Call resize_output_buffers() from set_channels(), fixing crash in Cha…

…nnelPanner; update SIGNALFLOW_NODE_INITIAL_OUTPUT_CHANNELS

source/include/signalflow/core/constants.h

@@ -44,11 +44,10 @@ typedef RingBuffer<sample> SampleRingBuffer;
 #define SIGNALFLOW_MAX_CHANNELS 64
 
 /*------------------------------------------------------------------------
- * Initial number of output buffers to allocate per node
- * TODO: Turn this into a run-time config parameter, and set default to 2
- *       Otherwise memory usage is very high by default
+ * Initial number of output channels to allocate per node.
+ * More channels are allocated as needed at runtime.
  *-----------------------------------------------------------------------*/
-#define SIGNALFLOW_NODE_INITIAL_OUTPUT_BUFFERS 64
+#define SIGNALFLOW_NODE_INITIAL_OUTPUT_CHANNELS 2
 
 /*------------------------------------------------------------------------
  * Max supported number of FFT bins.

source/include/signalflow/node/node.h

@@ -156,7 +156,7 @@ class Node
 
     /**------------------------------------------------------------------------
      * Get the number of output channels allocated in memory.
-     * Initially, a node allocates SIGNALFLOW_NODE_INITIAL_OUTPUT_BUFFERS
+     * Initially, a node allocates SIGNALFLOW_NODE_INITIAL_OUTPUT_CHANNELS
      * channels. During the course of graph construction, if more channels
      * than this are required, it re-allocates the memory.
      *

source/src/node/node.cpp

@@ -52,7 +52,7 @@ Node::Node()
         this->output_buffer_length = SIGNALFLOW_NODE_BUFFER_SIZE;
     }
 
-    this->resize_output_buffers(SIGNALFLOW_NODE_INITIAL_OUTPUT_BUFFERS);
+    this->resize_output_buffers(SIGNALFLOW_NODE_INITIAL_OUTPUT_CHANNELS);
 
     /*------------------------------------------------------------------------
      * last_num_frames caches the number of frames generated in the last
@@ -126,6 +126,18 @@ void Node::set_channels(int num_input_channels, int num_output_channels)
     this->num_input_channels = num_input_channels;
     this->num_output_channels = num_output_channels;
     this->matches_input_channels = false;
+
+    /*--------------------------------------------------------------------------------
+     * Added 2024-08-05 to address crash in which a multichannel ChannelPanner
+     * connected directly to AudioOut does not correctly allocate its buffers, as
+     * resize_output_buffers() currently only gets called in the
+     * `this->matches_input_channels` block in `update_channels()` (below).
+     *
+     * This means that resize_output_buffers() is called on every call to
+     * set_channels(). However, resize_output_buffers() is a no-op if no resize
+     * operation is needed, so this should have minimal impact on CPU.
+     *--------------------------------------------------------------------------------*/
+    this->resize_output_buffers(num_output_channels);
 }
 
 void Node::update_channels()
@@ -245,7 +257,7 @@ void Node::resize_output_buffers(int output_buffer_count)
     else
     {
         /*------------------------------------------------------------------------
-         * If not enough channels/frames  are allocated, dealloc the current
+         * If not enough channels/frames are allocated, dealloc the current
          * allocations and resize
          *-----------------------------------------------------------------------*/
         this->free();

source/src/python/constants.cpp

@@ -17,7 +17,7 @@ void init_python_constants(py::module &m)
         .export_values();
 
     m.attr("SIGNALFLOW_MAX_CHANNELS") = SIGNALFLOW_MAX_CHANNELS;
-    m.attr("SIGNALFLOW_NODE_INITIAL_OUTPUT_BUFFERS") = SIGNALFLOW_NODE_INITIAL_OUTPUT_BUFFERS;
+    m.attr("SIGNALFLOW_NODE_INITIAL_OUTPUT_CHANNELS") = SIGNALFLOW_NODE_INITIAL_OUTPUT_CHANNELS;
     m.attr("SIGNALFLOW_DEFAULT_FFT_SIZE") = SIGNALFLOW_DEFAULT_FFT_SIZE;
     m.attr("SIGNALFLOW_MAX_FFT_SIZE") = SIGNALFLOW_MAX_FFT_SIZE;
     m.attr("SIGNALFLOW_DEFAULT_FFT_HOP_SIZE") = SIGNALFLOW_DEFAULT_FFT_HOP_SIZE;