Winnov WNV1 video decoder, courtesy of Konstantin Shishkov

Originally committed as revision 4083 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 169 insertions, 0 deletions

diff --git a/libavcodec/wnv1.c b/libavcodec/wnv1.c
new file mode 100644
index 0000000000..36e39fa07f
--- /dev/null
+++ b/libavcodec/wnv1.c
@@ -0,0 +1,169 @@
+/*
+ * Winnov WNV1 codec
+ * Copyright (c) 2005 Konstantin Shishkov
+ *
+ * This library 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 of the License, or (at your option) any later version.
+ *
+ * This library 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 library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ */
+ 
+/**
+ * @file wnv1.c
+ * Winnov WNV1 codec.
+ */
+ 
+#include "avcodec.h"
+#include "common.h"
+
+
+typedef struct WNV1Context{
+    AVCodecContext *avctx;
+    AVFrame pic;
+
+    int shift;
+    /* bit buffer */
+    unsigned long bitbuf;
+    int bits;
+    uint8_t *buf;
+} WNV1Context;
+
+/* returns modified base_value */
+static inline int wnv1_get_code(WNV1Context *w, int base_value)
+{
+    int v = 0;
+            
+    if (w->bits < 16) { /* need to fill bit buffer */
+        w->bitbuf |= LE_16(w->buf) << w->bits;
+        w->buf += 2;
+        w->bits += 16;
+    }
+
+    /* escape code */
+    if ((w->bitbuf & 0xFF) == 0xFF) {
+        w->bitbuf >>= 8;
+        w->bits -= 8;
+        if (w->bits < 16) { /* need to fill bit buffer */
+            w->bitbuf |= LE_16(w->buf) << w->bits;
+            w->buf += 2;
+            w->bits += 16;
+        }
+        v = w->bitbuf & (0xFF >> w->shift);
+        w->bitbuf >>= 8 - w->shift;
+        w->bits -= 8 - w->shift;
+        return v << w->shift;
+    }
+
+    /* zero code */
+    if (!(w->bitbuf & 1)) {
+        w->bitbuf >>= 1;
+        w->bits--;
+        return base_value;
+    }
+    
+    /* reversed unary code and sign */
+    while (w->bits && w->bitbuf & 1) {
+        w->bitbuf >>= 1;
+        w->bits--;
+        v++;
+    }
+    w->bitbuf >>= 1;
+    w->bits--;
+    if(w->bitbuf & 1)
+        v = -v;
+    w->bitbuf >>= 1;
+    w->bits--;
+    v <<= w->shift;
+    return base_value + v;
+}
+
+static int decode_frame(AVCodecContext *avctx, 
+                        void *data, int *data_size,
+                        uint8_t *buf, int buf_size)
+{
+    WNV1Context * const l = avctx->priv_data;
+    AVFrame * const p= (AVFrame*)&l->pic;
+    unsigned char *Y,*U,*V;
+    int i, j;
+    int prev_y = 0, prev_u = 0, prev_v = 0;
+
+    if(p->data[0])
+        avctx->release_buffer(avctx, p);
+
+    p->reference = 0;
+    if(avctx->get_buffer(avctx, p) < 0){
+        av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
+        return -1;
+    }
+    p->key_frame = 1;
+    
+    l->bitbuf = 0;
+    l->bits = 0;
+    l->buf = buf + 8;
+    
+    if (buf[2] >> 4 == 6)
+        l->shift = 2;
+    else {
+        l->shift = 8 - (buf[2] >> 4);
+        if (l->shift > 4) {
+            av_log(avctx, AV_LOG_ERROR, "Unknown WNV1 frame header value %i, please upload file for study\n", buf[2] >> 4);
+            l->shift = 4;
+        }
+        if (l->shift < 1) {
+            av_log(avctx, AV_LOG_ERROR, "Unknown WNV1 frame header value %i, please upload file for study\n", buf[2] >> 4);
+            l->shift = 1;
+        }
+    }
+    
+    Y = p->data[0];
+    U = p->data[1];
+    V = p->data[2];
+    for (j = 0; j < avctx->height; j++) {
+        for (i = 0; i < avctx->width / 2; i++) {
+            Y[i * 2] = wnv1_get_code(l, prev_y);
+            prev_u = U[i] = wnv1_get_code(l, prev_u);
+            prev_y = Y[(i * 2) + 1] = wnv1_get_code(l, Y[i * 2]);
+            prev_v = V[i] = wnv1_get_code(l, prev_v);
+        }
+        Y += p->linesize[0];
+        U += p->linesize[1];
+        V += p->linesize[2];
+    }
+
+    
+    *data_size = sizeof(AVFrame);
+    *(AVFrame*)data = l->pic;
+    
+    return buf_size;
+}
+
+static int decode_init(AVCodecContext *avctx){
+    WNV1Context * const l = avctx->priv_data;
+
+    l->avctx = avctx;
+    avctx->pix_fmt = PIX_FMT_YUV422P;
+
+    return 0;
+}
+
+AVCodec wnv1_decoder = {
+    "wnv1",
+    CODEC_TYPE_VIDEO,
+    CODEC_ID_WNV1,
+    sizeof(WNV1Context),
+    decode_init,
+    NULL,
+    NULL,
+    decode_frame,
+    CODEC_CAP_DR1,
+};