Initial support for unified ADPCM decoder

git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@3757 b3059339-0415-0410-9bf9-f77b7e298cf2

1 files changed, 136 insertions, 0 deletions

diff --git a/adpcm.c b/adpcm.c
new file mode 100644
index 0000000000..91d56a6e0c
--- /dev/null
+++ b/adpcm.c
@@ -0,0 +1,136 @@
+/*
+    Unified ADPCM Decoder for MPlayer
+
+    (C) 2001 Mike Melanson
+*/
+
+#include "config.h"
+#include "bswap.h"
+#include "adpcm.h"
+
+#define BE_16(x) (be2me_16(*(unsigned short *)(x)))
+#define BE_32(x) (be2me_32(*(unsigned int *)(x)))
+#define LE_16(x) (le2me_16(*(unsigned short *)(x)))
+#define LE_32(x) (le2me_32(*(unsigned int *)(x)))
+
+// 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;
+// sign extend a 16-bit value
+#define SE_16BIT(x)  if (x & 0x8000) x -= 0x10000;
+
+void ima_dvi_decode_nibbles(unsigned short *output, int channels,
+  int predictor_l, int index_l,
+  int predictor_r, int index_r)
+{
+  int step[2];
+  int predictor[2];
+  int index[2];
+  int diff;
+  int i;
+  int sign;
+  int delta;
+  int channel_number = 0;
+
+  step[0] = adpcm_step[index_l];
+  step[1] = adpcm_step[index_r];
+  predictor[0] = predictor_l;
+  predictor[1] = predictor_r;
+  index[0] = index_l;
+  index[1] = index_r;
+
+  for (i = 0; i < IMA_ADPCM_SAMPLES_PER_BLOCK * channels; i++)
+  {
+    delta = output[i];
+
+    index[channel_number] += adpcm_index[delta];
+    CLAMP_0_TO_88(index[channel_number]);
+
+    sign = delta & 8;
+    delta = delta & 7;
+
+    diff = step[channel_number] >> 3;
+    if (delta & 4) diff += step[channel_number];
+    if (delta & 2) diff += step[channel_number] >> 1;
+    if (delta & 1) diff += step[channel_number] >> 2;
+
+    if (sign)
+      predictor[channel_number] -= diff;
+    else
+      predictor[channel_number] += diff;
+
+    CLAMP_S16(predictor[channel_number]);
+    output[i] = predictor[channel_number];
+    step[channel_number] = adpcm_step[index[channel_number]];
+
+    // toggle channel
+    channel_number ^= channels - 1;
+  }
+}
+
+int ima_adpcm_decode_block(unsigned short *output, unsigned char *input,
+  int channels)
+{
+  int initial_predictor_l = 0;
+  int initial_predictor_r = 0;
+  int initial_index_l = 0;
+  int initial_index_r = 0;
+  int stream_ptr = 0;
+  int i;
+
+  initial_predictor_l = BE_16(&input[stream_ptr]);
+  stream_ptr += 2;
+  initial_index_l = initial_predictor_l;
+
+  // mask, sign-extend, and clamp the predictor portion
+  initial_predictor_l &= 0xFF80;
+  SE_16BIT(initial_predictor_l);
+  CLAMP_S16(initial_predictor_l);
+
+  // mask and clamp the index portion
+  initial_index_l &= 0x7F;
+  CLAMP_0_TO_88(initial_index_l);
+
+  // handle stereo
+  if (channels > 1)
+  {
+    initial_predictor_r = BE_16(&input[stream_ptr]);
+    stream_ptr += 2;
+    initial_index_r = initial_predictor_r;
+
+    // mask, sign-extend, and clamp the predictor portion
+    initial_predictor_r &= 0xFF80;
+    SE_16BIT(initial_predictor_r);
+    CLAMP_S16(initial_predictor_r);
+
+    // mask and clamp the index portion
+    initial_index_r &= 0x7F;
+    CLAMP_0_TO_88(initial_index_r);
+  }
+
+  // break apart all of the nibbles in the block
+  if (channels == 1)
+    for (i = 0; i < IMA_ADPCM_SAMPLES_PER_BLOCK / 2; i++)
+    {
+      output[i * 2 + 0] = input[stream_ptr] & 0x0F;
+      output[i * 2 + 1] = input[stream_ptr] >> 4;
+      stream_ptr++;
+    }  
+  else
+    for (i = 0; i < IMA_ADPCM_SAMPLES_PER_BLOCK / 2 * 2; i++)
+    {
+      output[i * 4 + 0] = input[stream_ptr] & 0x0F;
+      output[i * 4 + 1] = input[stream_ptr + 1] & 0x0F;
+      output[i * 4 + 2] = input[stream_ptr] >> 4;
+      output[i * 4 + 3] = input[stream_ptr + 1] >> 4;
+      stream_ptr++;
+    }  
+
+  ima_dvi_decode_nibbles(output, channels,
+    initial_predictor_l, initial_index_l,
+    initial_predictor_r, initial_index_r);
+
+  return IMA_ADPCM_SAMPLES_PER_BLOCK * channels;
+}