X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=libavcodec%2Fhuffman.c;h=aef4929b1ca96ef900394a7fcdc3ba0e6139b4d2;hb=202c2acc40a6de8758b44ab3f5c85ab250079734;hp=f75346f4ccc2ca4e93eeeba702af55efcc8c487a;hpb=f1bf85b8cfa8b841122fc80ba61204324d5727a9;p=ffmpeg

diff --git a/libavcodec/huffman.c b/libavcodec/huffman.c
index f75346f4ccc..aef4929b1ca 100644
--- a/libavcodec/huffman.c
+++ b/libavcodec/huffman.c
@@ -1,61 +1,128 @@
-/**
- * @file huffman.c
- * huffman tree builder and VLC generator
+/*
  * Copyright (c) 2006 Konstantin Shishkov
+ * Copyright (c) 2007 Loren Merritt
  *
- * This file is part of FFmpeg.
+ * This file is part of Libav.
  *
- * FFmpeg is free software; you can redistribute it and/or
+ * Libav 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,
+ * Libav 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
+ * License along with Libav; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+/**
+ * @file
+ * huffman tree builder and VLC generator
+ */
+
 #include "avcodec.h"
-#include "bitstream.h"
+#include "get_bits.h"
 #include "huffman.h"
 
 /* symbol for Huffman tree node */
 #define HNODE -1
 
+typedef struct {
+    uint64_t val;
+    int name;
+} HeapElem;
+
+static void heap_sift(HeapElem *h, int root, int size)
+{
+    while (root * 2 + 1 < size) {
+        int child = root * 2 + 1;
+        if (child < size - 1 && h[child].val > h[child+1].val)
+            child++;
+        if (h[root].val > h[child].val) {
+            FFSWAP(HeapElem, h[root], h[child]);
+            root = child;
+        } else
+            break;
+    }
+}
+
+void ff_huff_gen_len_table(uint8_t *dst, const uint64_t *stats)
+{
+    HeapElem h[256];
+    int up[2*256];
+    int len[2*256];
+    int offset, i, next;
+    int size = 256;
+
+    for (offset = 1; ; offset <<= 1) {
+        for (i=0; i < size; i++) {
+            h[i].name = i;
+            h[i].val = (stats[i] << 8) + offset;
+        }
+        for (i = size / 2 - 1; i >= 0; i--)
+            heap_sift(h, i, size);
+
+        for (next = size; next < size * 2 - 1; next++) {
+            // merge the two smallest entries, and put it back in the heap
+            uint64_t min1v = h[0].val;
+            up[h[0].name] = next;
+            h[0].val = INT64_MAX;
+            heap_sift(h, 0, size);
+            up[h[0].name] = next;
+            h[0].name = next;
+            h[0].val += min1v;
+            heap_sift(h, 0, size);
+        }
+
+        len[2 * size - 2] = 0;
+        for (i = 2 * size - 3; i >= size; i--)
+            len[i] = len[up[i]] + 1;
+        for (i = 0; i < size; i++) {
+            dst[i] = len[up[i]] + 1;
+            if (dst[i] >= 32) break;
+        }
+        if (i==size) break;
+    }
+}
 
-static void get_tree_codes(uint32_t *bits, int16_t *lens, uint8_t *xlat, Node *nodes, int node, uint32_t pfx, int pl, int *pos)
+static void get_tree_codes(uint32_t *bits, int16_t *lens, uint8_t *xlat,
+                           Node *nodes, int node,
+                           uint32_t pfx, int pl, int *pos, int no_zero_count)
 {
     int s;
 
     s = nodes[node].sym;
-    if(s != HNODE || !nodes[node].count){
+    if (s != HNODE || (no_zero_count && !nodes[node].count)) {
         bits[*pos] = pfx;
         lens[*pos] = pl;
         xlat[*pos] = s;
         (*pos)++;
-    }else{
+    } else {
         pfx <<= 1;
         pl++;
-        get_tree_codes(bits, lens, xlat, nodes, nodes[node].n0, pfx, pl, pos);
+        get_tree_codes(bits, lens, xlat, nodes, nodes[node].n0, pfx, pl,
+                       pos, no_zero_count);
         pfx |= 1;
-        get_tree_codes(bits, lens, xlat, nodes, nodes[node].n0+1, pfx, pl, pos);
+        get_tree_codes(bits, lens, xlat, nodes, nodes[node].n0 + 1, pfx, pl,
+                       pos, no_zero_count);
     }
 }
 
