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>

libavcodec/Makefile

@@ -143,7 +143,7 @@ OBJS-$(CONFIG_AC3_ENCODER)             += ac3enc_float.o ac3enc.o ac3tab.o \
                                           ac3.o kbdwin.o
 OBJS-$(CONFIG_AC3_FIXED_ENCODER)       += ac3enc_fixed.o ac3enc.o ac3tab.o ac3.o
 OBJS-$(CONFIG_AIC_DECODER)             += aic.o
-OBJS-$(CONFIG_ALAC_DECODER)            += alac.o alac_data.o
+OBJS-$(CONFIG_ALAC_DECODER)            += alac.o alac_data.o alacdsp.o
 OBJS-$(CONFIG_ALAC_ENCODER)            += alacenc.o alac_data.o
 OBJS-$(CONFIG_ALIAS_PIX_DECODER)       += aliaspixdec.o
 OBJS-$(CONFIG_ALIAS_PIX_ENCODER)       += aliaspixenc.o

libavcodec/alac.c

@@ -57,6 +57,7 @@
 #include "unary.h"
 #include "mathops.h"
 #include "alac_data.h"
+#include "alacdsp.h"
 
 #define ALAC_EXTRADATA_SIZE 36
 
@@ -81,6 +82,8 @@ typedef struct ALACContext {
 
     int direct_output;
     int extra_bit_bug;
+
+    ALACDSPContext dsp;
 } ALACContext;
 
 static inline unsigned int decode_scalar(GetBitContext *gb, int k, int bps)
@@ -230,35 +233,6 @@ static void lpc_prediction(int32_t *error_buffer, int32_t *buffer_out,
     }
 }
 
-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];
-}
-
 static int decode_element(AVCodecContext *avctx, AVFrame *frame, int ch_index,
                           int channels)
 {
@@ -389,19 +363,24 @@ static int decode_element(AVCodecContext *avctx, AVFrame *frame, int ch_index,
         decorr_left_weight = 0;
     }
 
-    if (alac->extra_bits && alac->extra_bit_bug) {
-        append_extra_bits(alac->output_samples_buffer, alac->extra_bits_buffer,
-                          alac->extra_bits, channels, alac->nb_samples);
-    }
+    if (channels == 2) {
+        if (alac->extra_bits && alac->extra_bit_bug) {
+            alac->dsp.append_extra_bits[1](alac->output_samples_buffer, alac->extra_bits_buffer,
+                                           alac->extra_bits, channels, alac->nb_samples);
+        }
 
-    if (channels == 2 && decorr_left_weight) {
-        decorrelate_stereo(alac->output_samples_buffer, alac->nb_samples,
-                           decorr_shift, decorr_left_weight);
-    }
+        if (decorr_left_weight) {
+            alac->dsp.decorrelate_stereo(alac->output_samples_buffer, alac->nb_samples,
+                                         decorr_shift, decorr_left_weight);
+        }
 
-    if (alac->extra_bits && !alac->extra_bit_bug) {
-        append_extra_bits(alac->output_samples_buffer, alac->extra_bits_buffer,
-                          alac->extra_bits, channels, alac->nb_samples);
+        if (alac->extra_bits && !alac->extra_bit_bug) {
+            alac->dsp.append_extra_bits[1](alac->output_samples_buffer, alac->extra_bits_buffer,
+                                           alac->extra_bits, channels, alac->nb_samples);
+        }
+    } else if (alac->extra_bits) {
+        alac->dsp.append_extra_bits[0](alac->output_samples_buffer, alac->extra_bits_buffer,
+                                       alac->extra_bits, channels, alac->nb_samples);
     }
 
     switch(alac->sample_size) {
@@ -606,6 +585,8 @@ static av_cold int alac_decode_init(AVCodecContext * avctx)
         return ret;
     }
 
+    ff_alacdsp_init(&alac->dsp);
+
     return 0;
 }
 

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;
+}

libavcodec/alacdsp.h

@@ -0,0 +1,33 @@
+/*
+ * 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
+ */
+
+#ifndef AVCODEC_ALACDSP_H
+#define AVCODEC_ALACDSP_H
+
+#include <stdint.h>
+
+typedef struct ALACDSPContext {
+    void (*decorrelate_stereo)(int32_t *buffer[2], int nb_samples,
+                               int decorr_shift, int decorr_left_weight);
+    void (*append_extra_bits[2])(int32_t *buffer[2], int32_t *extra_bits_buffer[2],
+                                 int extra_bits, int channels, int nb_samples);
+} ALACDSPContext;
+
+void ff_alacdsp_init(ALACDSPContext *c);
+
+#endif /* AVCODEC_ALACDSP_H */