avcodec: add Direct Stream Transfer (DST) decoder

Signed-off-by: Paul B Mahol <onemda@gmail.com>

1 files changed, 86 insertions, 0 deletions

diff --git a/libavcodec/dsd.c b/libavcodec/dsd.c
new file mode 100644
index 0000000000..9104f38476
--- /dev/null
+++ b/libavcodec/dsd.c
@@ -0,0 +1,86 @@
+/*
+ * Direct Stream Digital (DSD) decoder
+ * based on BSD licensed dsd2pcm by Sebastian Gesemann
+ * Copyright (c) 2009, 2011 Sebastian Gesemann. All rights reserved.
+ * Copyright (c) 2014 Peter Ross
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg 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 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg 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 FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "libavcodec/internal.h"
+#include "libavcodec/mathops.h"
+#include "avcodec.h"
+#include "dsd_tablegen.h"
+#include "dsd.h"
+
+static av_cold void dsd_ctables_tableinit(void)
+{
+    int t, e, m, sign;
+    double acc[CTABLES];
+    for (e = 0; e < 256; ++e) {
+        memset(acc, 0, sizeof(acc));
+        for (m = 0; m < 8; ++m) {
+            sign = (((e >> (7 - m)) & 1) * 2 - 1);
+            for (t = 0; t < CTABLES; ++t)
+                acc[t] += sign * htaps[t * 8 + m];
+        }
+        for (t = 0; t < CTABLES; ++t)
+            ctables[CTABLES - 1 - t][e] = acc[t];
+    }
+}
+
+av_cold void ff_init_dsd_data(void)
+{
+    static int done = 0;
+    if (done)
+        return;
+    dsd_ctables_tableinit();
+    done = 1;
+}
+
+void ff_dsd2pcm_translate(DSDContext* s, size_t samples, int lsbf,
+                          const unsigned char *src, ptrdiff_t src_stride,
+                          float *dst, ptrdiff_t dst_stride)
+{
+    unsigned pos, i;
+    unsigned char* p;
+    double sum;
+
+    pos = s->pos;
+
+    while (samples-- > 0) {
+        s->buf[pos] = lsbf ? ff_reverse[*src] : *src;
+        src += src_stride;
+
+        p = s->buf + ((pos - CTABLES) & FIFOMASK);
+        *p = ff_reverse[*p];
+
+        sum = 0.0;
+        for (i = 0; i < CTABLES; i++) {
+            unsigned char a = s->buf[(pos                   - i) & FIFOMASK];
+            unsigned char b = s->buf[(pos - (CTABLES*2 - 1) + i) & FIFOMASK];
+            sum += ctables[i][a] + ctables[i][b];
+        }
+
+        *dst = (float)sum;
+        dst += dst_stride;
+
+        pos = (pos + 1) & FIFOMASK;
+    }
+
+    s->pos = pos;
+}