From a527e0f5080d801e87faf29960ee3f5cfc223e96 Mon Sep 17 00:00:00 2001
From: melanson <melanson@b3059339-0415-0410-9bf9-f77b7e298cf2>
Date: Thu, 27 Dec 2001 05:09:43 +0000
Subject: implemented open source MS ADPCM decoder

git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@3788 b3059339-0415-0410-9bf9-f77b7e298cf2
---
 adpcm.c | 140 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 140 insertions(+)

(limited to 'adpcm.c')

diff --git a/adpcm.c b/adpcm.c
index f178cf667b..933fb5c4ef 100644
--- a/adpcm.c
+++ b/adpcm.c
@@ -1,6 +1,11 @@
 /*
     Unified ADPCM Decoder for MPlayer
 
+    This file is in charge of decoding all of the various ADPCM data
+    formats that various entities have created. Details about the data
+    formats can be found here:
+      http://www.pcisys.net/~melanson/codecs/
+
     (C) 2001 Mike Melanson
 */
 
@@ -13,13 +18,60 @@
 #define LE_16(x) (le2me_16(*(unsigned short *)(x)))
 #define LE_32(x) (le2me_32(*(unsigned int *)(x)))
 
+// pertinent tables
+static int adpcm_step[89] =
+{
+  7, 8, 9, 10, 11, 12, 13, 14, 16, 17,
+  19, 21, 23, 25, 28, 31, 34, 37, 41, 45,
+  50, 55, 60, 66, 73, 80, 88, 97, 107, 118,
+  130, 143, 157, 173, 190, 209, 230, 253, 279, 307,
+  337, 371, 408, 449, 494, 544, 598, 658, 724, 796,
+  876, 963, 1060, 1166, 1282, 1411, 1552, 1707, 1878, 2066,
+  2272, 2499, 2749, 3024, 3327, 3660, 4026, 4428, 4871, 5358,
+  5894, 6484, 7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899,
+  15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794, 32767
+};
+
+static int adpcm_index[16] =
+{
+  -1, -1, -1, -1, 2, 4, 6, 8,
+  -1, -1, -1, -1, 2, 4, 6, 8
+};
+
+static int format_0x62_table[16] =
+{
+  1, 3, 5, 7, 9, 11, 13, 15,
+  -1, -3, -5, -7, -9, -11, -13, -15
+};
+
+static int ms_adapt_table[] =
+{
+  230, 230, 230, 230, 307, 409, 512, 614,
+  768, 614, 512, 409, 307, 230, 230, 230
+};
+
+static int ms_adapt_coeff1[] =
+{
+  256, 512, 0, 192, 240, 460, 392
+};
+
+static int ms_adapt_coeff2[] =
+{
+  0, -256, 0, 64, 0, -208, -232
+};
+
+// useful macros
 // clamp a number between 0 and 88
 #define CLAMP_0_TO_88(x)  if (x < 0) x = 0; else if (x > 88) x = 88;
 // clamp a number within a signed 16-bit range
 #define CLAMP_S16(x)  if (x < -32768) x = -32768; \
   else if (x > 32767) x = 32767;
+// clamp a number above 16
+#define CLAMP_ABOVE_16(x)  if (x < 16) x = 16;
 // sign extend a 16-bit value
 #define SE_16BIT(x)  if (x & 0x8000) x -= 0x10000;
+// sign extend a 4-bit value
+#define SE_4BIT(x)  if (x & 0x8) x -= 0x10;
 
 void ima_dvi_decode_nibbles(unsigned short *output, int channels,
   int predictor_l, int index_l,
@@ -129,3 +181,91 @@ int ima_adpcm_decode_block(unsigned short *output, unsigned char *input,
 
   return IMA_ADPCM_SAMPLES_PER_BLOCK * channels;
 }
+
+int ms_adpcm_decode_block(unsigned short *output, unsigned char *input,
+  int channels)
+{
+  int current_channel = 0;
+  int idelta[2];
+  int sample1[2];
+  int sample2[2];
+  int coeff1[2];
+  int coeff2[2];
+  int stream_ptr = 0;
+  int out_ptr = 0;
+  int upper_nibble = 1;
+  int nibble;
+  int snibble;  // signed nibble
+  int predictor;
+
+  // fetch the header information, in stereo if both channels are present
+  coeff1[0] = ms_adapt_coeff1[input[stream_ptr]];
+  coeff2[0] = ms_adapt_coeff2[input[stream_ptr]];
+  stream_ptr++;
+  if (channels == 2)
+  {
+    coeff1[1] = ms_adapt_coeff1[input[stream_ptr]];
+    coeff2[1] = ms_adapt_coeff2[input[stream_ptr]];
+    stream_ptr++;
+  }
+
+  idelta[0] = LE_16(&input[stream_ptr]);
+  stream_ptr += 2;
+  SE_16BIT(idelta[0]);
+  if (channels == 2)
+  {
+    idelta[1] = LE_16(&input[stream_ptr]);
+    stream_ptr += 2;
+    SE_16BIT(idelta[1]);
+  }
+
+  sample1[0] = LE_16(&input[stream_ptr]);
+  stream_ptr += 2;
+  SE_16BIT(sample1[0]);
+  if (channels == 2)
+  {
+    sample1[1] = LE_16(&input[stream_ptr]);
+    stream_ptr += 2;
+    SE_16BIT(sample1[1]);
+  }
+
+  sample2[0] = LE_16(&input[stream_ptr]);
+  stream_ptr += 2;
+  SE_16BIT(sample2[0]);
+  if (channels == 2)
+  {
+    sample2[1] = LE_16(&input[stream_ptr]);
+    stream_ptr += 2;
+    SE_16BIT(sample2[1]);
+  }
+
+  while (stream_ptr < MS_ADPCM_BLOCK_SIZE * channels)
+  {
+    // get the next nibble
+    if (upper_nibble)
+      nibble = snibble = input[stream_ptr] >> 4;
+    else
+      nibble = snibble = input[stream_ptr++] & 0x0F;
+    upper_nibble ^= 1;
+    SE_4BIT(snibble);
+
+    predictor = (
+      ((sample1[current_channel] * coeff1[current_channel]) +
+       (sample2[current_channel] * coeff2[current_channel])) / 256) +
+      (snibble * idelta[current_channel]);
+    CLAMP_S16(predictor);
+    sample2[current_channel] = sample1[current_channel];
+    sample1[current_channel] = predictor;
+    output[out_ptr++] = predictor;
+
+    // compute the next adaptive scale factor (a.k.a. the variable idelta)
+    idelta[current_channel] = 
+      (ms_adapt_table[nibble] * idelta[current_channel]) / 256;
+    CLAMP_ABOVE_16(idelta[current_channel]);
+
+    // toggle the channel
+    current_channel ^= channels - 1;
+  }
+
+  return MS_ADPCM_SAMPLES_PER_BLOCK * channels;
+}
-- 
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