Fraps v2 and v4 support

Originally committed as revision 6896 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/fraps.c

 /*
  * Fraps FPS1 decoder
  * Copyright (c) 2005 Roine Gustafsson
+ * Copyright (c) 2006 Konstantin Shishkov
  *
  * This file is part of FFmpeg.
  *
@@ -24,24 +25,42 @@
  * @file fraps.c
  * Lossless Fraps 'FPS1' decoder
  * @author Roine Gustafsson <roine at users sf net>
+ * @author Konstantin Shishkov
  *
  * Only decodes version 0 and 1 files.
  * Codec algorithm for version 0 is taken from Transcode <www.transcoding.org>
  *
- * Version 2 files, which are the most commonly found Fraps files, cannot be
- * decoded yet.
+ * Version 2 files support by Konstantin Shishkov
  */
 
 #include "avcodec.h"
+#include "bitstream.h"
+#include "dsputil.h"
 
 #define FPS_TAG MKTAG('F', 'P', 'S', 'x')
 
+/* symbol for Huffman tree node */
+#define HNODE -1
+
+/**
+ * Huffman node
+ * FIXME one day this should belong to one general framework
+ */
+typedef struct Node{
+    int16_t sym;
+    int16_t n0;
+    int count;
+}Node;
+
 /**
  * local variable storage
  */
 typedef struct FrapsContext{
     AVCodecContext *avctx;
     AVFrame frame;
+    Node nodes[512];
+    uint8_t *tmpbuf;
+    DSPContext dsp;
 } FrapsContext;
 
 
@@ -60,10 +79,110 @@ static int decode_init(AVCodecContext *avctx)
 
     s->avctx = avctx;
     s->frame.data[0] = NULL;
+    s->tmpbuf = NULL;
+
+    dsputil_init(&s->dsp, avctx);
 
     return 0;
 }
 
+/**
+ * Comparator - our nodes should ascend by count
+ * but with preserved symbol order
+ */
+static int huff_cmp(const Node *a, const Node *b){
+    return (a->count - b->count)*256 + a->sym - b->sym;
+}
+
+static void get_tree_codes(uint32_t *bits, int16_t *lens, Node *nodes, int node, uint32_t pfx, int pl)
+{
+    int s;
+
+    s = nodes[node].sym;
+    if(s != HNODE){
+        bits[s] = pfx;
+        lens[s] = pl;
+    }else{
+        pfx <<= 1;
+        pl++;
+        get_tree_codes(bits, lens, nodes, nodes[node].n0, pfx, pl);
+        pfx |= 1;
+        get_tree_codes(bits, lens, nodes, nodes[node].n0+1, pfx, pl);
+    }
+}
+
+static int build_huff_tree(VLC *vlc, Node *nodes)
+{
+    uint32_t bits[256];
+    int16_t lens[256];
+
+    get_tree_codes(bits, lens, nodes, 510, 0, 0);
+    return init_vlc(vlc, 9, 256, lens, 2, 2, bits, 4, 4, 0);
+}
+
+
+/**
+ * decode Fraps v2 packed plane
+ */
+static int fraps2_decode_plane(FrapsContext *s, uint8_t *dst, int stride, int w,
+                               int h, uint8_t *src, int size, int Uoff)
+{
+    int i, j;
+    int cur_node;
+    GetBitContext gb;
+    VLC vlc;
+    int64_t sum = 0;
+
+    for(i = 0; i < 256; i++){
+        s->nodes[i].sym = i;
+        s->nodes[i].count = LE_32(src);
+        s->nodes[i].n0 = -2;
+        src += 4;
+        sum += s->nodes[i].count;
+    }
+    size -= 1024;
+
+    if(sum >> 31) {
+        av_log(s->avctx, AV_LOG_ERROR, "Too high symbol frequencies. Tree construction is not possible\n");
+        return -1;
+    }
+    qsort(s->nodes, 256, sizeof(Node), huff_cmp);
+    cur_node = 256;
+    // FIXME how it will handle nodes with zero count?
+    for(i = 0; i < 511; i += 2){
+        s->nodes[cur_node].sym = HNODE;
+        s->nodes[cur_node].count = s->nodes[i].count + s->nodes[i+1].count;
+        s->nodes[cur_node].n0 = i;
+        for(j = cur_node; j > 0; j--){
+            if(s->nodes[j].count >= s->nodes[j - 1].count) break;
+            FFSWAP(Node, s->nodes[j], s->nodes[j - 1]);
+        }
+        cur_node++;
+    }
+    if(build_huff_tree(&vlc, s->nodes) < 0){
+        av_log(s->avctx, AV_LOG_ERROR, "Error building tree\n");
+        return -1;
+    }
+    /* we have built Huffman table and are ready to decode plane */
+
+    /* convert bits so they may be used by standard bitreader */
+    s->dsp.bswap_buf(s->tmpbuf, src, size >> 2);
+
+    init_get_bits(&gb, s->tmpbuf, size * 8);
+    for(j = 0; j < h; j++){
+        for(i = 0; i < w; i++){
+            dst[i] = get_vlc2(&gb, vlc.table, 9, 3);
+            /* lines are stored as deltas between previous lines
+             * and we need to add 0x80 to the first lines of chroma planes
+             */
+            if(j) dst[i] += dst[i - stride];
+            else if(Uoff) dst[i] += 0x80;
+        }
+        dst += stride;
+    }
+    free_vlc(&vlc);
+    return 0;
+}
 
