Fixed poor compression ratio of ANS

32vid-player-mini.lua

@@ -36,14 +36,22 @@ if bit32_band(flags, 3) == 1 then
         local R = file.read()
         local L = 2^R
         local Ls = readDict(c and 24 or 32)
+        if R == 0 then
+            decodingTable = file.read()
+            X = nil
+            return
+        end
         local a = 0
         for i = 0, #Ls do Ls[i] = Ls[i] == 0 and 0 or 2^(Ls[i]-1) a = a + Ls[i] end
         assert(a == L, a)
         decodingTable = {R = R}
         local x, step, next, symbol = 0, 0.625 * L + 3, {}, {}
         for i = 0, #Ls do
             next[i] = Ls[i]
-            for _ = 1, Ls[i] do x, symbol[x] = (x + step) % L, i end
+            for _ = 1, Ls[i] do
+                while symbol[x] do x = (x + 1) % L end
+                x, symbol[x] = (x + step) % L, i
+            end
         end
         for x = 0, L - 1 do
             local s = symbol[x]
@@ -63,6 +71,10 @@ if bit32_band(flags, 3) == 1 then
     end
     function read(nsym)
         local retval = {}
+        if X == nil then
+            for i = 1, nsym do retval[i] = decodingTable end
+            return retval
+        end
         local i = 1
         local last = 0
         while i <= nsym do
@@ -105,17 +117,21 @@ for _ = 1, nframes do
         local fg = read(width * height)
         local dctime = os.epoch "utc" - dcstart
         while os.epoch "utc" < start + vframe * 1000 / fps do end
+        local texta, fga, bga = {}, {}, {}
         for y = 0, height - 1 do
             local text, fgs, bgs = "", "", ""
             for x = 1, width do
                 text = text .. string.char(128 + screen[y*width+x])
                 fgs = fgs .. blitColors[fg[y*width+x]]
                 bgs = bgs .. blitColors[bg[y*width+x]]
             end
-            term.setCursorPos(1, y+1)
-            term.blit(text, fgs, bgs)
+            texta[y+1], fga[y+1], bga[y+1] = text, fgs, bgs
         end
         for i = 0, 15 do term.setPaletteColor(2^i, file.read() / 255, file.read() / 255, file.read() / 255) end
+        for y = 1, height do
+            term.setCursorPos(1, y)
+            term.blit(texta[y], fga[y], bga[y])
+        end
         local delete = {}
         for i, v in ipairs(subs) do
             if vframe <= v.frame + v.length then

src/generator.cpp

@@ -292,7 +292,7 @@ struct compare_node {bool operator()(tree_node *a, tree_node *b) {
 
