From 673c78183bfc17fdd79c012e93b83fbe601ef3a3 Mon Sep 17 00:00:00 2001
From: malc <av1474@comtv.ru>
Date: Thu, 20 Nov 2008 11:12:30 +0300
Subject: [PATCH] Audio decoder

---
 README  |  4 +++
 adpcm.c | 96 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 100 insertions(+)
 create mode 100644 adpcm.c

diff --git a/README b/README
index 81510ec..df11dd8 100644
--- a/README
+++ b/README
@@ -39,6 +39,10 @@ swizzling code: http://playstation2-linux.com/download/p2lsd/sparkys_swizzle_cod
 altivec code is based on:
    http://www.freevec.org/category/simd/algorithms/algebra/matrix_operations
 
+adpcm decoder is slightly modified:
+   PSX VAG-Packer, hacked by bITmASTER@bigfoot.com
+   with block interleave figured out by Antti Huovilainen
+
 Disorder handshakes
 -------------------
 Skal,   Unreal,    Ex, Coderipper,   dAS,   Action, Vastator,  pGeist,
diff --git a/adpcm.c b/adpcm.c
new file mode 100644
index 0000000..eef11e5
--- /dev/null
+++ b/adpcm.c
@@ -0,0 +1,96 @@
+/* Based on:
+
+   PSX VAG-Packer, hacked by bITmASTER@bigfoot.com
+
+   v0.1
+*/
+
+/* Block interleave figured out by Antti Huovilainen. */
+
+/* Usage:
+   $ cc -o adpcm adpcm.c
+   $ dd if=/path/to/sotc/dvd/XAD \
+     | ./adpcm | sox -t raw -r 22050 -s -w -c 2 - -t ossdsp /dev/dsp
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+
+static const double f[5][2] = { { 0.0, 0.0 },
+                                {  60.0 / 64.0,  0.0 },
+                                {  115.0 / 64.0, -52.0 / 64.0 },
+                                {  98.0 / 64.0, -55.0 / 64.0 },
+                                {  122.0 / 64.0, -60.0 / 64.0 } };
+
+int main (void)
+{
+    int predict_nr, shift_factor, flags;
+    int i, block = 0;
+    unsigned int d;
+    int s;
+    struct {
+        double s_1;
+        double s_2;
+        double s_11;
+        double s_21;
+    } ctxs[2] = {0}, *ctx = ctxs;
+    signed short int left[28*64], right[28*64];
+    signed short int *chan = left;
+    double samples[28];
+
+    for (;;) {
+        signed char data[16];
+
+        if (fread (data, 16, 1, stdin) != 1) {
+            perror ("fread");
+            exit (EXIT_FAILURE);
+        }
+
+        if (data[1] == 7) break;
+
+        predict_nr = data[0];
+        shift_factor = predict_nr & 0xf;
+        predict_nr >>= 4;
+
+        for (i = 0; i < 28; i += 2) {
+            d = data[i / 2 + 2];
+            s = (d & 0xf) << 12;
+            if (s & 0x8000)
+                s |= 0xffff0000;
+            samples[i] = (double) (s >> shift_factor);
+            s = (d & 0xf0) << 8;
+            if (s & 0x8000)
+                s |= 0xffff0000;
+            samples[i+1] = (double) (s >> shift_factor);
+        }
+
+        for (i = 0; i < 28; i++) {
+            samples[i] += ctx->s_1 * f[predict_nr][0] + ctx->s_2 * f[predict_nr][1];
+            ctx->s_2 = ctx->s_1;
+            ctx->s_1 = samples[i];
+            d = (int) (samples[i] + 0.5);
+            chan[i + block*28] = d;
+        }
+
+        block++;
+        if (block == 64) {
+            if (chan == left) {
+                chan = right;
+                ctx = &ctxs[1];
+            }
+            else {
+                chan = left;
+                ctx = &ctxs[0];
+
+                for (i = 0; i < 28*64; ++i) {
+                    fputc (left[i] >> 8, stdout);
+                    fputc (left[i], stdout);
+                    fputc (right[i] >> 8, stdout);
+                    fputc (right[i], stdout);
+                }
+            }
+            block = 0;
+        }
+    }
+    return 0;
+}
-- 
2.11.4.GIT