lavr: add option for dithering during sample format conversion to s16

1 files changed, 88 insertions, 0 deletions

diff --git a/libavresample/dither.h b/libavresample/dither.h
new file mode 100644
index 0000000000..8b30dd23e0
--- /dev/null
+++ b/libavresample/dither.h
@@ -0,0 +1,88 @@
+/*
+ * Copyright (c) 2012 Justin Ruggles <justin.ruggles@gmail.com>
+ *
+ * This file is part of Libav.
+ *
+ * Libav 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.
+ *
+ * Libav 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 Libav; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef AVRESAMPLE_DITHER_H
+#define AVRESAMPLE_DITHER_H
+
+#include "avresample.h"
+#include "audio_data.h"
+
+typedef struct DitherContext DitherContext;
+
+typedef struct DitherDSPContext {
+    /**
+     * Convert samples from flt to s16 with added dither noise.
+     *
+     * @param dst    destination float array, range -0.5 to 0.5
+     * @param src    source int array, range INT_MIN to INT_MAX.
+     * @param dither float dither noise array
+     * @param len    number of samples
+     */
+    void (*quantize)(int16_t *dst, const float *src, float *dither, int len);
+
+    int ptr_align;      ///< src and dst constraits for quantize()
+    int samples_align;  ///< len constraits for quantize()
+
+    /**
+     * Convert dither noise from int to float with triangular distribution.
+     *
+     * @param dst  destination float array, range -0.5 to 0.5
+     *             constraints: 32-byte aligned
+     * @param src0 source int array, range INT_MIN to INT_MAX.
+     *             the array size is len * 2
+     *             constraints: 32-byte aligned
+     * @param len  number of output noise samples
+     *             constraints: multiple of 16
+     */
+    void (*dither_int_to_float)(float *dst, int *src0, int len);
+} DitherDSPContext;
+
+/**
+ * Allocate and initialize a DitherContext.
+ *
+ * The parameters in the AVAudioResampleContext are used to initialize the
+ * DitherContext.
+ *
+ * @param avr  AVAudioResampleContext
+ * @return     newly-allocated DitherContext
+ */
+DitherContext *ff_dither_alloc(AVAudioResampleContext *avr,
+                               enum AVSampleFormat out_fmt,
+                               enum AVSampleFormat in_fmt,
+                               int channels, int sample_rate);
+
+/**
+ * Free a DitherContext.
+ *
+ * @param c  DitherContext
+ */
+void ff_dither_free(DitherContext **c);
+
+/**
+ * Convert audio sample format with dithering.
+ *
+ * @param c    DitherContext
+ * @param dst  destination audio data
+ * @param src  source audio data
+ * @return     0 if ok, negative AVERROR code on failure
+ */
+int ff_convert_dither(DitherContext *c, AudioData *dst, AudioData *src);
+
+#endif /* AVRESAMPLE_DITHER_H */