3 layout(local_size_x = 1) in;
5 const uint prob_bits = 12;
6 const uint prob_scale = 1 << prob_bits;
7 const uint RANS_BYTE_L = (1u << 23);
8 const uint BLOCKS_PER_STREAM = 320;
9 const uint STREAM_BUF_SIZE = 256; // In uint32s. 1 kB per stream ought to be enough for everyone :-)
10 const uint NUM_SYMS = 256;
11 const uint ESCAPE_LIMIT = NUM_SYMS - 1;
12 const uint WIDTH_BLOCKS = 160; // TODO: send in as a uniform.
14 #define MAPPING(s0, s1, s2, s3, s4, s5, s6, s7) ((s0) | (s1 << 2) | (s2 << 4) | (s3 << 6) | (s4 << 8) | (s5 << 10) | (s6 << 12) | (s7 << 14))
16 const uint luma_mapping[8] = {
17 MAPPING(0, 0, 1, 1, 2, 2, 3, 3),
18 MAPPING(0, 0, 1, 2, 2, 2, 3, 3),
19 MAPPING(1, 1, 2, 2, 2, 3, 3, 3),
20 MAPPING(1, 1, 2, 2, 2, 3, 3, 3),
21 MAPPING(1, 2, 2, 2, 2, 3, 3, 3),
22 MAPPING(2, 2, 2, 2, 3, 3, 3, 3),
23 MAPPING(2, 2, 3, 3, 3, 3, 3, 3),
24 MAPPING(3, 3, 3, 3, 3, 3, 3, 3),
27 layout(std430, binding = 10) buffer outputBuf
32 layout(std430, binding = 11) buffer outputBuf2
34 uint rans_bytes_written[];
37 layout(std140, binding = 13) uniform DistBlock
39 uvec4 ransdist[4 * 256];
44 uint stream_num; // const
45 uint lut_base; // const
46 uint sign_bias; // const
47 uint rans_start_offset; // const
54 layout(r16ui) uniform restrict readonly uimage2D dc_ac7_tex;
55 layout(r16ui) uniform restrict readonly uimage2D ac1_ac6_tex;
56 layout(r16ui) uniform restrict readonly uimage2D ac2_ac5_tex;
57 layout(r8i) uniform restrict readonly iimage2D ac3_tex;
58 layout(r8i) uniform restrict readonly iimage2D ac4_tex;
60 void RansPutByte(uint x, inout RansEncoder enc)
62 enc.bit_buffer = (enc.bit_buffer << 8) | x;
63 if (++enc.bytes_in_buffer == 4) {
64 rans_output[--enc.rans_offset] = enc.bit_buffer;
65 enc.bytes_in_buffer = 0;
69 void RansEncInit(uint streamgroup_num, uint coeff_row, uint coeff_col, uint dist_num, out RansEncoder enc)
71 enc.stream_num = streamgroup_num * 64 + coeff_row * 8 + coeff_col;
72 enc.lut_base = dist_num * 256;
73 enc.sign_bias = sign_biases[dist_num];
74 enc.rans_offset = enc.stream_num * STREAM_BUF_SIZE + STREAM_BUF_SIZE; // Starts at the end.
75 enc.rans_start_offset = enc.rans_offset;
76 enc.rans = RANS_BYTE_L;
78 enc.bytes_in_buffer = 0;
81 void RansEncRenorm(inout RansEncoder enc, uint freq, uint prob_bits)
83 uint x_max = ((RANS_BYTE_L >> prob_bits) << 8) * freq; // this turns into a shift.
84 while (enc.rans >= x_max) {
85 RansPutByte(enc.rans & 0xffu, enc);
90 void RansEncPut(inout RansEncoder enc, uint start, uint freq, uint prob_bits)
92 RansEncRenorm(enc, freq, prob_bits);
93 enc.rans = ((enc.rans / freq) << prob_bits) + (enc.rans % freq) + start;
96 void RansEncPutSymbol(inout RansEncoder enc, uvec4 sym)
99 uint rcp_freq = sym.y;
101 uint rcp_shift = (sym.w & 0xffffu);
102 uint cmpl_freq = (sym.w >> 16);
105 while (enc.rans >= x_max) {
106 RansPutByte(enc.rans & 0xffu, enc);
111 umulExtended(enc.rans, rcp_freq, q, unused);
112 enc.rans += bias + (q >> rcp_shift) * cmpl_freq;
115 uint RansEncFlush(inout RansEncoder enc)
117 RansPutByte(enc.rans >> 24, enc);
118 RansPutByte(enc.rans >> 16, enc);
119 RansPutByte(enc.rans >> 8, enc);
120 RansPutByte(enc.rans >> 0, enc);
122 uint num_bytes_written = (enc.rans_start_offset - enc.rans_offset) * 4 + enc.bytes_in_buffer;
124 // Make sure there's nothing left in the buffer.
