/* Appotech ax203 picframe decompression and compression code * For ax203 picture frames with firmware version 3.4.x * * Copyright (c) 2010 Hans de Goede * * This program 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. * * This program 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 this program; if not, write to the * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, * Boston, MA 02110-1301 USA */ #ifdef STANDALONE_MAIN #include #include <_stdint.h> #include #include #include #include #else #include "config.h" #ifdef HAVE_LIBGD #include #endif #include #include "ax203.h" #endif #define CLAMP_U8(x) (((x) > 255) ? 255 : (((x) < 0) ? 0 : (x))) static const int corr_tables[4][8] = { /* Table 0 depends on wrap around to get negative corrections!! */ { 0, 32, 64, 96, 128, 160, 192, 224 }, { 0, 16, 32, 48, -64, -48, -32, -16 }, { 0, 8, 16, 24, -32, -24, -16, -8 }, { 0, 4, 8, 12, -16, -12, -8, -4 }, }; #ifdef HAVE_LIBGD /* With in a compressed 4x4 block, the data is stored 4 component values at a time, compressed into 2 bytes, the first 5 bits are a starting value, then 2 bits encoding which correction/delta table to use and then 3x3 bits code deltas from the previous pixel. */ static void ax203_decode_component_values(char *src, char *dest) { int i, table, corr; dest[0] = src[0] & ~0x07; table = (src[0] >> 1) & 3; for (i = 1; i < 4; i++) { switch (i) { case 1: corr = (src[1] >> 5) & 7; break; case 2: corr = (src[1] >> 2) & 7; break; case 3: corr = ((src[1] << 1) & 6) | (src[0] & 1); break; } dest[i] = dest[i - 1] + corr_tables[table][corr]; } } /* The compressed data consists of blocks of 4x4 pixels, each encoded in 12 bytes */ static void ax203_decode_block_yuv_delta(char *src, int **dest, int dest_x, int dest_y) { int x, y, r, g, b; uint8_t Y[16]; int8_t U[4], V[4]; /* The compressed component order is: 4 Pixels U, 4 Pixels V, 16 pixels Y */ ax203_decode_component_values(src, (char *)U); src += 2; ax203_decode_component_values(src, (char *)V); src += 2; /* The Y components are stored 4 at a time in a pattern like this: 1 2 1 2 3 4 3 4 1 2 1 2 3 4 3 4 */ for (y = 0; y < 4; y += 2) { for (x = 0; x < 4; x += 2) { char buf[4]; ax203_decode_component_values(src, buf); Y[ y * 4 + x ] = buf[0]; Y[ y * 4 + x + 1] = buf[1]; Y[(y + 1) * 4 + x ] = buf[2]; Y[(y + 1) * 4 + x + 1] = buf[3]; src += 2; } } for (y = 0; y < 4; y++) { for (x = 0; x < 4; x++) { r = 1.164 * (Y[y * 4 + x] - 16) + 1.596 * V[(y / 2) * 2 + x / 2]; g = 1.164 * (Y[y * 4 + x] - 16) - 0.391 * U[(y / 2) * 2 + x / 2] - 0.813 * V[(y / 2) * 2 + x / 2]; b = 1.164 * (Y[y * 4 + x] - 16) + 2.018 * U[(y / 2) * 2 + x / 2]; dest[dest_y + y][dest_x + x] = gdTrueColor (CLAMP_U8(r), CLAMP_U8(g), CLAMP_U8(b)); } } } void ax203_decode_yuv_delta(char *src, int **dest, int width, int height) { int x, y; for (y = 0; y < height; y += 4) { for (x = 0; x < width; x += 4) { ax203_decode_block_yuv_delta(src, dest, x, y); src += 12; } } } static int ax203_find_closest_correction_signed(int8_t base, int8_t val, int table) { int closest_delta = 256; int i, delta, closest_idx = 0; int8_t corrected_val; for (i = 0; i < 