avcodec/alacdec: split off decorrelate_stereo and append_extra_bits as alacdsp

Reviewed-by: Michael Niedermayer <michaelni@gmx.at>
Signed-off-by: James Almer <jamrial@gmail.com>

1 files changed, 60 insertions, 0 deletions

diff --git a/libavcodec/alacdsp.c b/libavcodec/alacdsp.c
new file mode 100644
index 0000000000..608c0d8915
--- /dev/null
+++ b/libavcodec/alacdsp.c
@@ -0,0 +1,60 @@
+/*
+ * ALAC (Apple Lossless Audio Codec) decoder
+ * Copyright (c) 2005 David Hammerton
+ *
+ * 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 "libavutil/attributes.h"
+#include "alacdsp.h"
+#include "config.h"
+
+static void decorrelate_stereo(int32_t *buffer[2], int nb_samples,
+                               int decorr_shift, int decorr_left_weight)
+{
+    int i;
+
+    for (i = 0; i < nb_samples; i++) {
+        int32_t a, b;
+
+        a = buffer[0][i];
+        b = buffer[1][i];
+
+        a -= (b * decorr_left_weight) >> decorr_shift;
+        b += a;
+
+        buffer[0][i] = b;
+        buffer[1][i] = a;
+    }
+}
+
+static void append_extra_bits(int32_t *buffer[2], int32_t *extra_bits_buffer[2],
+                              int extra_bits, int channels, int nb_samples)
+{
+    int i, ch;
+
+    for (ch = 0; ch < channels; ch++)
+        for (i = 0; i < nb_samples; i++)
+            buffer[ch][i] = (buffer[ch][i] << extra_bits) | extra_bits_buffer[ch][i];
+}
+
+av_cold void ff_alacdsp_init(ALACDSPContext *c)
+{
+    c->decorrelate_stereo   = decorrelate_stereo;
+    c->append_extra_bits[0] =
+    c->append_extra_bits[1] = append_extra_bits;
+}