Westwood SND1 decoder, courtesy of Kostya

Originally committed as revision 4094 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 145 insertions, 0 deletions

diff --git a/libavcodec/ws-snd1.c b/libavcodec/ws-snd1.c
new file mode 100644
index 0000000000..5ac4c61bdc
--- /dev/null
+++ b/libavcodec/ws-snd1.c
@@ -0,0 +1,145 @@
+/*
+ * Westwood SNDx codecs
+ * 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
+ */
+#include "avcodec.h"
+
+/**
+ * @file ws-snd.c
+ * Westwood SNDx codecs.
+ *
+ * Reference documents about VQA format and its audio codecs
+ * can be found here:
+ * http://www.multimedia.cx
+ */
+
+typedef struct {
+} WSSNDContext;
+
+static const char ws_adpcm_2bit[] = { -2, -1, 0, 1};
+static const char ws_adpcm_4bit[] = {
+    -9, -8, -6, -5, -4, -3, -2, -1,
+     0,  1,  2,  3,  4,  5,  6,  8 };
+
+#define CLIP8(a) if(a>127)a=127;if(a<-128)a=-128;
+
+static int ws_snd_decode_init(AVCodecContext * avctx)
+{
+//    WSSNDContext *c = avctx->priv_data;
+    
+    return 0;
+}
+
+static int ws_snd_decode_frame(AVCodecContext *avctx,
+                void *data, int *data_size,
+                uint8_t *buf, int buf_size)
+{
+//    WSSNDContext *c = avctx->priv_data;
+    
+    int in_size, out_size;
+    int sample = 0;
+    int i;
+    short *samples = data;
+    
+    if (!buf_size)
+        return 0;
+
+    out_size = LE_16(&buf[0]);
+    *data_size = out_size * 2;
+    in_size = LE_16(&buf[2]);
+    buf += 4;
+    
+    if (in_size == out_size) {
+        for (i = 0; i < out_size; i++)
+            *samples++ = (*buf++ - 0x80) << 8;
+        return buf_size;
+    }
+    
+    while (out_size > 0) {
+        int code;
+        uint8_t count;
+        code = (*buf) >> 6;
+        count = (*buf) & 0x3F;
+        buf++;
+        switch(code) {
+        case 0: /* ADPCM 2-bit */
+            for (count++; count > 0; count--) {
+                code = *buf++;
+                sample += ws_adpcm_2bit[code & 0x3];
+                CLIP8(sample);
+                *samples++ = sample << 8;
+                sample += ws_adpcm_2bit[(code >> 2) & 0x3];
+                CLIP8(sample);
+                *samples++ = sample << 8;
+                sample += ws_adpcm_2bit[(code >> 4) & 0x3];
+                CLIP8(sample);
+                *samples++ = sample << 8;
+                sample += ws_adpcm_2bit[(code >> 6) & 0x3];
+                CLIP8(sample);
+                *samples++ = sample << 8;
+                out_size -= 4;
+            }
+            break;
+        case 1: /* ADPCM 4-bit */
+            for (count++; count > 0; count--) {
+                code = *buf++;
+                sample += ws_adpcm_4bit[code & 0xF];
+                CLIP8(sample);
+                *samples++ = sample << 8;
+                sample += ws_adpcm_4bit[code >> 4];
+                CLIP8(sample);
+                *samples++ = sample << 8;
+                out_size -= 2;
+            }
+            break;
+        case 2: /* no compression */
+            if (count & 0x20) { /* big delta */
+                char t;
+                t = count;
+                t <<= 3;
+                sample += t >> 3;
+                *samples++ = sample << 8;
+                out_size--;
+            } else { /* copy */
+                for (count++; count > 0; count--) {
+                    *samples++ = (*buf++ - 0x80) << 8;
+                    out_size--;
+                }
+                sample = buf[-1] - 0x80;
+            }
+            break;
+        default: /* run */
+            for(count++; count > 0; count--) {
+                *samples++ = sample << 8;
+                out_size--;
+            }
+        }
+    }
+    
+    return buf_size;
+}
+
+AVCodec ws_snd1_decoder = {
+    "ws_snd1",
+    CODEC_TYPE_AUDIO,
+    CODEC_ID_WESTWOOD_SND1,
+    sizeof(WSSNDContext),
+    ws_snd_decode_init,
+    NULL,
+    NULL,
+    ws_snd_decode_frame,
+};