Merge master.

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

diff --git a/src/lib/audio_buffers.cc b/src/lib/audio_buffers.cc
index e80142b8e518ad2efe66f5f1c1ee4b90f6dcafa6..4ada94db867b59d4fe7425fc6b048e0a251ae721 100644 (file)
--- a/src/lib/audio_buffers.cc
+++ b/src/lib/audio_buffers.cc
@@ -73,6 +73,9 @@ AudioBuffers::~AudioBuffers ()
 void
 AudioBuffers::allocate (int channels, int frames)
 {
+       assert (frames >= 0);
+       assert (channels >= 0);
+
        _channels = channels;
        _frames = frames;
        _allocated_frames = frames;
@@ -172,6 +175,11 @@ AudioBuffers::make_silent (int from, int frames)
 void
 AudioBuffers::copy_from (AudioBuffers const * from, int frames_to_copy, int read_offset, int write_offset)
 {
+       if (frames_to_copy == 0) {
+               /* Prevent the asserts from firing if there is nothing to do */
+               return;
+       }
+       
        assert (from->channels() == channels());
 
        assert (from);
@@ -210,9 +218,11 @@ AudioBuffers::move (int from, int to, int frames)
        }
 }
 
-/** Add data from from `from', `from_channel' to our channel `to_channel' */
+/** Add data from from `from', `from_channel' to our channel `to_channel'.
+ *  @param gain Linear gain to apply to the data before it is added.
+ */
 void
-AudioBuffers::accumulate_channel (AudioBuffers const * from, int from_channel, int to_channel)
+AudioBuffers::accumulate_channel (AudioBuffers const * from, int from_channel, int to_channel, float gain)
 {
        int const N = frames ();
        assert (from->frames() == N);
@@ -222,7 +232,7 @@ AudioBuffers::accumulate_channel (AudioBuffers const * from, int from_channel, i
        float* d = _data[to_channel];
 
        for (int i = 0; i < N; ++i) {
-               *d++ += *s++;
+               *d++ += (*s++) * gain;
        }
 }
 
@@ -253,6 +263,8 @@ void
 AudioBuffers::accumulate_frames (AudioBuffers const * from, int read_offset, int write_offset, int frames)
 {
        assert (_channels == from->channels ());
+       assert (read_offset >= 0);
+       assert (write_offset >= 0);
 
        for (int i = 0; i < _channels; ++i) {
                for (int j = 0; j < frames; ++j) {