Fix un/bypassing Aux-send panners

This fixes issues with send-panner bypass whenever the
target bus input-count is different from the send's channel count.

--

Previously, when the aux-send panner was bypassed, data was
copied using BufferSet::read_from().
This sets the channel count of the output buffer set (here: mixbufs)
to match the input (here: bufs).

e.g. mono to stereo, "1 in -> 2 out" out was changed to "1 in -> 1 out".

Un-bypassing the panner later does not reconfigure the I/O.
Mixbufs remained mono, and PannerShell::run() "1 in -> 1 out"
does nothing. The panner was effectively not functional.

1 files changed, 15 insertions, 1 deletions

diff --git a/libs/ardour/internal_send.cc b/libs/ardour/internal_send.cc
index 2dd90d010f..6bc67a0059 100644
--- a/libs/ardour/internal_send.cc
+++ b/libs/ardour/internal_send.cc
@@ -226,7 +226,21 @@ InternalSend::run (BufferSet& bufs, samplepos_t start_sample, samplepos_t end_sa
 	} else {
 		/* no panner or panner is bypassed */
 		assert (mixbufs.available () >= bufs.count ());
-		mixbufs.read_from (bufs, nframes);
+		/* BufferSet::read_from() changes the channel-conut,
+		 * so we manually copy bufs -> mixbufs
+		 */
+		for (DataType::iterator t = DataType::begin(); t != DataType::end(); ++t) {
+			/* iterate over outputs */
+			BufferSet::iterator i = bufs.begin (*t);
+			for (BufferSet::iterator o = mixbufs.begin (*t); o != mixbufs.end (*t); ++o) {
+				if (i == bufs.end (*t)) {
+					o->silence (nframes, 0);
+				} else {
+					o->read_from (*i, nframes);
+					++i;
+				}
+			}
+		}
 	}
 
 	/* main gain control: * mute & bypass/enable */