 /**
  * decode a frame
@@ -86,16 +205,18 @@ static int decode_frame(AVCodecContext *avctx,
     unsigned int x, y;
     uint32_t *buf32;
     uint32_t *luma1,*luma2,*cb,*cr;
+    uint32_t offs[4];
+    int i, is_chroma, planes;
 
 
     header = LE_32(buf);
     version = header & 0xff;
     header_size = (header & (1<<30))? 8 : 4; /* bit 30 means pad to 8 bytes */
 
-    if (version > 1) {
+    if (version > 2 && version != 4) {
         av_log(avctx, AV_LOG_ERROR,
                "This file is encoded with Fraps version %d. " \
-               "This codec can only decode version 0 and 1.\n", version);
+               "This codec can only decode version 0, 1, 2 and 4.\n", version);
         return -1;
     }
 
@@ -187,30 +308,50 @@ static int decode_frame(AVCodecContext *avctx,
         break;
 
     case 2:
+    case 4:
         /**
-         * Fraps v2 sub-header description. All numbers are little-endian:
-         * (this is all guesswork)
-         *
-         *       0:     DWORD 'FPSx'
-         *       4:     DWORD 0x00000010   unknown, perhaps flags
-         *       8:     DWORD off_2        offset to plane 2
-         *      12:     DWORD off_3        offset to plane 3
-         *      16: 256xDWORD freqtbl_1    frequency table for plane 1
-         *    1040:           plane_1
-         *     ...
-         *   off_2: 256xDWORD freqtbl_2    frequency table for plane 2
-         *                    plane_2
-         *    ...
-         *   off_3: 256xDWORD freqtbl_3    frequency table for plane 3
-         *                    plane_3
+         * Fraps v2 is Huffman-coded YUV420 planes
+         * Fraps v4 is the same except it works in grayscale
          */
-        if ((BE_32(buf) != FPS_TAG)||(buf_size < (3*1024 + 8))) {
+        avctx->pix_fmt = (version == 2) ? PIX_FMT_YUV420P : PIX_FMT_GRAY8;
+        planes = (version == 2) ? 3 : 1;
+        f->reference = 1;
+        f->buffer_hints = FF_BUFFER_HINTS_VALID |
+                          FF_BUFFER_HINTS_PRESERVE |
+                          FF_BUFFER_HINTS_REUSABLE;
+        if (avctx->reget_buffer(avctx, f)) {
+            av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
+            return -1;
+        }
+        /* skip frame */
+        if(buf_size == 8) {
+            f->pict_type = FF_P_TYPE;
+            f->key_frame = 0;
+            break;
+        }
+        f->pict_type = FF_I_TYPE;
+        f->key_frame = 1;
+        if ((LE_32(buf) != FPS_TAG)||(buf_size < (planes*1024 + 24))) {
             av_log(avctx, AV_LOG_ERROR, "Fraps: error in data stream\n");
             return -1;
         }
-
-        /* NOT FINISHED */
-
+        for(i = 0; i < planes; i++) {
+            offs[i] = LE_32(buf + 4 + i * 4);
+            if(offs[i] >= buf_size || (i && offs[i] <= offs[i - 1] + 1024)) {
+                av_log(avctx, AV_LOG_ERROR, "Fraps: plane %i offset is out of bounds\n", i);
+                return -1;
+            }
+        }
+        offs[planes] = buf_size;
+        for(i = 0; i < planes; i++){
+            is_chroma = !!i;
+            s->tmpbuf = av_realloc(s->tmpbuf, offs[i + 1] - offs[i] - 1024);
+            if(fraps2_decode_plane(s, f->data[i], f->linesize[i], avctx->width >> is_chroma,
+                    avctx->height >> is_chroma, buf + offs[i], offs[i + 1] - offs[i], is_chroma) < 0) {
+                av_log(avctx, AV_LOG_ERROR, "Error decoding plane %i\n", i);
+                return -1;
+            }
+        }
         break;
     }
 
@@ -233,6 +374,7 @@ static int decode_end(AVCodecContext *avctx)
     if (s->frame.data[0])
         avctx->release_buffer(avctx, &s->frame);
 
+    av_freep(&s->tmpbuf);
     return 0;
 }