129 return num_bytes_written;
132 int sign_extend(uint coeff, uint bits)
134 return int(coeff << (32 - bits)) >> (32 - bits);
137 void encode_coeff(int signed_k, inout RansEncoder enc)
139 uint k = abs(signed_k);
141 if (k >= ESCAPE_LIMIT) {
142 // Put the coefficient as a 1/(2^12) symbol _before_
143 // the 255 coefficient, since the decoder will read the
144 // 255 coefficient first.
145 RansEncPut(enc, k, 1, prob_bits);
149 uvec4 sym = ransdist[enc.lut_base + ((k - 1) & (NUM_SYMS - 1))];
150 RansEncPutSymbol(enc, sym);
153 enc.rans += enc.sign_bias;
157 void encode_end(inout RansEncoder enc)
159 uint bytes_written = RansEncFlush(enc);
160 rans_bytes_written[enc.stream_num] = bytes_written;
163 void encode_9_7(uint streamgroup_num, uint coeff_row, layout(r16ui) restrict readonly uimage2D tex, uint col1, uint col2, uint dist1, uint dist2)
165 RansEncoder enc1, enc2;
166 RansEncInit(streamgroup_num, coeff_row, col1, dist1, enc1);
167 RansEncInit(streamgroup_num, coeff_row, col2, dist2, enc2);
169 for (uint subblock_idx = 0; subblock_idx < BLOCKS_PER_STREAM; ++subblock_idx) {
170 // TODO: Use SSBOs instead of a texture?
171 uint x = (streamgroup_num * BLOCKS_PER_STREAM + subblock_idx) % WIDTH_BLOCKS;
172 uint y = (streamgroup_num * BLOCKS_PER_STREAM + subblock_idx) / WIDTH_BLOCKS;
173 uint f = imageLoad(tex, ivec2(x, y * 8 + coeff_row)).x;
175 encode_coeff(sign_extend(f & 0x1ffu, 9), enc1);
176 encode_coeff(sign_extend(f >> 9, 7), enc2);
183 void encode_8(uint streamgroup_num, uint coeff_row, layout(r8i) restrict readonly iimage2D tex, uint col, uint dist)
186 RansEncInit(streamgroup_num, coeff_row, col, dist, enc);
188 for (uint subblock_idx = 0; subblock_idx < BLOCKS_PER_STREAM; ++subblock_idx) {
189 // TODO: Use SSBOs instead of a texture?
190 uint x = (streamgroup_num * BLOCKS_PER_STREAM + subblock_idx) % WIDTH_BLOCKS;
191 uint y = (streamgroup_num * BLOCKS_PER_STREAM + subblock_idx) / WIDTH_BLOCKS;
192 int f = imageLoad(tex, ivec2(x, y * 8 + coeff_row)).x;
194 encode_coeff(f, enc);
202 uint streamgroup_num = gl_WorkGroupID.x;
203 uint coeff_row = gl_WorkGroupID.y; // 0..7
204 uint coeff_colset = gl_WorkGroupID.z; // 0 = dc+ac7, 1 = ac1+ac6, 2 = ac2+ac5, 3 = ac3, 4 = ac5
205 uint m = luma_mapping[coeff_row];
207 // TODO: DC coeff pred
209 if (coeff_colset == 0) {
210 uint dist_dc = bitfieldExtract(m, 0, 2);
211 uint dist_ac7 = bitfieldExtract(m, 14, 2);
212 encode_9_7(streamgroup_num, coeff_row, dc_ac7_tex, 0, 7, dist_dc, dist_ac7);
213 } else if (coeff_colset == 1) {
214 uint dist_ac1 = bitfieldExtract(m, 2, 2);
215 uint dist_ac6 = bitfieldExtract(m, 12, 2);
216 encode_9_7(streamgroup_num, coeff_row, ac1_ac6_tex, 1, 6, dist_ac1, dist_ac6);
217 } else if (coeff_colset == 2) {
218 uint dist_ac2 = bitfieldExtract(m, 4, 2);
219 uint dist_ac5 = bitfieldExtract(m, 10, 2);
220 encode_9_7(streamgroup_num, coeff_row, ac2_ac5_tex, 2, 5, dist_ac2, dist_ac5);
221 } else if (coeff_colset == 3) {
222 uint dist_ac3 = bitfieldExtract(m, 6, 2);
223 encode_8(streamgroup_num, coeff_row, ac3_tex, 3, dist_ac3);
225 uint dist_ac4 = bitfieldExtract(m, 8, 2);
226 encode_8(streamgroup_num, coeff_row, ac4_tex, 4, dist_ac4);