 std::string make32vid_cmp(const uchar * characters, const uchar * colors, const std::vector<Vec3b>& palette, int width, int height) {
     std::string screen, col, pal;
-    tree_node screen_nodes[32], color_nodes[24]; // color codes 16-23 = repeat last color 2^(n-15) times
+    tree_node screen_nodes[32] = {0}, color_nodes[24] = {0}; // color codes 16-23 = repeat last color 2^(n-15) times
     tree_node internal[31];
     tree_node * internal_next = internal;
     uchar * fgcolors = new uchar[width*height];
@@ -539,26 +539,30 @@ class ANSEncoder {
         start = new int32_t[Lsl];
         uint32_t * next = new uint32_t[Lsl];
         uint8_t * symbol = new uint8_t[L];
+        memset(symbol, 0xFF, L);
         uint32_t sumLs = 0;
-        const uint32_t step = 0.625 * L + 3;
+        const uint32_t step = ((L * 5) >> 3) + 3;
         for (uint8_t s = 0; s < Lsl; s++) {
             const uint32_t v = Ls[s];
-            const uint32_t ks = R - log2i(v);
-            nb[s] = (ks << (R+1)) - (v << ks);
-            start[s] = (int32_t)sumLs - (int32_t)v;
-            next[s] = v;
-            for (int i = 0; i < v; i++) {
-                symbol[X] = s;
-                X = (X + step) % L;
+            //std::cout << (int)s << " " << v << "\n";
+            if (v) {
+                const uint32_t ks = R - log2i(v);
+                nb[s] = (ks << (R+1)) - (v << ks);
+                start[s] = (int32_t)sumLs - (int32_t)v;
+                next[s] = v;
+                for (int i = 0; i < v; i++) {
+                    while (symbol[X] != 0xFF) X = (X + 1) % L;
+                    symbol[X] = s;
+                    X = (X + step) % L;
+                }
+                sumLs = sumLs + v;
             }
-            sumLs = sumLs + v;
         }
         // create encoding table
         encodingTable = new uint32_t[2*L];
         for (uint32_t x = L; x < 2*L; x++) {
             const uint8_t s = symbol[x - L];
-            encodingTable[start[s] + next[s]] = x;
-            next[s]++;
+            encodingTable[start[s] + next[s]++] = x;
         }
         X = L;
         // free temps
@@ -631,6 +635,7 @@ class ANSEncoder {
         uint8_t s = symbols[_size-1] & 0x1F;
         for (int i = _size-2; i >= 0; i--) {
             const uint8_t nbBits = ((X + nb[s]) >> (R + 1));
+            //std::cout << (int)s << " " << (int)nbBits << "\n";
             const uint8_t nexts = symbols[i] & 0x1F;
             bitstream[length++] = ((uint32_t)nbBits << 24) | (X & ((1 << nbBits) - 1));
             bitCount += nbBits;
@@ -685,7 +690,7 @@ static uint8_t ansdictcode(uint32_t n) {
 
 std::string make32vid_ans(const uchar * characters, const uchar * colors, const std::vector<Vec3b>& palette, int width, int height) {
     std::string screen, col, pal;
-    uint32_t screen_freq[32], color_freq[24]; // color codes 16-23 = repeat last color 2^(n-15) times
+    uint32_t screen_freq[32] = {0}, color_freq[24] = {0}; // color codes 16-23 = repeat last color 2^(n-15) times
     uchar * fgcolors = new uchar[width*height];
     uchar * bgcolors = new uchar[width*height];
     uchar *fgnext = fgcolors, *bgnext = bgcolors;
@@ -797,7 +802,7 @@ std::string make32vid_ans(const uchar * characters, const uchar * colors, const
     std::vector<uint32_t> screenLs = ANSEncoder::makeLs(screen_freq, 32, screenR);
     if (screenLs.size() == 1) {
         // encode a full-screen pattern of the same thing
-        screen = std::string(16, '\0') + std::string(1, screenLs[0]);
+        screen = std::string(17, '\0') + std::string(1, screenLs[0]);
     } else {
         // compress data
         screen += screenR;
@@ -813,7 +818,7 @@ std::string make32vid_ans(const uchar * characters, const uchar * colors, const
     std::vector<uint32_t> colorsLs = ANSEncoder::makeLs(color_freq, 24, colorsR);
     if (colorsLs.size() == 1) {
         // encode a full-screen pattern of the same thing
-        col = std::string(12, '\0') + std::string(1, colorsLs[0]);
+        col = std::string(13, '\0') + std::string(1, colorsLs[0]);
     } else {
         // compress data
         col += colorsR;

src/sanjuuni.cpp

@@ -1061,7 +1061,7 @@ int main(int argc, const char * argv[]) {
                     if (mode == OutputType::Vid32 && !separateStreams) {
                         Vid32Chunk combinedChunk;
                         Vid32Header header;
-                        combinedChunk.nframes = 0;
+                        combinedChunk.nframes = totalFrames;
                         combinedChunk.type = (uint8_t)Vid32Chunk::Type::Combined;
                         memcpy(header.magic, "32VD", 4);
                         header.width = width / 2;