-static int build_huff_tree(VLC *vlc, Node *nodes, int head)
+static int build_huff_tree(VLC *vlc, Node *nodes, int head, int flags)
 {
+    int no_zero_count = !(flags & FF_HUFFMAN_FLAG_ZERO_COUNT);
     uint32_t bits[256];
     int16_t lens[256];
     uint8_t xlat[256];
     int pos = 0;
 
-    get_tree_codes(bits, lens, xlat, nodes, head, 0, 0, &pos);
-    return init_vlc_sparse(vlc, 9, pos, lens, 2, 2, bits, 4, 4, xlat, 1, 1, 0);
+    get_tree_codes(bits, lens, xlat, nodes, head, 0, 0,
+                   &pos, no_zero_count);
+    return ff_init_vlc_sparse(vlc, 9, pos, lens, 2, 2, bits, 4, 4, xlat, 1, 1, 0);
 }
 
 
@@ -64,39 +131,43 @@ static int build_huff_tree(VLC *vlc, Node *nodes, int head)
  * first nb_codes nodes.count must be set
  */
 int ff_huff_build_tree(AVCodecContext *avctx, VLC *vlc, int nb_codes,
-                       Node *nodes, huff_cmp_t cmp, int hnode_first)
+                       Node *nodes, HuffCmp cmp, int flags)
 {
     int i, j;
     int cur_node;
     int64_t sum = 0;
 
-    for(i = 0; i < nb_codes; i++){
+    for (i = 0; i < nb_codes; i++) {
         nodes[i].sym = i;
         nodes[i].n0 = -2;
         sum += nodes[i].count;
     }
 
-    if(sum >> 31) {
-        av_log(avctx, AV_LOG_ERROR, "Too high symbol frequencies. Tree construction is not possible\n");
+    if (sum >> 31) {
+        av_log(avctx, AV_LOG_ERROR,
+               "Too high symbol frequencies. "
+               "Tree construction is not possible\n");
         return -1;
     }
     qsort(nodes, nb_codes, sizeof(Node), cmp);
     cur_node = nb_codes;
-    for(i = 0; i < nb_codes*2-1; i += 2){
+    nodes[nb_codes*2-1].count = 0;
+    for (i = 0; i < nb_codes * 2 - 1; i += 2) {
         nodes[cur_node].sym = HNODE;
-        nodes[cur_node].count = nodes[i].count + nodes[i+1].count;
+        nodes[cur_node].count = nodes[i].count + nodes[i + 1].count;
         nodes[cur_node].n0 = i;
-        for(j = cur_node; j > 0; j--){
-            if(nodes[j].count > nodes[j-1].count ||
-               (nodes[j].count == nodes[j-1].count &&
-                (!hnode_first || nodes[j].n0==j-1 || nodes[j].n0==j-2 ||
-                 (nodes[j].sym!=HNODE && nodes[j-1].sym!=HNODE))))
+        for (j = cur_node; j > 0; j--) {
+            if (nodes[j].count > nodes[j - 1].count ||
+                (nodes[j].count == nodes[j - 1].count &&
+                 (!(flags & FF_HUFFMAN_FLAG_HNODE_FIRST) ||
+                  nodes[j].n0 == j - 1 || nodes[j].n0 == j - 2 ||
+                  (nodes[j].sym!=HNODE && nodes[j-1].sym!=HNODE))))
                 break;
-            FFSWAP(Node, nodes[j], nodes[j-1]);
+            FFSWAP(Node, nodes[j], nodes[j - 1]);
         }
         cur_node++;
     }
-    if(build_huff_tree(vlc, nodes, nb_codes*2-2) < 0){
+    if (build_huff_tree(vlc, nodes, nb_codes * 2 - 2, flags) < 0) {
         av_log(avctx, AV_LOG_ERROR, "Error building tree\n");
         return -1;
     }