total_score;
scores[slice].overquant = int(q);
}
}