X-Git-Url: https://main.carlh.net/gitweb/?p=dcpomatic.git;a=blobdiff_plain;f=src%2Flib%2Faudio_buffers.cc;h=cceb1267213450ed8fc6cc3c4dbc3d8c913c032c;hp=f01f8baaff3c9b1ac834805875015763957a38b8;hb=915cecb8f2b4bb251e72bbcd6c41144b73f8bfd7;hpb=58dce923b9d438a27ce1cd7e3125370f74d46e3a

diff --git a/src/lib/audio_buffers.cc b/src/lib/audio_buffers.cc
index f01f8baaf..cceb12672 100644
--- a/src/lib/audio_buffers.cc
+++ b/src/lib/audio_buffers.cc
@@ -1,5 +1,5 @@
 /*
-    Copyright (C) 2012-2013 Carl Hetherington <cth@carlh.net>
+    Copyright (C) 2012-2017 Carl Hetherington <cth@carlh.net>
 
     This file is part of DCP-o-matic.
 
@@ -52,6 +52,12 @@ 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)
 {
@@ -125,16 +131,13 @@ 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;
 }
 
-/** Make all samples on all channels silent */
+/** Make all frames silent */
 void
 AudioBuffers::make_silent ()
 {
@@ -151,20 +154,26 @@ 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.
+ *  @param from Start frame.
+ *  @param frames Number of frames to silence.
+ */
 void
 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));
 	}
 }
 
@@ -198,7 +207,6 @@ AudioBuffers::copy_from (AudioBuffers const * from, int32_t frames_to_copy, int3
  *  @param to Offset to move to.
  *  @param frames Number of frames to move.
  */
-
 void
 AudioBuffers::move (int32_t frames, int32_t from, int32_t to)
 {
@@ -221,6 +229,9 @@ 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
@@ -264,14 +275,21 @@ 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.
+ *  @param from Audio buffers to get data from.
+ *  @param frames Number of frames to mix.
+ *  @param read_offset Offset within `from' to read from.
+ *  @param write_offset Offset within this to mix into.
+ */
 void
 AudioBuffers::accumulate_frames (AudioBuffers const * from, int32_t frames, int32_t read_offset, int32_t write_offset)
 {
@@ -311,6 +329,11 @@ AudioBuffers::channel (int c) const
 	return o;
 }
 
+/** Copy all the samples from a channel on another AudioBuffers to a channel on this one.
+ *  @param from AudioBuffers to copy from.
+ *  @param from_channel Channel index in `from' to copy from.
+ *  @param to_channel Channel index in this to copy into, overwriting what's already there.
+ */
 void
 AudioBuffers::copy_channel_from (AudioBuffers const * from, int from_channel, int to_channel)
 {
@@ -318,6 +341,7 @@ AudioBuffers::copy_channel_from (AudioBuffers const * from, int from_channel, in
 	memcpy (data(to_channel), from->data(from_channel), frames() * sizeof (float));
 }
 
+/** Make a copy of these AudioBuffers */
 shared_ptr<AudioBuffers>
 AudioBuffers::clone () const
 {
@@ -326,14 +350,17 @@ AudioBuffers::clone () const
 	return b;
 }
 
+/** Extend these buffers with the data from another.  The AudioBuffers must have the same number of channels. */
 void
 AudioBuffers::append (shared_ptr<const AudioBuffers> other)
 {
+	DCPOMATIC_ASSERT (channels() == other->channels());
 	ensure_size (_frames + other->frames());
 	copy_from (other.get(), other->frames(), 0, _frames);
 	_frames += other->frames();
 }
 
+/** Remove some frames from the start of these AudioBuffers */
 void
 AudioBuffers::trim_start (int32_t frames)
 {