8; i++) { /* Don't allow wrap around for tables other then table 0 */ if (table && ((base + corr_tables[table][i]) > 127 || (base + corr_tables[table][i]) < -128)) continue; /* We are used for U and V values skip correction vals which would lead to invalid U / V values */ corrected_val = base + corr_tables[table][i]; if (corrected_val < -112 || corrected_val > 111) continue; delta = abs(corrected_val - val); if (delta < closest_delta) { closest_delta = delta; closest_idx = i; } } return closest_idx; } static int ax203_find_closest_correction_unsigned(uint8_t base, uint8_t val, int table) { int closest_delta = 256; int i, delta, closest_idx = 0; uint8_t corrected_val; for (i = 0; i < 8; i++) { /* Don't allow wrap around for tables other then table 0 */ if (table && ((base + corr_tables[table][i]) > 255 || (base + corr_tables[table][i]) < 0)) continue; /* We are used for Y values skip correction vals which would lead to invalid Y values */ corrected_val = base + corr_tables[table][i]; if (corrected_val < 16 || corrected_val > 235) continue; delta = abs(corrected_val - val); if (delta < closest_delta) { closest_delta = delta; closest_idx = i; } } return closest_idx; } static void ax203_encode_signed_component_values(int8_t *src, char *dest) { int i, j, table, corr; int8_t base; /* Select a correction table */ for (i = 3; i > 0; i--) { base = src[0] & ~0x07; for (j = 1; j < 4; j++) { if ((base + corr_tables[i][3] + 4) < src[j] || (base + corr_tables[i][4] - 4) > src[j]) break; corr = ax203_find_closest_correction_signed (base, src[j], i); /* Calculate the base value for the next pixel */ base = base + corr_tables[i][corr]; } /* If we did not break out the above loop the min / max correction in the current table is enough */ if (j == 4) break; } table = i; /* And store the pixels */ base = src[0] & ~0x07; dest[0] = base; dest[0] |= table << 1; dest[1] = 0; for (i = 1; i < 4; i++) { corr = ax203_find_closest_correction_signed (base, src[i], table); switch (i) { case 1: dest[1] |= corr << 5; break; case 2: dest[1] |= corr << 2; break; case 3: dest[0] |= corr & 1; dest[1] |= corr >> 1; break; } /* Calculate the base value for the next pixel */ base = base + corr_tables[table][corr]; } } static void ax203_encode_unsigned_component_values(uint8_t *src, char *dest) { int i, j, table, corr; uint8_t base; /* Select a correction table */ for (i = 3; i > 0; i--) { base = src[0] & ~0x07; for (j = 1; j < 4; j++) { if ((base + corr_tables[i][3] + 4) < src[j] || (base + corr_tables[i][4] - 4) > src[j]) break; corr = ax203_find_closest_correction_unsigned (base, src[j], i); /* Calculate the base value for the next pixel */ base = base + corr_tables[i][corr]; } /* If we did not break out the above loop the min / max correction in the current table is enough */ if (j == 4) break; } table = i; /* And store the pixels */ base = src[0] & ~0x07; dest[0] = base; dest[0] |= table << 1; dest[1] = 0; for (i = 1; i < 4; i++) { corr = ax203_find_closest_correction_unsigned (base, src[i], table); switch (i) { case 1: dest[1] |= corr << 5; break; case 2: dest[1] |= corr << 2; break; case 3: dest[0] |= corr & 1; dest[1] |= corr >> 1; break; } /* Calculate the base value for the next pixel */ base = base + corr_tables[table][corr]; } } static void ax203_encode_block_yuv_delta(int **src, int src_x, int src_y, char *dest) { uint8_t Y[16]; int8_t U[4], V[4]; int x, y; /* Convert to YUV */ for (y = 0; y < 4; y++) { for (x = 0; x < 4; x++) { int p = src[src_y + y][src_x + x]; Y[y * 4 + x] = gdTrueColorGetRed(p) * 0.257 + gdTrueColorGetGreen(p) * 0.504 + gdTrueColorGetBlue(p) * 0.098 + 16; } } for (y = 0; y < 4; y += 2) { for (x = 0; x < 4; x += 2) { int p1 = src[src_y + y ][src_x + x ]; int p2 = src[src_y + y ][src_x + x + 1]; int p3 = src[src_y + y + 1][src_x + x ]; int p4 = src[src_y + y + 1][src_x + x + 1]; int r = (gdTrueColorGetRed(p1) + gdTrueColorGetRed(p2) + gdTrueColorGetRed(p3) + gdTrueColorGetRed(p4)) / 4; int g = (gdTrueColorGetGreen(p1) + gdTrueColorGetGreen(p2) + gdTrueColorGetGreen(p3) + gdTrueColorGetGreen(p4)) / 4; int b = (gdTrueColorGetBlue(p1) + gdTrueColorGetBlue(p2) + gdTrueColorGetBlue(p3) + gdTrueColorGetBlue(p4)) / 4; U[y + x / 2] = 0.439 * b - 0.291 * g - 0.148 * r; V[y + x / 2] = 0.439 * r - 0.368 * g - 0.071 * b; } } /* The compressed component order is: 4 Pixels U, 4 Pixels V, 16 pixels Y */ ax203_encode_signed_component_values(U, dest); dest += 2; ax203_encode_signed_component_values(V, dest); dest += 2; /* The Y components are stored 4 at a time in a pattern like this: 1 2 1 2 3 4 3 4 1 2 1 2 3 4 3 4 */ for (y = 0; y < 4; y += 2) { for (x = 0; x < 4; x += 2) { uint8_t buf[4]; buf[0] = Y[ y * 4 + x ]; buf[1] = Y[ y * 4 + x + 1]; buf[2] = Y[(y + 1) * 4 + x ]; buf[3] = Y[(y + 1) * 4 + x + 1]; ax203_encode_unsigned_component_values(buf, dest); dest += 2; } } } void ax203_encode_yuv_delta(int **src, char *dest, int width, int height) { int x, y; for (y = 0; y < height; y += 4) { for (x = 0; x < width; x += 4) { ax203_encode_block_yuv_delta(src, x, y, dest); dest += 12; } } } #endif #ifdef STANDALONE_MAIN int main(int argc, char *argv[]) { FILE *fin = NULL; FILE *fout = NULL; gdImagePtr im = NULL; int ret = 0; /* FIXME get these from the cmdline */ int width = 128, height = 128; if (argc != 4) { fprintf (stderr, "Usage: %s <-d|-c> \n", argv[0]); ret = 1; goto exit; } fin = fopen(argv[2], "r"); if (!fin) { fprintf (stderr, "Error opening: %s: %s\n", argv[2], strerror(errno)); ret = 1; goto exit; } fout = fopen(argv[3], "w"); if (!fout) { fprintf (stderr, "Error opening: %s: %s\n", argv[3], strerror(errno)); ret = 1; goto exit; } if (!strcmp(argv[1], "-d")) { const int bufsize = width * height * 3 / 4; char buf[bufsize]; if (fread(buf, 1, bufsize, fin) != bufsize) { fprintf (stderr, "Error reading: %s: %s\n", argv[2], strerror(errno)); ret = 1; goto exit; } im = gdImageCreateTrueColor(width, height); if (!im) { fprintf (stderr, "Error allocating memory\n"); ret = 1; goto exit; } ax203_decode(buf, im->tpixels, width, height); gdImagePng (im, fout); } else { fprintf (stderr, "%s: unkown option: %s\n", argv[0], argv[1]); ret = 1; goto exit; } exit: if (fin) fclose (fin); if (fout) fclose (fout); if (im) gdImageDestroy (im); return ret; } #endif