Add and use dB/linear conversion functions.

[dcpomatic.git] / src / lib / audio_buffers.cc

diff --git a/src/lib/audio_buffers.cc b/src/lib/audio_buffers.cc
index aea581a07311ea151d1508cd1a26b60dcd448009..cfe762659ebdb6d91128557b35cccb3c08c56144 100644 (file)
--- a/src/lib/audio_buffers.cc
+++ b/src/lib/audio_buffers.cc
@@ -1,5 +1,5 @@
 /*
-    Copyright (C) 2012-2017 Carl Hetherington <cth@carlh.net>
+    Copyright (C) 2012-2020 Carl Hetherington <cth@carlh.net>
 
     This file is part of DCP-o-matic.
 
@@ -18,6 +18,7 @@
 
 */
 
+#include "util.h"
 #include "audio_buffers.h"
 #include "dcpomatic_assert.h"
 #include <cassert>
@@ -52,6 +53,12 @@ AudioBuffers::AudioBuffers (boost::shared_ptr<const AudioBuffers> other)
        copy_from (other.get(), other->_frames, 0, 0);
 }
 
+AudioBuffers::AudioBuffers (boost::shared_ptr<const AudioBuffers> other, int32_t frames_to_copy, int32_t read_offset)
+{
+       allocate (other->_channels, frames_to_copy);
+       copy_from (other.get(), frames_to_copy, read_offset, 0);
+}
+
 AudioBuffers &
 AudioBuffers::operator= (AudioBuffers const & other)
 {
@@ -125,12 +132,9 @@ AudioBuffers::set_frames (int32_t f)
 {
        DCPOMATIC_ASSERT (f <= _allocated_frames);
 
-       for (int c = 0; c < _channels; ++c) {
-               for (int i = f; i < _frames; ++i) {
-                       _data[c][i] = 0;
-               }
+       if (f < _frames) {
+               make_silent (f, _frames - f);
        }
-
        _frames = f;
 }
 
@@ -151,9 +155,10 @@ AudioBuffers::make_silent (int c)
 {
        DCPOMATIC_ASSERT (c >= 0 && c < _channels);
 
-       for (int i = 0; i < _frames; ++i) {
-               _data[c][i] = 0;
-       }
+       /* This isn't really allowed, as all-bits-0 is not guaranteed to mean a 0 float,
+          but it seems that we can get away with it.
+       */
+       memset (_data[c], 0, _frames * sizeof(float));
 }
 
 /** Make some frames.
@@ -166,9 +171,10 @@ AudioBuffers::make_silent (int32_t from, int32_t frames)
        DCPOMATIC_ASSERT ((from + frames) <= _allocated_frames);
 
        for (int c = 0; c < _channels; ++c) {
-               for (int i = from; i < (from + frames); ++i) {
-                       _data[c][i] = 0;
-               }
+               /* This isn't really allowed, as all-bits-0 is not guaranteed to mean a 0 float,
+                  but it seems that we can get away with it.
+               */
+               memset (_data[c] + from, 0, frames * sizeof(float));
        }
 }
 
@@ -224,6 +230,9 @@ AudioBuffers::move (int32_t frames, int32_t from, int32_t to)
 }
 
 /** Add data from from `from', `from_channel' to our channel `to_channel'.
+ *  @param from Buffers to copy data from.
+ *  @param from_channel Channel index to read in \p from.
+ *  @param to_channel Channel index to accumulate into.
  *  @param gain Linear gain to apply to the data before it is added.
  */
 void
@@ -267,12 +276,13 @@ AudioBuffers::ensure_size (int32_t frames)
                if (!_data[i]) {
                        throw bad_alloc ();
                }
-               for (int j = _allocated_frames; j < frames; ++j) {
-                       _data[i][j] = 0;
-               }
        }
 
+       int32_t const old_allocated = _allocated_frames;
        _allocated_frames = frames;
+       if (old_allocated < _allocated_frames) {
+               make_silent (old_allocated, _allocated_frames - old_allocated);
+       }
 }
 
 /** Mix some other buffers with these ones.  The AudioBuffers must have the same number of channels.
@@ -300,7 +310,7 @@ AudioBuffers::accumulate_frames (AudioBuffers const * from, int32_t frames, int3
 void
 AudioBuffers::apply_gain (float dB)
 {
-       float const linear = pow (10, dB / 20);
+       float const linear = db_to_linear (dB);
 
        for (int i = 0; i < _channels; ++i) {
                for (int j = 0; j < _frames; ++j) {